CN101924721A - Method for Determining Transmission Mode of Downlink Multiple Access System and Devices at Transmitter and Receiver - Google Patents

Abstract

The present invention relates to a method for determining a multi-service transmission mode of a downlink multiple access system, and devices at a transmitting end and a receiving end. In the present invention, a multi-frame structure is adopted for information transmission, and the length of a time-domain data frame in the multi-frame structure is flexible and variable. The frequency slicing technology is as follows: time and subcarrier resources are divided into basic time-frequency units. The basic time-frequency unit is composed of one or more subcarriers located in the same time-domain data frame and occupies a fixed signal bandwidth; Time-frequency sub-channel allocation; determine the transmission mode according to the available resources of the system, channel conditions and multi-service requirements; obtain the transmitting end device based on the determination of the transmission mode; and obtain the corresponding time-frequency sub-channel according to the determination of the transmission mode and the transmitting end device Receiver device. The present invention supports the requirements of multiple service transmissions, and can flexibly schedule system resources and flexibly configure system parameters according to externally obtained system available resource information, channel conditions and specific service requirements.

Description

Method for Determining Transmission Mode of Downlink Multiple Access System and Devices at Transmitter and Receiver

technical field

The invention belongs to the technical field of digital information transmission, and in particular relates to a downlink multiple access system for realizing multi-service transmission in a broadband wireless mobile system or a broadband terrestrial broadcasting system, in particular to a method for determining a multi-service transmission mode of a downlink multiple access system, a transmitter, Receiver device.

Background technique

In digital communication systems, the common goal of broadband wireless mobile transmission and broadband terrestrial broadcast transmission is to make full use of available system resources (including bandwidth, power and complexity, etc.) in complex broadband wireless mobile and terrestrial broadcast transmission environments, according to Actual channel conditions to meet the growing multi-service requirements.

One of its core issues is: how to deal with the challenges of harsh transmission environments, that is, how to provide high spectral efficiency, high system capacity, high transmission reliability and multiple quality of service ( Quality of Service, QOS) and many other guarantees. For example, under the common delay spread channel of broadband wireless mobile and terrestrial broadcast transmission, in order to effectively overcome the inter-symbol interference or frequency selective fading caused by delay spread and make the actual transmission capacity approach the system transmission capacity, the physical layer frame structure , Modulation and coding technology, block transmission technology and receiver synchronization and channel estimation technology are all huge challenges.

The second core issue is: how to support the challenge of multi-service transmission, that is, how to schedule the available resources of the system to meet the different needs of various services according to actual channel conditions, including different transmission rates, different coverage areas, different multi-path environments, Different mobile speeds, different business priorities, and different receiver complexity. For example, the receiving equipment for the broadband digital terrestrial broadcasting system not only requires fixed reception, but also handheld and mobile reception. Among them, fixed receiving equipment has low requirements on the complexity of the receiving end and the mobile performance of the transmission system, but has high requirements on the transmission rate; handheld and mobile devices have low requirements on the transmission rate, but has high requirements on the complexity of the receiving end and the mobile performance of the transmission system. very high. Another example is that services supported by broadband wireless mobile systems not only require video and audio transmission, but also traditional voice transmission and basic data transmission. Among them, video transmission has high requirements on transmission rate and transmission reliability, but not high requirements on real-time performance; traditional voice transmission has low requirements on transmission rate and transmission reliability, but high requirements on real-time performance; basic data transmission It requires high transmission reliability and requires the transmission rate to approach the system transmission capacity.

In the broadband wireless mobile and terrestrial broadcasting transmission systems, the above two core issues are opposites and unity. Specifically, while satisfying different service requirements, multiple objectives of the transmission system need to achieve an optimal compromise. For example, there is a compromise between the maximum coverage and the highest spectrum efficiency of the terrestrial broadcasting system, so system design and resource scheduling (transmission mode) pursue higher spectrum efficiency while meeting the maximum coverage required by the business.

Aiming at the challenge of broadband wireless mobile and terrestrial broadcasting to "response to harsh transmission environments", block transmission technology is an effective technology against channel delay extension, among which Orthogonal Frequency Division Multiplexing (OFDM) and Single Carrier Frequency Domain Equalization (SC-FDE) ) are two typical block modulation technologies of the block transmission system, which have been widely used, including IEEE-802 series wireless access standards, DVB-T (European Digital Video Broadcasting Terrestrial Transmission Standard), ISDB-T (Japanese Terrestrial Integrated Service Digital broadcasting standard), and DTMB (Chinese digital TV multimedia broadcasting standard, that is, China's digital TV terrestrial broadcasting transmission standard) and other digital TV terrestrial broadcasting standards, DVB-H (European digital video broadcasting handheld equipment transmission standard), T-DMB (Korean Digital Multimedia Broadcasting Terrestrial Transmission Standard), Media-FLO (Qualcomm Mobile TV Standard) and CMMB (China Mobile Multimedia Mobile Phone TV Industry Standard) and many other handheld TV terrestrial broadcasting standards. Other effective transmission technologies include multi-antenna technology to improve transmission efficiency, time, frequency, antenna, and inter-symbol diversity technology to resist time and frequency selective fading.

Aiming at the challenge of "supporting multi-service transmission" in broadband wireless mobile and terrestrial broadcasting systems, the downlink multiple access technology based on physical layer sub-channel allocation is an effective technology to meet the needs of various services. Among them, traditional downlink multiple access technologies include time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), code division multiple access (CDMA) and space division multiple access (SDMA), etc. Among them, CDMA technology is the core technology of multiple third-generation mobile communication standards, while OFDM and OFDMA technology is expected to become the core technology of fourth-generation mobile communication systems. The combination of multiple downlink multiple access technologies is a trend in the development of broadband wireless mobile and terrestrial broadcasting systems. For example, in 1998, Richard D. Gitlin and others of AT&T Corporation of the United States proposed a time-frequency slicing technology (System and method for optimizing spectral efficiency using time-frequency-code slicing, US Patent 6064662). The basic idea is to divide the two-dimensional time-frequency space into flexible sub-slices (that is, physical layer sub-channels) and allocate them to different services to meet the requirements of different services for bandwidth and code rate (that is, transmission rate), so as to realize the utilization of channel resources. Optimal scheduling of rates. As another example, in the DVB-T2 (European second-generation digital video terrestrial broadcasting standard) system, the concept of a physical layer pipeline (similar to the physical layer sub-channel provided by downlink multiple access) is introduced, and its downlink multiple access technology is time-frequency division Chip (TFS, Time-Frequency-Slicing) technology, which integrates TDMA, FDMA and OFDMA technologies. The downlink multiple access technology based on physical layer subchannel allocation has the essential characteristics that each physical layer subchannel can perform independent internal subservice multiplexing, average power setting, scrambling, error correction coding, constellation mapping and interleaving, etc. In order to support flexible allocation of sub-channels in the physical layer, demodulation and decoding at the receiving end are usually supported by means of physical layer signaling. The receiving end can first demodulate, decode and analyze the signaling sub-channels that transmit the physical layer signaling, obtain the mapping pattern and demodulation and decoding information of each physical layer sub-channel in the entire transmission channel, and then perform the required physical layer sub-channel The business data is demodulated and decoded.

However, the existing broadband wireless mobile and terrestrial broadcasting systems still have the following problems in supporting multi-service transmission:

1) Spectrum aggregation and frequency band extension issues. On the one hand, the wireless space is open to all wireless transmission applications. With the development of wireless communication technology and the rapid growth of business requirements, wireless spectrum resources are becoming increasingly tight; on the other hand, wireless communication is developing towards broadband, and the total bandwidth that needs to be supported Higher and higher. Therefore, the difficulty is that it is more and more difficult to open up and plan spectrum resources with higher bandwidth. Obtaining a radio frequency channel by combining multiple spectrum segments is a good solution, but corresponding physical layer technical support is required.

2) Flexible configuration of system parameters. On the one hand, the allocation of spectrum resources is different in different countries, regions and frequency bands. On the other hand, wireless spectrum resources are becoming increasingly scarce, and allocated resources may not be fully utilized, and unallocated resources in free frequency bands may also be occupied. Therefore, Cognitive Radio (CR) technology has emerged, using spectrum sensing to obtain Spectrum resource information can be used for broadband wireless access and other transmissions. Therefore, the difficulty is that the formulation of broadband wireless mobile and terrestrial broadcasting standards must adapt to a variety of available spectrum resources (such as bandwidth) and time resources, and be able to flexibly configure system parameters, especially physical layer frame structure parameters, according to changes in system available resources .

3) Flexible scheduling of system resources. On the one hand, broadband wireless mobile and terrestrial broadcasting systems support larger and larger transmission bandwidths, higher total transmission rates, and stronger adaptability to harsh transmission environments, so they are suitable for supporting multi-service transmissions with diverse needs. On the other hand, the number of services and business needs will vary according to the receiving environment and the time period of the business. For example, the number of services during the day and night will change, and the types of business needs during peak hours and noon will change; for example, when the transmission conditions of data transmission services improve or the total rate of other services decreases, the transmission rate will be increased. Requires a lower transfer rate. Therefore, the existing difficulties are how to determine the frame structure of the physical layer, and how to re-plan the utilization of available spectrum resources according to the change of service requirements, including the allocation of physical layer sub-channels and the transmission mode of each physical layer sub-channel.

4) Diversity of business requirements. As mentioned above, broadband wireless mobile and terrestrial broadcasting systems are suitable for supporting multi-service transmission with diverse requirements. On the other hand, due to the huge difference in receiving conditions and transmission environments, the business requirements vary greatly. For example, in terms of transmission rate, the transmission rate of high-definition video services is as high as 20Mbits per second, while the transmission rate of mobile video services only needs 384Kbits per second; In terms of mobile performance, fixed reception does not need to consider the Doppler expansion brought by high-speed movement. Typical mobile speeds that need to be considered for handheld reception are 3 to 15 kilometers per hour, and high-speed mobile needs to support mobile speeds up to 350 kilometers per hour. Therefore, the difficulty is how to design the system framework and resource scheduling algorithm, especially the physical layer frame structure, to better support the huge differences in various business requirements.

However, the existing broadband wireless mobile and terrestrial broadcasting systems either cannot support the above problems, or need to be improved. Existing broadband wireless mobile and terrestrial broadcasting systems usually cannot support radio frequency channels obtained by combining spectrum segments, and the frequency band extension capability is limited; there are deficiencies in supporting a variety of available spectrum resources and flexible configuration of system parameters; usually there is a lack of channel conditions and business needs A mechanism for flexible scheduling of system resources; the physical layer frame structure designed by the system cannot well support the huge differences in various business requirements, especially the services with different mobile speeds cannot be effectively supported.

Contents of the invention

In order to overcome the defects of the existing broadband wireless mobile and terrestrial broadcasting systems in meeting the multi-service requirements, the present invention proposes a method for determining the multi-service transmission mode of the downlink multiple access system based on TDMA and OFDMA technology, a transmitter device and a receiver The device, in the downlink multiple access system oriented to broadband wireless mobile and terrestrial broadcasting, supports multiple service requirements, and can flexibly schedule system resources and flexibly configure system parameters according to externally obtained system resource information, channel conditions and specific service requirements .

To achieve the above object, the present invention adopts the following technical solutions:

The present invention provides a method for determining the multi-service transmission mode of a downlink multiple access system, the method comprising the following steps:

S1, obtaining system parameters and business information;

S2, determining the basic transmission mode according to system parameters and business information, including the following steps:

S2.1. Determine that the multiframe used in the transmission is composed of an auxiliary signal and one or more time-domain data frames of different lengths, the time-domain data frame is composed of a guard interval and a time-domain data block, and the time-domain data The blocks are in one-to-one correspondence with the frequency domain data blocks in the multiframe structure through time-frequency transformation, and the frequency domain data blocks are composed of subcarriers;

S2.2. Determine that the basic channel unit in transmission is a basic time-frequency unit composed of one or more subcarriers located in the same time-domain data frame, and the signal bandwidth occupied by the basic time-frequency unit is fixed, which is defined as the basic bandwidth;

S2.3. Determine that the physical layer subchannel in transmission is composed of one or more basic time-frequency units in one time-domain data frame in the multiframe structure, or multiple basic time-frequency units in multiple time-domain data frames. Time-frequency sub-channels composed of time-frequency units;

S3, obtaining information on available time-frequency resources, channel conditions and service requirements of the system;

S4. Under the guidance of the external subchannel allocation algorithm, according to the available resources of the system, channel conditions, and service requirements, and based on the basic transmission mode, determine the specific transmission mode adopted by the multi-service transmission, including the following steps:

S4.1, determine the specific multiframe structure used in the transmission of different services;

S4.2, determine the time-frequency mapping pattern of the mapping result of the basic time-frequency unit to the time-frequency sub-channel or the mapping result of the time-frequency sub-channel to the basic time-frequency unit, and complete the time-frequency resources of the time-frequency sub-channel required for the transmission of different services distribute;

S4.3. Determine the subchannel transmission mode of each time-frequency subchannel.

Preferably, after step S4, the following steps are also included:

S5, judging whether the system supports physical layer signaling and flexible scheduling, if not, then end, the system works according to the current specific transmission mode, otherwise execute step S6;

S6. If the system can send changes in time-frequency resources, channel conditions, or service demand information, return to step S3.

Preferably, in step S1, the system parameters include the system operating frequency band, the maximum channel bandwidth, and the maximum delay extension of channel transmission; the service information includes the maximum number of sub-channels supported, the maximum mobile speed, the maximum transmission rate, and real-time requirements;

Determining the basic transmission mode in step S2 also includes the following steps:

S2.4, defining the auxiliary signal form of the multiframe in step S2.1, selecting a spectrum shaping method, and determining the basic symbol interval and signal bandwidth according to the spectrum shaping method and the maximum channel bandwidth;

S2.5, according to the working frequency band and the maximum moving speed of different services, define one or more time-domain data block lengths;

S2.6, according to the maximum delay extension of the channel corresponding to different services, define one or more guard interval lengths, and one or more filling methods of the guard interval, and determine the step S2.1 according to the multi-service real-time requirements The length range of the multiframe;

S2.7, determining the specific size of the basic bandwidth of the basic time-frequency unit in step S2.2;

S2.8, defining the basic time-frequency unit division method of each frequency domain data block corresponding to the time domain data block in step S2.5, wherein each frequency domain data block shares the same basic time-frequency unit division method.

Preferably, in step S3, the system available resources include system available bandwidth, transmit power, and multiframe time-frequency resources; the channel conditions include channel delay spread, channel Doppler Extension, channel interference pattern; the service requirement information includes the number of required time-frequency sub-channels and the real-time requirements corresponding to each time-frequency sub-channel, transmission bandwidth requirements, QOS requirements, and transmission rate requirements;

In step S4.1, according to the business requirement information, combined with the external sub-channel allocation algorithm to determine the specific multiframe structure used, including determining the number of time domain data frames in the multiframe and the type of each time domain data frame;

In step S4.2, according to the available system resources, channel interference patterns and service transmission bandwidth requirements, under the guidance of the external subchannel allocation algorithm, allocate available time-frequency resources for each time-frequency subchannel corresponding to the service requirements , determine the mapping result of the basic time-frequency unit to the time-frequency sub-channel or the mapping result of the time-frequency sub-channel to the basic time-frequency unit, obtain the time-frequency mapping pattern, and complete the time-frequency resource allocation of the time-frequency sub-channel required for transmission of different services;

In step S4.3, the sub-channel transmission mode of each time-frequency sub-channel is determined according to the real-time service requirements, QOS requirements and transmission rate requirements.

Preferably, step S4.2 includes the following sub-steps:

S4.2.1, using the basic time-frequency unit determined in step S2.7 as a unit, determine the time-frequency resources available to the system;

S4.2.2. Determine the subchannel bandwidth of each time-frequency subchannel corresponding to the service requirement information, wherein the subchannel bandwidth is an integer multiple of the basic bandwidth;

S4.2.3, determining one or more frequency-domain data block positions corresponding to each time-frequency sub-channel;

S4.2.4. Determine all basic time-frequency units of each time-frequency sub-channel.

Preferably, if the basic time-frequency unit is composed of multiple subcarriers, the positions of the subcarriers corresponding to the basic time-frequency unit are placed centrally, or dispersedly, or a mixture of the two;

If the time-frequency sub-channel is composed of a plurality of basic time-frequency units, the positions of the basic time-frequency units corresponding to the time-frequency sub-channels are placed in a centralized manner, or dispersedly, or a mixture of the two.

Preferably, the basic bandwidth determined in step S2.7 is an integer multiple of the subcarrier spacing of any frequency domain data block in the multiframe.

Preferably, in step S4.2.4, corresponding to one or more frequency-domain data blocks of each time-frequency sub-channel, the positions of the basic time-frequency units constituting the time-frequency sub-channel in the frequency-domain data block are either the same, or mutually independent.

Preferably, in step S4.2.1, the system available resource information is provided by an external spectrum sensing module;

The multiframe time-frequency resources corresponding to the available resources of the system do not include the time-frequency resources reserved by the system or the time-frequency resources confirmed by the system as unavailable.

Preferably, if it is judged in step S5 that the system supports physical layer signaling and flexible scheduling, it also includes the step of allocating signaling sub-channels for transmitting signaling service data containing signaling information, the signaling information including specific use of The multi-frame structure, time-frequency mapping pattern and sub-channel transmission mode.

Preferably, the form of the auxiliary signal defined in step S2.4 is a preamble sequence, a superposition sequence, or a known training sequence between or after the time domain data frames in the multiframe, or a combination of various sequences, or no Auxiliary signal;

The filling method of the guard interval in step S2.6 is cyclic extension, zero sequence, or known training sequence of the time domain data block of the time domain data frame, or no guard interval, wherein the time domain data frame The guard intervals are either all the same, or set independently.

Preferably, the method is applied to a downlink multiple access OFDM block transmission system oriented to broadband digital terrestrial broadcasting to determine a multi-service transmission mode.

Preferably, the method is applied to a downlink multiple access OFDM block transmission system oriented to broadband wireless mobile communication to determine a multi-service transmission mode.

The present invention also provides a transmitting end device based on the above method, the transmitting end device includes:

The resource scheduling unit is used to determine the multi-frame structure, sub-channel transmission mode and time-frequency mapping pattern used in multi-service transmission by using the method described in claim 1, and generate signaling information and scheduling information including all time-frequency sub-channel parameters Information, the scheduling information includes sub-channel transmission mode and time-frequency mapping pattern, as well as control signals and timing signals of all other units at the transmitting end;

The signaling service multiplexing unit is used to multiplex the signaling information and filling information generated by the resource scheduling unit to obtain signaling data services, and output corresponding signaling service bits;

The sub-channel coding and modulation unit is used to encode and modulate signaling service bits or common service bits obtained from multi-service data according to the sub-channel transmission mode provided by the resource scheduling unit to obtain corresponding service symbols, and at the same time fill in time as required training symbols and/or virtual subcarriers required for frequency subchannels;

The frequency-domain data block composition unit is used to perform traffic symbols and training symbols of multiple time-frequency sub-channels belonging to the current frequency-domain data block according to the time-frequency mapping pattern provided by the resource scheduling unit and the timing signal of the current frequency-domain data block Multiplexing, obtaining the frequency-domain data block that completes subcarrier multiplexing and outputting it to the IDFT unit;

The IDFT unit performs an IDFT operation on the input frequency domain data block according to the length information of the current input frequency domain data block to obtain the current time domain data block;

The time-domain data frame framing unit, according to the multi-frame structure provided by the resource scheduling unit and the timing signal of the current time-domain data frame, obtains the guard interval for filling the required signal, and forms the time-domain data frame together with the guard interval and the time-domain data block And output to the multi-frame framing unit;

The multiframe framing unit, according to the time-frequency mapping pattern provided by the resource scheduling unit and the timing signal of the current multiframe, forms a multiframe signal together with one or more input time domain data frames and auxiliary signals;

The multiframe subsequent processing unit performs spectrum shaping, digital-to-analog conversion and radio frequency modulation postprocessing on the multiframe signal to obtain the final transmission signal.

Preferably, the coding and modulation operations of the sub-channel coding and modulation unit include scrambling, error correction coding, constellation mapping, interleaving, and power control;

One channel of common service bits input by the sub-channel coding and modulation unit is obtained by multiplexing one or more sub-service bits.

The present invention also provides a receiving end device based on the above method and corresponding to the above transmitting end device, the receiving end device includes:

The control unit is used to receive the signaling subchannel information preset by the system, part of the multiframe structure information and part of the time-frequency pattern mapping information determined in the basic transmission mode, and the information obtained by the signaling subchannel demodulation and signaling analysis unit. Order information and synchronization information provided by the front-end unit to obtain all the multiframe structure, time-frequency pattern mapping and required sub-channel transmission mode information required by the receiving end, and generate control signals and timing signals required by all other units at the receiving end;

The front-end unit is used to complete radio frequency demodulation and analog-to-digital conversion under the control of the control unit, and synchronize the receiving end according to the multi-frame structure to obtain multi-frame signals and synchronization signals;

The time-domain data frame separation unit, under the control of the control unit, first separates the required time-domain data frame from the multi-frame signal according to the multi-frame structure, and then separates the time-domain data block from the time-domain data frame, and outputs it to DFT unit;

The DFT unit, under the control of the control unit, performs DFT transformation according to the block length of the input time domain data block provided by the multiframe structure to obtain a frequency domain data block composed of subcarriers;

The frequency domain data block subchannel separation unit, under the control of the control unit, performs subchannel separation on the input frequency domain data block according to the multiframe structure, time-frequency mapping pattern and the timing signal of the current frequency domain data block, and obtains the corresponding signaling The signaling symbol block of the sub-channel, and the common symbol block corresponding to the common sub-channel for transmitting multi-service data;

The sub-channel demodulation and decoding unit is used to demodulate and decode signaling symbol blocks and/or common symbol blocks of different time-frequency sub-channels under the control of the control unit to obtain corresponding signaling service data and common service data;

The signaling analysis unit is configured to analyze the signaling service data under the control of the control unit, obtain signaling information included in the signaling service data, and output it to the control unit.

Preferably, the sub-channel demodulation and decoding unit includes a signaling sub-channel demodulation and decoding unit and a common sub-channel demodulation and decoding unit, wherein,

The sub-channel demodulation and decoding unit includes:

The signaling sub-channel estimation unit is used to perform channel estimation of the signaling sub-channel according to the transmission mode of the signaling sub-channel under the control of the control unit, and obtain the estimation result of the signaling sub-channel;

The signaling subchannel equalization unit is used to perform signaling subchannel equalization by using the signaling subchannel estimation results to obtain equalized data symbols;

The signaling subchannel demodulation and decoding execution unit is used to perform deinterleaving, constellation demapping, channel decoding, and descrambling demodulation and decoding operations on the equalized data symbols to obtain signaling service data and send them to the signaling analysis unit;

The common subchannel demodulation and decoding unit includes:

The ordinary subchannel estimation unit is used to perform channel estimation or update of the current ordinary subchannel according to the current ordinary subchannel transmission mode under the control of the control unit, so as to obtain the current ordinary subchannel estimation result;

The common sub-channel equalization unit performs channel equalization on the input common symbol block by using the current normal sub-channel estimation result to obtain equalized data symbols;

The common subchannel demodulation and decoding execution unit is used to perform demodulation and decoding operations of deinterleaving, constellation demapping, channel decoding and descrambling on the data symbols equalized by the common subchannel equalization unit, and obtain and output common service data.

Preferably, the output of the signaling subchannel demodulation and decoding unit is simultaneously input to the common subchannel demodulation and decoding unit;

The normal sub-channel estimation unit in the common sub-channel demodulation and decoding unit performs channel estimation or update of the current common sub-channel in combination with the output of the input signaling sub-channel demodulation and decoding unit.

Preferably, the device for implementing the receiving end includes two common subchannel demodulation and decoding units, one of which is a high priority subchannel demodulation and decoding unit, and the other is a low priority subchannel demodulation and decoding unit;

Among them, the results output by the high priority sub-channel demodulation and decoding unit are output to the low priority sub-channel demodulation and decoding unit, and the low priority sub-channel demodulation and decoding unit combines the input high priority sub-channel demodulation and decoding results to perform the current ordinary sub-channel demodulation and decoding. Channel estimation or update of the channel.

Utilizing the method for determining the multi-service transmission mode of the downlink multiple access system and the devices at the transmitting end and the receiving end provided by the present invention has the following beneficial effects: the system design can meet the transmission conditions of various bandwidths and various spectrum resources, and can meet the huge difference in requirements It can flexibly configure system parameters and adjust system resources according to business requirements. Combined with the sub-channel allocation algorithm, it can realize the optimal utilization of transmission channels. In addition, the method for allocating physical layer sub-channels and the implementing device at the transmitting end provided by the present invention can be applied to uplink multiple access systems of broadband wireless mobile and terrestrial broadcasting after modification.

Description of drawings

Figures 1a to 1b are schematic diagrams of the data flow at the transmitting end of two OFDM block transmission systems in the prior art;

FIG. 2 is a flowchart of a method for determining a multi-service transmission mode of a downlink multiple access system according to Embodiment 1 of the present invention;

FIG. 3 is a flow chart of determining the basic transmission mode according to system parameters and service information in Embodiment 1 of the present invention;

FIG. 4 is a schematic diagram of basic time-frequency units for centralized placement, scattered placement, and mixed placement of subcarriers in a frequency domain data block in Embodiment 1 of the present invention;

FIG. 5 is a schematic diagram of system available resources obtained by spectrum sensing in Embodiment 1 of the present invention;

FIG. 6 is a flow chart of determining the specific transmission mode adopted for multi-service transmission based on the basic transmission mode according to the available resources of the system, channel conditions, and service requirements according to Embodiment 1 of the present invention;

FIG. 7 is a schematic diagram of flexible multiframe structure decomposition in Embodiment 2 of the present invention;

8a-8c are three examples of flexible multiframe structures in Embodiment 2 of the present invention;

FIG. 9 is a block diagram of a transmitter device in Embodiment 3 of the present invention;

FIG. 10 is a block diagram of a receiver device corresponding to a single time-frequency sub-channel according to Embodiment 4 of the present invention;

FIG. 11 is a schematic diagram of a signaling subchannel demodulation and decoding unit in the receiver device in Embodiment 4 of the present invention;

FIG. 12 is a schematic diagram of a common subchannel demodulation and decoding unit in the receiver device in Embodiment 4 of the present invention;

FIG. 13 is a schematic diagram of a receiver device corresponding to hierarchical demodulation and decoding of low-priority sub-channels in Embodiment 4 of the present invention;

14 is a schematic diagram of the basic time-frequency unit of the frequency domain data block in the broadband digital terrestrial broadcasting downlink multiple access system in Embodiment 5 of the present invention;

15 is a schematic diagram of a multiframe structure of a broadband digital terrestrial broadcasting downlink multiple access system in Embodiment 5 of the present invention;

FIG. 16 is a time-frequency mapping pattern of the broadband digital terrestrial broadcasting downlink multiple access system in Embodiment 5 of the present invention;

17 is a schematic diagram of two kinds of time-domain data frames in the broadband wireless mobile communication downlink multiple access system in Embodiment 6 of the present invention;

FIG. 18 is a schematic diagram of a multiframe structure of a broadband wireless mobile communication downlink multiple access system in Embodiment 6 of the present invention;

FIG. 19 is a time-frequency mapping pattern of signaling subchannels of the broadband wireless mobile communication downlink multiple access system in Embodiment 6 of the present invention.

Detailed ways

The method for determining the multi-service transmission mode of the downlink multiple access system proposed by the present invention and the devices at the transmitting end and the receiving end are described as follows in conjunction with the accompanying drawings and embodiments.

For the convenience of description, some terms and concepts of the background technology are defined and described as follows in conjunction with the accompanying drawings.

Background Technology Definition of Terms

Data symbol: In a digital communication system, the complex symbol obtained after the data to be transmitted (usually bits) undergoes operations such as scrambling, error correction coding, constellation mapping, power adjustment, and interleaving.

Training symbol: In the digital communication system, the known complex symbol inserted in the frame structure of the sending end is used to carry training information, also known as "pilot symbol". The complex symbol whose value is fixed to zero is a special Training symbols, also known as "zero symbols". The training symbols are used for synchronization at the receiver, channel estimation at the receiver, spectrum shaping of the transmitted signal, and frame structure filling at the transmitter, etc.

Symbol: In a digital communication system, a complex symbol used to carry data or training information is a general term for data symbols and training symbols. Complex symbols are still complex symbols obtained after various linear transformations. Since the linear transformation can be either data symbols or training symbols, the complex symbols after linear transformation can only carry data symbols, can only carry training symbols, or can carry data symbols and training symbols at the same time. Complex symbols after linear transformation are also collectively referred to as symbols.

Time domain symbol: It is the expression form of the symbol in the time domain.

Basic symbol interval and basic symbol rate: The basic symbol interval Ts corresponds to the duration of a time-domain symbol or the interval between adjacent time-domain symbols, and is the reciprocal of the basic symbol rate Fs, that is, Ts=1/Fs. For example, in DVB-T and DVB-T2 systems with 8MHz bandwidth, the basic symbol rate Fs=64/7MHz, and the basic symbol interval is Ts=7/64us; in the DTMB system with 8MHz bandwidth, the basic symbol rate Fs=7.56MHz , the basic symbol interval is Ts=1/7.56us.

Signal bandwidth: According to the basic time-frequency analysis of the signal, the basic symbol rate determines the maximum bandwidth of the signal, and the actual bandwidth of the signal also depends on the specific characteristics of the signal. The actual bandwidth of the signal is defined as the signal bandwidth. In order to ensure the normal transmission of signals on the channel, the signal bandwidth is generally required to be smaller than the channel bandwidth. For example, in a DTMB system with a channel bandwidth of 8MHz, the signal bandwidth (3dB bandwidth) is equal to the basic symbol rate, which is 7.56MHz, which is smaller than the channel bandwidth. As another example, when the basic symbol rate Fs=64/7MHz is designed for DVB-T and DVB-T2 systems, the maximum possible bandwidth of the signal is 64/7MHz. Due to the spectrum shaping characteristics of the signal, the actual bandwidth is about 7.61MHz, which is smaller than the system specification 8MHz channel bandwidth.

Block transmission system: multiple symbols are composed of symbol data blocks (that is, symbol vectors), and time-domain data blocks are obtained after matrix transformation, and time-domain data frames are obtained after framing the time-domain data blocks, and then the time-domain data A system in which the symbols of a frame and other auxiliary signals are transmitted sequentially. In the block transmission system, the time-domain symbols to be transmitted are transmitted in the structure of time-domain data frames.

Time-domain data block: In the block transmission system, the result obtained after the symbol data block is transformed by the matrix is the time-domain data block, referred to as "data block", which is composed of multiple time-domain symbols. The time-domain data block length is the number of time-domain symbols corresponding to the time-domain data block, and the product of the time-domain data block length and the basic symbol interval is the duration of the time-domain data block. The time-domain data blocks either carry data symbols, or carry training symbols, or carry both data symbols and training symbols.

Guard interval: In the block transmission system, the time interval introduced between time-domain data blocks is to avoid the interference between time-domain data blocks caused by channel delay expansion (ie, IBI, Inter-Block-Interference). The guard interval length is the number of time-domain symbols corresponding to the guard interval, and the product of the guard interval length and the basic symbol interval is the duration of the guard interval. It is usually assumed that the guard interval length or duration is greater than the maximum delay spread of the channel. The guard interval corresponding to the time-domain data block and the time-domain data block together form a time-domain data frame. A special case of the guard interval is: no guard interval, that is, the guard interval length is zero.

Guard interval filling technology: generally speaking, the guard interval corresponding to the time-domain data block includes a pre-guard interval and a post-guard interval. The technology of filling a specific signal (expressed as a specific time-domain symbol) in the guard interval is the guard interval filling technology, including cyclic extension filling technology, zero sequence filling (Zero Padding, ZP) technology and known training sequence filling technology, respectively in the guard interval Cyclic extensions, zero sequences, and known training sequences to fill time-domain data blocks. Generally speaking, the guard interval is divided into two parts, the pre-guard interval before the time-domain data block and the post-guard interval after it. If only the front guard interval of the time-domain data block is considered, the corresponding cyclic extension filling technique is the well-known Cyclic Prefix (CP) filling technique. When the guard interval length is zero, there is no guard interval and no guard interval padding is required.

Time-domain data frame: It is the basic unit of the physical layer frame structure of the block transmission system. It is composed of time-domain data blocks and guard intervals before and after the time-domain data blocks. It is referred to as "data frame" or "signal frame". The active part of the time domain data frame is the time domain data block. The guard interval is an auxiliary part of the time domain data frame. The length of the time domain data frame is the sum of the length of the time domain data block and the corresponding guard interval length.

Block modulation technology: In a block transmission system, a technology that transforms a symbol data block into a matrix to obtain a time domain data block, such as Orthogonal Frequency Division Multiplexing (OFDM) technology and single carrier block modulation technology.

OFDM technology: The block modulation technology that performs IDFT transformation on the symbol data block to obtain the time domain data block. The receiving end can perform DFT transformation on the time domain data block to recover the transmitted symbol data block. IDFT is the inverse discrete Fourier transform, and DFT is the Discrete Fourier transform. The block transmission system using the OFDM block modulation technology is referred to as the OFDM block transmission system for short.

Single-carrier block modulation technology: a block modulation technology in which the symbol data block is converted into a time-domain data block through identity matrix transformation, and the symbols of the symbol data block and the symbols of the time-domain data block are mapped one by one. The single-carrier block modulation technology is also called the single-carrier frequency domain equalization (SC-FDE) technology, because the receiver uses the frequency domain equalization technology to demodulate the single carrier data block.

Frequency domain symbol: In the OFDM block transmission system, the expression form of the symbol in the frequency domain (that is, the DFT transform domain), also known as "subcarrier". The frequency-domain training symbol is also called "training sub-carrier" (PilotSub-Carrier), or "pilot" (Pilot) for short. The frequency domain symbol whose value is fixed to zero is a special frequency domain training symbol, also known as "Virtual Sub-Carrier". As we all know, the virtual subcarriers of the OFDM block transmission system can implement spectrum shaping, and the corresponding spectrum shaping technology is called "virtual subcarrier shaping technology".

Time-domain windowing shaping technology: For OFDM systems that use virtual subcarriers for spectrum shaping, the time-domain data frame is further multiplied with a specific time-domain window function, that is, each time-domain symbol of the time-domain data frame is A specific weighting operation is used to improve the roll-off characteristics of the transition band and the out-of-band attenuation characteristics of the spectrum shaping. When the length of the data block in the time domain is very large, or when the length of the guard interval is zero, or when the filling of the guard interval does not use cyclic extension, the time domain window shaping technique is usually not used. "Virtual subcarrier shaping technology" and "time domain windowing shaping technology" are collectively referred to as "frequency domain shaping technology", which are usually only used in OFDM block transmission systems.

Time-domain filtering shaping technology: that is, the technology of using time-domain shaping filters to realize spectrum shaping, in which the shape of the output spectrum directly depends on the system impulse response of the time-domain shaping filters. A commonly used time-domain shaping filter is a square root raised cosine roll-off function (Square-Root-Raised-Cosine, SRRC). The time-domain filtering shaping technique is equally effective for non-block transmission systems and block transmission systems, and equally effective for OFDM block transmission systems and single-carrier block transmission systems.

Frequency domain data block: In the OFDM block transmission system, the representation of the data block in the frequency domain (ie, the DFT transform domain) is composed of multiple frequency domain symbols (ie, subcarriers), and its IDFT transform is the time domain data block. The frequency domain symbols may be data symbols or training symbols, including special zero symbols. The frequency domain data block is the symbol data block of the OFDM block transmission system.

Subcarrier spacing: In the OFDM block transmission system, the spacing between adjacent subcarriers in the frequency domain is equal to the ratio of the basic symbol rate to the length of the frequency domain data block. For example, in a DTMB system with a channel bandwidth of 8MHz, the basic symbol rate is 7.56MHz, the frequency domain data block length is fixed at 3780 symbols, and the calculated subcarrier spacing is 2KHz.

Delay-spreading channel: A delay-spreading channel is a channel whose channel impulse response is extended in time, and its channel delay is extended to the duration of the non-zero value of the channel impulse response. The delay spread characteristic of the channel will cause Inter Symbol Interference (ISI) or frequency selective fading between symbols in the time domain. A channel without delay spread is a flat fading channel or an AWGN (Additive White Gaussian Noise) channel, which has no frequency selectivity.

Inter-symbol interference: Due to the influence of channel delay extension, the components of each propagation path of the transmitted signal will superimpose each other at the receiving end, resulting in inter-symbol interference, that is, ISI;

Inter-block interference: Due to the influence of channel delay extension, the propagation path components of adjacent transmitted time-domain data frames will overlap each other at the receiving end, resulting in interference between adjacent time-domain data frames, that is, IBI (Inter-Block -Interference).

Referring to accompanying drawings 1a and 1b, schematic diagrams of transmitting ends of two typical OFDM block transmission systems are given.

Figure 1a illustrates the OFDM signal generation process at the transmitter of the CMMB (China Mobile Multimedia Broadcasting Industry Standard) system: the data to be transmitted (usually bits) is passed through the data symbol pre-processing module to obtain the data symbols to be transmitted, wherein the data symbol pre-processing includes scrambling Code, error correction coding, bit interleaving, constellation mapping and symbol interleaving, etc.; data symbols to be transmitted, pilot symbols and virtual subcarriers used for frequency domain spectrum shaping are combined to obtain symbol data blocks (for OFDM system, i.e. frequency domain data block), the length of the frequency domain data block is 1024 or 4096; the frequency domain data block is transformed by the IDFT of the corresponding length to obtain the time domain data block; the time domain data block is cyclically expanded to obtain the time domain data frame ( That is, the OFDM symbol specified in the standard); in order to improve the quality of signal spectrum shaping, the time domain data frame is further multiplied with the time domain window to obtain the time domain data frame that completes the spectrum shaping; finally, the time domain data frame is post-processed to obtain The transmitted OFDM signal.

Figure 1b shows the OFDM signal generation process at the transmitter of the DTMB (China Digital TV Terrestrial Broadcasting Transmission National Standard) system: the data to be transmitted is obtained after the data symbol pre-processing module; the data symbol to be transmitted and the system transmission parameter signaling (TPS) system information symbols form a symbol data block together, and the length of the symbol data block is 3780; the DTMB system supports two block modulation modes of single carrier and OFDM, in which the symbol data block is transformed by the identity matrix to obtain a single carrier time domain data block , the OFDM time domain data block is obtained after IDFT transformation of 3780 points; the gating module obtains the corresponding time domain data block by gating according to the working mode of the transmitter; the time domain data block and the PN training sequence before filling the guard interval together obtain the time domain Data frame; in order to realize the spectrum shaping of transmission signal, the time domain data frame obtains the time domain data frame that completes spectrum shaping after the time domain shaping filtering further, wherein shaping filter is square root raised cosine roll-off (SRRC) filter; The domain data frame is post-processed to obtain the transmitted OFDM signal.

Definition of technical terms involved in the technical solution of the present invention

For the convenience of description and understanding, some terms and concepts involved in the technical solution of the present invention are defined and explained as follows in conjunction with the accompanying drawings.

Multiframe: In the block transmission system, for the flexibility and convenience of channel management and resource allocation, a higher-level frame structure is usually defined above the physical layer time domain data frame, and multiple time domain data frames and auxiliary signals are combined into A multiframe, and the multiframe is the basic frame structure for channel management and resource allocation. Auxiliary signals are usually used for multiframe delimitation and receiver synchronization. For example, the T2 frame of the DVB-T2 standard is a multiframe, and its P1 symbol is an auxiliary signal, which is used for T2 frame detection and receiver synchronization. At the same time, the training information (such as training symbols and training sequences) of the time domain data frame can also assist the delimitation of the multiframe and the synchronization of the receiving end. For example, a superframe with a length of 125ms defined by the DTMB standard is a multiframe without auxiliary signals, and the fixed training sequence filled with the guard interval of the time domain data frame (that is, the header of the signal frame) can assist the demarcation and reception of the superframe side sync. In the multi-level frame structure, the multi-frame as the basic unit can also be combined into a higher-level frame, such as the second frame and sub-frame defined by the DTMB standard.

In particular, it should be pointed out that a special case of the multi-frame structure contains only one time-domain data frame, and there may be no auxiliary signal.

Time slicing: A slicing technology that divides transmission signals into time slices in the time dimension, and each time slice can form an independent physical layer transmission channel. Time slicing technology corresponds to time division multiplexing (TDM) and time division multiple access (TDMA) technology.

Data frame fragmentation: In a block transmission system with a multiframe structure, each time domain data frame forms a natural time slice, and the present invention defines each time slice of a multiframe structure as a data frame slice to distinguish it from ordinary time slice. Each data frame slice can form an independent physical layer transmission channel.

Frequency slicing: A slicing technology that divides transmission signals into frequency slices in the frequency dimension, and each frequency slice can form an independent physical layer transmission channel. The frequency dimension can be the frequency dimension corresponding to the Fourier transform of continuous time or discrete time, and the corresponding frequency slicing technology corresponds to frequency division multiplexing (FDM) and frequency division multiple access (FDMA) technology; the frequency dimension can also be the corresponding The frequency dimension of the discrete Fourier transform of the time-domain data block, and the corresponding frequency slicing technology corresponds to Orthogonal Frequency Division Multiplexing (OFDM) and Orthogonal Frequency Division Multiple Access (OFDMA) technologies.

Subcarrier Slicing: In an OFDM block transmission system, each subcarrier in the discrete Fourier transform domain forms a natural frequency slice. The present invention defines each frequency slice of the OFDM block transmission system as a sub-carrier slice to distinguish it from common frequency slices. Each sub-carrier slice can form an independent physical layer transmission channel.

Time-frequency slicing: A slicing technology that divides the transmission signal into time slices in the time-frequency two-dimensional space, and then divides each time slice into multiple time-frequency slices, or divides the transmission signal into frequency slices first, and then Each frequency slice is divided into multiple time-frequency slices, and each time-frequency slice can form an independent physical layer transmission channel. Time-frequency slicing technology is a combination of time slicing and frequency slicing. The time-frequency slicing technology corresponds to the TDM-FDM hybrid multiplexing technology and the TDMA-FDMA hybrid multiple access technology, or the TDM-OFDM hybrid multiplexing technology and the TDMA-OFDMA hybrid multiple access technology.

Data frame subcarrier slicing: In an OFDM block transmission system with a multiframe structure, each subcarrier of each time domain data frame forms a natural time-frequency slice. The present invention defines each time-frequency slice of the OFDM block transmission system with a multi-frame structure as a data frame sub-carrier slice to distinguish it from ordinary time-frequency slices. Each data frame subcarrier slice can form an independent physical layer transmission channel.

In the block transmission system of the prior art, for the convenience of system design, channel management, resource allocation and signal processing, usually the length of each time domain data block is the same, the direct consequence is that it limits the support for various business requirements , especially limits the trade-off between mobile speed and system spectral efficiency.

Flexible multiframe: the multiframe structure in the present invention is different from the existing multiframe structure, and the length of the time domain data frame included in it is flexible and variable. Therefore, the present invention defines a flexible multiframe structure, and the flexible multiframe structure It has the following characteristics: the length of each time-domain data frame can be different, and for an OFDM block transmission system, it is equivalent to the fact that the sub-carrier intervals in each frequency-domain data block can be different. The flexible multiframe structure makes it possible to compromise between mobile speed and system spectrum efficiency, and can better support various business requirements. In short, the short frequency domain data block has a large subcarrier spacing, which is suitable for supporting high-speed mobile; the long frequency domain data block has a small subcarrier spacing, which is suitable for supporting a limited mobile speed, but can improve the system spectrum. efficiency.

Basic channel unit: Corresponding to the system time-frequency resources in the physical layer frame structure, a set of regular time or frequency symbols (time-domain or frequency-domain symbols) constitutes a basic channel unit, which regularly occupies a certain channel during channel transmission. These time, frequency, code word, or space (ie, antenna or antenna beam) resources are the smallest units that constitute a physical layer subchannel. For the OFDM block transmission system with a multi-frame structure concerned by the present invention, without considering code division/space division multiplexing or code division/space division multiple access, the basic channel unit refers to the data frame subcarrier slice, which only takes up time and frequency resources, each data frame subcarrier slice is a basic channel unit. If code division/space division multiplexing or code division/space division multiple access is considered, the basic channel unit needs an extended definition, and those skilled in the art can fully refer to the prior art and the description of the present invention for the extended definition.

Basic time-frequency unit and basic bandwidth: for the OFDM block transmission system with multi-frame structure, the present invention defines a special basic channel unit named as basic time-frequency unit, which has the following characteristics:

1) The basic time-frequency unit consists of one or more subcarriers located in the same time-domain data frame;

2) The signal bandwidth occupied by the basic time-frequency unit is fixed, which is defined as the basic bandwidth. Specifically, for each time-domain data frame or each frequency-domain data block, the number of subcarriers and subcarriers contained in the basic time-frequency unit The product of the interval is a fixed constant, that is, the basic bandwidth. Therefore, the number of basic time-frequency units of each time-domain data frame in the multiframe structure is fixed;

3) When the basic time-frequency unit is composed of multiple subcarriers in the same time-domain data frame, the positions of the corresponding subcarriers can be placed centrally, dispersedly, or a mixture of the two.

Physical layer subchannel: In the multiframe structure, the physical layer transmission subchannel composed of basic channel units regularly occupies certain time, frequency, codeword, or space (that is, antenna or antenna beam) during physical layer channel transmission. ) resources, which can be separated by the receiving end from the signal received at the physical layer.

Multiplexing: It is the case where a physical channel is shared by multiple service data of the same transmitter.

Downlink multiple access: It is a special multiplexing with the following characteristics: the physical channel shared by multiple service data at the same transmitter can be divided into independent physical layer sub-channels, and each sub-channel realizes the transmission of one channel of service data. Among them, One channel of service data can be obtained by multiplexing multiple channels of sub-service data.

Multiple access: usually refers to uplink multiple access, that is, a physical channel is shared by business data from different transmitters.

The essence of downlink multiple access and uplink multiple access is that the same physical channel is decomposed into multiple independent physical layer sub-channels.

Channel resource mapping: the mapping from the basic channel unit (the present invention specifically refers to the basic time-frequency unit) to the physical layer sub-channel (the present invention specifically refers to the time-frequency sub-channel) or the mapping from the physical layer sub-channel to the basic channel unit is defined as a channel resource Mapping, the corresponding mapping pattern is the channel resource mapping pattern.

Time-frequency mapping pattern: For the OFDM block transmission system with a multi-frame structure concerned by the present invention, channel resources specifically refer to time-frequency resources, so channel resource mapping specifically refers to time-frequency mapping, and the corresponding mapping patterns are time-frequency mapping patterns.

Time-frequency sub-channel and sub-channel bandwidth: for the OFDM block transmission system with multi-frame structure, the present invention defines a special physical layer sub-channel, named as time-frequency sub-channel, which can be used by the receiving end in the physical layer multi-frame signal and time-frequency sub-channel Separated from the domain data frame signal, the time-frequency sub-channel has the following characteristics:

1) The time-frequency sub-channel consists of one or more basic time-frequency units in one time-domain data frame, or consists of multiple basic time-frequency units in multiple time-domain data frames;

2) After determining the number of basic time-frequency units included in the time-frequency sub-channel, since the basic bandwidth of the basic time-frequency unit is fixed, the signal bandwidth occupied by the time-frequency sub-channel is also fixed, which is defined as the corresponding time-frequency sub-channel The channel bandwidth ("sub-channel bandwidth" for short), specifically, a time-frequency sub-channel contains a fixed number of basic time-frequency units in each corresponding time-domain data frame, and its sub-channel bandwidth is the basic bandwidth The product of the number of basic time-frequency units and the number of included basic time-frequency units, obviously, after all the time-frequency resources of the system are allocated, the sum of the bandwidths of all time-frequency sub-channels belonging to any time-domain data frame is equal to the total channel bandwidth;

3) When the time-frequency sub-channel is composed of multiple basic time-frequency units in one or more time-domain data frames, the corresponding basic time-frequency units can be placed centrally, or scattered, or a combination of both mix.

In particular, it should be pointed out that a special case of a physical layer subchannel includes all channel resources. Correspondingly, a special case of a time-frequency subchannel includes all basic time-frequency units, and a special case of a basic time-frequency unit includes all frequency domain subchannels. carrier.

Where there is no special description, the physical layer sub-channel or time-frequency sub-channel is referred to as “sub-channel” for short, and the bandwidth of the physical-layer sub-channel or time-frequency sub-channel is referred to as “sub-channel bandwidth” for short.

In a block transmission system with a multi-frame structure, physical layer sub-channels or time-frequency sub-channels can be used to carry symbols and transmit physical layer signaling service data, common service data, training data or a mixture of various data.

Sub-channel transmission mode: The symbols carried by each physical layer sub-channel or time-frequency sub-channel, its scrambling code, error correction coding, constellation mapping, average power and interleaving mode are defined as sub-channel transmission mode, sub-channel transmission mode can be based on Service requirements and channel conditions are set independently, which is the basis for the downlink multiple access system based on physical layer sub-channels to support multi-service transmission. Apparently, the transmission modes of various data located in the same physical layer sub-channel or time-frequency sub-channel are the same.

Physical layer signaling sub-channel: The present invention defines a physical layer sub-channel or a time-frequency sub-channel for transmitting physical layer signaling service data as a physical layer signaling sub-channel (referred to as "signaling sub-channel"), and the signaling sub-channel carries The physical layer signaling service data can also carry other filling data mixed with various data.

Sub-channel priority: Since the transmission modes of physical layer sub-channels or time-frequency sub-channels can be set independently, the average power, spectral efficiency, coverage, and receiver carrier-to-noise ratio thresholds of different physical layer sub-channels may also be different. Different subchannel transmission modes correspond to different subchannel priorities. Generally speaking, under the same channel conditions, it is easier to demodulate and decode the physical layer sub-channels with a lower carrier-to-noise ratio threshold at the receiving end. The corresponding physical layer sub-channels or time-frequency sub-channels are generally called high-priority sub-channels. On the contrary, it is difficult to demodulate and decode the physical layer sub-channels with a high carrier-to-noise ratio threshold at the receiving end, and the corresponding physical layer sub-channels or time-frequency sub-channels are generally called low-priority sub-channels. The priority of the subchannel depends on the average power of the physical layer subchannel, the spectral efficiency, and the required coverage of the subchannel.

For downlink multiple access multi-service transmission systems that support diverse business requirements, high-priority sub-channels can be independently demodulated and decoded; low-priority sub-channels can be independently demodulated and decoded, or high-priority The demodulation or decoding results of the sub-channels assist in demodulation and decoding.

Resource scheduling: A downlink multiple access system that supports multiple services. The available resources of the system (such as time-frequency resources and transmit power, etc.) are shared by all services. According to the channel conditions of the actual transmission environment (such as received signal level, channel fading characteristics, etc.) and Service requirements (such as transmission rate, service priority, receiving end SNR threshold, real-time performance, etc.) The operation of setting and allocating physical layer sub-channels for services is resource scheduling, where the setting of physical layer sub-channels includes determining the channel resource mapping pattern and sub-channel transmission modes.

Example 1

This embodiment provides a flow of a method for determining a multi-service transmission mode of a downlink multiple access system based on a multiframe structure and time-frequency sub-channels.

The method of determining the multi-service transmission mode of the downlink multiple access system needs to consider the application environment of the downlink multiple access system and corresponding system parameters; it needs to consider the service requirements of different target users and correspond to service information; at the same time, under the premise of meeting the service needs of the target users, The best compromise is achieved between multiple objectives such as system transmission efficiency and system implementation complexity.

As shown in Figure 2, based on the background technology and the above-mentioned definition of the multiframe structure and the description of the downlink multiple access OFDM block transmission system, the present invention proposes a flexible multiframe structure and time-frequency sub-channels to determine the multiple A method for a service transmission mode, comprising the following steps:

S1, obtaining system parameters and business information;

The system parameters include but not limited to the system operating frequency band, the system maximum channel bandwidth and the maximum delay extension of channel transmission, etc.; business information includes but not limited to the maximum number of supported sub-channels, maximum moving speed, maximum transmission rate and real-time requirements, etc. ;

S2. Determine the basic transmission mode according to the system parameters and service information. In this embodiment, determining the basic transmission mode includes determining the following information: determining the form of the multiframe, determining the form of the basic channel unit, determining the form of the physical layer subchannel, etc.;

Specifically include the following steps:

S2.1. Determine that the multiframe used in the transmission is composed of an auxiliary signal and one or more time-domain data frames of different lengths, wherein the time-domain data frame is composed of a guard interval and a time-domain data block, and the time-domain data The blocks are in one-to-one correspondence with the frequency domain data blocks in the multiframe structure through time-frequency transformation, and the frequency domain data blocks are composed of subcarriers;

The multiframe structure adopted in the transmission mode of the present invention is a multiframe structure whose parameters can be flexibly configured, and has the following characteristics:

1) The multiframe consists of an auxiliary signal and one or more time domain data frames;

2) The time-domain data frame is composed of a guard interval and a time-domain data block, and the lengths of each time-domain data block and its guard intervals are either all the same or set independently, wherein the time-domain data block and the time-domain data block Frames correspond one-to-one in multiframes;

3) The time-domain data block is obtained by IDFT (inverse discrete Fourier transform) of the frequency-domain data block. Data blocks correspond one-to-one in the multiframe structure;

4) The frequency-domain data block is composed of frequency-domain symbols (ie, subcarriers), where the frequency-domain symbols are effective subcarriers for transmitting service data symbols, pilots for transmitting training symbols, or virtual subcarriers for transmitting zero symbols, or The mixture of the three, the sum of the number of effective subcarriers, pilots, and virtual subcarriers of the frequency domain data block is equal to the total number of frequency domain symbols of the frequency domain data block;

5) Service data symbols are used to carry data services of one or more time-frequency sub-channels.

S2.2. Determine that the basic channel unit in transmission is a basic time-frequency unit composed of one or more subcarriers located in the same time-domain data frame, and the signal bandwidth occupied by the basic time-frequency unit is fixed, which is defined as the basic bandwidth;

The basic time-frequency unit corresponds to the system time-frequency resource in the multiframe structure of the physical layer, which is a set composed of a set of regular time or frequency symbols (time-domain or frequency-domain symbols), and is the smallest unit for forming a time-frequency sub-channel;

S2.3, determine that the physical layer subchannel in transmission is composed of one or more basic time-frequency units in one time-domain data frame in the multiframe structure, or multiple basic time-frequency units in multiple time-domain data frames Time-frequency sub-channels composed of units;

S3, obtaining information on available time-frequency resources, channel conditions and service requirements of the system;

The system available resources include but not limited to available bandwidth, transmit power and multiframe time-frequency resources; channel conditions include but not limited to channel delay spread, channel Doppler spread, and channel interference pattern of the transmission channel from the transmitter to the receiver of different services etc.; business requirement information includes but is not limited to the number of required time-frequency sub-channels and the real-time requirements, transmission bandwidth requirements, QOS (quality of service) requirements and transmission rate requirements corresponding to each time-frequency sub-channel; among them, the system available resources and channel Conditions are interrelated.

S4. Under the guidance of the external sub-channel allocation algorithm, according to the available resources of the system, channel conditions, and service requirements, determine the specific transmission mode adopted by the multi-service transmission based on the basic transmission mode, specifically determining but not limited to multi-service The multiframe structure, time-frequency mapping pattern and sub-channel transmission mode of each time-frequency sub-channel adopted during transmission specifically include the following steps:

S4.1, determine the specific multiframe structure used in the transmission of different services;

S4.2, determine the time-frequency mapping pattern of the mapping result of the basic time-frequency unit to the time-frequency sub-channel or the mapping result of the time-frequency sub-channel to the basic time-frequency unit, and complete the time-frequency resources of the time-frequency sub-channel required for the transmission of different services distribute;

S4.3. Determine the subchannel transmission mode of each time-frequency subchannel.

S5, judging whether the system supports physical layer signaling and flexible scheduling, if not, it means that the system transmission mode is fixed, the transmission mode is determined at the end, the system works according to the current specific transmission mode, otherwise step S6 is performed;

S6. If the system can transmit changes in time-frequency resources, channel conditions, or service demand information, return to step S3; otherwise, keep the system transmission mode unchanged.

Determining the basic transmission mode in step S2 in this embodiment also includes determining the following information: definition of spectrum shaping method, basic symbol interval, signal bandwidth, auxiliary signal of multiframe, type of time domain data frame length, guard interval filling method, multiframe length, the basic bandwidth of the basic time-frequency unit, and the division of the basic time-frequency unit.

As shown in Figure 3, determining the basic transmission mode in step S2 also includes the following steps:

S2.4, combined with the receiving end synchronization and channel estimation algorithm, define the auxiliary signal form of the multiframe in step S2.1, for example, select the preamble sequence or superposition sequence, or do not need the auxiliary signal; select the spectrum shaping method, according to the spectrum shaping method and The maximum channel bandwidth determines the basic symbol interval and signal bandwidth;

S2.5. Define one or more time-domain data block lengths according to the working frequency band and the maximum moving speed of different services. The type of time-domain data block length directly determines the type of frequency-domain data block subcarrier spacing;

S2.6, according to the maximum delay extension of the channel corresponding to different services, define one or more guard interval lengths and one or more filling methods of the guard interval; according to the real-time requirements of the business, determine the complex The length range of the frame, wherein the multiframe length can be changed within a certain range, and the receiving end can realize the multiframe synchronization of the receiving end according to the auxiliary signal or the time domain data frame structure;

S2.7, considering flexibility and realizability, determine the specific size of the basic bandwidth of the basic time-frequency unit in step S2.2, wherein, after the basic bandwidth is determined, the number of basic time-frequency units of each time-domain data frame is also determined accordingly;

S2.8, considering flexibility, algorithm complexity, multi-channel multiplexing gain, frequency domain diversity gain and system transmission efficiency, define the basic time of each frequency domain data block corresponding to the time domain data block in step S2.5 Frequency unit division method, wherein a frequency domain data block shares the same basic time-frequency unit division method.

In order to ensure the simple correspondence between the basic time-frequency unit and the subcarriers of the frequency domain data block, the principle of the basic bandwidth definition is as follows: the basic bandwidth determined in step S2.7 is an integer multiple of the subcarrier interval corresponding to any frequency domain data block in the multiframe structure , or the subcarrier spacing of any frequency-domain data block can be divisible by the basic bandwidth.

Regarding the steps S2.5 and S2.6 of the rough design of the system, the supplementary explanation is as follows: In order to achieve the best compromise between multiple system design goals, the number of each time domain data frame in the multiframe structure may not be specified, It is also possible not to specify the total number of all time-domain data frames in the multiframe structure.

Regarding the determination of the basic bandwidth in step S2.7, further discussion is as follows: assuming that the signal bandwidth is BW, and the basic bandwidth corresponding to the basic time-frequency unit is BI, then each frequency domain data block includes BW/BI basic time-frequency units, For the convenience of basic time-frequency unit division and sub-channel allocation, BW/BI is required to be an integer. Assume that the length of the i-th (i is a natural number) frequency domain data block is N _i symbols, and the duration is N _i *Ts, where Ts is the basic symbol interval, then the subcarrier spacing of the i-th frequency domain data block is Fs/ N _i , where Fs is the basic symbol rate Fs=1/Ts, then the number of sub-carriers C _i =BI*N _i /Fs contained in a basic time-frequency unit of the i-th frequency domain data block; for basic time-frequency unit division And the convenience of sub-channel allocation requires that C _i be an integer. Obviously, the basic bandwidth is an integer multiple of the subcarrier spacing of any frequency domain data block in the multiframe structure, or in other words, the subcarrier spacing of any frequency domain data block in the multiframe structure can be divisible by the basic bandwidth, so after the basic bandwidth is determined, the frequency domain data The subcarrier interval of the block can no longer be selected arbitrarily, which is equivalent to the fact that the length of the data block in the time domain cannot be selected arbitrarily.

Regarding the division of basic time-frequency units in step S2.8, further discussion is as follows:

Referring to Figure 4, in a frequency domain data block, if the basic time-frequency unit is composed of multiple subcarriers, the multiple subcarriers corresponding to a basic time-frequency unit can be placed in a centralized manner (left figure), scattered (middle figure), or Mixed placement is possible (pictured right). The frequency domain data block in the figure contains 12 subcarriers (indicated by horizontal arrows), which are divided into three basic time-frequency units (marked as units 1, 2, and 3). The subcarrier sets corresponding to the three basic time-frequency units in the left figure are { 1, 2, 3, 4}, {5, 6, 7, 8}, and {9, 10, 11, 12}; the subcarrier sets corresponding to the three basic time-frequency units in the middle figure are {1, 4, 7, 10}, {2, 5, 8, 11}, and {3, 6, 9, 12}; the subcarrier sets corresponding to the three basic time-frequency units in the right figure are {1, 2, 7, 8} in turn , {3, 4, 9, 10}, and {5, 6, 11, 12}.

After the basic bandwidth is determined, the division of basic time-frequency units has a great impact on system performance. Centralized placement can obtain multi-channel multiplexing gain (different sub-channels have different frequency selectivity, and the system can choose the most favorable sub-channel allocation method), and can also reduce interference between basic time-frequency units for channels with inter-subcarrier interference. And it is convenient to avoid sub-carriers with channel interference. Scattered placement can obtain frequency diversity gain, but for channels with inter-subcarrier interference, the interference between basic time-frequency units will be aggravated, and it is not convenient to avoid sub-carriers with channel interference. The flexibility of mixed placement is the highest, but the design is complex, which is not limited in the present invention, and can be freely selected according to system parameters and business information.

Referring to FIG. 5 , the system available resources in step S3 can be obtained through an existing spectrum sensing module. For a two-way communication system, the channel condition in step S3 can be obtained by feedback from the receiving end through the uplink channel, or the channel condition can be estimated directly based on the signal from the receiving end to the transmitting end through the reverse channel.

With the support of OFDM technology and multi-frame structure, in the transmission mode of the downlink multiple access multi-service transmission system of the present invention, all time-frequency sub-channels can flexibly allocate time-frequency resources, so the time-frequency resources occupied by the entire downlink multiple access system It can also be allocated flexibly, so that time and frequency resources that have been reserved for uplink multiple access transmission can be avoided, and time and frequency resources occupied by interference signals or other systems can also be avoided, so the system available resource information is very important.

On the other hand, based on the available resource information of the system, a higher maximum signal bandwidth can be selected when determining the basic transmission mode, so that the actual signal available bandwidth can be adjusted according to the actual situation. Of course, it will increase the calculation for the transmitter or receiver. volume and complexity.

For step S4, as shown in Figure 6, specifically in this embodiment:

In step S4.1, according to business requirements, combined with the external subchannel allocation algorithm, determine the specific multiframe structure used, including determining the number of time-frequency data frames in the multiframe and the type of each time-domain data frame, wherein the time-domain data The frame type is mainly determined by the time domain data frame length, guard interval length and guard interval filling mode;

In step S4.2, according to the available system resources, channel interference patterns and service transmission bandwidth requirements, under the guidance of the external subchannel allocation algorithm, allocate available time-frequency resources for each time-frequency sub-channel corresponding to service requirements, and determine the basic time-frequency resources. The mapping result of the frequency unit to the time-frequency sub-channel or the mapping result of the time-frequency sub-channel to the basic time-frequency unit to obtain the time-frequency mapping pattern, wherein the time-frequency mapping pattern information includes the bandwidth of each time-frequency sub-channel, the corresponding one or Multiple time-domain data frame positions, basic time-frequency unit positions occupied in each time-domain data frame; thus completing time-frequency resource allocation of time-frequency sub-channels required for transmission of multiple different services;

In step S4.3, according to the real-time service requirements, QOS requirements and transmission rate requirements, determine the transmission mode for each time-frequency sub-channel, including but not limited to scrambling code, error correction coding, constellation mapping, interleaving mode, and average power , where the subchannel allocation algorithm optimizes the average power of each subchannel under the constraint of the total transmit power.

If it is judged in step S5 that the system supports physical layer signaling and flexible scheduling, it needs to be supported by a corresponding scheduling module. The scheduling module needs signaling service data, where the signaling service data includes all the information needed to assist the receiving end in demodulating and decoding arbitrary time-frequency sub-channel data, such as the number and length of time-domain data frames, guard interval length and filling mode , time-frequency mapping pattern, and sub-channel transmission mode, etc. The scheduling module needs to allocate dedicated time-frequency sub-channels, ie, signaling sub-channels, for signaling service data. Signaling may require dynamic configuration. Therefore, the present invention proposes that signaling service data may also contain filling information in addition to signaling information, so as to facilitate the allocation of signaling subchannels. The signaling information includes specifically adopted multiframe structure, time Frequency mapping pattern and sub-channel transmission mode. The signaling sub-channel is usually set with a high priority to ensure normal demodulation and decoding of signaling service data. If the system does not support physical layer signaling and flexible scheduling, it does not need to generate physical layer signaling, and does not need to allocate dedicated signaling subchannels. It should be emphasized that in order to ensure the demodulation and decoding of signaling service data at the receiving end, the time-frequency pattern corresponding to the signaling sub-channel is required to be one of the preset modes and should not be adjusted flexibly.

With the support of physical layer signaling, the dynamic adjustment of system settings can effectively meet various business needs while improving system transmission capacity. For example, if a data service requires to increase or decrease the transmission rate, the system needs to adjust the resource allocation or sub-channel transmission mode; when the available resources of the system change, the system needs to adjust the multi-frame structure, time-frequency mapping pattern, or sub-channel transmission mode. To meet the requirements of certain data services for high transmission capacity; if the channel conditions of one or more data services change, the system needs to adjust the sub-channel transmission mode or time-frequency mapping pattern to meet service requirements.

A further description of "obtaining the time-frequency mapping pattern" in step S4.2 is as follows, which specifically includes the steps:

S4.2.1, using the basic time-frequency unit determined in step S2.7 as a unit, determine the available time-frequency resources of the system; the basic time-frequency units outside the channel bandwidth are not available, and the corresponding system within the channel bandwidth reserves time-frequency resources or system confirmation Basic time-frequency units that are unavailable (such as strong interference or other legal signals) are also unavailable, for example, the bandwidth reserved for uplink transmission in a frequency division duplex (FDD) system; The frequency is also unavailable due to strong interference or other legal signals, for example, uplink time slots reserved for time division duplex (TDD) in the multiframe structure.

S4.2.2, according to the external sub-channel allocation algorithm, determine the sub-channel bandwidth of each time-frequency sub-channel corresponding to the service demand information, wherein the sub-channel bandwidth is an integer multiple of the basic bandwidth; when sub-channel bandwidth allocation needs comprehensive consideration The peak rate of the frequency sub-channel, the complexity of the receiver and the available time-frequency resources of the system.

S4.2.3. According to the external subchannel allocation algorithm, determine one or more frequency domain data block positions corresponding to each time frequency subchannel, that is, one or more time domain data frame positions. When allocating frequency-domain data blocks for time-frequency sub-channels, it is particularly necessary to consider the guard interval filling of the corresponding time-domain data frames and the transmission rate required by the sub-channels.

S4.2.4, according to the external sub-channel allocation algorithm, determine all the basic time-frequency units of each time-frequency sub-channel; one or more frequency-domain data blocks corresponding to each time-frequency sub-channel constitute the basic time-frequency sub-channel The position of the time-frequency unit in the frequency-domain data block is either the same or independent of each other; for each time-frequency sub-channel, when the sub-channel bandwidth is determined, the corresponding basic time-frequency unit contained in each frequency-domain data block The number is also determined, and each frequency-domain data block needs to be allocated an appropriate basic time-frequency unit. However, the positions for allocating basic time-frequency units for each frequency domain data block can be different, so as to achieve the effect of frequency hopping diversity.

The result of the time-frequency subchannel allocation is represented by a time-frequency map pattern. Obviously, the total time-frequency resources occupied by all time-frequency sub-channels cannot be greater than the available time-frequency resources of the system, but can be smaller than the available time-frequency resources of the system, that is, some time-frequency resources are not allocated.

As mentioned above, the sub-channel allocation algorithm for time-frequency mapping optimization to obtain the time-frequency mapping pattern is provided externally, which is not the scope of the present invention. The present invention only proposes some principles for sub-channel allocation, which are summarized as follows:

1) Input: system available resources (including multi-frame time-frequency resources expressed in basic time-frequency units), number of time-frequency sub-channels, channel conditions corresponding to each time-frequency sub-channel, and services corresponding to each time-frequency sub-channel need.

2) One of the goals: to meet the needs of multiple services, while taking into account the implementation of the transmitting end, the implementation of the receiving end and the complexity of the system scheduling algorithm. For example, if the basic bandwidth of the basic time-frequency unit is large, the system scheduling algorithm is simpler.

3) Goal 2: On the premise of meeting the business needs of target users, achieve the best compromise between multiple system design goals such as system transmission efficiency and system implementation complexity. For example, the typical fading of broadband wireless mobile and terrestrial broadcasting is the frequency selective fading caused by channel time domain expansion. In the downlink multiple access environment, if the frequency selective fading of multiple time-frequency sub-channels is uncorrelated, you can choose the appropriate The frequency domain resource scheduling algorithm can obtain multi-user multiplexing gain, and the basic bandwidth of the basic time-frequency unit is small, the system scheduling algorithm is more flexible, and it is more effective for mining multi-user multiplexing gain.

4) Output: the time-frequency mapping pattern corresponding to the multiframe structure.

Example 2

The flow of the method for determining the multi-service transmission mode of the downlink multiple access system in this embodiment is based on Embodiment 1. This embodiment specifically provides the multi-frame structure adopted in the multi-service transmission mode in the method described in Embodiment 1.

The multiframe structure is the starting point of the transmission mode determination, work flow and implementation device of the present invention. With reference to accompanying drawing 7, the multiframe structure that the present invention proposes for the downlink multiple access OFDM block transmission system has the following characteristics:

1) The multiframe consists of an auxiliary signal and one or more time domain data frames;

2) The auxiliary signal is one of the following forms: a preamble sequence, a superposition sequence, a known training sequence between or after time-domain data frames, or a combination of multiple sequences, or there is no auxiliary signal (that is, the auxiliary signal is an empty signal);

3) The time-domain data frame is composed of a guard interval and a time-domain data block, and the length of each time-domain data block and its guard interval can be set independently, wherein the time-domain data block and the time-domain data frame are combined in a multiframe structure one-to-one correspondence;

4) The guard interval fills the cyclic extension, zero sequence or known training sequence of the time-domain data block. The guard interval filling mode of each time-domain data frame can be set independently. When the guard interval length is zero, it degenerates into no guard interval ( That is, the guard interval fills the empty signal);

5) The time-domain data block is obtained by IDFT transforming the frequency-domain data block, wherein the length of the frequency-domain data block (ie, the number of IDFT points) is the same as the length of the time-domain data block, and the frequency-domain data block and the time-domain data block are in a multi-frame structure one-to-one correspondence;

6) The frequency domain data block is composed of frequency domain symbols (i.e. subcarriers), where the frequency domain symbols include effective subcarriers for transmitting service symbols, pilots for transmitting training symbols, virtual subcarriers for transmitting zero symbols, or a mixture of the three , the sum of the number of effective subcarriers, pilots, and virtual subcarriers of a frequency domain data block is equal to the length of the frequency domain data block (expressed in symbols);

7) Traffic symbols are used to carry signaling data traffic and/or other data traffic of one or more time-frequency sub-channels.

In summary, the main parameters of the multiframe structure include: symbol definition, auxiliary signal definition, multiframe length, guard interval type, time domain data block type, definition of each time domain data frame, and each time domain data frame parameters.

Referring to the accompanying drawing 8a, the multiframe is composed of a preamble sequence (PreambleSequence) with a length of K and N time domain data frames, wherein N is an integer greater than zero, and the multiframe length is the sum of the length of the preamble sequence and all time domain data frames . The length of the i-th time-domain data frame is Li symbols, _i =1, 2, . The multiframe in Fig. 8b is composed of a superimposed sequence (Super-imposed Sequence) and N time-domain data frames, where N is an integer greater than zero, and the length of the multiframe is the sum of the lengths of all time-domain data frames. The length of the superposition sequence is M, which is not greater than the sum of the lengths of all time-domain data frames in the multiframe. The multiframe in Fig. 8c is composed of three time domain data frames, two training sequences (Training Sequence) between adjacent time domain data frames, and the last training sequence of the multiframe. Among them, the first time-domain data frame uses cyclic extension to fill the guard interval, and has pre-cyclic extension and post-cyclic extension; the second time-domain data frame has no guard interval; the front guard interval of the third time-domain data frame is filled with zero sequences.

In the multiframe structures shown in Figs. 8a to 8c, the preamble sequence, the superposition sequence, and the training sequence between or after the time domain data frames are all auxiliary signals. The main body of the multi-frame structure is one or more time-domain data frames, and the frequency-domain symbols positioned at the frequency-domain data blocks corresponding to the time-domain data frames constitute one or more physical layer sub-channels (the present invention specifically refers to time-frequency sub-channels), Used to carry one or more channels of business data. If there is no auxiliary symbol and the multiframe contains only one time domain data frame, the multiframe structure degenerates into a simple time domain data frame structure.

Example 3

This embodiment provides a transmitter device based on the method for determining a downlink multiple access multiple service transmission mode proposed by the present invention.

Referring to accompanying drawing 9, based on the background technology and the above-mentioned description about the multi-frame structure definition and the downlink multiple-access OFDM block transmission system, the present invention proposes a transmitter device based on the above-mentioned method for determining the downlink multiple-access multi-service transmission mode, including: Scheduling unit, signaling service multiplexing unit, sub-channel coding and modulation unit, frequency domain data block composition unit, IDFT unit, time domain data frame framing unit, multiframe framing unit and multiframe subsequent processing unit, used to combine Signaling service data and other common service data are converted into OFDM transmission signals with a multi-frame structure, where each service data occupies different time-frequency sub-channels.

The functions and signal connections of each unit are described as follows:

1) A resource scheduling unit, configured to use the method described in Embodiment 1 to determine the multiframe structure, subchannel transmission mode, and time-frequency mapping pattern used in multi-service transmission, that is, the system available resources according to the multiframe structure and external feedback and the actual channel conditions and input system business requirements, with the support of the external sub-channel allocation algorithm (shown in the shaded box in the figure), allocate time-frequency sub-channels for each service, and generate a signal containing all time-frequency sub-channel parameters Command information and scheduling information, as well as control signals for all other units at the transmitter. According to the signaling information obtained by demodulation and decoding, the receiving end can analyze and obtain the required time-frequency sub-channel parameters, wherein the scheduling information includes the sub-channel transmission mode, guard interval filling mode, time-frequency mapping pattern and the configuration of the entire transmitting end implementation device. Control signals, etc., wherein the control signals include timing signals of each component of the multiframe structure (such as auxiliary signals and frequency domain data blocks).

2) The signaling service multiplexing unit multiplexes the physical layer signaling information and filling information to obtain the signaling data service, and outputs the corresponding service bits (or other suitable input formats, such as service bytes, depending on the sub-channel coding modulation specific method).

3) The sub-channel coding and modulation unit, according to the sub-channel transmission mode provided by the resource scheduling unit, performs coding and modulation on the input service bits such as scrambling, error correction coding, constellation mapping, interleaving and power control, to obtain corresponding service symbols, and at the same time according to The training symbols required by the time-frequency sub-channel need to be filled. The sub-channel coding and modulation units of the signaling service and the common data service are common. What needs to be emphasized is that one input data service can be obtained by multiplexing one or more data subservices, but the transmission mode of one or more data subservices belonging to one subchannel is the same.

4) The frequency-domain data block composition unit, according to the time-frequency mapping pattern (instant-frequency sub-channel information) provided by the resource scheduling unit and the timing signal of the current frequency-domain data block, multiple time-frequency sub-channels belonging to the current frequency-domain data block Multiplex the service symbols and training symbols to obtain the frequency domain data block that completes the subcarrier multiplexing;

5) The IDFT unit performs IDFT operation (ie OFDM modulation) on the input frequency domain data block according to the length information of the current frequency domain data block provided by the resource scheduling unit to obtain a time domain data block. The number of IDFT points is consistent with the length of the frequency domain data block, and, according to the multiframe structure, the number of IDFT operation points of different frequency domain data blocks can be different, so the IDFT unit needs to support all possible operation points;

6) The time-domain data frame framing unit, according to the guard interval filling mode provided by the resource scheduling unit and the timing signal of the current time-domain data frame, obtains the guard interval for filling the required signal, and forms the guard interval and the time-domain data block together domain data frame;

7) The multiframe framing unit, according to the time-frequency mapping pattern provided by the resource scheduling unit and the timing signal of the current multiframe, forms a multiframe signal together with one or more input time domain data frames and auxiliary signals;

8) The multi-frame subsequent processing unit performs post-processing such as spectrum shaping, digital-to-analog conversion, and radio frequency modulation on the multi-frame signal to obtain the final transmission signal.

Example 4

This embodiment provides a receiver device corresponding to a single time-frequency sub-channel in a downlink multiple access OFDM block transmission system proposed by the present invention.

Referring to accompanying drawing 10, corresponding to the said transmitting end implementing device of embodiment 3, the present invention further proposes a kind of receiving end reference implementing device corresponding to a single time-frequency sub-channel in the downlink multiple access OFDM block transmission system (abbreviated as receiving end implementing device ), the receiving end implementation device works on the receiving end corresponding to the transmitting end implementation device, and is used for demodulation and decoding of a single time-frequency sub-channel, the receiving end device includes: a front-end unit, a time domain data frame separation unit, a DFT unit , a frequency domain data block sub-channel separation unit, a signaling sub-channel demodulation and decoding unit, a common sub-channel demodulation and decoding unit and a control unit.

The control unit receives known information (including signaling subchannel information preset by the system, part of the multiframe structure information and part of time-frequency pattern mapping information, etc.), and the signaling obtained by demodulating the signaling subchannel and analyzing the signaling service data. Information and synchronization information provided by the front-end unit, obtain all the multiframe structure, time-frequency pattern mapping and required sub-channel transmission mode information required by the receiving end, and generate control signals and timing signals required by other units;

The front-end unit, under the control of the control unit, completes radio frequency demodulation, analog-to-digital conversion, and performs receiver synchronization according to the characteristics of the multiframe structure (such as auxiliary signals or time-domain data frame guard interval filling modes) to obtain multiframe signals and Synchronization information;

The time-domain data frame separation unit, under the control of the control unit, first separates the required time-domain data frame from the multi-frame signal according to the multi-frame structure, and then separates the required time-domain data block from the time-domain data frame, and outputs to subsequent DFT units;

The DFT unit, under the control of the control unit, performs DFT transformation according to the frame length of the input time domain data block provided by the multiframe structure to obtain a frequency domain data block composed of subcarriers; wherein, the DFT unit needs to support corresponding to different time domain data All possible operation points of the block length;

The frequency domain data block subchannel separation unit, under the control of the control unit, according to the multiframe structure, time-frequency mapping pattern and the timing signal of the current frequency domain data block, input frequency domain data block (corresponding to a certain channel time frequency resource time slice) to separate the subchannels to obtain the signaling symbol blocks corresponding to the signaling subchannels and the common symbol blocks corresponding to the required common subchannels;

Referring to accompanying drawing 11, signaling sub-channel demodulation and decoding unit, under the control of the control unit, according to the transmission mode of the signaling sub-channel, first utilizes the multiframe auxiliary signal, combined with the training symbols inside the signaling sub-channel, to perform signaling sub-channel Channel estimation of the channel to obtain signaling sub-channel estimation results; use signaling sub-channel estimation results to perform signaling sub-channel equalization to obtain equalized data symbols, perform deinterleaving, constellation demapping, and channel decoding on the equalized data symbols , and descrambling operations to obtain signaling service data (generally expressed in bits) and send it to the signaling analysis unit; in addition, the intermediate or final results of signaling sub-channel demodulation and decoding are output to the ordinary sub-channel demodulation and decoding unit;

The signaling parsing unit, under the control of the control unit, analyzes the signaling service data according to the signaling format and syntax, obtains and outputs the signaling information and filling information contained in the signaling service data, wherein the signaling information is output to the control unit. The signaling information includes multiframe structure, basic time-frequency unit definition, time-frequency mapping pattern and sub-channel transmission mode, etc.

The signaling sub-channel is a special time-frequency sub-channel containing signaling service data, which is different from other common time-frequency sub-channels; the signaling sub-channel can also transmit filling information in addition to signaling information. If the required service data is contained in the stuffing information of the signaling subchannel, it is not necessary to demodulate other time-frequency subchannels.

Referring to Figure 12, the common subchannel demodulation and decoding unit, under the control of the control unit, according to the current subchannel transmission mode, first uses the intermediate or final result of the externally input signaling subchannel demodulation and decoding, combined with the current subchannel internal The training symbol of the current sub-channel is estimated or updated to obtain the current sub-channel estimation result; the channel equalization is performed on the input data symbol by using the current sub-channel estimation result, and the equalized data symbol is obtained, and the equalized data symbol is decomposed Operations such as interleaving, constellation demapping, channel decoding, and descrambling are performed to obtain and output common service data (generally expressed in bits).

In the downlink multiple access OFDM block transmission system proposed by the present invention, the priorities of different time-frequency sub-channels may be different. The above device for realizing the receiving end can be oriented to both high priority services and low priority services. At the receiving end, the high-priority time-frequency sub-channel usually requires a lower CNR threshold for demodulation and decoding, while the low-priority time-frequency sub-channel requires a higher CNR threshold. In particular, the signaling subchannel usually has a high priority, so the demodulation and decoding results of the signaling subchannel can also assist the demodulation and decoding of common time-frequency subchannels.

Referring to FIG. 13 , the present invention further proposes a receiver-end reference implementation device for hierarchical demodulation and decoding corresponding to low-priority sub-channels. When demodulating and decoding the data symbols transmitted by the low-priority time-frequency sub-channel, the signaling sub-channel and/or the data symbols of the high-priority time-frequency sub-channel can be demodulated first, and the intermediate or final As a result, low-priority time-frequency sub-channels are assisted in channel estimation. The high and low priority sub-channel demodulation and decoding units are similar to the common sub-channel demodulation and decoding units, and will not be described in detail.

Apparently, the receiving end of hierarchical demodulation and decoding can be generalized to systems with more than two priorities. In addition, the demodulation and decoding of the low-priority sub-channel may use multiple demodulation and decoding results of high priority, and may also use the demodulation and decoding results of the same priority.

Example 5

On the basis of Embodiment 1 to Embodiment 4, this embodiment presents the application of the method for determining the transmission mode of the downlink multiple access system proposed by the present invention in the downlink multiple access OFDM block transmission system oriented to broadband digital terrestrial broadcasting. The flow of the method for determining the multi-service transmission mode of the downlink multiple access system, the device at the transmitting end, and the device at the receiving end are described in detail as follows.

The method for determining the transmission mode of the downlink multiple access system includes the following steps:

1. Obtain system parameters and business information

The system faces a typical digital TV broadcast channel with a bandwidth of 8MHz, and the working frequency band is the UHF TV band of 470-806MHz. It is required to provide mobile TV service, standard definition digital TV service and high definition digital TV service within 8MHz bandwidth. The three services are respectively required to support high-speed mobile (such as moving speed up to 350 km/h), basic mobile (such as moving speed not higher than 120 km hourly) and fixed reception.

2. Determine the basic transmission mode according to system parameters and business information

The system bandwidth is 8MHz, and all time-frequency resources are available, so the channel bandwidth is also 8MHz. Referring to the Chinese Digital TV Terrestrial Broadcasting Standard (GB 20600-2006, China National Standardization Committee, Digital TV Terrestrial Broadcasting System Frame Structure, Channel Coding and Modulation, August 18, 2006), time-domain filtering is used for shaping, and the shaping filter is selected as SRRC filter, the roll-off factor is 0.05, the selected basic symbol rate is Fs=7.56MHz, and the basic symbol interval is 1/7.56us.

Referring to the TDS-OFDM technology, the multiframe auxiliary signal is selected to be composed of OFDM training data blocks and their guard intervals. The training data blocks are obtained from known frequency-domain binary sequences through IDFT transformation, and the length is 512 symbols. The guard interval adopts training data blocks The cyclic extension of the auxiliary signal is used to improve the ability of the auxiliary signal to resist channel time domain extension, wherein the front guard interval and the rear guard interval are each 256 symbols, and the total length of the auxiliary signal is 1024 symbols.

In order to simplify the design, each multiframe only includes three kinds of time-domain data frames, and the lengths are 2048 symbols, 4096 symbols and 8192 symbols respectively. In order to increase the transmission rate of the system, the three time-domain data frames do not use guard intervals, so the time-domain data frames are instant-domain data blocks. Each time-domain data block is obtained from the frequency-domain data block through IDFT transformation, and the two lengths are the same.

Considering that the system uses time-domain spectrum shaping and auxiliary signals to achieve synchronization and channel estimation, the frequency-domain data blocks are all composed of data symbols, excluding training symbols (i.e. pilots) and zero symbols (i.e. special pilots, or virtual sub- carrier). The frequency domain data block does not transmit virtual subcarriers, so the signal bandwidth (3dB bandwidth) is equal to the basic symbol rate, which is 7.56MHz. Considering the roll-off factor of 0.05 of the shaping filter, the actual signal bandwidth is smaller than the channel bandwidth.

Define BwI=7.56MHz/8192=922.8516KHz, signal bandwidth BW=7.56MHz=8192*BwI, and the frequency domain data block subcarrier intervals corresponding to the three time domain data frames are 4*BwI, 2*BwI, and BwI in turn. In order to simplify the time-frequency pattern mapping, the basic bandwidth is selected as 2048*BwI, that is, each frequency domain data block only includes 4 time-frequency units.

Referring to FIG. 14 , the subcarriers corresponding to the basic time-frequency units are selected and placed centrally, and each frequency-domain data block in the DFT transform domain includes four basic time-frequency units in turn. The box corresponding to the time-domain data frame in the figure represents the basic time-frequency unit, and the horizontal arrows represent 512 consecutively placed subcarriers.

3. Obtain information on available time-frequency resources, channel conditions and business requirements of the system

The system is oriented to broadcast users, all bandwidths are available, the total transmission power is not considered here, and the multi-frame time-frequency resources are all available; the channel conditions are three transmission channels for three types of service receiving ends, among which the high-speed mobile channel has a large Doppler expansion , the Doppler extension of the basic mobile channel is medium, and the Doppler extension of the fixed receiving channel can be ignored; the transmission rate requirement of mobile TV service is low, the transmission rate requirement of SD TV service is medium, the transmission rate requirement of HDTV service is high, and all services have no real-time requirements .

4. Determine the specific transmission mode adopted for multi-service transmission based on the basic transmission mode according to the available resources of the system, channel conditions, and business requirements

This system does not consider the backhaul channel, so the available resource information and channel conditions of the system remain unchanged. To simplify the design, the system does not support physical layer signaling, so no signaling sub-channel is required. The specific transmission mode determination will obtain the complete multiframe structure, time-frequency mapping pattern and sub-channel transmission mode of each time-frequency sub-channel.

Referring to Figure 15, the available resources of the integrated system, channel conditions and service requirements, determine that the multiframe structure includes an auxiliary signal with a total length of 1024 symbols, a first time domain data frame with a length of 2048 symbols, and a second time domain with a length of 4096 symbols A data frame and a third time-domain data frame with a length of 8192, where the time-domain data frame is an instant-domain data block without a guard interval, and the time-domain data frame is directly obtained from the frequency-domain data block through the IDFT operation of the corresponding number of points.

Referring to the time-frequency mapping pattern in Figure 16, the shaded part in the figure represents the first subchannel to the fifth subchannel, and the horizontal arrows indicate 512 consecutively placed subcarriers. The external subchannel allocation algorithm is as follows:

High-speed mobile services require large sub-carrier spacing, so a frequency domain data block with a length of 2048 is selected to support mobile TV high-speed mobile services. According to the transmission rate required by mobile TV and the analysis of system time-frequency resources, the design supports two channels of mobile TV services, which are respectively carried by the first time-frequency sub-channel and the second time-frequency sub-channel.

The basic mobile service requires a medium subcarrier interval, so a frequency domain data block with a length of 4096 is selected to support the basic mobile service of standard definition TV. According to the transmission rate required by standard TV and the analysis of system time-frequency resources, the design supports two channels of standard definition TV services, respectively. The 3 time-frequency sub-channels and the 4th time-frequency sub-channel carry.

The fixed reception service does not require high subcarrier spacing, so the frequency domain data block with a length of 8192 is selected to support the high-definition television fixed reception service. Due to the high transmission rate required by HDTV, combined with the consideration of system time-frequency resources, it is designed to support one HDTV service, which is carried by the fifth time-frequency sub-channel.

The subchannel allocation result is fixed, and its time-frequency mapping pattern is also fixed.

Table 1. Sub-channel transmission mode setting results

Referring to Table 1, under the condition of meeting business requirements, the transmission mode settings of all time-frequency sub-channels are as follows, and the scrambling code, interleaving, etc. will not be described in detail.

In terrestrial broadcasting, the channel conditions for high-speed mobile are very poor, and the transmission rate required by mobile TV is very low. Therefore, for the first time-frequency sub-channel, QPSK low-order constellation mapping and low-bit-rate error-correcting coding with a code rate of 0.4 are selected ( Such as LDPC code), after calculation, the transmission rate of the first time-frequency sub-channel is R ₁ =7.56*(1/15)*2*0.4=0.4032Mbps (where bps represents bits per second), which can support one 384kbps mobile phone TV sub-business. In the case of sacrificing a little coverage or the threshold of carrier-to-noise ratio at the receiving end, the constellation mapping order or error correction coding rate can be appropriately increased, so select QPSK low-order constellation mapping and code rate 0.6 for the second time-frequency sub-channel Medium bit rate error correction coding, after calculation, the transmission rate of the second time-frequency sub-channel is R ₂ =7.56*(1/15)*2*0.6=0.6048Mbps, which can support 1 channel of 384Kbps mobile TV sub-service and 1 channel 220.8Kbps high-speed mobile data sub-service. In order to further improve the coverage of the first time-frequency sub-channel, its average power is 3dB higher than the reference power, and the average power of the second time-frequency sub-channel is the same as the reference power.

In terrestrial broadcasting, the channel conditions for basic mobile are medium, and the transmission rate required for SDTV is medium. Correspondingly, 16QAM medium-order constellation mapping and 0.6 medium-rate error correction coding are selected for the third and fourth time-frequency sub-channels. After calculation, the transmission rates of the third and fourth time-frequency sub-channels are both R ₃ =R ₄ =7.56*(2/15)*4*0.6=2.4192 Mbps. In order to further improve the coverage of the third time-frequency sub-channel, its average power is 3dB higher than the reference power, and the average power of the fourth time-frequency sub-channel is the same as the reference power.

In terrestrial broadcasting, the channel conditions for fixed reception are very good, and at the same time, the transmission rate required by HDTV is very high. Correspondingly, 64QAM high-order constellation mapping and high bit rate error correction coding of 0.8 are selected for the fifth time-frequency sub-channel. The calculated transmission rate of the fifth time-frequency sub-channel is R ₅ =7.56*(8/15)*6*0.8=19.3536 Mbps. The average power of the fifth time-frequency sub-channel is the same as the reference power.

Since the system does not support signaling, the result of determining the transmission mode includes the preset multiframe structure, time-frequency pattern mapping, and sub-channel transmission mode information; the output of the determination of the transmission mode is directly used to guide the transmitting end device and the receiving end device .

5. System configuration fixed, end.

Referring to the definition of technical terms in the invention, the time-frequency sub-channel technology proposed in the present invention is a special time-frequency slicing technology, and the receiving end can use the technical characteristics of time-frequency slicing to reduce the receiving bandwidth, reduce computational complexity and save power consumption . For example, for the design results of this embodiment, the signal bandwidth occupied by the first and third time-frequency sub-channels is limited, so the receiving end can use a front-end unit with a narrowband filter to receive radio frequency signals, and then demodulate and decode the first and/or first 3 Time-frequency sub-channel service data; as another example, the signal time occupied by the auxiliary signal and the first time-frequency sub-channel is limited, so the receiving end only needs to work in the signal time occupied by the auxiliary signal and the first time-frequency sub-channel, and then resolve The business data of the first time-frequency sub-channel is adjusted to reduce the computational complexity and power consumption of the receiver.

Referring to the receiver device corresponding to the hierarchical demodulation and decoding of low-priority sub-channels proposed in Embodiment 4, for the design results of this embodiment, the third sub-time-frequency channel is a low-priority channel, and the first time-frequency sub-channel is a high-priority channel. level channel. The intermediate or final result of the demodulation and decoding of the first time-frequency sub-channel can assist the channel estimation of the third time-frequency sub-channel and improve the receiving performance of the third time-frequency sub-channel. Similarly, the intermediate or final result of the demodulation and decoding of the second time-frequency sub-channel can assist the channel estimation of the fourth time-frequency sub-channel and improve the receiving performance of the fourth time-frequency sub-channel. Similarly, the demodulation and decoding intermediate or final results of the 1st and 3rd time-frequency sub-channels can assist the channel estimation of the 2nd or 4th time-frequency sub-channels. At the same time, the demodulation and decoding of the 2nd and 4th time-frequency sub-channels The intermediate or final result can assist the channel estimation of the fifth time-frequency sub-channel and improve the receiving performance of the fifth time-frequency sub-channel.

Example 6

On the basis of Embodiment 1 to Embodiment 4, this embodiment provides the application of the method for determining the multi-service transmission mode of the downlink multiple access system proposed by the present invention in the downlink multiple access OFDM block transmission system oriented to broadband wireless mobile communication. The specific steps of the method for determining the multi-service transmission mode of the downlink multiple access system are as follows:

Step 1. Obtain system parameters and business information

The downlink multiple access OFDM block transmission system is oriented to a broadband wireless mobile channel with a channel bandwidth up to 20MHz, and needs to support three nominal channel bandwidths of 20MHz, 10MHz and 5MHz, and the working frequency band is 2.4GHz; the system is required to support downlink multiple access while retaining uplink Channel, that is, to achieve time division duplex (TDD); the maximum cell radius is 2.5Km, and the maximum delay extension is 8.33us; there may be serious narrow-band interference in the channel bandwidth, and the interference frequency is unknown, and the system needs to avoid the interference frequency, so The effective channel bandwidth will be lower than the nominal bandwidth; it is required to provide two real-time services within a bandwidth of up to 20MHz, the first is a high-priority service supporting high-speed mobility, and the second is a low-priority service supporting low-speed mobility.

Step 2. Determine the basic transmission mode based on system parameters and business information

Referring to the China Mobile Multimedia Broadcasting industry standard CMMB, frequency domain subcarrier shaping and time domain window shaping technology are combined to achieve spectrum shaping, and the time domain window is selected as a raised cosine roll-off window.

Considering the frequency-domain subcarrier shaping and the highest channel bandwidth, the basic symbol rate is selected as Fs=30.72MHz, and the basic symbol interval Ts=(1/30.72)us≈0.0326us. Among them, frequency-domain subcarriers outside the effective signal bandwidth are used to carry zero symbols (ie, virtual subcarriers), and any bandwidth not greater than 20MHz can be supported by adjusting the number and position of virtual subcarriers.

Considering the transition band required for spectrum shaping, the actual signal bandwidths are selected as 18MHz, 9MHz, and 4.5MHz, corresponding to three nominal channel bandwidths of 20MHz, 10MHz, and 5MHz, respectively.

Select two kinds of subcarrier spacing, 30kHz subcarrier spacing supports high-speed mobile services, and 6kHz subcarrier spacing supports low-speed mobile services, so the multi-frame structure includes two time-domain data block lengths, and the short data block length is 30.72MHz/30kHz=1024 The symbol and long data block lengths are 30.72MHz/6kHz=5120 symbols, and the durations are (1024/30.72)us=33.33us and (5120/30.72)=166.67us respectively.

Considering that the maximum delay extension is 8.33us and the needs of time-domain window spectrum shaping, the selected lengths are 288 symbols and 328 symbol guard intervals respectively, and the corresponding durations are (288/30.72)=9.38us and (328/30.72)us= 10.68us.

With reference to accompanying drawing 17, guard interval and time domain data block form time domain data frame together, and short data frame continues (1024+328)=1352 symbols, and long data frame continues (5120+288)=5408 symbols; Short data frame adopts cycle The extended guard interval is filled, the front guard interval is 308 symbols, and the post guard interval is 20; the long data frame is filled with a cyclic prefix guard interval, the length of the front guard interval is 288 symbols, and there is no post guard interval. Because the number of IDFT calculation points for short data frames is small, the performance of frequency-domain subcarrier spectrum shaping is poor, so it is necessary to increase the time-domain window spectrum shaping, so the length of the guard interval needs to be increased to ensure that the effective guard interval is not less than the maximum delay extension of the channel. If the roll-off coefficient of the time domain window is selected as 40/1352=2.96%, the effective guard interval of the short data frame is also 288 symbols. Because the IDFT operation points of the long data frame are large, the subcarrier spectrum shaping performance in the frequency domain is good, so no additional time domain window spectrum shaping is required.

The multiframe structure uses the law of the time domain data frame and the cyclic extension of the guard interval to perform multiframe synchronization without including auxiliary signals; the channel estimation is realized by the pilot frequency inside each time-frequency sub-channel.

Considering the need to support real-time services, the multiframe should not be too long, requiring a duration of about 10ms. The selected multiframe length is 5408*64=346112 symbols, and the duration is about 11.3ms.

In order to support three effective signal bandwidths of 18MHz, 9MHz and 4.5MHz, simplify the time-frequency pattern mapping, and take into account the serious interference at some frequency points within the channel bandwidth, the basic bandwidth is selected as 300kHz, and each frequency domain data block corresponds to the signal bandwidth The effective basic time-frequency units of 18MHz/9MHz/4.5MHz are 60, 30, and 15 respectively.

Referring to FIG. 18 , taking the center frequency F0 and the effective signal bandwidth BW=4.5MHz as an example, the frequency-domain subcarriers corresponding to the basic time-frequency units are placed in a centralized manner, and the basic time-frequency units are therefore numbered 1 to 15.

Step 3. Obtain information on available time-frequency resources, channel conditions and service requirements of the system

According to the requirement of time division duplex, determine the time resource reserved for the uplink channel, assuming that the uplink channel resource is at least 25% and at most 75%.

Considering that there may be frequency point interference in the system, it is assumed that the frequency pattern corresponding to the interference has been obtained.

The service requirement information is assumed to be known, including the number of high-priority services for high-speed movement and the number of low-priority services for low-speed movement. Each service is a point-to-point service from a transmitter to a receiver, and the channel conditions are known.

Step 4. According to the available resources of the system, channel conditions, and service requirements, determine the specific transmission mode adopted by the multi-service transmission based on the basic transmission mode

As mentioned in step 3, the time-frequency resources available to the system need flexible scheduling, not only the uplink and downlink time-frequency resources need flexible scheduling, but also the time-frequency resources occupied by high-priority services and low-priority services also need flexible scheduling, so the system needs to give For physical layer signaling, the multiframe structure needs to open up a dedicated signaling sub-channel.

Referring to Figure 18, the complete multiframe structure obtained by determining the specific transmission mode adopted for multi-service transmission, the total length of the multiframe is (5408*64) symbols, and can support up to 64 long data frames or 256 short data frames. In the figure, each box represents a time-domain data frame, which is sequentially labeled from 1 to the maximum value. The time-frequency resources designed for downlink multiple-access multi-service transmission are located at the end of the multiframe structure, occupying a length of (5408*C) symbols, C is an integer, the minimum is 16 (corresponding to 25% of the time-frequency resources of the multiframe), and the maximum is 48 (corresponding to 75% of the multiframe time-frequency resources), and other resources are used for uplink multiple access transmission, meeting the requirement of time division duplex.

For the convenience of signaling subchannel allocation and the convenience of receiver synchronization, the first 16+A1 data frames of the multiframe structure are short data frames, followed by A2 long data frames and reserved for uplink multiple access transmission Symbol, where (16+A1)/4+A2+C=64 requires A1 to be a positive integer that is an integral multiple of 4. Apparently, A1, A2, and C are multiframe structure parameters, which are determined according to uplink and downlink service requirements and high and low priority services.

Referring to Fig. 19, a signaling subchannel time-frequency allocation pattern is given. The vertical axis is the frequency axis, the center frequency is F0=2.4GHz, and the effective bandwidth is BW=4.5MHz as an example. Each frequency domain data block includes 15 basic time-frequency units, numbered 1 to 15 in sequence. The horizontal axis is the time axis, T0 is the starting moment of the multiframe, T1=(16*1352/30.72)=704.2us is the duration of the first 16 short data frames of the multiframe. The signaling subchannels are only located in the first 16 short data frames of the multiframe, and are numbered 1 to 16 in sequence, so it does not depend on the multiframe structure parameters A1, A2, and C, effectively ensuring the normal demodulation of the signaling subchannels at the receiving end. As mentioned above, there may be serious narrow-band interference within the channel bandwidth, and the interference frequency point is unknown, and the signaling sub-channel must be pre-configured, so the signaling sub-channel uses frequency hopping technology to ensure the reliability of the signaling sub-channel; Within 16 short data frames, the number of basic time-frequency units occupied by the signaling sub-channel will change regularly. Finally, the bandwidth of the signaling sub-channel is 0.9 MHz, corresponding to three consecutive basic time-frequency units of the frequency-domain data block of each short data frame. Taking an effective bandwidth of 4.5MHz as an example, the ratio of the time-frequency resources of the entire multiframe occupied by signaling is (0.9/4.5)*(16*1352)/(5408*64)=1.25%.

The time-frequency resource allocation of ordinary sub-channels is similar to that of signaling sub-channels, in which short data frames carry high-speed services and have low spectrum utilization, while long data frames carry low-speed services and have high spectrum utilization. In order to improve indicators such as system transmission reliability and system spectrum efficiency, the time-frequency resource allocation of ordinary sub-channels is optimized by the sub-channel allocation algorithm according to system available resources, channel conditions, and service requirements, and will not be described in detail.

Considering the multiframe synchronization at the receiving end, the synchronization of the signaling sub-channel and channel estimation, the frequency domain data block corresponding to the signaling sub-channel needs to add pilot frequency, which will not be described in detail. The signaling sub-channel has the highest priority, so low-order modulation and low-bit-rate error-correcting coding are used, which will not be described in detail.

Finally, according to the service transmission rate requirements, determine the transmission mode for each time-frequency sub-channel, including but not limited to scrambling code, error correction coding, constellation mapping, interleaving mode, and average power, where the sub-channel allocation algorithm is based on the total transmission power Under the constraint, the average power of each subchannel is optimized. Generally, sub-channels carrying high-priority services use low-order modulation and/or low-rate error correction coding, and sub-channels carrying low-priority services use high-order modulation and/or high-code error correction coding, which will not be described in detail here. As described in Embodiment 4, the signaling sub-channel and the sub-channel carrying high-priority services can assist the sub-channel carrying low-priority services to perform channel estimation.

Information such as the complete multiframe structure, time-frequency mapping pattern, and sub-channel transmission mode of each time-frequency sub-channel obtained by determining the specific transmission mode used for multi-service transmission is carried by the signaling sub-channel to ensure that all time-frequency sub-channel services Data demodulation and decoding; determine the output of the specific transmission mode adopted for multi-service transmission, and guide the realization of the transmitting end device (base station) and receiving end device (mobile terminal).

Step 5. Since the system supports physical layer signaling and flexible scheduling, go to step 6.

Step 6. If system available resources, channel conditions, and service requirements change, return to step 3; otherwise, keep system settings unchanged.

The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Those of ordinary skill in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all Equivalent technical solutions also belong to the category of the present invention, and the scope of patent protection of the present invention should be defined by the claims.

Claims (19)

1. the method for a definite downlink multi-access system multi-service transmission mode is characterized in that, this method may further comprise the steps:

S1 obtains system parameters and business information;

S2 determines basic transmission mode according to system parameters and business information, may further comprise the steps:

S2.1, the multi-frame that is adopted in determining to transmit is made up of the time domain data frame of auxiliary signal and one or more different lengths, described time domain data frame is made up of protection interval and time-domain data blocks, described time-domain data blocks is corresponding one by one in multi-frame structure with block of frequency domain data through time-frequency conversion, and described block of frequency domain data is made up of subcarrier;

S2.2 determines the serve as reasons basic time frequency unit of one or more subcarriers compositions of being positioned at same time domain data frame of basic channel unit in the transmission, and the signal bandwidth that described basic time frequency unit occupies is fixed, and is defined as primary bandwidth;

S2.3 determines that physical-layer sub-channel in the transmission is the time frequency subchannel of being made up of the one or more basic time frequency unit in the time domain data frame in the described multi-frame structure or being made up of a plurality of basic time frequency unit in a plurality of time domain data frames;

S3, the acquisition system can use running time-frequency resource, channel conditions and traffic demand information;

S4, externally the subchannel allocation algorithm instructs down, according to described system available resources, channel condition and business demand, based on described basic transmission mode, determines the concrete transmission mode that the multi-service transmission is adopted, and may further comprise the steps:

S4.1, the concrete multi-frame structure that adopts when determining the different business transmission;

S4.2, determine basic time frequency unit then frequency subchannel mapping result or the time frequency subchannel to the time-frequency mapping pattern of the mapping result of basic time frequency unit, finish the time-frequency resource allocating of transmission different business frequency subchannel when required;

S4.3, the subchannel transmission pattern of frequency subchannel when determining each.

2. the method for claim 1 is characterized in that, also comprises the steps: after the step S4

S5 judges whether system supports physical layer signaling and flexible dispatching, if do not support, then finishes, and system is by current concrete transmission mode work, otherwise execution in step S6;

S6 changes if system can use running time-frequency resource, channel condition or business demand information to send, and returns execution in step S3.

3. method as claimed in claim 1 or 2 is characterized in that,

Among the step S1, described system parameters comprises the maximum delay expansion of system works frequency range, maximum channel bandwidth and Channel Transmission; Described business information comprises maximum subchannel number, maximum translational speed, peak transfer rate and the real-time requirement of supporting;

Determine among the step S2 that basic transmission mode is further comprising the steps of:

S2.4, the auxiliary signal form of multi-frame is selected the spectral shaping method among the definition step S2.1, determines basic symbol interval and signal bandwidth according to spectral shaping method and maximum channel bandwidth;

S2.5 according to the maximum translational speed of working frequency range and different business, defines one or more time domain data block lengths;

S2.6 according to the maximum delay expansion of different business respective channels, defines one or more protection gap lengths, reaches protection one or more filling modes at interval, according to multi-service real-time demand, and the length range of multi-frame among the determining step S2.1;

S2.7, the concrete size of the primary bandwidth of basic time frequency unit among the determining step S2.2;

S2.8 defines the basic time frequency unit dividing mode of the every kind block of frequency domain data corresponding with time-domain data blocks among the step S2.5, and wherein every kind of block of frequency domain data is shared identical basic time frequency unit dividing mode.

4. the method for claim 1 is characterized in that,

Among the step S3, described system available resources comprise system's available bandwidth, transmitting power and multi-frame running time-frequency resource; Described channel condition comprises channel delay expansion, channel Doppler expansion, the channel disturbance pattern of transmitting terminal to the transmission channel of different business receiving terminal; Described business demand information comprise required time-frequency subchannel number and corresponding each the time frequency subchannel real-time require, transmission bandwidth requires, QOS requires and transmission rate request;

Among the step S4.1,, determine the concrete multi-frame structure that adopts, comprise the number of time domain data frame in definite multi-frame and the kind of each time domain data frame in conjunction with outside subchannel allocation algorithm according to described business demand information;

Among the step S4.2, according to described system available resources, channel disturbance pattern and service transmission bandwidth requirement, externally under the guidance of subchannel allocation algorithm, frequency subchannel distributes available running time-frequency resource during for each of the described business demand of correspondence, determine basic time frequency unit then frequency subchannel mapping result or the time frequency subchannel to the mapping result of basic time frequency unit, obtain time-frequency mapping pattern, finish the time-frequency resource allocating of transmission different business frequency subchannel when required;

Among the step S4.3, require and transmission rate request the subchannel transmission pattern of frequency subchannel when determining each according to described professional real-time requirement, QOS.

5. method as claimed in claim 4 is characterized in that, step S4.2 comprises following substep:

S4.2.1, the basic time frequency unit of determining with step S2.7 is a unit, determines that system can use running time-frequency resource;

S4.2.2, the subchannel bandwidth of frequency subchannel when determining each of corresponding described business demand information, wherein, subchannel bandwidth is the integral multiple of primary bandwidth;

S4.2.3, one or more block of frequency domain data position of frequency subchannel correspondence when determining each;

S4.2.4, all basic time frequency unit of frequency subchannel when determining each.

6. as claim 1,2,4 or 5 arbitrary described methods, it is characterized in that,

If basic time frequency unit consists of a plurality of sub-carriers, the position of the corresponding subcarrier of basic time frequency unit institute is concentrated and is placed, or disperses placement, or the mixing of the two;

If the time frequency subchannel forms by a plurality of basic time frequency unit, the time frequency subchannel correspondence the position of basic time frequency unit concentrate and place, or disperse placement, or the mixing of the two.

7. method as claimed in claim 3 is characterized in that, the primary bandwidth that step S2.7 determines is the integral multiple of any block of frequency domain data subcarrier spacing in the described multi-frame.

8. method as claimed in claim 5, it is characterized in that, among the step S4.2.4, corresponding each the time frequency subchannel one or more block of frequency domain data, the position of the basic time frequency unit of frequency subchannel in block of frequency domain data or identical, perhaps separate when constituting this.

9. method as claimed in claim 5 is characterized in that,

Among the step S4.2.1, system's available resource information is provided by outside frequency spectrum sensing module;

The multi-frame running time-frequency resource of system's available resources correspondence does not comprise that the running time-frequency resource or the system validation of system's reservation is disabled running time-frequency resource.

10. method as claimed in claim 2 is characterized in that,

If step S5 judges the system that draws and supports physical layer signaling and flexible dispatching, comprise that also branch is used in the step of signaling subchannel that transmission package contains the signaling traffic data of signaling information, described signaling information comprises multi-frame structure, time-frequency mapping pattern and the subchannel transmission pattern of concrete employing.

11. method as claimed in claim 3 is characterized in that,

Defined auxiliary signal form is in targeting sequencing, stack sequence or the described multi-frame between the time domain data frame or known training sequence afterwards among the step S2.4, or is the combination of multiple sequence, or does not have auxiliary signal;

The filling mode at interval of protection described in the S2.6 is cyclic extensions, null sequence or the known training sequence of the time-domain data blocks of described time domain data frame; or do not protect at interval; the protection interval of wherein said time domain data frame or all identical, perhaps independent the setting.

12. the method for claim 1 is characterized in that, this method is applied in the downlink multi-access OFDM block transmission system of wideband digital terrestrial broadcasting determines multiple services transmission mode.

13. the method for claim 1 is characterized in that, this method is applied in the downlink multi-access OFDM block transmission system of wideband wireless mobile communication determines multiple services transmission mode.

14. the transmitting end device based on the described method of claim 1 is characterized in that, this transmitting end device comprises:

The scheduling of resource unit, the multi-frame structure, subchannel transmission pattern and the time-frequency that are used for utilizing the described method of claim 1 to determine that the multi-service transmission is adopted shine upon pattern, the signaling information of frequency subchannel parameter and schedule information when generation comprises all, described schedule information comprises subchannel transmission pattern and time-frequency mapping pattern, and the control signal of all other unit of transmitting terminal and clock signal;

The signaling traffic Multi-connection unit is used for signaling information that the scheduling of resource unit is produced and filling information and carries out multiple connection and obtain the signaling data business, the signaling traffic bit that output is corresponding;

The subchannel coding modulating unit, the subchannel transmission pattern that provides according to the scheduling of resource unit is provided, encode and modulate to the signaling traffic bit or by the general service bit that multi-service data obtains, obtain the corresponding service symbol, required training symbol and/or the virtual subnet carrier wave of frequency subchannel when filling as required simultaneously;

The block of frequency domain data component units, the time-frequency that is used for providing according to the scheduling of resource unit shines upon the clock signal of pattern and current block of frequency domain data, the service symbol and the training symbol of frequency subchannel carries out multiple connection when belonging to current block of frequency domain data a plurality of, obtains finishing the block of frequency domain data of subcarrier multiple connection and exports to the IDFT unit;

The IDFT unit according to the length information of current input frequency domain data block, carries out the IDFT computing to the block of frequency domain data of input, obtains current time-domain data blocks;

Time domain data frame framing unit, the multi-frame structure that provides according to the scheduling of resource unit and the clock signal of current time domain data frame, obtain filling the protection interval of desired signal, will protect interval and time-domain data blocks to form the time domain data frame together and output to multi-frame framing unit;

Multi-frame framing unit, the clock signal of the time-frequency that provides according to scheduling of resource unit mapping pattern and current multi-frame is formed the multi-frame signal together with the one or more time domain data frames and the auxiliary signal of input;

Multi-frame subsequent treatment unit carries out the reprocessing of spectral shaping, digital to analog conversion and rf modulations to the multi-frame signal, must transmit to the end.

15. transmitting end device as claimed in claim 14 is characterized in that,

The coded modulation operation of described subchannel coding modulating unit comprises scrambler, error correction coding, constellation mapping, interweaves and power control;

The road general service bit that described subchannel coding modulating unit is imported is obtained by the bit multiple connection of one or more subservices.

16. one kind based on the described method of claim 3 with corresponding to the receiving end device of the described transmitting end device of claim 14, it is characterized in that this receiving end device comprises:

Control unit, be used for the signaling subchannel information that receiving system presets, part multi-frame structure information and the part frequency patterns map information determined in the basic transmission mode, the synchronizing information that signaling information that obtains according to the demodulation of signaling subchannel and signaling resolution unit and front end unit provide, obtain the required whole multi-frame structures of receiving terminal, frequency patterns mapping and required subchannel transmission pattern information, produce required control signal and the clock signal in all other unit of receiving terminal;

Front end unit is used for finishing radio demodulating, analog-to-digital conversion under the control of control unit, and it is synchronous to carry out receiving terminal according to multi-frame structure, obtains multi-frame signal and synchronizing signal;

Time domain data frame separative element under the control of control unit, according to multi-frame structure, at first separates required time domain data frame from the multi-frame signal, isolate time-domain data blocks then from the time domain data frame, outputs to the DFT unit;

The DFT unit, under the control of control unit, the block length of the input time-domain data blocks that provides according to multi-frame structure carries out the DFT conversion, obtains the block of frequency domain data of being made up of subcarrier;

Block of frequency domain data subchannel separative element, under the control of control unit, clock signal according to multi-frame structure, time-frequency mapping pattern and current block of frequency domain data, the input frequency domain data block is carried out subchannel separates, obtain the signaling symbols piece and the corresponding ordinary symbol piece that transmits the common subchannel of multi-service data of corresponding signaling subchannel;

Subchannel demodulating and decoding unit is used under the control of control unit, and the signaling symbols piece of frequency subchannel and/or ordinary symbol piece carry out demodulating and decoding during to difference, obtains corresponding signaling traffic data and general service data;

The signaling resolution unit is used under the control of control unit the signaling traffic data being resolved, and obtains the signaling information that the signaling traffic data comprise and exports to control unit.

17. receiving end device as claimed in claim 16 is characterized in that, described subchannel demodulating and decoding unit comprises signaling subchannel demodulating and decoding unit and common subchannel demodulating and decoding unit, wherein,

Subchannel demodulating and decoding unit comprises:

Signaling subchannel estimation unit is used under the control of control unit, carries out the channel estimating of signaling subchannel according to signaling subchannel transmission pattern, obtains signaling subchannel estimated result;

Signaling subchannel balanced unit is used to utilize signaling subchannel estimated result to carry out the equilibrium of signaling subchannel, obtains the balanced data symbol;

Signaling subchannel demodulating and decoding performance element is used for the balanced data symbol is carried out the demodulating and decoding operation that mapping, channel-decoding and descrambling are separated in deinterleaving, constellation, obtains the signaling traffic data, gives the signaling resolution unit;

Described common subchannel demodulating and decoding unit comprises:

Common subchannel estimation unit is used under the control of control unit, according to current common subchannel transmission pattern, carries out the channel estimating or the renewal of current common subchannel, obtains current common subchannel estimated result;

Common subchannel balanced unit utilizes current common subchannel estimated result that input ordinary symbol piece is carried out channel equalization, obtains the balanced data symbol;

Common subchannel demodulating and decoding performance element is used for common subchannel balanced unit balanced data symbol is carried out the demodulating and decoding operation that mapping, channel-decoding and descrambling are separated in deinterleaving, constellation, obtains general service data and output.

18. receiving end device as claimed in claim 17 is characterized in that,

The output of described signaling subchannel demodulating and decoding unit is input to common subchannel demodulating and decoding unit simultaneously;

Common subchannel estimation unit in the described common subchannel demodulating and decoding unit carries out the channel estimating or the renewal of current common subchannel in conjunction with the output of the signaling subchannel demodulating and decoding unit of input.

19. receiving end device as claimed in claim 17, it is characterized in that, this receiving terminal implement device comprises two common subchannel demodulating and decoding unit, and one of them is high priority subchannel demodulating and decoding unit, and another is low priority subchannel demodulating and decoding unit;

Wherein the result of high priority subchannel demodulating and decoding unit output outputs to low priority subchannel demodulating and decoding unit, and low priority subchannel demodulating and decoding unit carries out the channel estimating or the renewal of current common subchannel in conjunction with the high priority subchannel demodulating and decoding result of input.

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