HK1203708B

HK1203708B - Dual interpretation of a length field of a signal unit

Info

Publication number: HK1203708B
Application number: HK15103533.1A
Authority: HK
Inventors: S‧韦玛尼; M‧H‧塔格哈弗纳斯拉巴蒂; S‧莫林; S‧P‧阿伯拉翰
Original assignee: 高通股份有限公司
Priority date: 2011-09-06
Filing date: 2014-10-29
Publication date: 2018-09-21

Description

Dual interpretation of length fields of signal units

The patent application of the invention is a divisional application of an invention patent application with the international application number of PCT/US2012/053966, the international application date of 2012, 9 and 6, and the application number of 201280054474.3, namely 'double interpretation of length field of signal unit' in China.

Cross Reference to Related Applications

This application is a divisional application of U.S. patent application No.13/604,030 filed on 5/9/2012 and claiming priority, the latter claiming priority from the following commonly owned U.S. provisional patent applications, the contents of which are expressly incorporated herein by reference in their entirety: no.61/531,584 submitted on 6/9/2011, No.61/562,063 submitted on 21/11/2011, No.61/564,177 submitted on 28/2011, No.61/566,961 submitted on 5/2011, No.61/580,616 submitted on 27/2011, No.61/585,479 submitted on 11/2012, No.61/585,573 submitted on 11/2012, No.61/670,092 submitted on 10/2012, and No.61/684,248 submitted on 17/2012.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to wireless communications, and more particularly to Signal (SIG) units communicated via a wireless network.

Background

In many telecommunication systems, a communication network is used to exchange messages between several spatially separated interacting devices. Networks may be classified according to geographic scope, which may be, for example, a broad area, a city area, a local area, or a personal area. Such networks may be designated as Wide Area Networks (WANs), Metropolitan Area Networks (MANs), Local Area Networks (LANs), or Personal Area Networks (PANs), respectively. The network also differs according to the switching/routing technology used to interconnect the various network nodes and devices (e.g., circuit-switched-packet-switched), the type of physical medium used for transmission (e.g., wired-wireless), and the communication protocol suite being used (e.g., internet protocol suite, SONET (synchronous optical networking), ethernet, etc.).

Wireless networks tend to be preferred when network elements are mobile and thus have dynamic connectivity requirements, or where the network architecture is formed in an ad hoc (ad hoc) topology rather than a fixed topology. Wireless networks employ intangible physical media in an unguided propagation mode using electromagnetic waves in the radio, microwave, infrared, optical, etc. frequency bands. Wireless networks advantageously facilitate user mobility and rapid field deployment when compared to fixed wired networks.

Devices in a wireless network may transmit/receive information between each other. This information may include packets, which may be referred to in some aspects as data units. The packet may include overhead information (e.g., header information, packet properties, etc.) that helps route the packet through the network, identify data in the packet, process the packet, etc., as well as data (e.g., user data, multimedia content, etc.) that may be carried in the packet's payload.

SUMMARY

The systems, methods, and devices of the present disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled "detailed description" one will understand how the features of this disclosure provide advantages that include reducing overhead in transmitting payloads in data packets.

In a particular embodiment, a method includes receiving, at a first wireless device, a Signal (SIG) unit including a length field and an aggregation field from a second wireless device. The method also includes interpreting the length field as a number of symbols in response to determining that the aggregation field has a first value and interpreting the length field as a number of bytes in response to determining that the aggregation field has a second value.

In another particular embodiment, a method includes generating, at a second wireless device, a SIG unit to transmit to a first wireless device, wherein the SIG unit includes a length field and an aggregation field. The method also includes setting the aggregation field to a first value and the length field to a number of symbols in response to determining to use the aggregated transmission to the first wireless device. The method further includes setting the aggregation field to a second value and setting the length field to a number of bytes in response to determining not to use aggregated transmissions to the first wireless device.

In another particular embodiment, a method includes receiving, at a wireless device, a frame via a sub-1 gigahertz (GHz) wireless network. The frame includes a SIG unit having a length field and an aggregation field. The method also includes, in response to determining that the frame is associated with a1 megahertz (MHz) bandwidth mode, interpreting a length field as a number of bytes or a number of symbols based on a value of an aggregation field. The method further includes determining whether the frame includes a short format preamble or a long format preamble in response to determining that the frame is not associated with the 1MHz bandwidth mode. The method includes interpreting a length field as a number of bytes or a number of symbols based on a value of an aggregation field in response to determining that the frame includes a short format preamble. The method also includes determining whether the frame is a Single User (SU) frame or a multi-user (MU) frame in response to determining that the frame includes the long format preamble. The method further includes, in response to determining that the frame is a SU frame, interpreting the length field as a number of bytes or a number of symbols based on a value of the aggregation field. The method includes interpreting a length field as a number of symbols in response to determining that the frame is an MU frame.

In another particular embodiment, an apparatus includes a receiver configured to receive a SIG unit having a length field and an aggregation field. The apparatus also includes a processor configured to interpret the length field as a number of symbols in response to determining that the aggregation field has a first value and interpret the length field as a number of bytes in response to determining that the aggregation field has a second value.

In another particular embodiment, an apparatus includes a processor configured to generate a SIG unit having a length field and an aggregation field. The processor is also configured to set the aggregation field to a first value and set the length field to a number of symbols in response to determining to use aggregated transmission. The processor is further configured to set the aggregation field to a second value and set the length field to a number of bytes in response to determining not to use aggregated transmission. The apparatus also includes a transmitter configured to transmit the SIG unit.

Brief description of the drawings

Fig. 1 illustrates an example of a wireless communication system in which aspects of the present disclosure may be employed.

Fig. 2 illustrates a functional block diagram of an exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Fig. 3 illustrates a functional block diagram of exemplary components that may be used in the wireless device of fig. 2 to communicate wireless communications.

Fig. 4 illustrates a functional block diagram of exemplary components that may be used in the wireless device of fig. 2 to receive wireless communications.

Fig. 5 illustrates an example of a physical layer data unit.

FIG. 6 illustrates a flow chart of an aspect of an exemplary method for generating and transmitting data units.

Fig. 7 illustrates a flow diagram of another aspect of an exemplary method for receiving and processing data units including signal units.

FIG. 8 illustrates a flow chart of another aspect of an exemplary method for generating and transmitting data units.

Fig. 9 illustrates a flow diagram of another aspect of an exemplary method for receiving and processing data units including signal units.

Fig. 10 is a functional block diagram of another exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Fig. 11 is a functional block diagram of yet another exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Detailed Description

Various aspects of the present systems, devices, and methods are described more fully below with reference to the accompanying drawings. The teachings of the present disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the present disclosure is intended to cover any aspect of the novel systems, apparatuses, and methods disclosed herein, whether implemented independently or in combination with any other aspect of the present disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the present disclosure is intended to cover such an apparatus or method practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the present disclosure set forth herein. It should be understood that any aspect disclosed herein may be implemented by one or more elements of a claim.

Although specific aspects are described herein, numerous variations and permutations of these aspects are within the scope of the present disclosure. Although some benefits and advantages of particular aspects are mentioned, the scope of the present disclosure is not intended to be limited to the particular benefits, uses, or objectives. Rather, aspects of the disclosure are intended to apply broadly to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the figures and the following description. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.

Wireless network technologies may include various types of Wireless Local Area Networks (WLANs). WLANs may be used to interconnect nearby devices together using widely used networking protocols. The various aspects described herein may be applied to any communication standard, such as WiFi, or more generally any member of the IEEE 802.11 family of wireless protocols. For example, various aspects described herein may be used as part of an IEEE 802.11ah protocol using the sub-1 GHz band.

In some aspects, wireless signals in the sub-gigahertz band may be transmitted according to the 802.11ah protocol using Orthogonal Frequency Division Multiplexing (OFDM), Direct Sequence Spread Spectrum (DSSS) communications, a combination of OFDM and DSSS communications, or other schemes. Implementations of the 802.11ah protocol may be used for sensor, metering, and smart grid networks. Advantageously, aspects of certain devices implementing the 802.11ah protocol may consume less power than devices implementing other wireless protocols and/or may be used to transmit wireless signals across relatively long distances (e.g., about 1 kilometer or more).

In some implementations, a WLAN includes various devices that are components of an access wireless network. For example, there may be two types of devices: an access point ("AP") and a client (also referred to as a station, or "STA"). Generally, the AP serves as a hub or base station for the WLAN, while the STA serves as a user of the WLAN. For example, the STA may be a laptop computer, a Personal Digital Assistant (PDA), a mobile phone, and the like. In one example, the STAs connect to the AP via a wireless link that conforms to WiFi (e.g., IEEE 802.11 protocol such as 802.11ah) to obtain general connectivity to the internet or to other wide area networks. In some implementations, the STA may also be used as an AP.

An access point ("AP") may also include, be implemented as, or be referred to as a node B, a radio network controller ("RNC"), an evolved node B, a base station controller ("BSC"), a base transceiver station ("BTS"), a base station ("BS"), a transceiver function ("TF"), a radio router, a radio transceiver, or some other terminology.

A station ("STA") may also include, be implemented as, or be referred to as an access terminal ("AT"), a subscriber station, a subscriber unit, a mobile station, a remote terminal, a user agent, a user device, user equipment, or some other terminology. In some implementations, an access terminal may comprise a cellular telephone, a cordless telephone, a session initiation protocol ("SIP") phone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device having wireless connection capability, or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or smart phone), a computer (e.g., a laptop), a portable communication device, a handset, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device, or a satellite radio), a gaming device or system, a global positioning system device, or any other suitable device configured to communicate via a wireless medium.

As discussed above, certain devices described herein may implement, for example, the 802.11ah standard. Such devices (whether functioning as STAs or APs or other devices) may be used for smart metering or in smart grid networks. Such devices may provide sensor applications or be used in home automation. These devices may alternatively or additionally be used in a healthcare environment, for example for personal healthcare. These devices may also be used for supervision to enable extended range internet connectivity (e.g., for use with hotspots), or to enable machine-to-machine communication.

Fig. 1 illustrates an example of a wireless communication system 100 in which aspects of the present disclosure may be employed. The wireless communication system 100 may operate in accordance with a wireless standard, such as the 802.11ah standard. The wireless communication system 100 may include an AP104 in communication with STAs 106.

Various procedures and methods may be used for transmissions between the AP104 and the STA106 in the wireless communication system 100. For example, signals may be transmitted and received between the AP104 and the STAs 106 according to OFDM/OFDMA techniques. If this is the case, the wireless communication system 100 may be referred to as an OFDM/OFDMA system. Alternatively, signals may be transmitted and received between the AP104 and the STA106 according to CDMA techniques. If this is the case, the wireless communication system 100 may be referred to as a CDMA system.

The communication link that facilitates transmission from AP104 to one or more STAs 106 may be referred to as Downlink (DL)108, while the communication link that facilitates transmission from one or more STAs 106 to AP104 may be referred to as Uplink (UL) 110. Alternatively, downlink 108 may be referred to as the forward link or forward channel, and uplink 110 may be referred to as the reverse link or reverse channel.

The AP104 may act as a base station and provide wireless communication coverage in a Basic Service Area (BSA) 102. The AP104, along with STAs 106 associated with the AP104 and communicating using the AP104, may be referred to as a Basic Service Set (BSS). It should be noted that the wireless communication system 100 may not have a central AP104, but may function as a peer-to-peer network between STAs 106. Accordingly, the functions of the AP104 described herein may alternatively be performed by one or more STAs 106.

As further described herein, a packet (e.g., the illustrative packet 140) (alternatively referred to herein as a data unit or frame) transmitted between the AP104 and the STA106 may include a Signal (SIG) unit (alternatively referred to herein as a SIG field). For example, the SIG unit may be included in a physical layer (PHY) preamble of the packet. The SIG unit may include control information that may be used to decode the packet or its data payload. In particular embodiments, the length field of the SIG unit may indicate the length of the packet or its data payload. The length field may have a fixed size, such as 9 bits. However, the unit of measurement represented by the length field may vary. For example, the length field may represent the number of bytes when data aggregation is not in use (e.g., indicated by the aggregation field of the SIG unit having a first value). Because 2⁹The SIG unit may be able to indicate a packet size from 0 to 511 bytes, 512. When data aggregation is in use (e.g., indicated by the aggregation field of the SIG unit having the second value), the length field may represent the number of symbols and may therefore be able to represent a size greater than 511 bytes.

As further described herein, in particular embodiments, one or more fields of the SIG unit may support the use of "exception" values to indicate alternate data formats, payload lengths, and types. For example, a particular value of a particular field of a SIG unit that is part of a packet having a zero-length payload or that is part of a particular type of packet may indicate that another field of the SIG unit is to be interpreted unconventionally. For example, a particular value of a Modulation and Coding Scheme (MCS) field may indicate that the SIG unit is part of an Acknowledgement (ACK) packet with a zero-length payload (e.g., an ACK packet that is entirely represented by PHY data).

Fig. 2 illustrates various components that may be employed in a wireless device 202 that may be employed within the wireless communication system 100. Wireless device 202 is an example of a device that may be configured to implement the various methods described herein. For example, the wireless device 202 may include the AP104 or one of the STAs 106.

The wireless device 202 may include a processor 204 that controls the operation of the wireless device 202. The processor 204 may also be referred to as a Central Processing Unit (CPU). Memory 206, which may include both Read Only Memory (ROM) and Random Access Memory (RAM), provides instructions and data to the processor 204. A portion of the memory 206 may also include non-volatile random access memory (NVRAM). The processor 204 typically performs logical and arithmetic operations based on program instructions stored within the memory 206. The instructions in the memory 206 may be executable to implement the methods described herein.

The processor 204 may include or be a component of a processing system implemented with one or more processors. The one or more processors may be implemented with any combination of general purpose microprocessors, microcontrollers, Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGAs), Programmable Logic Devices (PLDs), controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable entity capable of performing a calculus or other manipulation of information.

The processing system may also include a machine-readable medium for storing the software. Software should be construed broadly to mean any type of instructions, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The instructions may include code (e.g., in source code format, binary code format, executable code format, or any other suitable code format). The instructions, when executed by the one or more processors, cause the processing system to perform the various functions described herein.

The wireless device 202 may also include a housing 208, and the housing 208 may contain a transmitter 210 and a receiver 212 to allow transmission and reception of data between the wireless device 202 and a remote location. The transmitter 210 and receiver 212 may be combined into a transceiver 214. An antenna 216 may be attached to the housing 208 and electrically coupled to the transceiver 214. The wireless device 202 may also include (not shown) multiple transmitters, multiple receivers, multiple transceivers, and/or multiple antennas. As further described herein, the transmitter 210 may be an apparatus for transmitting the SIG unit and the receiver 212 may be an apparatus for receiving the SIG unit.

The wireless device 202 may also include a signal detector 218 that may be used in an effort to detect and quantify the level of signals received by the transceiver 214. The signal detector 218 may detect characteristics of the signal such as total energy, energy per subcarrier per symbol, power spectral density. The wireless device 202 may also include a Digital Signal Processor (DSP)220 for use in processing signals. DSP220 may be configured to generate data units for transmission. In some aspects, the data unit may comprise a physical layer data unit (PPDU). In some aspects, the PPDU is referred to as a packet. As further described herein, one or more of the processor 204, the signal detector 218, and the DSP220 may be means for generating the SIG unit, means for interpreting a length field of the SIG unit, means for determining whether a field of the SIG unit has a payload indicating zero length, and/or means for decoding the SIG unit based on the determination.

In some aspects, the wireless device 202 may further include a user interface 222. The user interface 222 may include a keypad, a microphone, a speaker, and/or a display. User interface 222 may include any element or component that conveys information to a user of wireless device 202 and/or receives input from the user.

The various components of the wireless device 202 may be coupled together by a bus system 226. The bus system 226 may include, for example, a data bus, as well as a power bus, a control signal bus, and a status signal bus in addition to the data bus. Those skilled in the art will appreciate that the components of the wireless device 202 may be coupled together or use some other mechanism to accept or provide input to each other.

Although several separate components are illustrated in fig. 2, those skilled in the art will recognize that one or more of these components may be combined or implemented collectively. For example, the processor 204 may be used to implement not only the functionality described above with respect to the processor 204, but also the functionality described above with respect to the signal detector 218 and/or the DSP 220. In addition, each of the components illustrated in fig. 2 may be implemented using a plurality of separate elements.

As discussed above, the wireless device 202 may include an AP104 or STA106 and may be used to transmit and/or receive communications. For example, the wireless device 202 may communicate a packet 240 including a SIG unit. As further described herein, the packet 240 may include a SIG unit having a length field that may be interpreted in a variety of ways based on the value of another field in the SIG unit. For example, the length field may be interpreted as a number of bytes or a number of symbols based on the value of the aggregation field. Alternatively or additionally, the presence of a particular value in a particular field of the SIG unit may indicate that the packet 240 has a zero-length payload (e.g., is a short ACK represented entirely by PHY data).

Fig. 3 illustrates various components that may be used in a wireless device 202 to communicate wireless communications. The components illustrated in fig. 3 may be used, for example, to transmit OFDM communications. In some aspects, the components illustrated in fig. 3 are used to transmit data units (e.g., packets 240 of fig. 2) with signal units in various communication modes, as will be discussed in more detail below. For ease of reference, the wireless device 202 configured with the components illustrated in fig. 3 is referred to hereinafter as wireless device 202 a.

Wireless device 202a may include a modulator 302, which modulator 302 is configured to modulate bits for transmission. For example, the modulator 302 may determine a plurality of symbols from bits received from the processor 204 or the user interface 222, e.g., by mapping bits to the plurality of symbols according to a constellation. These bits may correspond to user data or control information. In some aspects, the bits are received in a codeword. In one aspect, modulator 302 comprises a QAM (Quadrature amplitude modulation) modulator, such as a 16-QAM modulator or a 64-QAM modulator. In other aspects, the modulator 302 comprises a Binary Phase Shift Keying (BPSK) modulator or a Quadrature Phase Shift Keying (QPSK) modulator.

Wireless device 202a may further include a transform module 304, the transform module 304 configured to convert symbols or otherwise modulated bits from modulator 302 to the time domain. In fig. 3, the transform module 304 is illustrated as being implemented by an Inverse Fast Fourier Transform (IFFT) module. In some implementations, there may be multiple transform modules (not shown) that transform data units of different sizes.

In fig. 3, the modulator 302 and the transform module 304 are illustrated as being implemented in the DSP 220. However, in some aspects, one or both of the modulator 302 and the transformation module 304 are implemented in the processor 204 or in another element of the wireless device 202.

As discussed above, the DSP220 may be configured to generate data units for transmission. In some aspects, the modulator 302 and the transform module 304 may be configured to generate a data unit comprising a plurality of fields including control information and a plurality of data symbols. The fields that include control information may include, for example, one or more training fields and one or more Signal (SIG) fields. Each of these training fields may comprise a known sequence of bits or symbols. Each of these SIG fields may include information about the data unit, such as a description of the length or data rate of the data unit.

Returning to the description of fig. 3, the wireless device 202a may further include a digital-to-analog converter (DAC, denoted "D/a" in fig. 3) 306, the digital-to-analog converter 306 configured to convert the output of the transformation module into an analog signal. For example, the time domain output of the transform module 304 may be converted to a baseband OFDM signal by a digital-to-analog converter 306. The digital-to-analog converter 306 may be implemented in the processor 204 or in another element of the wireless device 202. In some aspects, the digital to analog converter 306 is implemented in the transceiver 214 or in the data transmit processor.

The analog signal may be wirelessly transmitted by the transmitter 210. The analog signal may be further processed, e.g., filtered or upconverted to an intermediate or carrier frequency, before being transmitted by the transmitter 210. In the aspect illustrated in fig. 3, the transmitter 210 includes a transmit amplifier 308. The analog signal may be amplified by a transmit amplifier 308 before being transmitted. In some aspects, the amplifier 308 comprises a Low Noise Amplifier (LNA).

The transmitter 210 is configured to transmit one or more packets or data units in a wireless signal based on the analog signal. These data units may be generated using the processor 204 and/or the DSP220, for example, using the modulator 302 and transform module 304 discussed above. Data units that may be generated and transmitted as discussed above are described in more detail with respect to fig. 5-11.

Fig. 4 illustrates various components that may be used in a wireless device 202 for receiving wireless communications. The components illustrated in fig. 4 may be used, for example, to receive OFDM communications. In some aspects, the components illustrated in fig. 4 are used to receive a data unit (e.g., packet 240 of fig. 2) that includes one or more signal units, as will be discussed in more detail below. For example, the components illustrated in fig. 4 may be used to receive data units transmitted by the components discussed above with reference to fig. 3. For ease of reference, the wireless device 202 configured with the components illustrated in fig. 4 is referred to below as wireless device 202 b.

The receiver 212 is configured to receive one or more packets or data units in a wireless signal. Data units that may be received and decoded or otherwise processed as discussed below are described in more detail with reference to fig. 5-11.

In the aspect illustrated in fig. 4, the receiver 212 includes a receive amplifier 401. The receive amplifier 401 may be configured to amplify wireless signals received by the receiver 212. In some aspects, the receiver 212 is configured to adjust the gain of the receive amplifier 401 by using an Automatic Gain Control (AGC) procedure. In some aspects, automatic gain control uses information in one or more received training fields, such as, for example, a received Short Training Field (STF), to adjust the gain. One of ordinary skill in the art will appreciate methods for performing AGC. In some aspects, amplifier 401 comprises an LNA.

The wireless device 202b may include an analog-to-digital converter (ADC, represented as "a/D" in fig. 4) 402, the analog-to-digital converter 402 configured to convert the amplified wireless signal from the receiver 212 into a digital representation thereof. After being amplified, the wireless signal may be processed, e.g., filtered or downconverted to an intermediate or baseband frequency, before being converted by the analog-to-digital converter 402. The analog-to-digital converter 402 may be implemented in the processor 204 or in another element of the wireless device 202. In some aspects, the analog-to-digital converter 402 is implemented in the transceiver 214 or in a data receiving processor.

The wireless device 202b may further include a transformation module 404, the transformation module 404 configured to convert the representation of the wireless signal to a frequency spectrum. In fig. 4, the transform module 404 is illustrated as being implemented by a Fast Fourier Transform (FFT) module. The transform module 404 may be programmable and may be configured to perform FFTs in different configurations. In one aspect, for example, the transform module 404 may be configured to perform a 32-point FFT or a 64-point FFT. In some aspects, the transform module 404 may identify the symbol for each point it uses.

The wireless device 202b can further include a channel estimator and equalizer 405 configured to form an estimate of a channel over which the data unit was received and to remove certain effects of the channel based on the channel estimate. For example, the channel estimator 405 may be configured to approximate a channel function, and the channel equalizer may be configured to apply an inverse of the function to the data in the spectrum.

In some aspects, the channel estimator and equalizer 405 estimates the channel using information in one or more received training fields, such as, for example, a Long Training Field (LTF). The channel estimate may be formed based on one or more LTFs received at the beginning of the data unit. This channel estimate may then be used to equalize the data symbols following the one or more LTFs. One or more additional LTFs may be received in a data unit after a certain time period or after a certain number of data symbols. Using these additional LTFs, the channel estimate may be updated or a new estimate may be formed. The new or updated channel estimate may be used to equalize the data symbols following the additional LTFs. In some aspects, the new or updated channel estimate is used to re-equalize the data symbols that precede the additional LTFs. One of ordinary skill in the art will appreciate the methods used to form the channel estimates.

Wireless device 202b may further include a demodulator 406, the demodulator 406 configured to demodulate the equalized data. For example, the demodulator 406 may determine a number of bits from the symbols output by the transform module 404 and the channel estimator and equalizer 405, e.g., by reversing the bit to symbol mapping in the constellation. These bits may be processed or evaluated by the processor 204 or used to display or otherwise output information to the user interface 222. In this manner, data and/or information may be decoded. In some aspects, the bits correspond to a codeword. In one aspect, demodulator 406 comprises a QAM (Quadrature amplitude modulation) demodulator, such as a 16-QAM demodulator or a 64-QAM demodulator. In other aspects, demodulator 406 comprises a Binary Phase Shift Keying (BPSK) demodulator or a Quadrature Phase Shift Keying (QPSK) demodulator.

In fig. 4, transform module 404, channel estimator and equalizer 405, and demodulator 406 are illustrated as being implemented in DSP 220. However, in some aspects, one or more of transform module 404, channel estimator and equalizer 405, and demodulator 406 are implemented in processor 204 or in another element of wireless device 202.

As discussed above, the wireless signal received at the receiver 212 includes one or more data units. Using the functions or components described above, a data unit or data symbol therein may be decoded, evaluated, or otherwise evaluated or processed. For example, the processor 204 and/or the DSP220 may be used to decode data symbols in data units using the transform module 404, the channel estimator and equalizer 405, and the demodulator 406.

The data units exchanged by the AP104 and the STAs 106 may include control information or data, as discussed above. At the Physical (PHY) layer, these data units may be referred to as physical layer protocol data units (PPDUs). In some aspects, a PPDU may be referred to as a packet or a physical layer packet. Each PPDU may include a preamble and a payload. The preamble may include a training field and a SIG field. The payload may include, for example, a Media Access Control (MAC) header or other layer of data, and/or user data. In various embodiments, the data units may include Mac Protocol Data Units (MPDUs) and/or aggregated Mac protocol data units (a-MPDUs). The payload may be transmitted using one or more data symbols. Systems, methods, and devices herein may utilize a data unit with a training field whose peak power ratio has been minimized.

The data units may be transmitted, for example, in a 1MHz mode or a 2MHz mode. The preamble is common for the 1MHz normal mode and for the 1MHz 2x repeat mode. In the 2MHz mode, the SIG field may span 52 data tones. In some embodiments, the SIG field may be replicated every 2MHz for transmissions greater than 2 MHz. Additionally, for transmissions greater than 2MHz, there may be 2 SIG-a fields and 1 SIG-B field for MU mode. In some embodiments, there are 6 SIG a fields in the 1MHz mode. In the 1MHz mode, the SIG field may span 24 data tones. In some embodiments, a 2MHz PHY transmission is an OFDM-based waveform consisting of 64 tones (52 data tones, 4 pilot tones, 7 guard tones, and 1 DC tone). The tone spacing for the other bandwidth modes may be the same as the tone spacing for the 2MHz mode. In some embodiments, the 1MHz mode includes 32 tones (24 data tones, 2 pilot tones, 5 guard tones, and 1 DC tone).

Fig. 5 illustrates an example of a data unit 500. The data unit 500 may comprise a PPDU for use with the wireless device 202. In an embodiment, data unit 500 may be used by legacy devices or devices implementing a legacy standard or a down-converted version thereof.

The data unit 500 includes a preamble 510. The preamble 510 may include a variable number of repeated STF512 symbols, and one or more LTF514 symbols. In one implementation, 10 repeated STF512 symbols may be sent, followed by 2 LTF512 symbols. The STF512 may be used by the receiver 212 to perform automatic gain control to adjust the gain of the receive amplifier 401, as discussed above. In addition, the STF512 sequence may be used by the receiver 212 for packet detection, coarse timing, and other settings. LTF514 may be used by channel estimator and equalizer 405 to form an estimate of the channel over which data unit 500 was received.

Following the preamble 510 in the data unit 500 is a signal unit 520. The signal 520 unit may be represented using OFDM and may include information related to a transmission rate, a length of the data unit 500, and the like. The data unit 500 additionally includes a variable number of data symbols 530, such as OFDM data symbols. In one embodiment, the preamble 510 may include a signal unit 520. In an embodiment, one or more data symbols 530 may be a payload.

When the data unit 500 is received at the wireless device 202b, the size of the data unit 500, including the LTF514, may be calculated based on the signal unit 520, and the STF512 may be used by the receiver 212 to adjust the gain of the receive amplifier 401. Further, the LTF may be used by the channel estimator and equalizer 405 to form an estimate of the channel over which the data unit 500 was received. The channel estimate may be used by DSP220 to decode a number of data symbols 530 following preamble 510.

The data units 500 illustrated in fig. 5 are merely examples of data units that may be used in the system 100 and/or with the wireless device 202. One of ordinary skill in the art will appreciate that a greater or lesser number of STFs 412 or LTFs 514 and/or data symbols 530 may be included in the data unit 500. In addition, one or more symbols or fields not illustrated in fig. 5 may be included in the data unit 500, and one or more illustrated fields or symbols may be omitted.

When OFDM is used, several orthogonal subcarriers of the frequency band may be used. The number of subcarriers used may depend on various considerations, including the available frequency band for use, the bandwidth, and any associated regulatory constraints. The number of subcarriers used is related to the size of the FFT module, as each modulated subcarrier is an input to the IFFT module to create the OFDM signal to be transmitted. As such, in some implementations, a larger FFT size (e.g., 64, 128, 256, or 512) (corresponding to using more subcarriers to transmit data) may be desired to achieve a larger bandwidth. In other implementations, a smaller FFT size may be used for transmitting data at a narrow bandwidth. The number of subcarriers and thus the FFT size may be chosen to follow a regulatory domain with certain bandwidth constraints. For example, an FFT of size 32 may be provided for certain implementations (e.g., for a down-conversion implementation), and an FFT of size 32 may be provided for use by 802.11 ah. As such, wireless device 202a may include several transform modules 304, each implemented as an FFT or IFFT module, each having a different size in order to comply with the regulations governing the number of subcarriers used. According to certain aspects described herein, at least one transform module 304 may be a 32-point size IFFT or FFT module. In an embodiment, the transform module 304 may be configured to selectively perform a plurality of different sized FFTs based on the detected FFT mode. In an aspect, the multi-mode transform module may include a plurality of FFT modules, each configured to use a different FFT size, respective outputs being selectable based on a detected FFT mode.

As discussed above with respect to fig. 2 and 3, the wireless device 202a may be configured to operate in various FFT modes. In various embodiments, the wireless device 202a may be configured to use a 64-point FFT size in conjunction with a channel of higher bandwidth than a 32-point FFT channel. For example, a 64-point FFT channel may have twice the bandwidth of a 32-point FFT channel. In an embodiment, the transform module 304 may be configured to use a 64-point FFT size in conjunction with a 2MHz channel, and the transform module 304 may be configured to use a 32-point FFT channel, which may be a 1MHz channel. In an embodiment, the transform module 304 may be configured to selectively use a plurality of different FFT sizes. In another embodiment, the various different IFFTs may each be configured to use different FFT sizes, the outputs of which may be selectively routed to the DAC 306.

In some embodiments, the data unit 500 may include a partial Air Identifier (AID) or PAID field. The PAID field includes a partial identifier for one or more receivers or STAs 106. The PAID field may be used by each STA106 as an early indicator of whether the STA106 should receive and decode the remainder of the data unit 500. For example, if the PAID field indicates that the data unit 500 is not intended for a particular STA106, the STA106 may discontinue processing the data unit 500 in order to conserve power.

In some embodiments, the PAID field includes a unique identification of the STA106, such as a full partial identifier (e.g., AID) of the STA 106. In some embodiments, the PAID field includes a partial identifier of the STA106, such as a portion of the AID, e.g., a number of Least Significant Bits (LSBs) of the AID. In some embodiments, the PAID field includes a partial local identifier of the STA106 and a partial local identifier of the associated BSS or AP 104.

In some embodiments, the PAID field is not explicitly transmitted, but is encoded in another field, such as a Cyclic Redundancy Check (CRC) field. For example, the PAID field and other fields to be transmitted by the data unit 500 may be used to calculate the CRC. The STA106 receives the transmitted field and the CRC field. The STA106 then calculates the CRC based on the received fields and the PAID field indicating that the STA106 should continue processing the data unit 500. If the CRC computed by the STA106 matches the received CRC, the STA106 continues processing the data unit 500.

In some embodiments, the data unit 500 includes multiple parameter sets. The first set of parameters may include parameters for determining how long the STA106 is in the power down mode if the data unit 500 is not intended for the STA 106. The second set of parameters may include other parameters of the data unit 500, such as those discussed below. The PAID field may be included in the second set. In some embodiments, each parameter set is covered by an independent CRC specific to that set. Each STA106 determines whether to decode the data unit 500 based on the PAID field. If the data unit 500 is not decoded, the STA106 defers for a period of time based on the information in the first parameter set. In some embodiments, the CRC is in the SIG field. In some embodiments, the CRC of the second parameter set is in the service field after the preamble, e.g., if the data unit 500 is for a non-AMPDU.

In some embodiments, the PAID field is in the service field. In such embodiments, the PAID field may be transmitted with the same MCS as the data in the SIG field. In some embodiments, the PAID field may immediately precede the MAC header.

In some embodiments, the data unit 500 includes a random seed for the STA106 to use for descrambling the data. In some embodiments, at least a portion of the PAID field may also be a seed. In some embodiments, the STA106 may identify multiple, e.g., consecutive PAID fields as new seeds for retransmission.

In some embodiments, data unit 500 does not include a service field. In such embodiments, the bandwidth may be indicated, for example, in the SIG field or in the MAC header. Similarly, the CRC may be included in, for example, the SIG field or the MAC header. Additionally or alternatively, the random seed may be included in, for example, the SIG field or the MAC header. In some embodiments, the random seed may also be included in the PAID field.

In some embodiments, the PAID field is scrambled with data in the SIG field and the scrambled sequence is covered by a CRC. Alternatively, the PAID field may be appended to the SIG field and the set covered by a CRC.

In some embodiments, the PAID field is not static over multiple transmissions to the STA 106. For example, the PAID field may change on a per transmission basis or may change after every certain number of transmissions. The PAID field may vary depending on the algorithm common to both the transmitting device and the receiving STA 106. For example, the next in a series of numbers may be used. In some embodiments, the next PADI field value is equal to the previous PAID field value plus 1. In some embodiments, the algorithm includes generating the PAID field based in part on a Timing Synchronization Function (TSF) of the network or a hash of the TSF. The calculation of the PAID field may occur, for example, every second, every 2, 3, 4, 5, or other number of seconds, every minute, every 2, 3, 4, 5, or other number of minutes. Therefore, errors due to TSF misalignment will be minimal.

In some embodiments, the receiving STA106 communicates a PAID field value or an indication of the PAID field value to the transmitting device for the next transmission. For example, the next PAID field value or an indication of the next PAID field value may be included in an ACK sent in response to a transmission received from a transmitting device.

For example, in the first data unit, the AP104 uses the default PAID field value to which the STA106 responds by decoding the first data unit. The STA106 sends an ACK to acknowledge receipt of the first data unit. In the ACK communication, the STA106 indicates a next PAID field value. Then, in the second data unit, the AP104 uses the next PAID field value to which the STA106 responds by decoding the second data unit.

The default PAID field value may be, for example, a broadcast PAID field value or may be, for example, a PAID field value associated with a particular STA106 for which the first and second data units are intended. The next PAID field value may be, for example, the next in a series of digits, or may be, for example, a hash of at least a portion of the first data unit, such as the data of the first data unit.

In some embodiments, if the AP104 does not receive the ACK, the AP104 may transmit the second data unit using the default PAID field value or the most recent PAID field value for which the ACK was received. Accordingly, the STA106 may be configured to decode a data unit including any of a plurality of PAID field values. For example, the STA106 may be configured to decode a data unit including any of a default PAID field value, a PAID field value for a most recently received and decoded data unit, and a PAID field value indicated in a most recent ACK transmitted by the STA 106. In such embodiments, the AP104 may be configured to select one of a plurality of PAID field values for the STA 106. Such selection may be random or pseudo-random, for example.

In some embodiments, the PAID field is assigned by the AP104 with, for example, an administrative exchange. For example, the PAID field may be reassigned periodically. In some embodiments, the STA106 may request or assign a new PAID field for the next transmission from the AP 104. For example, if the STA106 decodes multiple data units that are not intended for the STA106, the STA106 may request or specify a new PAID field value.

In some systems, unicast packet filtering by MAC address is possible. In such systems, the PAID field may be useful in enhancing packet filtering based on packet content.

In some embodiments, the PAID field may identify the type of data unit. In some embodiments, the PAID field may additionally identify the content of the data unit. For example, if the data unit includes a Traffic Indication Map (TIM) for a group of STAs, the PAID field may identify the group of STAs to which the data unit is intended. In some embodiments, certain values of the PAID field may be used to indicate that the data unit is a beacon and to identify a beacon change sequence number. If the STA is already up-to-date, the STA may ignore the rest of the data unit after processing the PAID field.

In one embodiment, for a 64-point FFT signal, the data unit 500 may include a preamble 510 of 240 μ s. The preamble 510 may include a single 2-symbol STF512, a single 2-symbol LTF514, and a 2-symbol signal unit 520. The signal unit 520 may include one or more fields shown in table 1 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, the signal unit 520 has all of the fields shown in table 1. In some embodiments, signal unit 520 has only the fields shown in table 1. In some embodiments, the signal unit 520 has the fields shown in table 1 in the order shown in table 1. In some embodiments, at least a portion of the information of the plurality of fields shown in table 1 is included in a single field. For example, the first and second fields of table 1 may be reduced to a single field that includes information for both the first and second fields.

TABLE 1

In the aspect shown in table 1, the signal unit 520 may include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 12 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 4095 bytes. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long.

The signal unit 520 may further include a Bandwidth (BW) field indicating a BW to be used. The "BW" field may be 2 bits long. In various embodiments, the 2-bit "BW" field may indicate whether the bandwidth is 2MHz, 4MHz, 8MHz, or 16 MHz. The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long.

The signal unit 520 may further include an Air Identification (AID) field indicating an AID over the air associated with the data unit 500. The "AID" field may be 12 bits long. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "smoothing" field indicating whether smoothing is recommended for the channel estimate. The "smooth" field may be 1 bit long.

The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 4 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

The signal unit 520 may further include one or more reserved bits. As shown in the implementation of table 1, signal unit 520 may include 1 reserved bit. As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver: there are sections in the signal unit 520 that may enable the receiver to mitigate the effects of "high time channel variations" during the transmission of the signal unit 520.

In an embodiment, the signal unit 520 may include one or more fields shown in table 2 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, the signal unit 520 has all of the fields shown in table 2. In some embodiments, signal unit 520 has only the fields shown in table 2. In some embodiments, the signal unit 520 has the fields shown in table 2 in the order shown in table 2. In some embodiments, at least a portion of the information of the plurality of fields shown in table 2 is included in a single field. For example, the first and second fields of table 2 may be reduced to a single field that includes information for both the first and second fields.

SIG-A field (64 points FFT)	Bits
		MCS	4
Num SS	2

SGI	1
		Length of	12
Aggregation	1
		BW	2
Encoding	1
		AID	13
STBC	1
		Through beam forming	1
Retention	0
		CRC	8
Tail part	6
		Total up to	52

TABLE 2

In the aspect shown in table 2, the signal unit 520 may include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include an Air Identification (AID) field indicating an AID over the air associated with the data unit 500. The "AID" field may be 13 bits long. In some embodiments, the "AID" field carries an AID for the SU, while for the MU, the first bitReserved, the next 6 bits carry a Group Identifier (GID), and the last 6 bits carry the number of space-time streams (N) for the second, third, and fourth users_sts). In some embodiments, certain outliers of the "AID" field may be used to identify the specific content of the packet, e.g., whether the packet is for multicast or broadcast. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "beamformed" field that indicates whether a beamforming steering matrix is applied to the waveform in the SU transmission. The "beamformed" field may be 1 bit long.

The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 8 bits or 4 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

The signal unit 520 may further include one or more reserved bits. The signal unit 520 may include, for example, 0 or 4 reserved bits. As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver: there are sections in the signal unit 520 that may enable the receiver to mitigate the effects of "high time channel variations" during the transmission of the signal unit 520.

In one embodiment, for a 32-point FFT signal, the data unit 500 may include a preamble of 360 μ s. The preamble may include a single 4-symbol STF512, a single 2-symbol LTF514, and a 3-symbol signal unit 520. The signal unit 520 may include one or more fields shown in table 3 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 3. In some embodiments, signal unit 520 has only the fields shown in table 3. In some embodiments, signal unit 520 has the fields shown in table 3 in the order shown in table 3. In some embodiments, at least a portion of the information of the plurality of fields shown in table 3 is included in a single field. For example, the first and second fields of table 3 may be reduced to a single field that includes information for both the first and second fields.

TABLE 3

In the aspect shown in table 3, the signal unit 520 may include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 11 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 4095 bytes. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long.

The signal unit 520 may further include one or more reserved bits. As shown in the implementation of table 3, signal unit 520 may include 5 reserved bits. As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In the implementation shown in table 3, the signal unit 520 for the 32-point FFT may omit one or more fields used in the signal unit 520 for the 64-point FFT shown in table 1 above. For example, the "BW", "AID" and "smooth" fields are omitted. In an embodiment, certain fields may be omitted because the receiving device may implicitly know the parameters indicated in those fields.

In various embodiments, symbols, fields, and/or data units may be repeated in order to increase the effective signal-to-noise ratio (SNR) of the transmission. For example, a 32-point FFT transmission may repeat two, three, four, eight, etc. In one embodiment, the repetition may be accomplished in conjunction with the down-conversion of the transmission.

In one embodiment, for a 32-point FFT signal with a twice repetition pattern, the data unit 500 may include a preamble of 440 μ s. The preamble may include a single 4-symbol STF512, a single 3-symbol LTF514, and a 4-symbol signal unit 520. The signal unit 520 may include one or more fields shown in table 4 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 4. In some embodiments, signal unit 520 has only the fields shown in table 4. In some embodiments, signal unit 520 has the fields shown in table 4 in the order shown in table 4. In some embodiments, at least a portion of the information for the plurality of fields shown in table 4 is included in a single field. For example, the first and second fields of table 4 may be reduced to a single field that includes information for both the first and second fields.

SIG-A field (32 point FFT, 2x repeat)	Bits
		Length of	9
Retention	8
		Parity	1
Tail part	6
		Total up to	24

TABLE 4

In the aspect shown in table 4, the signal unit 520 may include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 4095 bytes.

Signal unit 520 may further include a "parity" field that indicates the parity result computed for one or more fields of signal unit 520. The "parity" field may be 1 bit long. In an embodiment, another error detection code may be used instead of or in addition to the parity bits. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

The signal unit 520 may further include one or more reserved bits. As shown in the implementation of table 4, signal unit 520 may include 8 reserved bits. As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In the implementation shown in table 4, the signal unit 520 for the 32-point FFT may omit one or more fields used in the signal unit 520 for the 64-point FFT shown in table 1 above. For example, the "MCS", "Num SS", "SGI", "BW", "AID", "aggregation", "coding", and "STBC" fields are omitted. In an embodiment, certain fields may be omitted because the receiving device may implicitly know the parameters indicated in those fields.

In an embodiment, a single signal unit 520 format may be used for a 32-point FFT in both non-repeating and twice repeating patterns. The single signal unit 520 may be included in a "combined" preamble. In one embodiment, the combined preamble may be 520 μ s long. The preamble may include a single 4-symbol STF512, a single 3-symbol LTF514, and a 6-symbol signal unit 520. The signal unit 520 may include one or more fields shown in table 5 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 5. In some embodiments, signal unit 520 has only the fields shown in table 5. In some embodiments, signal unit 520 has the fields shown in table 5 in the order shown in table 5. In some embodiments, at least a portion of the information of the plurality of fields shown in table 5 is included in a single field. For example, the first and second fields of table 5 may be reduced to a single field that includes information for both the first and second fields.

SIG-A field (32 points FFT combined)	Bits
		MCS	4
Num SS	2
		SGI	1
Length of	11
		Aggregation	1
Encoding	1
		STBC	1
Smoothing	1
		Retention	4
CRC	4

Tail part	6
		Total up to	36

TABLE 5

In the aspect shown in table 5, the signal unit 520 may include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "smoothing" field indicating whether smoothing is recommended for the channel estimate. The "smooth" field may be 1 bit long.

The signal unit 520 may further include one or more reserved bits. As shown in the implementation of table 5, signal unit 520 may include 4 reserved bits. As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In the implementation shown in table 5, the signal unit 520 for the 32-point FFT may omit one or more fields used in the signal unit 520 for the 64-point FFT shown in table 1 above. For example, the "BW" and "AID" fields are omitted. In an embodiment, certain fields may be omitted because the receiving device may implicitly know the parameters indicated in those fields.

In an embodiment, a single signal element 520 format may be used for a 32-point FFT in normal and 2x repetition modes. The signal unit 520 may include one or more fields shown in table 6 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 6. In some embodiments, signal unit 520 has only the fields shown in table 6. In some embodiments, signal unit 520 has the fields shown in table 6 in the order shown in table 6. In some embodiments, at least a portion of the information for the plurality of fields shown in table 6 is included in a single field. For example, the first and second fields of table 6 may be reduced to a single field that includes information for both the first and second fields.

TABLE 6

In the aspect shown in table 6, the signal unit 520 may include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 11 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 2047 bytes. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "beamformed" field that indicates whether a beamforming steering matrix is applied to the waveform in the SU transmission. The "beamformed" field may be 1 bit long.

The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 4 bits or 8 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

The signal unit 520 may further include one or more reserved bits. The signal unit 520 may include, for example, 0 or 4 reserved bits. As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In the implementation shown in table 6, the signal unit 520 for the 32-point FFT may omit one or more fields used in the signal unit 520 for the 64-point FFT shown in table 1 above. For example, the "BW" and "AID" fields are omitted. In an embodiment, certain fields may be omitted because the receiving device may implicitly know the parameters indicated in those fields.

In an embodiment, a single signal unit 520 format may be used for the 64-point FFT SIG-B MU mode. The signal unit 520 may be transmitted for each user to which precoding is applied. The signal unit 520 may include one or more fields shown in table 7 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 7. In some embodiments, signal unit 520 has only the fields shown in table 7. In some embodiments, signal unit 520 has the fields shown in table 7 in the order shown in table 7. In some embodiments, at least a portion of the information of the plurality of fields shown in table 7 is included in a single field. For example, the first and second fields of table 7 may be reduced to a single field that includes information for both the first and second fields.

SIG-B field (64-point FFT MU mode)	Bits
		MCS	4
Encoding	1
		Retention	11
CRC	4
		Tail part	6
Total up to	26

TABLE 7

In the aspect shown in table 7, the signal unit 520 may include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long.

The signal unit 520 may further include one or more reserved bits. The signal unit 520 may include, for example, 11 reserved bits. As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In the implementation shown in table 7, the signal unit 520 for the 32-point FFT may omit one or more fields used in the signal unit 520 for the 64-point FFT shown in table 1 above. For example, the "BW" and "AID" fields may be omitted. In an embodiment, certain fields may be omitted because the receiving device may implicitly know the parameters indicated in those fields.

In one embodiment, for a 2MHz, 64 point FFT signal, the data unit 500 may support multiple users. The preamble may include a 2-symbol signal unit 520. The signal unit 520 may include one or more fields shown in table 8 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 8. In some embodiments, signal unit 520 has only the fields shown in table 8. In some embodiments, signal unit 520 has the fields shown in table 8 in the order shown in table 8. In some embodiments, at least a portion of the information for the plurality of fields shown in table 8 is included in a single field. For example, the first and second fields of table 8 may be reduced to a single field that includes information for both the first and second fields.

SIG-A field (64 points FFT)	Bits
		BW	2
First retention	1
		STBC	1
Num SS	2
		AID/GID+Nsts	12
Second reservation	1
		SGI	1
Encoding	1
		MCS	4
Through beam forming	1
		Aggregation	1
Length of	12
		Third Retention	3
CRC	4
		Tail part	6
Total up to	52

TABLE 8

In some embodiments, a first symbol of the signal unit 520 includes "BW", "first reservation", "STBC", "NumSS", "AID/GID + Nsts", "second reservation", "SGI", "coding", "MCS", and "beamformed" fields, and a second symbol of the signal unit 520 includes "aggregation", "length", "third reservation", "CRC", and "tail" fields.

In the aspect shown in table 8, the signal unit 520 may include a "Bandwidth (BW) field indicating a BW used. The "BW" field may be 2 bits long. In various embodiments, the 2-bit "BW" field may indicate whether the bandwidth is 2MHz, 4MHz, 8MHz, or 16 MHz. The signal unit 520 may further include a "first reserved" bit. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long.

The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long. Signal unit 520 may further include an "AID/GID + Nsts" field indicating an on-Air Identification (AID) associated with data unit 500. The "AID/GID + Nsts" field may be 12 bits long. In some embodiments, the "AID/GID + Nsts" field carries an AID for SU, while for MU, the first 6 bits carry GID and the last 6 bits carry N for the second, third and fourth users_sts. In some embodiments, certain outliers of the "AID/GID + Nsts" field may be used to identify the specific content of the packet, e.g., whether the packet is for multicast or broadcast. The "AID" bit of the "AID/GID + Nsts" field may be used during SU mode for embodiments using cellular offload so that other devices can save power during transmission. The signal unit 520 may further include a "second reserved" bit.

The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long. The signal unit 520 may further include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include a "beamformed" field that indicates whether a beamforming steering matrix is applied to the waveform in the SU transmission. The "beamformed" field may be 1 bit long.

The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long. The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 12 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 4095 bytes. The signal unit 520 may further include 3 "third reserved" bits. In an alternative embodiment, the "length" field is 9 bits long and the signal unit 520 includes 6 "third reserved" bits.

As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, reserved bits may be used to extend the preceding field. For example, in the example shown in table 8, the "first reserved" bit may be used as the third bit of the "BW" field, the "second reserved" bit may be used as the 13 th bit of the "AID/GID + Nsts" field, and/or one or more of the "third reserved" bits may be used as additional bits of the "length" field. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In an embodiment, a single signal unit 520 format may be used for the 64-point FFT SIG-B MU mode. The signal unit 520 may include one or more fields shown in table 9 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 9. In some embodiments, signal unit 520 has only the fields shown in table 9. In some embodiments, signal unit 520 has the fields shown in table 9 in the order shown in table 9. In some embodiments, at least a portion of the information for the plurality of fields shown in table 9 is included in a single field. For example, the first and second fields of table 9 may be reduced to a single field that includes information for both the first and second fields.

SIG-B field (64-point FFT MU mode)	Bits
		MCS	4
Encoding	1
		Retention	7
CRC	8
		Tail part	6
Total up to	26

TABLE 9

In the aspect shown in table 9, the signal unit 520 may include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long.

The signal unit 520 may further include 7 reserved bits. The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 8 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In an embodiment, for a 1MHz SIG-a packet, the signal unit 520 may include one or more fields shown in table 10 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 10. In some embodiments, signal unit 520 has only the fields shown in table 10. In some embodiments, signal unit 520 has the fields shown in table 10 in the order shown in table 10. In some embodiments, at least a portion of the information for the plurality of fields shown in table 10 is included in a single field. For example, the first and second fields of table 10 may be reduced to a single field that includes information for both the first and second fields.

Watch 10

In the aspect shown in table 10, the signal unit 520 may include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long. The signal unit 520 may further include a "beamformed" field that indicates whether a beamforming steering matrix is applied to the waveform in the SU transmission. The "beamformed" field may be 1 bit long.

The signal unit 520 may further include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 11 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 2047 bytes.

The signal unit 520 may further include 4 reserved bits. The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 4 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, reserved bits may be used to extend the preceding field. For example, in the example shown in table 10, reserved bits may be used as additional bits for the "length" field. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In an embodiment, for a 1MHz SIG-a packet, the signal unit 520 may include one or more fields shown in table 11 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 11. In some embodiments, signal unit 520 has only the fields shown in table 11. In some embodiments, signal unit 520 has the fields shown in table 11 in the order shown in table 11. In some embodiments, at least a portion of the information for the plurality of fields shown in table 11 is included in a single field. For example, the first and second fields of table 11 may be reduced to a single field that includes information for both the first and second fields.

TABLE 11

In the aspect shown in table 11, the signal unit 520 may include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate that the length of the payload 530 is indicated in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes.

The signal unit 520 may further include 0 reserved bits. The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 4 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

In an embodiment, for a 1MHz SIG-a packet, the signal unit 520 may include one or more fields shown in table 12 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 12. In some embodiments, signal unit 520 has only the fields shown in table 12. In some embodiments, signal unit 520 has the fields shown in table 12 in the order shown in table 12. In some embodiments, at least a portion of the information for the plurality of fields shown in table 12 is included in a single field. For example, the first and second fields of table 12 may be reduced to a single field that includes information for both the first and second fields.

TABLE 12

In the aspect shown in table 12, the signal unit 520 may include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long.

The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long. The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes.

The signal unit 520 may further include 3 reserved bits. The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 4 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, reserved bits may be used to extend the preceding field. For example, in the example shown in table 12, one or more reserved bits may be used as additional bits for the "length" field. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In an embodiment, for a 1MHz SIG-a packet, the signal unit 520 may include one or more fields shown in table 13 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 13. In some embodiments, signal unit 520 has only the fields shown in table 13. In some embodiments, signal unit 520 has the fields shown in table 13 in the order shown in table 13. In some embodiments, at least a portion of the information for the plurality of fields shown in table 13 is included in a single field. For example, the first and second fields of table 13 may be reduced to a single field that includes information for both the first and second fields.

Watch 13

In the aspect shown in table 13, the signal unit 520 may include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes.

The signal unit 520 may further include 1 reserved bit. Signal unit 520 may further include a "parity" field that indicates the parity result computed for one or more fields of signal unit 520. The "parity" field may be 1 bit long. In an embodiment, another error detection code may be used instead of or in addition to the parity bits. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, reserved bits may be used to extend the preceding field. For example, in the example shown in table 13, reserved bits may be used as additional bits for the "length" field. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In an embodiment, a single signal unit 520 format may be used for the 64-point FFT SIG-B MU mode. The signal unit 520 may include one or more fields shown in table 14 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 14. In some embodiments, signal unit 520 has only the fields shown in table 14. In some embodiments, signal unit 520 has the fields shown in table 14 in the order shown in table 14. In some embodiments, at least a portion of the information for the plurality of fields shown in table 14 is included in a single field. For example, the first and second fields of table 14 may be reduced to a single field that includes information for both the first and second fields.

SIG-B field (64-point FFT MU mode)	Bits
		MCS	4
Encoding	1
		Length of	9-11
Retention	0-2
		CRC	4
Tail part	6
		Total up to	26

TABLE 14

In the aspect shown in table 14, the signal unit 520 may include an "Modulation and Coding Scheme (MCS) field indicating the MCS used. The "MCS" field may be 4 bits long. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9-11 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. The signal unit 520 may further include 0-2 reserved bits. In one embodiment, the sum of the bits used for the length field and the reserved bits is 11. In such embodiments, reserved bits may be used to extend the preceding field. For example, in the example shown in table 14, reserved bits may be used as additional bits for the "length" field.

In one embodiment, for a 2MHz, 64 point FFT signal, the data unit 500 may support multiple users. The preamble may include a 2-symbol signal unit 520. The signal unit 520 may include one or more fields shown in table 15 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 15. In some embodiments, signal unit 520 has only the fields shown in table 15. In some embodiments, signal unit 520 has the fields shown in table 15 in the order shown in table 15. In some embodiments, at least a portion of the information for the plurality of fields shown in table 15 is included in a single field. For example, the first and second fields of table 15 may be reduced to a single field that includes information for both the first and second fields.

SIG-A field (64 points FFT)	Bits
		BW	2
First retention	1
		STBC	1
Num SS	2
		AID/GID+Nsts	12
Second reservation	1
		SGI	1
Encoding	2
		MCS	4
Through beam forming	1
		Aggregation	1
Length of	9
		Third Retention	5
CRC	4
		Tail part	6

Total up to

52

Watch 15

In some embodiments, a first symbol of the signal unit 520 includes "BW", "first reservation", "STBC", "NumSS", "AID/GID + Nsts", "second reservation", "SGI", "code", and "MCS" fields, and a second symbol of the signal unit 520 includes "beamformed", "aggregated", "length", "third reservation", "CRC", and "tail" fields.

In the aspect shown in table 15, the signal unit 520 may include a "Bandwidth (BW) field indicating the BW used. The "BW" field may be 2 bits long. In various embodiments, the 2-bit "BW" field may indicate whether the bandwidth is 2MHz, 4MHz, 8MHz, or 16 MHz. The signal unit 520 may further include a "first reserved" bit. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long.

The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long. Signal unit 520 may further include an "AID/GID + Nsts" field indicating an on-Air Identification (AID) associated with data unit 500. The AID/GID + Nsts field may be 12 bits long and may include a PAID field as discussed above. In some embodiments, the "AID/GID + Nsts" field carries an AID for SU, while for MU, the first 6 bits carry GID and the last 6 bits carry N for the second, third and fourth users_sts. In some embodiments, certain outliers of the "AID/GID + Nsts" field may be used to identify the specific content of the packet, e.g., whether the packet is for multicast or broadcast. The "AID" bit of the "AID/GID + Nsts" field may be used during SU mode for embodiments using cellular offload so that other devices can save power during transmission. The signal unit 520 may further include a "second reserved" bit.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 2 bits long. The first bit of the "encode" field may indicate the type of encoding for a single user or for user 0 (if multi-user). The second bit of the "encode" field may be used to indicate whether LDPC coding is generated in the extra symbol. If multi-user, the second bit of the "encode" field may be used to indicate whether Low Density Parity Check (LDPC) coding is generated in the extra symbols for any user. The signal unit 520 may further include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. For multiple users, some bits of the "MCS" field may be used to indicate the coding for users 1-3. For example, the first, second, and third bits of the "MCS" field may be used to indicate coding for users 1, 2, and 3, respectively. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example.

The signal unit 520 may further include a "beamformed" field that indicates whether a beamforming steering matrix is applied to the waveform in the SU transmission. The "beamformed" field may be 1 bit long. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long. The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes. The signal unit 520 may further include 5 "third reserved" bits.

As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, reserved bits may be used to extend the preceding field. For example, in the example shown in table 14, the "first reserved" bit may be used as the third bit of the "BW" field, the "second reserved" bit may be used as the 13 th bit of the "AID/GID + Nsts" field, and/or one or more of the "third reserved" bits may be used as additional bits of the "length" field. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In an embodiment, a single signal unit 520 format may be used for the 64-point FFT SIG-B MU mode. The signal unit 520 may be transmitted for each user to which precoding is applied. The signal unit 520 may include one or more fields shown in table 16 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 16. In some embodiments, signal unit 520 has only the fields shown in table 16. In some embodiments, signal unit 520 has the fields shown in table 16 in the order shown in table 16. In some embodiments, at least a portion of the information for the plurality of fields shown in table 16 is included in a single field. For example, the first and second fields of table 16 may be reduced to a single field that includes information for both the first and second fields.

SIG-B field (64-point FFT MU mode)	Bits
		MCS	4
Retention	8
		CRC	8
Tail part	6
		Total up to	26

TABLE 16

In the aspect shown in table 16, the signal unit 520 may include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. For multiple users, some bits of the "MCS" field may be used to indicate the coding for users 1-3. For example, the first, second, and third bits of the "MCS" field may be used to indicate coding for users 1, 2, and 3, respectively. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example.

The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 8 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

The signal unit 520 may further include one or more reserved bits. The signal unit 520 may include, for example, 8 reserved bits. As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In the implementation shown in table 16, the signal unit 520 for the 32-point FFT may omit one or more fields used in the signal unit 520 for the 64-point FFT shown in table 1 above. For example, the "BW" and "AID" fields are omitted. In an embodiment, certain fields may be omitted because the receiving device may implicitly know the parameters indicated in those fields.

In an embodiment, for a 1MHz SIG-a packet, the signal unit 520 may include one or more fields shown in table 17 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 17. In some embodiments, signal unit 520 has only the fields shown in table 17. In some embodiments, signal unit 520 has the fields shown in table 17 in the order shown in table 17. In some embodiments, at least a portion of the information for the plurality of fields shown in table 17 is included in a single field. For example, the first and second fields of table 17 may be reduced to a single field that includes information for both the first and second fields.

TABLE 17

In the aspect shown in table 17, the signal unit 520 may include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 2 bits long. The first bit of the "encode" field may indicate the type of encoding for a single user or for user 0 (if multi-user). The second bit of the "encode" field may be used to indicate whether LDPC coding is generated in the extra symbol. If multi-user, the second bit of the "encode" field may be used to indicate whether LDPC coding is generated in the extra symbols for any user. The signal unit 520 may further include a "beamformed" field that indicates whether a beamforming steering matrix is applied to the waveform in the SU transmission. The "beamformed" field may be 1 bit long.

The signal unit 520 may further include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. For multiple users, some bits of the "MCS" field may be used to indicate the coding for users 1-3. For example, the first, second, and third bits of the "MCS" field may be used to indicate coding for users 1, 2, and 3, respectively. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long.

The signal unit 520 may further include 5 reserved bits. The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 4 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, reserved bits may be used to extend the preceding field. For example, in the example shown in table 17, one or more reserved bits may be used as additional bits for the "length" field. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In an embodiment, for a 1MHz SIG-a packet, the signal unit 520 may include one or more fields shown in table 18 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 18. In some embodiments, signal unit 520 has only the fields shown in table 18. In some embodiments, signal unit 520 has the fields shown in table 18 in the order shown in table 18. In some embodiments, at least a portion of the information for the plurality of fields shown in table 18 is included in a single field. For example, the first and second fields of table 18 may be reduced to a single field that includes information for both the first and second fields.

Watch 18

In the aspect shown in table 18, the signal unit 520 may include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long.

The signal unit 520 may further include an Air Identification (AID) field indicating an AID over the air associated with the data unit 500. The "AID" field may be 9 to 13 bits long and may include the PAID field as described above. The signal unit 520 may further include 2 to 6 first reserved bits. The bits for the "AID" field and the first reserved bits may add up to 15. The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes.

The signal unit 520 may further include 2 second reserved bits. The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 4 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may further include a "tail" field for resetting the state of the convolutional encoder and/or decoder. The "trailer" field may be 6 bits long.

As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, reserved bits may be used to extend the preceding field. For example, in the example shown in table 18, one or more first reserved bits may be used as additional bits for the "AID" field, and one or more second reserved bits may be used as additional bits for the "length" field. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In an embodiment, for a 1MHz SIG-a packet, the signal unit 520 may include one or more fields shown in table 19 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 19. In some embodiments, signal unit 520 has only the fields shown in table 19. In some embodiments, signal unit 520 has the fields shown in table 19 in the order shown in table 19. In some embodiments, at least a portion of the information for the plurality of fields shown in table 19 is included in a single field. For example, the first and second fields of table 19 may be reduced to a single field that includes information for both the first and second fields.

Watch 19

In the aspect shown in table 19, the signal unit 520 may include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long.

The signal unit 520 may further include an Air Identification (AID) field indicating an AID over the air associated with the data unit 500. The "AID" field may be 9 bits long and may include the PAID field as discussed above. The signal unit 520 may further include 2 reserved bits. The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes.

As discussed below, in various embodiments, reserved bits may be used to carry additional information for different packet types. For example, the reserved bits may include additional information related to an Acknowledgement (ACK) packet. In some embodiments, reserved bits may be used to extend the preceding field. For example, in the example shown in table 19, one or more reserved bits may be used as additional bits for the "AID" field. In some embodiments, one or more reserved bits are used as one or more doppler mitigation bits to signal to the receiver that there are sections in the signal element 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal element 520.

In an embodiment, for a 1MHz SIG-a packet, the signal unit 520 may include one or more fields shown in table 20 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 20. In some embodiments, signal unit 520 has only the fields shown in table 20. In some embodiments, signal unit 520 has the fields shown in table 20 in the order shown in table 20. In some embodiments, at least a portion of the information for the plurality of fields shown in table 20 is included in a single field. For example, the first and second fields of table 20 may be reduced to a single field that includes information for both the first and second fields.

Watch 20

In the aspect shown in table 20, the signal unit 520 may include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long.

The signal unit 520 may further include an Air Identification (AID) field indicating an AID over the air associated with the data unit 500. The "AID" field may be 12 bits long and may include the PAID field as discussed above. The signal unit 520 may further include 0-6 first reserved bits.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes. The signal unit 520 may further include 0-6 second reserved bits.

In an embodiment, for a 1MHz SIG-a packet, the signal unit 520 may include one or more fields shown in table 21 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 21. In some embodiments, signal unit 520 has only the fields shown in table 21. In some embodiments, signal unit 520 has the fields shown in table 21 in the order shown in table 21. In some embodiments, at least a portion of the information for the plurality of fields shown in table 21 is included in a single field. For example, the first and second fields of table 21 may be reduced to a single field that includes information for both the first and second fields.

TABLE 21

In the aspect shown in table 21, the signal unit 520 may include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a "Num SS" field indicating the number of spatial streams used. The "Num SS" field may be 2 bits long.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 1 bit long. The signal unit 520 may further include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. For multiple users, some bits of the "MCS" field may be used to indicate the coding for users 1-3. For example, the first, second, and third bits of the "MCS" field may be used to indicate coding for users 1, 2, and 3, respectively. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes. The signal unit 520 may further include doppler/reserved bits that may be used as reserved bits or as doppler mitigation bits to signal to the receiver that there are sections in the signal unit 520 that may cause the receiver to mitigate the effects of "high time channel variations" during transmission of the signal unit 520.

The signal unit 520 may further include a "CRC" field indicating the result of a Cyclic Redundancy Check (CRC) calculated over one or more fields of the signal unit 520. The "CRC" field may be 4 bits long. In an embodiment, another error detection code may be used instead of or in addition to the CRC. The signal unit 520 may omit a "tail" field for resetting the state of the convolutional encoder and/or decoder and, for example, use truncation as will be described more fully below.

In an embodiment, for a 2MHz SIG packet with a short preamble, the signal unit 520 may include one or more fields shown in table 22 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 22. In some embodiments, signal unit 520 has only the fields shown in table 22. In some embodiments, signal unit 520 has the fields shown in table 22 in the order shown in table 22. In some embodiments, at least a portion of the information for the plurality of fields shown in table 22 is included in a single field. For example, the first and second fields of table 22 may be reduced to a single field that includes information for both the first and second fields.

As discussed below, an outlier in one or more fields shown in table 22 may indicate that one or more fields of signal unit 520 should be interpreted differently. For example, when one field in a signal unit includes an abnormal state, one or more other fields of the signal unit 520 may include other information related to an alternate frame type (such as an ACK frame, a beacon frame, a SYNC beacon frame, a link adaptation frame, etc.). Other information may include synchronization information, beacon information, link adaptation information, acknowledgement information, and the like. In general, a zero-length payload may be indicated by one or more fields in the signal unit 520 having an abnormal status.

In one embodiment, an all 0 value in the "length" field of the 2MHz SIG packet may indicate that one or more reserved bits may indicate an alternate frame type. In another embodiment, an all 1 value in the "MCS" field may indicate that the payload length is 0, and one or more bits of the "length" field contain data related to the alternate frame type. In another embodiment, a non-zero value in the one or more "reserved" bits may indicate that the payload length is 0, and one or more bits of the "length" field contain data related to the alternate frame type. In some embodiments, an outlier in the "length" field may indicate how the SIG field should be interpreted. In some embodiments, an outlier in the "length" field may indicate the number of data symbols after the PHY preamble, and optionally at what MCS these symbols are encoded. The outlier of the "length" field may include, for example, a small length, such as 0, 1, 2, 3, or a value less than, for example, 5 or 10.

TABLE 22

In the aspect shown in table 22, the signal unit 520 may include a first "reserved" field that may be 1 bit long. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a second "reserved" field, which may be 1 bit long.

The signal unit 520 may further include a Bandwidth (BW) field indicating a BW to be used. The "BW" field may be 2 bits long. In various embodiments, the 2-bit "BW" field may indicate whether the bandwidth is 2MHz, 4MHz, 8MHz, or 16 MHz. The signal unit 520 may further include an "Nsts" field. The "Nsts" field may provide the number of space-time streams (STS). The "Nsts" field may be 2 bits long.

The signal unit 520 may further include a "PAID" field indicating a partial association identifier associated with the data unit 500. The "PAID" field may be 9 bits long. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 2 bits long. The signal unit 520 may further include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. For multiple users, some bits of the "MCS" field may be used to indicate the coding for users 1-3. For example, the first, second, and third bits of the "MCS" field may be used to indicate coding for users 1, 2, and 3, respectively. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include a "smoothing" field indicating whether smoothing is recommended for the channel estimate. The "smooth" field may be 1 bit long. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes. The signal unit 520 may further include an "ACK indication" field that indicates whether the signal unit is an acknowledgement. In an embodiment, the "ACK indication" field may indicate whether the signal unit 520 is an acknowledgement (0x00), a block acknowledgement (0x01), or a non-acknowledgement (0x 10). The value (0x11) may be retained. The "ACK indication" field may be 2 bits long. The signal unit may include a third "reserved" field. The third "reserved" field may be 2 bits long.

In an embodiment, the first "reserved" field, the "STBC" field, the second "reserved" field, the "BW" field, the "Nsts" field, the "PAID" field, the "SGI" field, the "coding" field, the "MCS" field, and the "smooth" field may be encoded using the first symbol of SIG-a. In an embodiment, the "aggregation" field, the "length" field, the "ACK indication" field, the third "reserved" field, the "CRC" field, and the "tail" field may be encoded using the second symbol of SIG-a.

In an embodiment, for a 2MHz SIG-a packet with a long preamble and intended for a single user, the signal unit 520 may include one or more fields shown in table 23 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 23. In some embodiments, signal unit 520 has only the fields shown in table 23. In some embodiments, signal unit 520 has the fields shown in table 23 in the order shown in table 23. In some embodiments, at least a portion of the information for the plurality of fields shown in table 23 is included in a single field. For example, the first and second fields of table 23 may be reduced to a single field that includes information for both the first and second fields.

As discussed below, outliers in one or more fields shown in table 23 may indicate that one or more fields of signal unit 520 should be interpreted differently. For example, when one field in the signal unit includes an outlier, one or more other fields of the signal unit 520 may include other information related to the replacement frame type (such as an ACK frame, a beacon frame, a SYNC beacon frame, a link adaptation frame, etc.). Other information may include synchronization information, beacon information, link adaptation information, acknowledgement information, and the like. In general, a zero-length payload may be indicated by one or more fields in the signal unit 520 having an abnormal status.

In one embodiment, an all 0 value in the "length" field of the 2MHz SIG-a packet may indicate that one or more reserved bits may indicate an alternate frame type. In another embodiment, an all 1 value in the "MCS" field may indicate that the payload length is 0, and one or more bits of the "length" field contain data related to the alternate frame type. In another embodiment, a non-zero value in the one or more "reserved" bits may indicate that the payload length is 0, and one or more bits of the "length" field contain data related to the alternate frame type. In some embodiments, an outlier in the "length" field may indicate how the SIG field should be interpreted. In some embodiments, an outlier in the "length" field may indicate the number of data symbols after the PHY preamble, and optionally at what MCS these symbols are encoded. The outlier of the "length" field may include, for example, a small length, such as 0, 1, 2, 3, or a value less than, for example, 5 or 10.

TABLE 23

In the aspect shown in table 23, signal unit 520 may include a "MU/SU" field that indicates whether the signal unit is for a single user or multiple users. The "MU/SU" field may be 1 bit long. The "MU/SU" field may be set to 0 for a single user. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a first "reserved" field, which may be 1 bit long.

The signal unit 520 may further include a Bandwidth (BW) field indicating a BW to be used. The "BW" field may be 2 bits long. In various embodiments, the 2-bit "BW" field may indicate whether the bandwidth is 2MHz, 4MHz, 8MHz, or 16 MHz. The signal unit 520 may further include an "Nsts" field. The "Nsts" field may provide the number of space-time streams (STS). The "Nsts" field may be 2 bits long. The signal unit 520 may further include a "PAID" field indicating a partial association identifier associated with the data unit 500. The "PAID" field may be 9 bits long.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 2 bits long. In an embodiment, the first bit of the "encode" field is a coding type for a single user and the second bit is a coding type for LDPC Nsym ambiguity. The signal unit 520 may further include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. The "MCS" field may indicate coding for a single user. For multiple users, some bits of the "MCS" field may be used to indicate the coding for users 1-3. For example, the first, second, and third bits of the "MCS" field may be used to indicate coding for users 1, 2, and 3, respectively. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include a "beam change indication" field indicating whether the orthogonal component matrix (Q matrix) changes the start data STF (D-STF). The "beam change indication" field may be 1 bit long. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes. The signal unit 520 may further include an "ACK indication" field that indicates whether the signal unit is an acknowledgement. In an embodiment, the "ACK indication" field may indicate whether the signal unit 520 is an acknowledgement (0x00), a block acknowledgement (0x01), or a non-acknowledgement (0x 10). The value (0x11) may be retained. The "ACK indication" field may be 2 bits long. The signal unit may include a second "reserved" field. The "reserved" field may be 2 bits long.

In an embodiment, the "MU/SU" field, the "STBC" field, the first "reserved" field, the "BW" field, the "Nsts" field, the "PAID" field, the "SGI" field, the "coding" field, the "MCS" field, and the "beam change indication" field may be coded using the first symbol of SIG-a. In an embodiment, the "aggregation" field, the "length" field, the "ACK indication" field, the second "reserved" field, the "CRC" field, and the "tail" field may be encoded using the second symbol of SIG-a.

In an embodiment, for a 2MHz SIG-a packet with a long preamble and intended for multiple users, the signal unit 520 may include one or more fields as shown in table 24 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 24. In some embodiments, signal unit 520 has only the fields shown in table 24. In some embodiments, signal unit 520 has the fields shown in table 24 in the order shown in table 24. In some embodiments, at least a portion of the information for the plurality of fields shown in table 24 is included in a single field. For example, the first and second fields of table 24 may be reduced to a single field that includes information for both the first and second fields.

As discussed below, an outlier in one or more fields shown in table 24 may indicate that one or more fields of signal unit 520 should be interpreted differently. For example, when one field in a signal unit includes an abnormal state, one or more other fields of the signal unit 520 may include other information related to an alternate frame type (such as an ACK frame, a beacon frame, a SYNC beacon frame, a link adaptation frame, etc.). Other information may include synchronization information, beacon information, link adaptation information, acknowledgement information, and the like. In general, a zero-length payload may be indicated by one or more fields in the signal unit 520 having an abnormal status.

Watch 24

In the aspect shown in table 24, signal unit 520 may include a "MU/SU" field that indicates whether the signal unit is for a single user or multiple users. The "MU/SU" field may be 1 bit long. The "MU/SU" field may be set to 1 for multiple users. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a first "reserved" field, which may be 1 bit long.

The signal unit 520 may further include a Bandwidth (BW) field indicating a BW to be used. The "BW" field may be 2 bits long. In various embodiments, the 2-bit "BW" field may indicate whether the bandwidth is 2MHz, 4MHz, 8MHz, or 16 MHz. The signal unit 520 may further include an "Nsts" field. The "Nsts" field may provide the number of space-time streams (STS). The "Nsts" field may be 8 bits long. Two bits of the "Nsts" field may be provided per user for up to 4 users. The signal unit 520 may further include a "GID" field indicating a group identifier associated with the data unit 500. The "GID" field may be 6 bits long.

The signal unit 520 may further include an "encoding I" field indicating the type of encoding used. The "coding I" field may be 4 bits long. Each bit may indicate a coding type for each of the four users. The signal unit 520 may further include an "encoding II" field indicating LDPC Nsym ambiguity. The signal unit 520 may further include a "beam change indication" field indicating whether the Q matrix changes the starting D-STF. The "beam change indication" field may be 1 bit long.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes. The signal unit 520 may further include an "ACK indication" field that indicates whether the signal unit is an acknowledgement. In an embodiment, the "ACK indication" field may indicate whether the signal unit 520 is an acknowledgement (0x00), a block acknowledgement (0x01), or a non-acknowledgement (0x 10). The value (0x11) may be retained. The "ACK indication" field may be 2 bits long. The signal unit may include a second "reserved" field. The "reserved" field may be 1 bit long.

In an embodiment, the "MU/SU" field, the "STBC" field, the first "reserved" field, the "BW" field, the "Nsts" field, the "GID" field, the "SGI" field, and the "coding I" field may be encoded using the first symbol of SIG-a. In an embodiment, the "encode II" field, the "beam change indication" field, the "length" field, the "ACK indication" field, the second "reserved" field, the "CRC" field, and the "tail" field may be encoded using the second symbol of SIG-a.

In an embodiment, for a 1MHz SIG packet, the signal unit 520 may include one or more fields shown in table 25 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 25. In some embodiments, signal unit 520 has only the fields shown in table 25. In some embodiments, signal unit 520 has the fields shown in table 25 in the order shown in table 25. In some embodiments, at least a portion of the information for the plurality of fields shown in table 25 is included in a single field. For example, the first and second fields of table 25 may be reduced to a single field that includes information for both the first and second fields.

As discussed below, outliers in one or more fields shown in table 25 may indicate that one or more fields of signal unit 520 should be interpreted differently. For example, when one field in a signal unit includes an abnormal state, one or more other fields of the signal unit 520 may include other information related to an alternate frame type (such as an ACK frame, a beacon frame, a SYNC beacon frame, a link adaptation frame, etc.). Other information may include synchronization information, beacon information, link adaptation information, acknowledgement information, and the like. In general, a zero-length payload may be indicated by one or more fields in the signal unit 520 having an abnormal status.

In one embodiment, an all 0 value in the "length" field of the 1MHz SIG packet may indicate that one or more reserved bits may indicate an alternate frame type. In another embodiment, an all 1 value in the "MCS" field may indicate that the payload length is 0, and one or more bits of the "length" field contain data related to the alternate frame type. In another embodiment, a non-zero value in the one or more "reserved" bits may indicate that the payload length is 0, and one or more bits of the "length" field contain data related to the alternate frame type. In some embodiments, an outlier in the "length" field may indicate how the SIG field should be interpreted. In some embodiments, an outlier in the "length" field may indicate the number of data symbols after the PHY preamble, and optionally at what MCS these symbols are encoded. The outlier of the "length" field may include, for example, a small length, such as 0, 1, 2, 3, or a value less than, for example, 5 or 10.

TABLE 25

In the aspect shown in table 25, signal unit 520 may include an "Nsts" field. The "Nsts" field may provide the number of space-time streams (STS). The "Nsts" field may be 2 bits long. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 2 bits long. The 1 bit may indicate a coding type (LDPC/BCC). The second bit may indicate LDPC N_symAmbiguity. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a first "reserved" field, which may be 1 bit long.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes. The signal unit 520 may further include an "ACK indication" field that indicates whether the signal unit is an acknowledgement. In an embodiment, the "ACK indication" field may indicate whether the signal unit 520 is an acknowledgement (0x00), a block acknowledgement (0x01), or a non-acknowledgement (0x 10). The value (0x11) may be retained. The "ACK indication" field may be 2 bits long. The signal unit may include a second "reserved" field. The "reserved" field may be 3 bits long.

In one embodiment, one reserved bit is placed just after the first symbol. This may provide new PHY features. This provides a total of four (4) reserved bits.

In an embodiment, for a 2MHz SIG packet with a short preamble, the signal unit 520 may include one or more fields shown in table 26 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths.

The ordering of the fields may affect the peak-to-average power ratio at which the packet is received or transmitted or generated. Thus, in some embodiments, the ordering of the fields may be changed to reduce the peak-to-average power ratio experienced when receiving or transmitting or generating packets. Peak-to-average power ratio measurements have been made for packets having the fields and field order shown in table 26. The measurement shows a peak to average power ratio of 11.59 db for the first symbol and 9.86 db for the second symbol when the reserved bit is set to one (1). When the reserved bit is set to 0, experimental results have shown that there is a peak-to-average power ratio of 13.4845 db for the first symbol and 10.4742 db for the second symbol when the reserved bit is set to zero (0).

In some embodiments, signal unit 520 has all of the fields shown in table 26. In some embodiments, signal unit 520 has only the fields shown in table 26. In some embodiments, the signal unit 520 has the fields shown in table 26 in the order shown in table 26. In some embodiments, at least a portion of the information for the multiple fields shown in table 26 is included in a single field. For example, the first and second fields of table 26 may be reduced to a single field that includes information for both the first and second fields.

As discussed below, an outlier in one or more fields shown in table 26 may indicate that one or more fields of signal unit 520 should be interpreted differently. For example, when one field in a signal unit includes an abnormal state, one or more other fields of the signal unit 520 may include other information related to an alternate frame type (such as an ACK frame, a beacon frame, a SYNC beacon frame, a link adaptation frame, etc.). Other information may include synchronization information, beacon information, link adaptation information, acknowledgement information, and the like. In general, a zero-length payload may be indicated by one or more fields in the signal unit 520 having an abnormal status.

Watch 26

In the aspect shown in table 26, the signal unit 520 may include a first "reserved" field that may be 1 bit long. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a second "reserved" field, which may be 1 bit long.

The signal unit 520 may further include a Bandwidth (BW) field indicating a BW to be used. The "BW" field may be 2 bits long. In various embodiments, the 2-bit "BW" field may indicate whether the bandwidth is 2MHz, 4MHz, 8MHz, or 16 MHz.

The signal unit 520 may further include an "Nsts" field. The "Nsts" field may provide the number of space-time streams (STS). The "Nsts" field may be 2 bits long.

The signal unit 520 may further include a "length" field indicating the length of the payload 530. The "length" field may be 9 bits long. In an embodiment, the "length" field may indicate the length of the payload 530 in symbol units when an a-MPDU is being used. The "length" field may indicate the length of the payload 530 in bytes when the a-MPDU is not being used. In an embodiment, a-MPDUs are used for packet sizes larger than 511 bytes. The signal unit 520 may further include an "SGI" field indicating a Short Guard Interval (SGI) used. The "SGI" field may be 1 bit long. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 8 μ s. In some embodiments, the short guard interval may be 2 μ s and the normal guard interval may be 4 μ s.

The signal unit 520 may further include a "PAID" field indicating a partial association identifier associated with the data unit 500. The "PAID" field may be 9 bits long. The signal unit 520 may further include an "ACK indication" field that indicates whether the signal unit is an acknowledgement. In an embodiment, the "ACK indication" field may indicate whether the signal unit 520 is an acknowledgement (0x00), a block acknowledgement (0x01), or a non-acknowledgement (0x 10). The value (0x11) may be retained. The "ACK indication" field may be 2 bits long. The signal unit may include a third "reserved" field. The third "reserved" field may be 2 bits long.

In an embodiment, the first "reserved" field, the "STBC" field, the second "reserved" field, the "BW" field, the "Nsts" field, the "length" field, the "SGI" field, the "coding" field, the "MCS" field, and the "smooth" field may be encoded using the first symbol of SIG-a. In an embodiment, the "aggregation" field, the "PAID" field, the "ACK indication" field, the third "reserved" field, the "CRC" field, and the "tail" field may be encoded using the second symbol of SIG-a.

In one embodiment, one reserved bit is placed in the first symbol. This may provide new PHY features.

In an embodiment, generating or receiving a 2MHz first symbol with a short preamble SIG field in the field order as shown in table 26 may provide a maximum peak-to-average power ratio (PAPR) of less than 7.1 decibels. This PAPR can be measured using open loop transmission, 256 byte grouping, aggregation off, ACK indication field set to ACK, one stream, MCS0, and MCS 7. All combinations of the remaining unspecified fields may be considered in determining such a PAPR. The CRC field uses the four Least Significant Bits (LSBs) of a conventional 8-bit CRC field in 802.11n or 802.11 ac. QBPSK modulation is used on both SIG symbols. A 4x oversampled IFFT is also used. The maximum PAPR value described above is determined by measuring the PAPR over all combinations of unspecified fields.

In an embodiment, for a 2MHz SIG-a packet with a long preamble and intended for a single user, the signal unit 520 may include one or more fields shown in table 27 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths.

The ordering of the fields may affect the peak-to-average power ratio at which the packet is received or transmitted or generated. Thus, in some embodiments, the ordering of the fields may be changed to reduce the peak-to-average power ratio experienced when receiving or transmitting or generating packets. Peak-to-average power ratio measurements have been made for packets having the fields and field order shown in table 27. The measurement shows a peak to average power ratio of 11.1304 db for the first symbol and 10.4442 db for the second symbol when the reserved bit is set to one (1). When the reserved bit is set to 0, experimental results have shown that there is a peak-to-average power ratio of 13.4845 db for the first symbol and 8.8606 db for the second symbol when the reserved bit is set to zero (0).

In some embodiments, signal unit 520 has all of the fields shown in table 27. In some embodiments, signal unit 520 has only the fields shown in table 27. In some embodiments, signal unit 520 has the fields shown in table 27 in the order shown in table 27. In some embodiments, at least a portion of the information for the plurality of fields shown in table 27 is included in a single field. For example, the first and second fields of table 27 may be reduced to a single field that includes information for both the first and second fields.

As discussed below, outliers in one or more fields shown in table 27 may indicate that one or more fields of signal unit 520 should be interpreted differently. For example, when one field in a signal unit includes an abnormal state, one or more other fields of the signal unit 520 may include other information related to an alternate frame type (such as an ACK frame, a beacon frame, a SYNC beacon frame, a link adaptation frame, etc.). Other information may include synchronization information, beacon information, link adaptation information, acknowledgement information, and the like. In general, a zero-length payload may be indicated by one or more fields in the signal unit 520 having an abnormal status.

Watch 27

In the aspect shown in table 27, signal unit 520 may include a "MU/SU" field that indicates whether the signal unit is for a single user or multiple users. The "MU/SU" field may be 1 bit long. The "MU/SU" field may be set to 0 for a single user. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a first "reserved" field, which may be 1 bit long.

The signal unit 520 may further include an "encoding" field indicating the type of encoding used. The "code" field may be 2 bits long. In an embodiment, the first bit of the "encode" field is a coding type for a single user and the second bit is a coding type for LDPC Nsym ambiguity. The signal unit 520 may further include an "Modulation and Coding Scheme (MCS) field indicating a used MCS. The "MCS" field may be 4 bits long. The "MCS" field may indicate coding for a single user. For multiple users, some bits of the "MCS" field may be used to indicate the coding for users 1-3. For example, the first, second, and third bits of the "MCS" field may be used to indicate coding for users 1, 2, and 3, respectively. In an embodiment, the "MCS" field may indicate that Quadrature Phase Shift Keying (QPSK) is used, for example. The signal unit 520 may further include a "beam change indication" field indicating whether the Q matrix changes the starting D-STF. The "beam change indication" field may be 1 bit long. The signal unit 520 may further include an "aggregation" field that indicates whether an a-MPDU is being used. The "aggregation" field may be 1 bit long.

The signal unit 520 may further include a "PAID" field indicating a partial association identifier associated with the data unit 500. The "PAID" field may be 9 bits long.

The signal unit 520 may further include an "ACK indication" field that indicates whether the signal unit is an acknowledgement. In an embodiment, the "ACK indication" field may indicate whether the signal unit 520 is an acknowledgement (0x00), a block acknowledgement (0x01), or a non-acknowledgement (0x 10). The value (0x11) may be retained. The "ACK indication" field may be 2 bits long. The signal unit may include a second "reserved" field. The "reserved" field may be 2 bits long.

In an embodiment, the "MU/SU" field, the "STBC" field, the first "reserved" field, the "BW" field, the "Nsts" field, the length "field, the" SGI "field, the" coding "field, the" MCS "field, and the" beam change indication "field may be coded using the first symbol of SIG-a. In an embodiment, the "aggregation" field, the "PAID" field, the "ACK indication" field, the second "reserved" field, the "CRC" field, and the "tail" field may be encoded using the second symbol of SIG-a.

In an embodiment, generating or receiving a 2MHz first symbol of a long preamble single user SIG-a field with fields ordered as described in table 27 may result in a maximum peak to average power ratio of less than 8.7 db. This PAPR can be measured using a single user BF transmission, 256 byte packets, aggregation off, ACK indication field set to ACK, one stream and MCS 7. All combinations of the remaining unspecified fields may be considered in determining this PAPR. The CRC field uses the four Least Significant Bits (LSBs) of a conventional 8-bit CRC field in 802.11n or 802.11 ac. QBPSK modulation is used for both SIG symbols. A 4x oversampled IFFT is also used. The above maximum PAPR value is determined by measuring the PAPR for all combinations of unspecified fields.

In an embodiment, for a 2MHz SIG-a packet with a long preamble and intended for multiple users, the signal unit 520 may include one or more fields as shown in table 28 below. Although the fields are shown as having a particular length and in a particular order, in various embodiments one or more fields may be rearranged, added, omitted, or may have different lengths. In some embodiments, signal unit 520 has all of the fields shown in table 28.

The ordering of the fields may affect the peak-to-average power ratio at which the packet is received or transmitted or generated. Thus, in some embodiments, the ordering of the fields may be changed to reduce the peak-to-average power ratio experienced when receiving or transmitting or generating packets. Peak-to-average power ratio measurements have been made for packets having the fields and field order shown in table 28. The measurement shows a peak to average power ratio of 11.8997 db for the first symbol and 11.014 db for the second symbol when the reserved bit is set to one (1). When the reserved bit is set to 0, experimental results have shown that there is a peak-to-average power ratio of 10.6865 db for the first symbol and 11.8570 db for the second symbol when the reserved bit is set to zero (0).

In some embodiments, signal unit 520 has only the fields shown in table 28. In some embodiments, the signal unit 520 has the fields shown in table 28 in the order shown in table 28. In some embodiments, at least a portion of the information for the plurality of fields shown in table 28 is included in a single field. For example, the first and second fields of table 28 may be reduced to a single field that includes information for both the first and second fields.

As discussed below, outliers in one or more fields shown in table 28 may indicate that one or more fields of signal unit 520 should be interpreted differently. For example, when one field in a signal unit includes an abnormal state, one or more other fields of the signal unit 520 may include other information related to an alternate frame type (such as an ACK frame, a beacon frame, a SYNC beacon frame, a link adaptation frame, etc.). Other information may include synchronization information, beacon information, link adaptation information, acknowledgement information, and the like. In general, a zero-length payload may be indicated by one or more fields in the signal unit 520 having an exception status.

Watch 28

In the aspect shown in table 28, signal unit 520 may include a "MU/SU" field that indicates whether the signal unit is for a single user or multiple users. The "MU/SU" field may be 1 bit long. The "MU/SU" field may be set to 1 for multiple users. The signal unit 520 may further include an "STBC" field indicating whether space-time block coding (STBC) is used. The "STBC" field may be 1 bit long. The signal unit 520 may further include a first "reserved" field, which may be 1 bit long.

The signal unit 520 may further include an "Nsts" field. The "Nsts" field may provide the number of space-time streams (STS). The "Nsts" field may be 8 bits long. Two bits of the "Nsts" field may be provided per user for up to 4 users. The signal unit 520 may further include a Bandwidth (BW) field indicating a BW to be used. The "BW" field may be 2 bits long. In various embodiments, the 2-bit "BW" field may indicate whether the bandwidth is 2MHz, 4MHz, 8MHz, or 16 MHz. The signal unit 520 may further include a "GID" field indicating a group identifier associated with the data unit 500. The "GID" field may be 6 bits long.

In an embodiment, generating or receiving a second symbol of the 8MHz, long preamble multi-user SIG field with fields in the order as described in table 28 may result in a maximum peak-to-average power ratio (PAPR) of less than 11.1 db. This PAPR can be measured using a multi-user transmission with three users. The group ID is set to three (3). A 1500 byte packet is used with the ACK indication field set to block ACK (ba), one stream per user, and MCS 7. All combinations of the remaining unspecified fields may be considered in determining this maximum PAPR. The CRC field uses the four Least Significant Bits (LSBs) of a conventional 8-bit CRC field in 802.11n or 802.11 ac. QBPSK modulation is used on both SIG symbols. A 4x oversampled IFFT is also used. The maximum PAPR value is determined by measuring the PAPR over all combinations of unspecified fields.

Because each of the seven symbols of signal unit 520 is represented by a BPSK constellation having a rotation state on either the real axis or the imaginary axis, the rotation state of each symbol may convey additional bits of information. For example, if the first symbol is on the real axis, this may convey that STBC is enabled. Any bit of signal unit 520 may be conveyed by the symbol rotation state. In the example shown in table 28, at least one bit is conveyed by the rotation state of one of the symbols. In some embodiments, up to 6 reserved bits may be conveyed by the symbol rotation state. The reserved bits conveyed by the symbol rotation state may be the first reserved bit, the second reserved bit, or a combination of the first and second reserved bits. In some embodiments, for robustness, a single bit may be conveyed by the rotation state of multiple symbols.

In various embodiments, one or more fields in the signal unit 520 may include one or more "abnormal" states or values. The abnormal state may include, for example, a field value that will not normally occur. For example, if the value of the "MCS" field may be "00", "01", or "10" normally, a value of all 1's (e.g., "11") may be considered an abnormal state. As another example, all 0 values in the "Length" field may be exception status. As another example, a non-0 value in any one of the "reserved" bits may be an abnormal state.

The exception field status may indicate that one or more fields of the signal unit 520 should be interpreted differently. For example, when one field in a signal unit includes an abnormal state, one or more other fields of the signal unit 520 may include other information related to an alternate frame type (such as an ACK frame, a beacon frame, a SYNC beacon frame, a link adaptation frame, etc.). Other information may include synchronization information, beacon information, link adaptation information, acknowledgement information, and the like. In general, a zero-length payload may be indicated by one or more fields in the signal unit 520 having an abnormal status.

In one embodiment, an all 0 value in the "length" field may indicate that one or more reserved bits may indicate an alternate frame type. In another embodiment, an all 1 value in the "MCS" field may indicate that the payload length is 0, and one or more bits of the "length" field contain data related to the alternate frame type. In another embodiment, a non-zero value in the one or more "reserved" bits may indicate that the payload length is 0, and one or more bits of the "length" field contain data related to the alternate frame type. In some embodiments, an outlier in the "length" field may indicate how the SIG field should be interpreted. In some embodiments, an outlier in the "length" field may indicate the number of data symbols after the PHY preamble, and optionally at what MCS these symbols are encoded. The outlier of the "length" field may include, for example, a small length, such as 0, 1, 2, 3, or a value less than, for example, 5 or 10.

In some embodiments, an outlier in the "reserved" bit indicates whether the ACK packet follows the current frame. In some implementations, the "reserved" bit may indicate that the current frame is a control frame and the remaining bits are reserved for MAC indication, including length.

Table 29-SIG fields for short format preamble, 2MHz and higher

Table 29 illustrates an example of a SIG field that may be used for a short format preamble in a bandwidth mode of 2MHz or higher. The first 10 fields of the SIG field (i.e., reserved, STBC, reserved, BW, Nsts, length, SGI, coding, MCS, and smoothing) may be in the first symbol of the SIG field, and the last 6 fields of the SIG field (i.e., aggregation bits, PAID, ACK indication, reserved, CRC, and tail) may be in the second symbol of the SIG field. In particular embodiments, at least one reserved bit may be included in the first symbol of the SIG field to provide subsequently developed PHY features.

Table 30-SIG-a field for long format preamble, 2MHz and higher, SU

Table 30 illustrates an example of a SIG-a field that may be used for a long format preamble in a bandwidth mode of 2MHz or higher for a Single User (SU) transmission. The first 10 fields of the SIG-a field (i.e., MU/SU bits, STBC, reserved, BW, Nsts, length, SGI, coding, MCS, and beam change indication bits) may be in the first symbol of the SIG-a field, and the last 6 fields of the SIG-a field (i.e., aggregation bits, PAID, ACK indication, reserved, CRC, and tail) may be in the second symbol of the SIG-a field.

Table 31-SIG-a field for long format preamble, 2MHz and higher, MU

Table 31 illustrates an example of a SIG-a field that may be used for a long format preamble in a bandwidth mode of 2MHz or higher for multi-user (MU) transmissions (e.g., for up to 4 users). The first 8 fields of the SIG-a field (i.e., MU/SU bits, STBC, reserved, Nsts, BW, GID, SGI, and code I) may be in the first symbol of the SIG-a field, and the last 7 fields of the SIG-a field (i.e., code II, reserved, length, ACK indication, reserved, CRC, and tail) may be in the second symbol of the SIG-a field. It will be noted that the order of the Nsts and BW fields may be reversed compared to the SU SIG-a fields shown in table 30. This reversal may result in improved peak-to-average power ratio (PAPR) for the MU SIG-a field shown in table 31.

Table 32-SIG field for 1MHz mode

Table 32 illustrates an example of a SIG field that may be used for a 1MHz transmission. In a particular embodiment, the SIG field of table 32 occupies 6 symbols (36 bits in the case of 6 bits per symbol for a 1MHz bandwidth).

Fig. 6 illustrates a flow diagram of an aspect of an exemplary method 600 for generating and transmitting data units. The method 600 may be used to generate any of the data units and signal units described above. These data units may be generated at the AP or STA and transmitted to another device in the wireless network. Although the method 600 is described below with respect to elements of the wireless device 202a (fig. 3), one of ordinary skill in the art will appreciate that other components may be used to implement one or more of the steps described herein. Although the steps may be described as occurring in a particular order, the steps may be reordered, steps may be omitted, and/or additional steps may be added.

At 602, the processor 204 generates a signal unit 520. The signal unit 520 includes at least an encoded PAID field. The PAID field has a value that indicates that a portion of the signal unit is to be decoded by one or more devices that receive the signal unit, and the value of the PAID field indicates that the portion of the signal unit is not to be decoded by one or more other devices that receive the signal unit. In an embodiment, modulator 302 may modulate a transmission including signal unit 520, and transform module 304 may convert the tones corresponding to the transmission to the time domain. Proceeding to 604, the transmitter 210 transmits the data unit including the signal unit over a wireless channel.

Fig. 7 illustrates a flow diagram of another aspect of an exemplary method 700 for receiving and processing a data unit including a signal unit 520. Method 700 may be used to receive any of the data units described above. These packets may be received at the AP or STA from another device in the wireless network. Although the method 700 is described below with respect to elements of the wireless device 202b (fig. 4), one of ordinary skill in the art will appreciate that other components may be used to implement one or more of the steps described herein. Although the steps may be described as occurring in a particular order, the steps may be reordered, steps may be omitted, and/or additional steps may be added.

At 702, the receiver 212 receives a signal unit 520. The signal unit 520 includes at least an encoded PAID field. For example, the signal unit 520 may include one or more of the fields shown in tables 1-28 above. Proceeding to 704, the processor 204 decodes the PAID field. Continuing to 706, the processor 204 determines whether the PAID field has a value that indicates that an undecoded portion of the signal unit 520 is to be decoded. At 708, if the value of the PAID field has a value that indicates that the signal unit 520 is to be decoded, the processor 204 decodes the signal unit 520. At 710, if the value of the PAID field does not have a value indicating that the signal unit 520 is to be decoded, the processor 204 defers for a period of time.

In at least some embodiments discussed above, the signal unit 520 is encoded using a convolutional code, and the tail bits are included in the signal unit 520. The tail bits may be all 0's, as in a "0 tail code," and may be used to return the encoder to the 0 state so that the decoding process at the receiver may be initiated from the 0 state. The encoder returns to the 0 state before each signal element 520 by adding a tail bit to the end of each signal element 520. Thus, each signal unit 520 may be encoded separately from each other signal unit 520 by re-initializing the encoder before each signal unit 520. The independently coded signal units 520 may also be independently modulated. Furthermore, the start and end states of the encoder are known to the decoder for decoding the signal unit 520. Thus, each signal unit 520 may be decoded and (in some cases) demodulated separately from each other signal unit 520.

In some embodiments, the signal unit 520 may be transmitted as a short block code. For example, any of the embodiments discussed herein may be transmitted as a short block code. Thus, in some embodiments, signal element 520 has no tail bits (referred to as "tail-biting"). For example, signal unit 520 may be the same as any of the other embodiments discussed herein, except that there are no tail bits. For example, any of the embodiments discussed with reference to tables 1-28 may be transmitted as a short block code without tail bits.

The signal unit 520 may be encoded as a linear block code or a short block code using, for example, a spread Hamming (Hamming) code, such as a (8, 4) ratio 1/2 spread Hamming code. The signal unit 520 may be encoded as a short block code using, for example, an extended Golay code, such as a (24, 12, 8) ratio 1/2 extended Golay code. The signal unit 520 may be encoded as a short block code using, for example, a Quadratic Residue (QR) code, such as a (48, 24, 12) ratio 1/2QR code. The signal unit 520 may be encoded as a short block code using, for example, a tail-biting convolutional code (TBCC), such as the TBCC code discussed below.

When truncation is used, no tail bits are included in the signal unit 520. Instead, the last, e.g., "n", bits of the signal unit 520 (where "n" represents a predetermined number of bits) are used to initialize the encoder so that the starting and ending states of the encoder are the same, but not necessarily 0. By initializing the encoder with the last "n" bits of the signal unit 520, each field or subfield of the signal unit 520 may be encoded separately from each other field or subfield by applying convolutional encoding to each field or subfield cycle. The independently coded fields or subfields may also be independently modulated. In the case of truncation coding, the decoder knows that the starting and ending states of the encoder are the same but does not know what those states are. Therefore, the decoder must be able to determine the start and end states in order to decode a received field or subfield, for example by applying convolutional decoding to repetitions of the field or subfield. The decoder may be able to determine the starting and ending status of a field or sub-field from information provided in the preamble. Thus, each field or subfield may be decoded and (in some cases) demodulated separately from each other field or subfield in the signal unit 520. When truncation is used, a CRC may also be added to each field or subfield so that a determination may be made as to whether each field or subfield has been successfully decoded independently of each other field or subfield in signal unit 520. The encoding process may result in a sequence of code symbols for each field or subfield that may be chunked together and mapped to a signal constellation to generate one or more modulation symbols for each field or subfield.

Fig. 8 illustrates a flow diagram of an aspect of an exemplary method 800 for generating and transmitting data units. The method 800 may be used to generate any of the data units and signal units 410 described above. The data unit may be generated at the AP 104 or the STA 106 and transmitted to another node in the wireless network. Although the method 800 is described below with respect to elements of the wireless device 202a (fig. 3), one of ordinary skill in the art will appreciate that other components may be used to implement one or more of the steps described herein. Although the steps may be described as occurring in a particular order, the steps may be reordered, steps may be omitted, and/or additional steps may be added.

At 802, the processor 204 generates a signal unit 520. The signal unit 520 includes at least a length field and one or more additional fields. For example, the signal unit 520 may include one or more of the fields shown in tables 1-28 above. A first field of the one or more additional fields may include an outlier indicating a zero-length payload. As discussed above, the outliers may include field values outside of the normal operating range. In an embodiment, modulator 302 may modulate a transmission including signal unit 520, and transform module 304 may convert tones corresponding to signal unit 520 to the time domain. At 804, the transmitter 210 transmits a data unit including the signal unit 520 over a wireless channel.

Fig. 9 illustrates a flow diagram of another aspect of an exemplary method 900 for receiving and processing a data unit including signal unit 520. Method 900 may be used to receive any of the data units described above. These packets may be received at the AP 104 or the STA 106 from another node in the wireless network. Although the method 900 is described below with respect to elements of the wireless device 202b (fig. 4), one of ordinary skill in the art will appreciate that other components may be used to implement one or more of the steps described herein. Although the steps may be described as occurring in a particular order, the steps may be reordered, steps may be omitted, and/or additional steps may be added.

At 902, the receiver 212 receives a signal unit 520. The signal unit 520 includes at least a length field and one or more additional fields. For example, the signal unit 520 may include one or more of the fields shown in tables 1-28 above. Continuing to 904, the processor 204 determines whether a first field of the one or more additional fields has an outlier that indicates a zero-length payload. As discussed above, the outliers may include field values outside of the normal operating range.

Proceeding to 906, the processor 204 decodes the length field based on the determined outlier. For example, the MCS field may include all 1 outliers. The processor 204 may then decode the reserved bits and determine an alternate frame type. For example, the processor 204 may determine the ACK frame type. Processor 204 may then decode bits in the length field with respect to one or more parameters of the ACK frame.

In a particular embodiment, a device may generate a SIG unit (e.g., signal unit 520) that includes a length field and an aggregation field. For example, the length field may be 9 bits long and the aggregation field may be 1 bit long. Before, after, or during generation of the SIG unit, the device may determine whether to use aggregated transmissions (e.g., a-MPDUs). In a particular embodiment, the aggregated transmission may be mandatory for frame sizes greater than or equal to 512 bytes in size, but may be optional for frame sizes less than 512 bytes. In response to determining to use the aggregated transmission, the device sets the aggregation field to a first value (e.g., "1") and the length field to the number of symbols. In response to determining not to use the aggregated transmission, the device sets the aggregation field to a second value (e.g., "0") and sets the length field to a number of bytes. The device may transmit the SIG unit via a wireless network (a sub-1 GHz network that conforms to the IEEE 802.11ah protocol). The SIG unit may be included in a preamble of a frame, such as a Single User (SU) or multi-user (MU) frame.

In a particular embodiment, a device may receive a SIG unit (e.g., signal unit 520) that includes a length field and an aggregation field. The device may interpret the length field as a number of symbols in response to determining that the aggregation field has a first value (e.g., "1"). The device may interpret the length field as a number of bytes in response to determining that the aggregation field has a second value (e.g., "1").

In another particular embodiment, the apparatus may initially determine whether a frame including the SIG unit is associated with a 1MHz bandwidth. If the frame is associated with a 1MHz bandwidth, the device may interpret the length field as a number of bytes or a number of symbols based on the value of the aggregation field, as described above. However, if the frame is not associated with a 1MHz bandwidth, the device may determine whether the frame has a short format preamble or a long format preamble (e.g., by checking for rotation of the SIG unit). If the frame has a short format preamble, the device may interpret the length field as a number of bytes or a number of symbols based on the value of the aggregation field as described above. Conversely, if the frame has a long-format preamble, the device may determine whether the frame is an SU frame or an MU frame (e.g., by checking the SU/MU field). If the frame is a SU frame, the device may interpret the length field as a number of bytes or a number of symbols based on the value of the aggregation field, as described above. If the frame is an MU frame, the device may automatically interpret the length field as a number of symbols (e.g., because a wireless protocol or standard, such as IEEE 802.11ah, may force the length of an MU frame with a long format preamble to be interpreted as a number of symbols).

Fig. 10 is a functional block diagram of another example wireless device 1000 that may be employed in accordance with the present disclosure. The device 1000 includes a generating module 1002 for generating a data unit for wireless transmission. The generation module 1002 may be configured to perform one or more of the functions discussed above with respect to block 602 of fig. 6 and/or block 802 of fig. 8. The generating module 1002 may correspond to one or more of the processor 204 and the DSP 220. The device 1000 further comprises a transmitting module 1004 for wirelessly transmitting the data unit. The transmitting module 1004 may be configured to perform one or more of the functions discussed above with respect to block 604 of fig. 6 and/or block 804 of fig. 8. The transmitting module 1004 may correspond to the transmitter 210. In particular embodiments, the data unit may include a signal unit (e.g., signal unit 520) in which a length field of the signal unit is interpreted based on a value of an aggregation field and/or in which a particular field of the signal unit has a value indicating a zero-length payload.

Fig. 11 is a functional block diagram of yet another example wireless device 1100 that may be employed in accordance with the present disclosure. The device 1100 comprises a receiving module 1102 for wirelessly receiving data units. The receiving module 1102 may be configured to perform one or more of the functions discussed above with respect to block 702 of fig. 7 and/or block 902 of fig. 9. The receiving module 1102 may correspond to the receiver 212 and may include the amplifier 401.

The device 1100 further comprises a determining module 1104 for determining various characteristics of the data unit. For example, determination module 1140 may determine whether a first field of the one or more additional fields has an outlier that indicates a zero-length payload. As discussed above, the outliers may include field values outside of the normal operating range. As another example, the determination module may determine that the PAID field has a value indicating that an un-decoded portion of the SIG unit is to be decoded. The determination module 1104 may be configured to perform one or more of the functions discussed above with respect to block 904 of fig. 9 and/or block 706 of fig. 7. The determining module 1104 may correspond to one or more of the processor 204, the signal detector 218, and the DSP 220.

The device 1100 further comprises a decoding module 1106 for decoding data. For example, the decoding module 1106 can decode the length field based on the determined outlier. The decoding module 1106 can also decode the PAID field and the SIG unit if the value of the PAID field indicates that the SIG unit is to be decoded. If the value of the PAID field indicates that the SIG unit is not to be decoded, the decoding module 1106 defers for a period of time. The decode module 1106 may be configured to perform one or more of the functions discussed above with respect to block 704 of fig. 7, block 708 of fig. 7, block 710 of fig. 7, and/or block 906 of fig. 9. The decoding module 1106 may correspond to one or more of the processor 204, the signal detector 218, and the DSP220, and may include a channel estimator and equalizer 405.

As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" can include calculating, computing, processing, deriving, studying, looking up (e.g., looking up in a table, database, or other data structure), ascertaining, and the like. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Also, "determining" may include resolving, selecting, choosing, establishing, and the like. In addition, "channel width" as used herein may encompass in some aspects or may also be referred to as bandwidth.

As used herein, a phrase referring to "at least one of a list of items refers to any combination of those items, including a single member. By way of example, "at least one of a, b, or c" is intended to encompass: only a, only b, only c, a and b, a and c, b and c, and a, b and c.

The various operations of the methods described above may be performed by any suitable means capable of performing the operations, such as various hardware and/or software components, circuits, and/or modules. In general, any of the operations illustrated in the figures may be performed by corresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a field programmable gate array signal (FPGA) or other Programmable Logic Device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

In one or more aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks (disks) usually reproduce data magnetically, while discs (discs) reproduce data optically with lasers. Thus, in some aspects, computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media). Additionally, in some aspects, the computer readable medium may comprise a transitory computer readable medium (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.

The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

The functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions on a computer-readable medium. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk, and Blu-ray discDisks, where a disk (disk) usually reproduces data magnetically, and a disk (disc) reproduces data optically with a laser.

Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For certain aspects, the computer program product may include packaging materials.

The software or instructions may also be transmitted over a transmission medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of transmission medium.

Further, it is to be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station where applicable. For example, such a device can be coupled to a server to facilitate the transfer of an apparatus for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage device (e.g., RAM, ROM, a physical storage medium such as a Compact Disc (CD) or floppy disk, etc.) such that, upon coupling or providing the storage device to a user terminal and/or base station, the apparatus can obtain the various methods. Further, any other suitable technique suitable for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various changes, substitutions and alterations in the arrangement, operation and details of the method and apparatus described above may be made without departing from the scope of the claims.

While the foregoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. A method for interpreting a length field of a signal unit, comprising:

receiving, at a wireless device, a frame via a sub-1 gigahertz (GHz) wireless network, wherein the frame comprises the Signal (SIG) unit including the length field and an aggregation field;

in response to determining that the frame is associated with a1 megahertz (MHz) bandwidth mode, interpreting the length field as a number of bytes or a number of symbols based on a value of the aggregation field;

in response to determining that the frame is not associated with the 1MHz bandwidth mode, determining whether the frame includes a short format preamble or a long format preamble;

in response to determining that the frame includes the short format preamble, interpreting the length field as a number of bytes or a number of symbols based on the value of the aggregation field;

in response to determining that the frame includes the long-format preamble, determining whether the frame is a single-user (SU) frame or a multi-user (MU) frame;

in response to determining that the frame is the SU frame, interpreting the length field as a number of bytes or a number of symbols based on the value of the aggregation field; and

in response to determining that the frame is the MU frame, interpreting the length field as a number of symbols, wherein the sub-1 GHz wireless network operates in accordance with an institute of Electrical and electronics (IEEE)802.11ah protocol.

2. A method for interpreting a length field of a signal unit, comprising:

in response to determining that the frame is the MU frame, interpreting the length field as a number of symbols, wherein the aggregation field indicates whether data received by the wireless device corresponds to one or more aggregated media entry control (MAC) protocol data units (A-MPDUs).

3. A method for interpreting a length field of a signal unit, comprising:

interpreting the length field as a number of symbols in response to determining that the frame is the MU frame, wherein the length field is a 9-bit field.

4. A method for interpreting a length field of a signal unit, comprising:

interpreting the length field as a number of symbols in response to determining that the frame is the MU frame, wherein the aggregation field is a 1-bit field.

5. A method for interpreting a length field of a signal unit, comprising:

in response to determining that the frame is the MU frame, interpreting the length field as a number of symbols, wherein the SIG unit is included in a preamble of the frame.

6. A method for interpreting a length field of a signal unit, comprising:

in response to determining that the frame is the MU frame, interpreting the length field as a number of symbols, wherein the SIG unit further includes a Partial Association Identifier (PAID) field.

7. The method of claim 6, wherein the PAID field is a 9-bit field.

8. A method for interpreting a length field of a signal unit, comprising:

in response to determining that the frame is the MU frame, interpreting the length field as a number of symbols, wherein the length field is a 9-bit field and the aggregation field is a 1-bit field, and wherein the frame includes the short-format preamble:

the SIG unit corresponds to the short format preamble and a bandwidth mode greater than or equal to 2 MHz; and

the SIG unit further includes:

a 1-bit first reserved field;

a 1-bit space-time block coding (STBC) field;

a 2-bit bandwidth field;

a number of 2 bit space-time streams field;

a 1-bit Short Guard Interval (SGI) field;

a 2-bit encoded field;

a 4-bit Modulation and Coding Scheme (MCS) field;

a 1-bit smoothing field;

a 4-bit Cyclic Redundancy Check (CRC) field; and

a 6-bit tail field.

9. The method of claim 8, wherein the SIG unit further comprises two Orthogonal Frequency Division Multiplexing (OFDM) symbols, wherein the SIG unit is encoded at 1/2 rate, and wherein the SIG unit corresponds to a Binary Phase Shift Keying (BPSK) constellation.

10. A method for interpreting a length field of a signal unit, comprising:

in response to determining that the frame is the MU frame, interpreting the length field as a number of symbols, wherein the length field is a 9-bit field and the aggregation field is a 1-bit field, and wherein the frame is the SU frame:

the SIG unit corresponds to the long-format SU preamble and a bandwidth mode greater than or equal to 2 MHz; and

the SIG unit further includes:

a 1-bit MU/SU field;

a 1-bit space-time block coding (STBC) field;

a 2-bit bandwidth field;

a number of 2 bit space-time streams field;

a 1-bit Short Guard Interval (SGI) field;

a 2-bit encoded field;

a 4-bit Modulation and Coding Scheme (MCS) field;

a 1-bit beam change indication field;

a 4-bit Cyclic Redundancy Check (CRC) field; and

a 6-bit tail field.

11. The method of claim 10, wherein the SIG unit further comprises two Orthogonal Frequency Division Multiplexing (OFDM) symbols, wherein the SIG unit is encoded at 1/2 rate, and wherein the SIG unit corresponds to a Binary Phase Shift Keying (BPSK) constellation.

12. A method for interpreting a length field of a signal unit, comprising:

in response to determining that the frame is the MU frame, interpreting the length field as a number of symbols, wherein the length field is a 9-bit field and the aggregation field is a 1-bit field, and wherein the frame is associated with a 1MHz bandwidth mode:

the SIG unit corresponds to the 1MHz bandwidth mode, and

the SIG unit further includes:

a number of 2 bit space-time streams field;

a 1-bit Short Guard Interval (SGI) field;

a 2-bit encoded field;

a 1-bit space-time block coding (STBC) field;

a 1-bit first reserved field;

a 4-bit Modulation and Coding Scheme (MCS) field;

a 4-bit Cyclic Redundancy Check (CRC) field; and

a 6-bit tail field.

13. The method of claim 12, wherein the SIG unit further comprises six Orthogonal Frequency Division Multiplexing (OFDM) symbols, wherein the SIG unit is encoded at a rate of 1/2, and wherein the SIG unit corresponds to a Binary Phase Shift Keying (BPSK) constellation.

14. An apparatus for interpreting a length field of a signal unit, comprising:

a receiver configured to receive a frame via a sub-1 gigahertz (GHz) wireless network, wherein the frame has the Signal (SIG) unit that includes the length field and an aggregation field; and

a processor configured to:

interpreting the length field as a number of symbols in response to determining that the frame is the MU frame.

15. The apparatus of claim 14, wherein the aggregation field indicates whether the data received by the receiver corresponds to one or more aggregated media entry control (MAC) protocol data units (a-MPDUs).

16. An apparatus for interpreting a length field of a signal unit, comprising:

means for receiving a frame via a sub-1 gigahertz (GHz) wireless network, the frame having the Signal (SIG) unit that includes the length field and an aggregation field; and

a processor configured to:

17. The apparatus of claim 16, wherein the sub-1 GHz wireless network operates in accordance with an institute of electrical and electronics (IEEE)802.11ah protocol.

18. A non-transitory computer-readable medium comprising instructions that, when executed by a computer, cause the computer to:

receiving a frame via a sub-1 gigahertz (GHz) wireless network, the frame having a Signal (SIG) unit including a length field and an aggregation field;

19. The non-transitory computer-readable medium of claim 18, wherein the sub-1 GHz wireless network operates according to an institute of electrical and electronics (IEEE)802.11ah protocol.