WO2003067802A1

WO2003067802A1 - A adaptive modulation and encoding method for high speed data transmission

Info

Publication number: WO2003067802A1
Application number: PCT/CN2002/000072
Authority: WO
Inventors: Jiangbo Dong; Ping Wang; Yongsheng Zhang; Yongzhong Zou
Original assignee: Linkair Communications, Inc.
Priority date: 2002-02-08
Filing date: 2002-02-08
Publication date: 2003-08-14
Also published as: CN1496623A; AU2002233136A1

Abstract

A adaptive modulation and encoding method for high speed data transmission, characterized in that: the invention adopts Turbo product code to perform adaptive modulation and encode for high speed data. According to real time channel quality, proper encode and modulation mode are selected to encode transmitted information bits at transmitting terminal- The coding includes at least encoding with Turbo product code; encoded bits are modulated in accordance with real time channel quality at transmitting terminal; after encoding and modulating, produced transmitting signal is generated with the transmitted information bits, and the signal and control signal are multiplexed and then transmitted over channel; the received signal is demodulated and decoded at receiving terminal. The decoding includes at least decoding with Turbo product code.

Description

Adaptive modulation and coding method for high-speed data transmission

The present invention belongs to the technical field of electrical communication, and particularly relates to a link adaptation technology for adaptive modulation and coding (Adaptive Modulation and Coding) for high-speed data transmission. Specifically, it is an adaptive modulation and coding method for high-speed data transmission.

Background technique

Any type of communication system is based on three types of indicators: the quantity and quality of communication transmission: continuous optimization of effectiveness, reliability and security. The so-called validity refers to occupying as few channel resources as possible (such as frequency bands, time slots, and power) to transmit as much source information as possible. It is a quantitative indicator of communication. The so-called reliability mainly refers to the resistance to transmission during transmission. Ability of objective natural interference, but it also includes electronic countermeasures in military communications, that is, the ability to resist human-made interference; the so-called security mainly refers to the security and confidentiality in transmission, that is, anti-eavesdropping at the end and anti-counterfeiting at the end And tampering capabilities.

Adaptive modulation and coding technology (AMC) is a method to improve the effectiveness of communication systems. The enhanced GSM system using adaptive modulation and coding can provide a data rate up to 384 Kbps, but if it does not use adaptive modulation and coding, it can only provide a data rate of 100 Kbps. In addition, the 1.25M CDMA system uses adaptive modulation and coding, which can provide a peak data rate of up to 5 Mbps. If adaptive modulation and coding is not used, in general, it can only provide a peak data rate of 460 Kbps. The main advantages of using AMC technology are (1) users in good channel quality locations can perform higher-speed data transmission, thereby improving the average throughput of the cell; (2) the impact of interference changes can be reduced, because the link of the AMC is Adaptation is based on changing modulation / coding schemes, not on changing transmission power. Adaptive modulation and coding means that the communication system can select an appropriate modulation method and forward error correction coding scheme for each user according to the change in channel quality, that is, select different levels of

MCS (Modulation and Coding Schemes), so that the system selects a higher modulation method and a higher bit rate coding scheme when the channel quality is higher, and selects a lower modulation method and a lower bit rate when the channel quality is lower. Coding scheme. This not only ensures that the system has a lower frame error rate (that is, the ratio of frames received in error to the frames sent), but also enables the system to achieve higher throughput (the so-called throughput refers to the user's (Such as the number of information bits that can be correctly received in a subframe).

Specifically: In an adaptive modulation and coding system, users who have good channel quality, such as users near the base station, usually assign higher-level modulation methods and higher-bit-rate coding schemes, that is, higher-level In the case of users with poor channel quality, such as users at the edge of the cell, the system usually allocates a lower level modulation scheme and a lower code rate coding scheme, that is, a lower level MCS. This can increase the average data transmission rate of the system.

There are also disadvantages to adaptive modulation and coding. It is more sensitive to channel estimation errors and delays. In order to select the proper modulation and coding, the channel quality must be accurately known. An incorrect channel estimation will cause the system to choose an inappropriate modulation and coding scheme, which will result in the following two situations: 1) When the channel quality is better, a lower-level MCS method is selected, thereby wasting system resources; 2) the channel When the quality is low, a higher-level MCS mode is selected, thereby increasing the frame error rate of the system, reducing the transmission reliability, and reducing the system's effectiveness. The time delay when performing channel estimation will also reduce the reliability of channel quality estimation due to the constant change of the mobile channel. Adaptive modulation and coding technology is often combined with automatic retransmission (ARQ) technology to improve the performance of adaptive modulation and coding, which can effectively improve system throughput, enhance link reliability, and support high-speed data rates. Claim. The coding technology in adaptive modulation and coding technology can adopt a variety of coding structures. At present, the parallel concatenated convolutional codes used in 3GPP, that is, Turbo codes of PCCC (Parallel Concatenated Convolutional Codes) coding structure are used more. Its different code rates can be achieved by using a Rate Compatible Punctured Turbo (RCPT) method. In this method, a turbo code with a code rate of 1 / M is truncated (Puncturing) to form a set of truncated turbo codes to meet the requirements of different MCS level code rates in adaptive modulation and coding technology. The advantage of RCPT is that only one encoder and one decoder are needed, which can meet the requirements of different code rates in different AMCs. At present, in addition to the PCCC coding structure, the coding technology in adaptive modulation and coding technology also uses other coding methods. For example, Qualcomm's HDR system uses the SCCC (Serial Concatenated Convolutional Codes) coding structure, and its different code rates use QCTC. (Quasi-Complementary Turbo Codes).

Product Coding, or n-dimensional product code, is a special type of composite code composed of n sub-codes (generally simpler block codes). It can be regarded as n n-dimensional product codes. The codeword obtained by one-dimensional encoding is then performed. In practical applications, product codes are a class of good codes that can correct both random errors and burst errors and have simple code construction. They are especially suitable for error control systems with complex channel interference. The system can obtain a more flexible code rate by selecting subcodes reasonably and truncating them appropriately.

In J. Hagenauer, E. Offer and L. Papke, "Iterative Decoding of Binary Block and Convolutional Codes," IEEE Trans. Infom. Theory, vol. 42, pp. 429-445, Mar 1996. states that when When the bit rate is greater than 2/3, the performance of the TPC scheme is better than the PCCC scheme. In addition, TPC is more suitable for short frame structures.

Product code is the first error-correcting code that can realize error-free transmission at a non-zero code rate after Shannon's information theory. At that time, due to the limitation of the hardware level, its superiority could not be effectively applied. in recent years In the future, iterative decoding is widely used due to its powerful error correction performance and low complexity. Iterative decoding is to use soft input value and external information value to decode and generate soft output value. According to the soft output value, calculate a new external information value and feed it back to the decoder input to decode again. This process is repeated until a predetermined number of iterations is completed or a predetermined decoding performance is reached. The soft input value includes the hard decision value and reliable value of the received sequence; the soft output value includes the hard decision value and reliable value of the decoded sequence; the external information value is the change value of the reliable value of the decoded sequence after decoding, and it is expressed as The difference between the soft output value and the soft input value. With the application of iterative decoding algorithms, product codes have once again received attention due to their unique advantages. Similarly, the decoding structure of the higher-dimensional product code can be deduced by analogy with the decoding structure of the two-dimensional product code.

Summary of the Invention

An object of the present invention is to provide an adaptive modulation and coding method for high-speed data transmission, and apply Turbo Product Code (TPC) to adaptive modulation and coding (AMC) technology. Due to the advantages of TPC codes that support high bit rates and low complexity of decoding algorithms, the use of TPC in coding schemes for adaptive modulation and coding of MCS at various levels can fully utilize TPC in adaptive modulation and coding The advantages are that the effect of adaptive modulation and coding technology in the field of high-speed data transmission is enhanced.

The technical solution of the present invention is:

An adaptive modulation and coding method for high-speed data transmission is characterized in that

The TURBO product code completes the adaptive modulation and coding of high-speed data.

The transmitting end selects an appropriate coding and modulation method to encode the transmitted information bits according to the real-time channel quality, and the encoding includes at least TURBO product code encoding; the transmitting end modulates the encoded bits according to the real-time channel quality;

Generating the transmission signal after the transmitted information bits are encoded and modulated, The transmission signal is multiplexed with the control signal and transmitted via a channel;

The receiving end demodulates and decodes the received signal, and the decoding includes at least TURBO product code decoding.

The TURBO product code may be a concatenation of a block code and a block code.

The TURBO product code may be a concatenation of a convolutional code and a block code.

The product code may be an n-dimensional product code.

The product code may be a two-dimensional product code. Code encoding.

The modulation method may be phase shift keying modulation, amplitude keying modulation, or amplitude and phase combined modulation.

The phase shift keying modulation can be BPSK, QPSK, DQPSK, 8PSK, D8PS, 16PSK.

The amplitude modulation may be 2ASK, 4AS, 6ASK, 8ASK.

The amplitude and phase joint modulation may be 4QAM, 8QAM, 16QAM, 32QAM,

64QAM, 16APSK, 16DAPSK, 32APSK, 64APSK, 32DAPSK, 64DAPSK.

The control signal may be an MCS level control signal, and the MCS level control signal may be determined according to a channel quality measured by a dedicated pilot channel.

The determining of the MCS level control signal includes: the MCS level control signal is obtained after the mobile station performs channel quality measurement and calculation, and sends the obtained MCS level control signal to the base station via an uplink.

The determining of the MCS level control signal includes: the mobile station performs channel quality measurement, and sends a report of the channel quality measurement to the base station via the uplink, and the base station according to the received channel quality The report of the measurement determines the required MCS level.

The determining of the MCS level control signal includes: The MCS level control signal may be directly given by a higher layer.

The decoding may be a TURBO product code iterative decoding.

The decoding may be a TURBO product code iterative decoding based on sub-code adjoint decoding.

The adaptive modulation and coding method for high-speed data transmission includes the steps of: the transmitting end encodes the transmitted information bits according to the real-time channel quality, and the encoding includes at least TURBO product code encoding;

The transmitting end modulates the coded bits sent according to the real-time channel quality;

The transmitted information bits are encoded and modulated to generate a transmission signal, and the transmission signal is multiplexed with the control signal and transmitted through the channel;

The receiving end detects the control signal;

The method for adaptive modulation and coding for high-speed data transmission may further include:

The transmitting end encodes the transmitted information bits according to the real-time channel quality, and the encoding includes at least a TURBO product code encoding;

The transmitted information bits are encoded and modulated to generate a transmission signal, which is multiplexed with the MCS level control signal and transmitted via the channel;

The receiving end detects the MCS level control signal;

The receiving end uses the constellation diagram corresponding to the transmitting end to demodulate the received signal; The receiving end uses the TURBO product code structure corresponding to the transmitting end for iterative decoding.

The method for adaptive modulation and coding for high-speed data transmission includes the following steps:

On the sending side of the downlink:

Step 401: The base station determines the length of the information frame according to the feedback MCS level control signal, and starts sending information bits.

Step 402: Add a CRC check bit to the transmitted information bits.

Step 403: Determine and encode the TURBO product code length according to the MCS level control signal, and determine the modulation mode according to the MCS level control signal.

Step 404: Generate a service signal after the encoding and modulation.

Step 405: After detecting the MCS level control signal fed back to the base station, perform error protection on the detected ICS level control signal;

Step 406: Modulate the MCS level control signal detected by the base station after the error protection.

Step 407: Perform channel mapping on the MCS level control signal detected by the modulated base station;

Step 408: Multiplex the service signal and the control signal.

Step 409: The service signal and the control signal are multiplexed and sent to the code channel together; at the receiving end of the downlink:

Step 410: Deduplicate the received signal;

Step 411, Step 412, the demultiplexed signal is divided into a service signal and a control signal; Step 414, the demultiplexed service signal selects the MCS level corresponding to the transmitting end according to the detected MCS level control signal, that is, the corresponding modulation Mode and coding structure, and perform corresponding solutions Harmonic decoding

Step 416: Perform a CRC check on the received frame.

Step 417, determine the received frame;

Step 418: If the received frame is incorrect, determine whether the number of retransmissions is less than the maximum number of retransmissions;

Step 419: If the number of retransmissions is less than the maximum number of retransmissions, use HARQ for retransmission; Step 421, when the number of retransmissions has reached the maximum number of retransmissions, discard the bad frame;

Step 420: If the received frame is correct, accept the frame;

According to the multiplexed signal transmitted in the code channel in step 409:

Step 413: Perform channel quality estimation on the user end.

Step 415: Generate an MCS level control signal according to the estimated channel quality and feed it back to the base station via the uplink to be used as an AMC control signal for the next frame.

The beneficial effects of the present invention are:

The invention improves the effectiveness of the communication system, enables users in good channel quality locations to perform higher-speed data transmission, and improves the average throughput of the cell; it can reduce the impact of interference changes, and thus the system has a lower Frame error rate and achieve higher throughput. At the same time, it can enhance the reliability of the link and support the requirements of high-speed data rates.

The product code used in the present invention is a kind of good code that can correct random errors and burst errors at the same time and has a simple code structure. It is particularly suitable for an error control system with complex channel interference. The use of TPC in the coding scheme of MCS at various levels of adaptive modulation and coding can make full use of the advantages of TPC in adaptive modulation and coding technology, and enhance the effect of adaptive modulation and coding technology in the field of high-speed data transmission. The iterative decoding scheme adopted by the invention also obtains the highest possible coding gain and transmission rate with the lowest possible system complexity. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an encoder structure of a two-dimensional product code;

FIG. 2 shows a code structure diagram of a TPC used in the method of the present invention;

FIG. 3 is a block diagram of a decoder of a two-dimensional product code;

4 is a flowchart of an AMC using a TPC according to the method of the present invention;

FIG. 7 is a system throughput simulation result of the AMC using TPC in the embodiment of the present invention. detailed description

As shown in FIG. 1, the present invention is an adaptive modulation and coding method for high-speed data transmission, which is characterized in that a TURBO product code is used to complete adaptive modulation and coding of high-speed data.

The transmitted information bits are generated by the encoding and the modulation to generate a transmission signal, and the transmission signal is multiplexed with a control signal and transmitted through a channel;

In a preferred embodiment of the present invention, the transmitting end may use a two-dimensional product code encoding structure composed of a row encoder 11 and a column encoder 12 to perform row encoding and column encoding on the input information bits. Is a matrix consisting of row and column subcodes.

As shown in FIG. 2, in the preferred embodiment of the present invention, two systematic linear block codes can be selected, dd ^ G (¾, A, i¾) as the TPC subcode, and G (¾,, 4) is used for pairing.亍 Information Bit Editor The code, G (H ,,) is used to encode the column information bits. It can be known from the structure of the linear block code that the A row in the TPC is a codeword of G (n ₂ , J ₂ , and all the columns are codewords of (nkd ^).

As shown in FIG. 3, in a preferred embodiment of the present invention, the receiving end may adopt a two-dimensional product code iterative decoding structure composed of a row decoder 31, a column decoder 32, and a decider 33. In the process of iterative decoding, the row decoder 31 and the column decoder 32 continuously exchange and utilize external information values, and after a certain number of decoding times or a predetermined decoding performance is reached, the obtained soft information value passes the decision. The decoder 33 outputs decoded bits. In a preferred embodiment of the present invention, a better TPC decoding method may also be selected. The method is described in the application number PCT-CN01-01289, and the invention name is "level based on subcode accompanying decoding" The iterative decoding method of concatenated block codes is disclosed in detail. According to the TPC decoding method, an iterative decoding method suitable for concatenated block codes and special forms of product codes can be provided, that is, a linear block code decoding algorithm with reduced complexity is applied to iterative decoding of product codes This method can ensure that the subcode generates an optimized codeword list, so it has good decoding performance, and obtains better decoding performance without increasing the algorithm complexity, and can support more types of subcodes. The selection of this method enables the method of the invention to obtain the highest possible coding gain and transmission efficiency with the lowest possible system complexity.

As shown in FIG. 4, the modulation method may be phase shift keying modulation, amplitude keying modulation, or amplitude and phase joint modulation.

The phase shift keying modulation can be BPSK, QPSK, DQPSK, 8PS, D8PS, 16PSK.

The amplitude modulation may be 2ASK, 4ASK, 6ASK, 8ASK.

The amplitude and phase joint modulation can be 4QAM, 8QAM, 16QAM, 32QAM, 64QAM, 16APSK, 16DAPSK, 32APSK, 64APSK, 32DAPS, 64DAPS. In the preferred embodiment of the present invention, the AMC modulation scheme can be changed from QPSK, 16QAM, Select in 64QAM. Product code encoding. In the preferred embodiment of the present invention, the encoding method in the AMC may adopt TPC with extended Hamming code as the member code, and the length of the member code is from (16,1 1) * (8,4), (16,11 ) * (16,1 1), (32,26) * (16,11), (32,26) * (32,26), (64,57) * (32,26), (64,57) * (64,57), 4 MCSs were selected. The control signal may be an MCS level control signal, and the MCS level control signal may be determined according to a channel quality measured by a dedicated pilot.

The determination of the MCS level control signal may also be obtained after the mobile station performs channel quality measurement and calculation, and sends the obtained MCS level control signal to the base station via the uplink.

The determining of the MCS level control signal may further include: the mobile station performs channel quality measurement, and sends a report of the channel quality measurement to the base station via the uplink, and the base station determines the required channel according to the received channel quality measurement report. MCS level.

The determining of the MCS level control signal may further include: The MCS level control signal may be directly given by a higher layer.

A preferred embodiment of the present invention may adopt that the mobile station MS performs channel quality measurement according to the received downlink signal, and then calculates an appropriate MCS level signal, thereby completing adaptive modulation and coding of the turbo product code.

The specific steps of the preferred embodiment of the present invention are as follows:

On the downlink transmitting end, in step 401, the base station BS selects an appropriate information frame length according to the feedback MCS level control signal, and starts transmitting information bits. In step 402, CRC correction is added to the transmitted information bits. Check the position; then in step 403, select an appropriate modulation mode and corresponding coding scheme according to the MCS level control signal. At the same time, the MCS level control signal fed back to the base station also needs to perform error protection step 405 and modulation step 406, and the obtained signal completes channel mapping step 407. Multiplexed with the encoded and modulated service signal 404 In step 408, they are collectively sent to step 409 in the code channel. At the receiving end of the downlink, a signal decompression step 410 is first performed, and the demultiplexed signal is divided into a service signal step 411 and a control signal step 412. The demultiplexed service signal is subjected to corresponding demodulation and decoding steps 414 according to the detected expression and coding structure. Then, a CRC check step 416 is performed to determine whether the received frame is correct step 417. If it is incorrect, then in step 418, it is further judged whether the number of retransmissions is less than the maximum number of retransmissions. If the number of retransmissions is less than the maximum number of retransmissions, HARQ (Hybrid-ARQ) is used to perform the retransmission step 419. When the number of retransmissions has reached When the maximum number of retransmissions is reached, the bad frame step 421 is abandoned. In addition, according to the multiplexed signal transmitted in the code channel in step 409, a channel quality estimation step 413 is performed on the user side, and an MCS level control signal is generated according to the estimated channel quality. Step 415 is fed back to the base station via the uplink for use as the next frame. AMC control signal.

The encoding of the TPC code can be performed by high-dimensional encoding of various block codes / convolution codes, and the decoding can be performed by iterative decoding.

FIG. 5 is a corresponding BLER (Block Error Rate) obtained through simulation in an AWGN channel in a combination of different modulation modes and coding code rates. The simulation parameters are shown in Table 1.

Chip rate 1.28Mchip / s

MCS level transformation period 1 sub-frame (2387 chips)

Channel environment AWGN coding method TPC

Input soft decision information of TPC decoder FIG. 6 is a throughput performance curve that can be achieved by the system in a combination of coding and modulation corresponding to FIG. 5. Simulation parameters are still shown in Table 1. The principle of selecting MCS in the example of the present invention is determined by the error rate and the throughput. Under the specific signal-to-noise ratio and modulation mode, according to the principle that the error rate is as small as possible and the throughput is as large as possible, a TPC member code with a smaller error rate is selected when the throughput is not large, and when the error rate is not large. Select a TPC member code with a larger throughput. According to the simulation results of Figure 5 error rate and Figure 6 throughput, select a set of possible MCS as follows (but not only this option):

MCS1: TPC code with (16,11) * (16,11) extended Hamming code as member code; QPSK modulation;

MCS2: TPC code with (16,11) * (16,11) extended Hamming code as member code; 16QAM modulation;

MCS3: TPC code with (32,26) * (16,1 1) extended Hamming code as member code; 16QAM modulation;

MCS4: TPC code with (32,26) * (32,26) extended Hamming code as member code; 64QAM modulation;

After selecting the MCS at each level, it is framed after rate matching according to the specific frame structure.

FIG. 7 is a simulation curve of the system throughput after using the above-mentioned four-level MCS and the system throughput after using the AMC technology in the embodiment.

Before obtaining the system throughput curve after adopting the AMC technology, first, the throughput curves obtained from the four MCS levels shown in FIG. 7 are needed to determine the MCS conversion threshold at each level. The obtained thresholds for each level are shown in Table 2. Finally, after adopting the AMC technology, the system changes the MCS level of the system in real time according to the channel quality status at this time and the obtained threshold value comparison. Table 2

It can be seen from FIG. 7 that after using the AMC technology, the system throughput obtained is an outsourced network using only one of the MCS's throughput curves. Therefore, using AMC technology can maximize system throughput.

The invention improves the effectiveness of the communication system, so that users in good channel quality locations can perform higher-speed data transmission, thereby increasing the average throughput of the cell; it can reduce the impact of interference changes, and thus the system has lower errors. Frame rate and achieve higher throughput. At the same time, it can enhance the reliability of the link and support the requirements of high-speed data rates.

The product code used in the present invention is a kind of good code that can simultaneously correct random errors and burst errors and has a simple code structure. It is particularly suitable for error control systems with complex channel interference. The use of TPC in the coding scheme of MCS at various levels of adaptive modulation and coding can fully utilize the advantages of TPC in adaptive modulation and coding technology and enhance the effect of adaptive modulation and coding technology in the field of high-speed data transmission. The iterative decoding scheme used in the present invention also achieves the highest possible coding gain and transmission rate with the lowest possible system complexity.

Claims

Rights request

1. An adaptive modulation and coding method for high-speed data transmission, characterized in that a TURBO product code is used to complete adaptive modulation and coding of high-speed data.

2. The method according to claim 1, characterized in that: the transmitting end selects an appropriate encoding and modulation method to encode the transmitted information bits according to the real-time channel quality, the encoding including at least TURBO product code encoding; the transmitting end according to the real-time channel The quality modulates the encoded bits;

3. The method according to claim 1 or 2, wherein: the TURBO product code is a concatenation of a block code and a block code.

4. The method according to claim 1 or 2, wherein: the TURBO product code is a concatenation of a convolutional code and a block code.

5. The method according to claim 1 or 2, wherein: the product code is an n-dimensional product code.

6. The method according to claim 1 or 2, wherein the product code is a two-dimensional product code.

7. The method according to claim 1 or 2, characterized in that: the coding is TURBO product code coding using a Hamming code or an extended Hamming code as a member code.

8. The method according to claim 1 or 2, wherein: the modulation method It can be phase shift keying modulation, amplitude keying modulation, or combined amplitude and phase modulation.

9. The method according to claim 1 or 2 or 8, characterized in that the phase shift keying modulation is BPSK, QPSK, DQPS, 8PS, D8PSK, 16PSK.

10. The method according to claim 1 or 2 or 8, characterized in that: said amplitude modulation can be 2ASK, 4AS, 6ASK, 8ASK.

11. The method according to claim 1 or 2 or 8, wherein the amplitude and phase modulation can be 4QAM, 8QA, 16QAM, 32QA, 64QAM, 16APSK, 16DAPS, 32APS, 64APSK, 32DAPS, 64DAPSK .

12. The method according to claim 2, wherein the control signal is an MCS level control signal; and the MCS level control signal can be determined by a base station based on a channel quality measured by a dedicated pilot. .

13. The method according to claim 2, wherein the control signal is an MCS level control signal; and the MCS level control signal is obtained after a channel quality measurement and calculation by a mobile station, and The obtained MCS level control signal is transmitted to the base station via the uplink.

14. The method according to claim 1, wherein the control signal is a CS-level control signal; and the MCS-level control signal can be used by a mobile station to perform channel quality measurement and report the channel quality measurement. It is sent to the base station via the uplink, and the base station determines the required MCS level according to the report of the received channel quality measurement.

15. The method according to claim 1, wherein the control signal is

MCS level control signal; the MCS level control signal may be directly given by a higher layer.

16. The method according to claim 2, wherein: the decoding is a TURBO product code iterative decoding.

17. The method according to claim 2, wherein: the decoding is a TURBO product code iterative decoding based on sub-code adjoint decoding.

18. The method according to claim 1, comprising the steps of:

The transmitting end modulates the transmitted bits according to the real-time channel quality;

The receiving end detects the control signal;

19. The method according to claim 1 or 2, wherein the steps include:

The transmitting end modulates the encoded bits according to the real-time channel quality;

The receiving end detects the MCS level control signal;

The receiver uses the constellation diagram corresponding to the transmitter to demodulate the received signal; the receiver uses the TURBO product code structure corresponding to the transmitter to perform iterative decoding.

20. The method according to claim 1 or 2, wherein the steps include:

On the sending side of the downlink: Step 401: The base station determines an information frame length according to the feedback MCS level control signal, and starts sending information bits.

Step 402: Add a CRC check bit to the transmitted information bits.

Step 404: Generate a service signal after the encoding and modulation.

Step 405: After detecting the MCS level control signal fed back to the base station, perform error protection on the detected MCS level control signal.

Step 408: Multiplex the service signal and the control signal.

Step 409: The service signal and the control signal are multiplexed and sent to the code channel together. At the downlink receiving end:

Step 410: Deduplicate the received signal;

Step 411, step 412, divide the demultiplexed signal into a service signal and a control signal; step 414, select the MCS level corresponding to the transmitting end according to the detected MCS level control signal, that is, the corresponding modulation Mode and coding structure, and perform corresponding demodulation and decoding;

Step 416: Perform a CRC check on the received frame.

Step 417, determine the received frame; Step 418: If the received frame is incorrect, determine whether the number of retransmissions is less than the maximum number of retransmissions. Step 419, if the number of retransmissions is less than the maximum number of retransmissions, use HARQ for retransmission; step 421, when the number of retransmissions has reached the maximum When retransmitting times, discard the bad frame;

Step 420: If the received frame is correct, accept the frame;

Step 413: Perform channel quality estimation on the user end.

Step 415: Generate an MCS level control signal according to the estimated channel quality, and feed it back to the base station via the uplink to be used as an AMC control signal for the next frame.