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WO2018183015A1 - Multiplexage par répartition orthogonale de la fréquence sans préfixe cyclique avec des signaux d'alignement - Google Patents

Multiplexage par répartition orthogonale de la fréquence sans préfixe cyclique avec des signaux d'alignement Download PDF

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Publication number
WO2018183015A1
WO2018183015A1 PCT/US2018/023116 US2018023116W WO2018183015A1 WO 2018183015 A1 WO2018183015 A1 WO 2018183015A1 US 2018023116 W US2018023116 W US 2018023116W WO 2018183015 A1 WO2018183015 A1 WO 2018183015A1
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WO
WIPO (PCT)
Prior art keywords
wireless communication
ofdm symbol
channel
signal
communication channel
Prior art date
Application number
PCT/US2018/023116
Other languages
English (en)
Inventor
Zekeriyya Esat Ankarali
Alphan Sahin
Huseyin Arslan
Original Assignee
University Of South Florida
Idac Holdings, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University Of South Florida, Idac Holdings, Inc. filed Critical University Of South Florida
Publication of WO2018183015A1 publication Critical patent/WO2018183015A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2626—Arrangements specific to the transmitter only
    • H04L27/2646—Arrangements specific to the transmitter only using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03343—Arrangements at the transmitter end
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure
    • H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
    • H04L27/2607—Cyclic extensions

Definitions

  • Orthogonal frequency division multiplexing has been a dominant technology for the wireless high speed communication standards (e.g., Wi-Fi and LTE), because of OFDM's qualities such as robustness against frequency selective channels and simplicity in equalization.
  • OFDM is a prominent signaling form for 5G among waveform candidates.
  • Systems, procedures, and instrumentalities are disclosed that may use alignment signals at the transmitter to remove the requirement of a cyclic prefix (CP).
  • Systems, procedures, and instrumentalities are disclosed to generate a cancellation signal at a transmitter based on the channel.
  • a cancellation signal at a transmitter may compensate for inter-symbol interference (ISI) and/or may maintain the circular channel convolution.
  • Systems, procedures, and instrumentalities are disclosed to add an alignment signal (AS) to a transmitted CP-less OFDM signal.
  • the AS may correspond to a summation of an interference cancelling signal and a circularity providing signal, and be aligned to a target region of the received signal.
  • a method of wireless communication may include estimating channel effects for a wireless communication channel; determining an AS is determined for a current OFDM symbol that will result in cancelation of the ISI between the current OFDM symbol and a prior OFDM symbol, after the current symbol has passed through the wireless communication channel; combining the AS with the current OFDM symbol, possibly by summation; and transmitting the combination, without a CP, over the wireless communication channel.
  • the AS may further provides circularity to combination of the AS and the current CP-less OFDM symbol, after passing through the wireless communication channel.
  • determining the AS may comprise identifying a null space of a multiplication of a channel convolution matrix and an imaginary CP removal matrix.
  • a method of wireless communication may comprise transmitting a first combined transmission signal over a wireless communication channel, the first combined transmission signal comprising a first orthogonal frequency division multiplexing (OFDM) symbol and a first alignment signal (AS); subsequently determining a second alignment signal (AS) from the first combined transmission signal based at least in part on applying an estimate of channel effects for the wireless communication channel; combining a second OFDM symbol and the second AS to form a second combined transmission signal, possibly by summation; and transmitting the second combined transmission signal over the wireless communication channel.
  • OFDM orthogonal frequency division multiplexing
  • AS first alignment signal
  • the second AS may be configured to, when combined with the second OFDM symbol, cancel inter-symbol interference (ISI) between the second OFDM and the first OFDM symbol at a receiver that receives the first combined signal and the second combined signal over the wireless communication channel.
  • ISI inter-symbol interference
  • the first combined signal and the second combined signal do not comprise a cyclic prefix (CP).
  • the method may further include determining the estimate of channel effects for the wireless communication channel. Determining the estimate of channel effects may comprise, e.g. estimating the estimate of channel effects for the wireless communication channel; or receiving the estimate of channel effects for the wireless communication channel.
  • subsequently determining the second AS may comprise determining a signal to be precoded based at least in part on the estimate of channel effects as applied to a leakage between previous combined transmission signals, the previous combined transmission signals comprising at least the second transmission signal; and precoding the signal to be precoded by using a null space of a multiplication of a channel convolution matrix and an imaginary cyclic prefix (CP) removal matrix.
  • CP cyclic prefix
  • FIG. 1 A is a system diagram of an example communications system in which one or more disclosed embodiments may be implemented.
  • FIG. 1 B is a system diagram of an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A.
  • FIG. 1 C is a system diagram of an example radio access network (RAN) and an example core (CN) network that may be used within the communications system illustrated in FIG. 1 A.
  • RAN radio access network
  • CN core
  • FIG. 1 D is a system diagram of another example RAN and another example CN that may be used within the communications system illustrated in FIG. 1A.
  • FIG. 1 E is a system diagram of another example RAN and another example CN that may be used within the communications system illustrated in FIG. 1A.
  • FIG. 2A is an example of signals at a transmitter and at a receiver.
  • FIG. 2B is a representation of orthogonal frequency division multiplexing (OFDM) signal components.
  • FIGs. 3A and 3B show an example of signals at a transmitter and at a receiver without a cyclic prefix (CP), according to some embodiments.
  • FIG. 4A is a block diagram of a transmitter and receiver, according to some embodiments.
  • FIG. 4B is a flow diagram of a method of operating the transmitter of FIG. 4A.
  • FIG. 5 is an exemplary plot of bit-error-rate (BER) performance for CP-less-OFDM signals versus CP-OFDM signals.
  • BER bit-error-rate
  • FIG. 6 is an exemplary plot of peak-to-average-power ratio (PAPR) results for CP-less-OFDM signals versus CP-OFDM signals.
  • PAPR peak-to-average-power ratio
  • FIG. 7 is an exemplary plot of power spectral density (PSD) of an OFDM signal, a CP cancelling (CC) signal, and the combination.
  • PSD power spectral density
  • FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented.
  • the communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users.
  • the communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth.
  • Exemplary communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.
  • CDMA code division multiple access
  • TDMA time division multiple access
  • FDMA frequency division multiple access
  • OFDMA orthogonal FDMA
  • SC-FDMA single-carrier FDMA
  • ZT UW DTS-s OFDM zero-tail unique-word DFT-Spread OFDM
  • UW-OFDM unique word OFDM
  • FBMC filter bank multicarrier
  • the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 103/104/105, a core network (CN) 106/107/109, a public switched telephone network (PSTN) 108, the internet 110, and other networks 112, although it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements.
  • Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment.
  • the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head- mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like.
  • UE user equipment
  • PDA personal digital assistant
  • HMD head- mounted display
  • a vehicle a drone
  • the communications systems 100 may also include a base station 114a and/or a base station
  • Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106/107/109, the Internet 110, and/or the other networks 112.
  • the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a
  • the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.
  • the base station 114a may be part of the RAN 103/104/105, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc.
  • BSC base station controller
  • RNC radio network controller
  • the base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum.
  • a cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors.
  • the cell associated with the base station 114a may be divided into three sectors.
  • the base station 114a may include three transceivers, i.e., one for each sector of the cell.
  • the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell.
  • MIMO multiple-input multiple output
  • beamforming may be used to transmit and/or receive signals in desired spatial directions.
  • the base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 115/116/117, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.).
  • the air interface 115/116/117 may be established using any suitable radio access technology (RAT).
  • RAT radio access technology
  • the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like.
  • the base station 114a in the RAN 103/104/105 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115/116/117 using wideband CDMA (WCDMA).
  • WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+).
  • HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and/or High-Speed Uplink (UL) Packet Access (HSUPA).
  • the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/or LTE-Advanced Pro (LTE-A Pro).
  • E-UTRA Evolved UMTS Terrestrial Radio Access
  • LTE Long Term Evolution
  • LTE-A LTE-Advanced
  • LTE-A Pro LTE-Advanced Pro
  • the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface
  • the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies.
  • the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles.
  • DC dual connectivity
  • the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., a evolved Node B and a gNB).
  • the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.
  • IEEE 802.11 i.e., Wireless Fidelity (WiFi)
  • IEEE 802.16 i.e., Worldwide Interoperability for Microwave Access (WiMAX)
  • CDMA2000, CDMA2000 1X, CDMA2000 EV-DO Code Division Multiple Access 2000
  • IS-95 Interim Standard 95
  • IS-856 Interim Standard 856
  • GSM Global System for
  • the base station 114b in FIG. 1 A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like.
  • the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN).
  • WLAN wireless local area network
  • the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN).
  • the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell.
  • the base station 114b may have a direct connection to the Internet 110.
  • the base station 114b may not be required to access the Internet 110 via the CN 106/107/109.
  • the RAN 103/104/105 may be in communication with the CN 106/107/109, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d.
  • the data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like.
  • QoS quality of service
  • the CN 106/107/109 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication.
  • the RAN 103/104/105 and/or the CN 106/107/109 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 103/104/105 or a different RAT.
  • the CN 106/107/109 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.
  • the CN 106/107/109 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or the other networks 112.
  • the PSTN 108 may include circuit- switched telephone networks that provide plain old telephone service (POTS).
  • POTS plain old telephone service
  • the Internet 110 may include a global system of interconnected computer networks and devices that use common
  • the networks 112 may include wired and/or wireless communications networks owned and/or operated by other service providers.
  • the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 103/104/105 or a different RAT.
  • Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links).
  • the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.
  • FIG. 1 B is a system diagram illustrating an example WTRU 102.
  • the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a
  • the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.
  • the base stations 114a and 114b, and/or the nodes that base stations 114a and 114b may represent, such as but not limited to transceiver station (BTS), a Node-B, a site controller, an access point (AP), a home node-B, an evolved home node-B (eNodeB), a home evolved node-B (HeNB or HeNodeB), a home evolved node-B gateway, and proxy nodes, among others, may include some or all of the elements depicted in FIG. 1 B and described herein.
  • BTS transceiver station
  • Node-B a Node-B
  • AP access point
  • eNodeB evolved home node-B
  • HeNB or HeNodeB home evolved node-B gateway
  • proxy nodes among others, may include some or all of the elements depicted in FIG. 1 B and described herein.
  • the processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like.
  • the processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment.
  • the processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.
  • the transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 115/116/117.
  • a base station e.g., the base station 114a
  • the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals.
  • the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example.
  • the transmit/receive element 122 may be configured to transmit and/or receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.
  • the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in some embodiments, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 115/116/117.
  • the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 115/116/117.
  • the transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122.
  • the WTRU 102 may have multi-mode capabilities.
  • the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR, UTRA, and IEEE 802.11 , for example.
  • the processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit).
  • the processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128.
  • the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132.
  • the non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device.
  • the removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like.
  • SIM subscriber identity module
  • SD secure digital
  • the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).
  • the processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102.
  • the power source 134 may be any suitable device for powering the WTRU 102.
  • the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.
  • the processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102.
  • location information e.g., longitude and latitude
  • the WTRU 102 may receive location information over the air interface 115/116/117 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.
  • the processor 118 may further be coupled to other peripherals 138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity.
  • the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and/or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and/or Augmented Reality (VR/AR) device, an activity tracker, and the like.
  • FM frequency modulated
  • the peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and/or a humidity sensor.
  • a gyroscope an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and/or a humidity sensor.
  • the WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and/or simultaneous.
  • the full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118).
  • the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).
  • a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).
  • FIG. 1 C is a system diagram of the RAN 103 and the CN 106 according to an embodiment.
  • the RAN 103 may employ a UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 115.
  • the RAN 103 may also be in communication with the CN 106.
  • the RAN 103 may include Node-Bs 140a, 140b, 140c, which may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 115.
  • the Node-Bs 140a, 140b, 140c may each be associated with a particular cell (not shown) within the RAN 103.
  • the RAN 103 may also include RNCs 142a, 142b. It will be appreciated that the RAN 103 may include any number of Node-Bs and RNCs while remaining consistent with an embodiment.
  • the Node-Bs 140a, 140b may be in communication with the RNC 142a. Additionally, the Node-B 140c may be in communication with the RNC 142b. The Node-Bs 140a, 140b, 140c may communicate with the respective RNCs 142a, 142b via an lub interface. The RNCs 142a, 142b may be in communication with one another via an lur interface. Each of the RNCs 142a, 142b may be configured to control the respective Node-Bs 140a, 140b, 140c to which it is connected. In addition, each of the RNCs 142a, 142b may be configured to carry out or support other functionality, such as outer loop power control, load control, admission control, packet scheduling, handover control, macrodiversity, security functions, data encryption, and the like.
  • outer loop power control such as outer loop power control, load control, admission control, packet scheduling, handover control, macrodiversity, security functions, data encryption, and the like.
  • the CN 106 shown in FIG. 1 C may include a media gateway (MGW) 144, a mobile switching center (MSC) 146, a serving GPRS support node (SGSN) 148, and/or a gateway GPRS support node (GGSN) 150. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any one of these elements may be owned and/or operated by an entity other than the CN operator.
  • MGW media gateway
  • MSC mobile switching center
  • SGSN serving GPRS support node
  • GGSN gateway GPRS support node
  • the RNC 142a in the RAN 103 may be connected to the MSC 146 in the CN 106 via an luCS interface.
  • the MSC 146 may be connected to the MGW 144.
  • the MSC 146 and the MGW 144 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices.
  • the RNC 142a in the RAN 103 may also be connected to the SGSN 148 in the CN 106 via an luPS interface.
  • the SGSN 148 may be connected to the GGSN 150.
  • the SGSN 148 and the GGSN 150 may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between and the WTRUs 102a, 102b, 102c and IP-enabled devices.
  • the CN 106 may facilitate communications with other networks.
  • the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices.
  • the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108.
  • IMS IP multimedia subsystem
  • the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers.
  • the CN 106 may also be connected to the networks 112, which may include other wired or wireless networks that are owned and/or operated by other service providers.
  • FIG. 1 D is a system diagram of the RAN 104 and the CN 107 according to an embodiment.
  • the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116.
  • the RAN 104 may also be in communication with the CN 107.
  • the RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment.
  • the eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116.
  • the eNode-Bs 160a, 160b, 160c may implement MIMO technology.
  • the eNode-B 160a for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.
  • Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink (UL) and/or downlink (DL), and the like. As shown in FIG. 1 D, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.
  • the CN 107 shown in FIG. 1 D may include a mobility management gateway (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway 166. While each of the foregoing elements are depicted as part of the CN 107, it will be appreciated that any one of these elements may be owned and/or operated by an entity other than the CN operator.
  • MME mobility management gateway
  • SGW serving gateway
  • PDN gateway 166 packet data network gateway
  • the MME 162 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface and may serve as a control node.
  • the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular SGW during an initial attach of the WTRUs 102a, 102b, 102c, and the like.
  • the MME 162 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.
  • the SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via the S1 interface.
  • the SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c.
  • the SGW 164 may also perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.
  • the SGW 164 may also be connected to the PDN gateway 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.
  • the PDN gateway 166 may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.
  • the CN 107 may facilitate communications with other networks.
  • the CN 107 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices.
  • the CN 107 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 107 and the PSTN 108.
  • IMS IP multimedia subsystem
  • the CN 107 may provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks that are owned and/or operated by other service providers.
  • the RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with some embodiments.
  • the eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 115/1 16/117.
  • the eNode-Bs 160a, 160b, 160c may implement MIMO technology.
  • the eNode-B 160a for example, may use multiple antennas to transmit wireless signals to, and/or receive wireless signals from, the WTRU 102a.
  • Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and/or DL, and the like. As shown in FIG. 1 D, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.
  • the CN 107 shown in FIG. 1 D may include a mobility management entity (MME) 162, a SGW 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and/or operated by an entity other than the CN operator.
  • MME mobility management entity
  • SGW Serving Gateway
  • PGW packet data network gateway
  • the MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 103 via an S1 interface and may serve as a control node.
  • the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular SGW during an initial attach of the WTRUs 102a, 102b, 102c, and the like.
  • the MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and/or WCDMA.
  • the SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 103 via the S1 interface.
  • the SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c.
  • the SGW 164 may perform other functions, such as anchoring user planes during inter- eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.
  • the SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.
  • packet-switched networks such as the Internet 110
  • FIG. 1 E is a system diagram of the RAN 105 and the CN 109 according to an embodiment.
  • the RAN 105 may be an access service network (ASN) that employs IEEE 802.16 radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 117.
  • ASN access service network
  • the communication links between the different functional entities of the WTRUs 102a, 102b, 102c, the RAN 105, and the CN 109 may be defined as reference points.
  • the RAN 105 may include base stations 180a, 180b, 180c, and an ASN gateway 182, though it will be appreciated that the RAN 105 may include any number of base stations and ASN gateways while remaining consistent with an embodiment.
  • the base stations 180a, 180b, 180c may each be associated with a particular cell (not shown) in the RAN 105 and may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 117.
  • the base stations 180a, 180b, 180c may implement MIMO technology.
  • the base station 180a for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.
  • the base stations 180a, 180b, 180c may also provide mobility management functions, such as handoff triggering, tunnel establishment, radio resource management, traffic classification, quality of service (QoS) policy enforcement, and the like.
  • the ASN gateway 182 may serve as a traffic aggregation point and may be responsible for paging, caching of subscriber profiles, routing to the CN 109, and the like.
  • the air interface 117 between the WTRUs 102a, 102b, 102c and the RAN 105 may be defined as an R1 reference point that implements the IEEE 802.16 specification.
  • each of the WTRUs 102a, 102b, 102c may establish a logical interface (not shown) with the CN 109.
  • the logical interface between the WTRUs 102a, 102b, 102c and the CN 109 may be defined as an R2 reference point, which may be used for authentication, authorization, IP host configuration management, and/or mobility management.
  • the communication link between each of the base stations 180a, 180b, 180c may be defined as an R8 reference point that includes protocols for facilitating WTRU handovers and the transfer of data between base stations.
  • the communication link between the base stations 180a, 180b, 180c and the ASN gateway 182 may be defined as an R6 reference point.
  • the R6 reference point may include protocols for facilitating mobility management based on mobility events associated with each of the WTRUs 102a, 102b, 102c.
  • the RAN 105 may be connected to the CN 109.
  • the communication link between the RAN 105 and the CN 109 may defined as an R3 reference point that includes protocols for facilitating data transfer and mobility management capabilities, for example.
  • the CN 109 may include a mobile IP home agent (MIP-HA) 184, an authentication, authorization, accounting (AAA) server 186, and a gateway 188. While each of the foregoing elements are depicted as part of the CN 109, it will be appreciated that any one of these elements may be owned and/or operated by an entity other than the CN operator.
  • MIP-HA mobile IP home agent
  • AAA authentication, authorization, accounting
  • the MIP-HA may be responsible for IP address management, and may enable the WTRUs 102a, 102b, 102c to roam between different ASNs and/or different CNs.
  • the MIP-HA 184 may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.
  • the AAA server 186 may be responsible for user authentication and for supporting user services.
  • the gateway 188 may facilitate interworking with other networks.
  • the gateway 188 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices.
  • the gateway 188 may provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks that are owned and/or operated by other service providers.
  • RAN 105 may be connected to other ASNs and the CN 109 may be connected to other CNs.
  • the communication link between the RAN 105 the other ASNs may be defined as an R4 reference point, which may include protocols for coordinating the mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and the other ASNs.
  • the communication link between the CN 109 and the other CNs may be defined as an R5 reference, which may include protocols for facilitating interworking between home CNs and visited CNs.
  • the WTRU is described in FIGs. 1 A-1 E as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.
  • the other network 112 may be a WLAN.
  • a WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP.
  • the AP may have an access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS.
  • Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs.
  • Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations.
  • Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA.
  • the traffic between STAs within a BSS may be considered and/or referred to as peer-to- peer traffic.
  • the peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS).
  • the DLS may use an 802.11e DLS or an 802.11 z tunneled DLS (TDLS).
  • a WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other.
  • the IBSS mode of communication may sometimes be referred to herein as an "ad- hoc" mode of communication.
  • the AP may transmit a beacon on a fixed channel, such as a primary channel.
  • the primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling.
  • the primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP.
  • Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in in 802.11 systems.
  • the STAs e.g., every STA, including the AP, may sense the primary channel. If the primary channel is sensed/detected and/or determined to be busy by a particular STA, the particular STA may back off.
  • One STA (e.g., only one station) may transmit at any given time in a given BSS.
  • High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.
  • VHT STAs may support 20MHz, 40 MHz, 80 MHz, and/or 160 MHz wide channels.
  • the 40 MHz, and/or 80 MHz, channels may be formed by combining contiguous 20 MHz channels.
  • a 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two non-contiguous 80 MHz channels, which may be referred to as an 80+80 configuration.
  • the data, after channel encoding may be passed through a segment parser that may divide the data into two streams.
  • Inverse Fast Fourier Transform (IFFT) processing, and time domain processing may be done on each stream separately.
  • IFFT Inverse Fast Fourier Transform
  • the streams may be mapped on to the two 80 MHz channels, and the data may be transmitted by a transmitting STA.
  • the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).
  • MAC Medium Access Control
  • Sub 1 GHz modes of operation are supported by 802.11af and 802.11 ah.
  • the channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11 ah relative to those used in 802.11 ⁇ , and 802.11ac.
  • 802.11 af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum
  • 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non- TVWS spectrum.
  • 802.11 ah may support Meter Type
  • MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and/or limited bandwidths.
  • the MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).
  • WLAN systems which may support multiple channels, and channel bandwidths, such as 802.11 ⁇ , 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel.
  • the primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS.
  • the bandwidth of the primary channel may be set and/or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode.
  • the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.
  • Carrier sensing and/or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.
  • STAs e.g., MTC type devices
  • NAV Network Allocation Vector
  • the available frequency bands which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.
  • one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s) described herein, may be performed by one or more emulation devices (not shown).
  • the emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein.
  • the emulation devices may be used to test other devices and/or to simulate network and/or WTRU functions.
  • the emulation devices may be designed to implement one or more tests of other devices in a lab environment and/or in an operator network environment.
  • the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the
  • the one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network.
  • the emulation device may be directly coupled to another device for purposes of testing and/or may performing testing using over-the-air wireless communications.
  • the one or more emulation devices may perform the one or more, including all, functions while not being implemented/deployed as part of a wired and/or wireless communication network.
  • the emulation devices may be utilized in a testing scenario in a testing laboratory and/or a non-deployed (e.g., testing) wired and/or wireless communication network in order to implement testing of one or more components.
  • the one or more emulation devices may be test equipment. Direct RF coupling and/or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and/or receive data.
  • RF circuitry e.g., which may include one or more antennas
  • Orthogonal frequency division multiplexing OFDM
  • Orthogonal frequency division multiplexing has been a dominant technology for the wireless high speed communication standards (e.g., Wi-Fi and LTE), because of OFDM's qualities such as robustness against frequency selective channels and simplicity in equalization. OFDM is a prominent signaling form for 5G among waveform candidates.
  • FIG. 2A is an example of generic signals at a transmitter 202 and at a receiver 204, after passing through a channel 201.
  • the transmitted signal 210 is shown comprising two symbols: Si 203a and the subsequent symbol, SM 205a.
  • Channel 201 is represented by transfer function plot 201 a that includes response weights 201 b, 201 c and 201 d, and denoted as h.
  • the received signal 211 having passed through channel 201 and been subject to the transfer function operation, comprises two symbols: s, that comprises portions 203b and 203c, and the subsequent symbol, SM that comprises portions 205b and 205c.
  • Portion 205b of received symbol SM comprises both the initial portion of transmitted symbol SM 205a and also a portion of s, 203a that arrived late, due to delayed multi-path effects of channel 201.
  • This delayed portion of s, 203a that overlaps with the first portion 205b of the received symbol SM is inter- symbol interference (ISI).
  • ISI inter- symbol interference
  • portion 203b of received symbol Si comprises both the initial portion of transmitted symbol Si 203a and also a portion of a prior-transmitted symbol (not shown) that arrived late.
  • the remaining portion 203c of the received symbol Si should also be relatively free from ISI.
  • the signal frame 212 comprises a CP 213 followed by a data portion 214.
  • the duration of the CP may be set such that it occupies the duration of the problematic ISI period. For example, in highly dispersive channels, the CP rate might be large to maintain a low complex frequency domain equalization. The spectral efficiency of OFDM communications systems may thus be negatively affected when using CPs to counter ISI.
  • Systems, procedures, and instrumentalities are disclosed that may use alignment signals at the transmitter to remove the requirement of a CP.
  • Systems, procedures, and instrumentalities are disclosed to generate a cancellation signal at a transmitter based on the channel.
  • a cancellation signal at a transmitter may compensate for ISI and/or may maintain the circular channel convolution.
  • Systems, procedures, and instrumentalities are disclosed to add an alignment signal (AS) to a transmitted CP-less OFDM signal.
  • the AS may correspond to a summation of an interference cancelling signal and a circularity providing signal, and be aligned to a target region of the received signal.
  • FIGs. 3A and 3B show an example of CP-less signals at a transmitter 302 and at a receiver 304, after passing through a channel 201.
  • FIGs. 3A and 3B both show the same set of signals, although the element numbering is omitted from some portions of FIG. 3A, for clarity of illustration.
  • the CP-less signal symbols Si 303a and SM 305a pass from transmitter 302, through channel 201 (with a transfer function denoted as h), and arrive at receiver 304 as symbols s, (comprising portions 303b and 303c) and SM
  • Signals Ci 308a and CM 308b are alignment signals, which are combined with the OFDM signals.
  • AS Ci 308a may cancel ISI in received signal Si portion 303b
  • AS CM 308b may cancel ISI in received signal SM portion 305b.
  • An AS cancels interference and/or adds a required part such that the resulting effect of channel 201 renders a received OFDM symbol circular.
  • a symbol-specific AS may be added on top of a CP-less OFDM signal (a transmission signal) as:
  • an AS may align to the target region.
  • an AS may align to the target region after passing through channel 201 (at receiver 304 side).
  • an aligned AS e.g., Cj
  • Cj an aligned AS
  • the null space of the multiplication of channel convolution matrix and/or an imaginary CP removal matrix may (e.g., may first) be determined.
  • the complex valued channel convolution matrix H ⁇ c (i +R)xi may be: hit) o 0
  • auxiliary matrix B ⁇ ⁇ -R)XN+R ma y ⁇ ⁇ j e fj nec ] suc h that the auxiliary matrix B removes the first and the last R samples of the received symbol.
  • the null space (e.g., required null space) may be calculated as:
  • P G ⁇ C NxR ker(BH) Eq. (5) where ker(-) may correspond to a kernel extracting operation.
  • a vector w; ⁇ ( C Rxl multiplied by P may provide an AS aligning on the first and last R samples of the OFDM symbol after passing through the channel, i.e., Htj.
  • the vector Wj ⁇ ( C Rxl may leak to the next symbol after it passes through the channel. [0094]
  • the leaking to the next symbol may cause interference, but may be canceled by the next symbol's AS.
  • AS may be calculated as:
  • the alignment signal may be confined in a predefined region (e.g., defined by B) at the receiver side.
  • the values of wj may be calculated to obtain the desired signal (e.g., Cj).
  • the ith received signal may be:
  • the second term of y (e. g. , Hq) may cancel Hpt;. ⁇ Hq may be added to maintain the circular channel convolution, e.g., H p Sj, as described herein.
  • q may be interpreted as a column vector whose first R elements may cancel inter-symbol- interference (ISI) and/or introduce circularity.
  • the other (e.g., (N - R)) elements may be zero. If the second term of y; is rewritten as
  • HPw the last (N - R) elements of q may be zero.
  • the multiplication of HPw may be focused, which may provide the required values as the first R elements of q. If HPw is named as Cj R) (i.e., Cj R) is the first R elements of q), w can be calculated as
  • FIG. 4A is a block diagram of a system 400 comprising a transmitter 402 and a receiver 404, according to some embodiments.
  • transmitter 402 and receiver 404 may be similar to transmitter 302 and receiver 304 of FIGs. 3A and 3B.
  • a set 401 of data is to be transmitted across channel 201.
  • the data 401 is fed into a map process 403 and then into an inverse discrete Fourier transform (IDFT) 405 to produce a symbol s, which is used to calculate a.
  • IDFT inverse discrete Fourier transform
  • a preprocessing process 407 uses an estimate (Channel H) of channel 201 and the prior symbol t-i to feed a precoder 409.
  • Precoder 409 may operate to perform the operations of Eq. (5).
  • Preprocessing process 407 generates Wj as a function of the channel H, the previous symbols and the current symbol tj.
  • the resulting c, is added to s, in summer 41 1 to produce t (according to Eq. (1 )).
  • This is then upconverted to RF in RF module 413, and transmitted across channel 201.
  • Receiver 404 picks up the received signal and feeds it into RF module 415 and then a DFT process 417. After a de-mapping process 419 and frequency domain equalization process 421 , the detected data 423 is output. Because c, compensated for the effects of channel 201 , the use of a CP was avoided.
  • FIG. 4B is a flow diagram of a method 450 of operating transmitter 402 of FIG. 4A.
  • a processor such as processor 118 (of FIG. 1 B) may perform calculations similar to those described with reference to FIG. 3B, in support of method 450.
  • Method 450 begins with estimating channel effects for a wireless communication channel in process box 451.
  • an AS is determined for a current CP-less OFDM symbol (perhaps a data symbol) that will result in cancelation of the ISI between the current CP-less OFDM symbol and a prior CP-less OFDM symbol, after the current symbol has passed through the wireless communication channel.
  • the AS is combined with the current CP-less OFDM symbol, possibly by summation, in box 455, and the combination is transmitted - without a CP - over the wireless
  • the AS may further provide circularity to combination of the AS and the current CP-less OFDM symbol, after passing through the wireless communication channel.
  • determining the AS may comprise identifying a null space of a multiplication of a channel convolution matrix and an imaginary CP removal matrix.
  • FIG. 5 is an exemplary plot 501 of bit-error-rate (BER) performance for CP-less-OFDM signals 505 versus CP-OFDM signals 503.
  • BER bit-error-rate
  • CCDF cumulative distribution function
  • FIG. 7 an exemplary CCDF diagram 701 of signal power spectral density (PSD) is shown in FIG. 7.
  • PSD signal power spectral density
  • CC CP cancelling
  • OFDM + CC summed combination signal 707
  • FIG. 7 the impact on the PSD is also increased less than 0.2dB over OFDM-only, according to the simulation results.
  • OOBE out-of- band emission
  • a WTRU may refer to an identity of the physical device, or to the user's identity such as subscription related identities, e.g., MSISDN, SIP URI, etc.
  • WTRU may refer to application-based identities, e.g., user names that may be used per application.
  • modules that carry out (i.e., perform, execute, and the like) various functions that are described herein in connection with the respective modules.
  • a module includes hardware (e.g., one or more processors, one or more microprocessors, one or more microcontrollers, one or more microchips, one or more application-specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more memory devices) deemed suitable by those of skill in the relevant art for a given implementation.
  • ASICs application-specific integrated circuits
  • FPGAs field programmable gate arrays
  • Each described module may also include instructions executable for carrying out the one or more functions described as being carried out by the respective module, and it is noted that those instructions could take the form of or include hardware (i.e., hardwired) instructions, firmware instructions, software instructions, and/or the like, and may be stored in any suitable non-transitory computer-readable medium or media, such as commonly referred to as RAM, ROM, etc.
  • ROM read only memory
  • RAM random access memory
  • register cache memory
  • semiconductor memory devices magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs).
  • a processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

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Abstract

L'invention concerne des systèmes et des procédés permettant d'ajouter un signal d'alignement (AS) à un signal de multiplexage par répartition orthogonale de la fréquence (OFDM) sans préfixe cyclique transmis. Le signal AS peut correspondre à une sommation d'un signal d'annulation d'interférence et d'un signal de fourniture de circularité, aligné sur une région cible du signal reçu. Les systèmes et les procédés de l'invention peuvent éliminer le besoin d'un préfixe cyclique, ce qui permet d'améliorer l'efficacité spectrale.
PCT/US2018/023116 2017-03-31 2018-03-19 Multiplexage par répartition orthogonale de la fréquence sans préfixe cyclique avec des signaux d'alignement WO2018183015A1 (fr)

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EP2316209A1 (fr) * 2008-08-20 2011-05-04 Telefonaktiebolaget L M Ericsson (publ) Précodeur pour système de communication et procédés utilisés dans ledit système de communication

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EP2316209A1 (fr) * 2008-08-20 2011-05-04 Telefonaktiebolaget L M Ericsson (publ) Précodeur pour système de communication et procédés utilisés dans ledit système de communication

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