A Baseband Signal Coding Method Based on LDPC Code

Abstract

A baseband signal encoding method based on LDPC code relates to the technical field of baseband signal encoding. According to preset LDPC encoding parameters of a communication link, an original baseband signal is encoded to generate an encoded signal and transmit it; a receiving end decodes the received codeword to obtain an estimated bit sequence of the original baseband data and a bit error rate of a current feedback sliding window of each communication link; the receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and a lookup table, and generates an optimal LDPC encoding parameter according to the lookup table, a bit error rate threshold, an occupied bandwidth corresponding to a codeword generated by different LDPC encoding parameters, a remaining bandwidth of each communication link and a signal-to-noise ratio level, and feeds back the optimal LDPC encoding parameter to a transmitting end; a transmitting end updates the preset LDPC encoding parameters of the communication link for the fedback encoding result, and meets the higher requirements of future wireless communications on speed, reliability and delay.

Description

Technical Field

[0001] The invention relates to the technical field of baseband signal coding, and in particular to a baseband signal coding method based on LDPC codes. Background Art

[0002] The prior art "adaptive coding modulation method for intersatellite link data transmission of satellite navigation system" calculates the distance between any two satellites in the constellation through an intersatellite distance calculator, estimates the signal-to-noise ratio of the signal received by the receiving end, and the coding modulation scheme selector selects the corresponding LDPC-CPM scheme based on the target bit error rate algorithm and the throughput-to-bandwidth ratio algorithm and sends it to the receiver through a pilot. The data signal is generated by an LDPC code encoder, a random interleaver and a CPM modulator to generate a modulated signal and sent to an additive white Gaussian noise channel. The pilot signal is analyzed by a coding modulation scheme estimator, and the data signal superimposed with additive white Gaussian noise channel noise is iteratively detected by a CPM demodulator, a deinterleaver, an LDPC decoder and a random interleaver, and the LDPC decoder makes a hard decision to output data. The present invention can effectively improve the reliability and effectiveness of the intersatellite adaptive coding modulation system.

[0003] The prior art "A codeword diversity frequency hopping anti-interference method based on LDPC channel coding" adopts LDPC code as the channel coding codeword scheme on the basis of the original frequency hopping communication system, and transmits exactly the same diversity copies of the transmitted information in multiple channels. The receiving end performs interference detection on multiple copies of the received signal to determine the position of the interfered bit and erases the soft information carried by the corresponding bit to zero. Then, each group of bits is coherently combined to obtain the decoder input, thereby optimizing the original bit initial prior probability information, thereby improving the decoding reliability. With the help of diversity combining, this method can reduce the impact of signal loss caused by non-ideal characteristics of the channel, and by increasing the number of diversity sets, it can achieve a bit error rate performance close to the theoretical limit. The present invention is applicable to fields such as communications to suppress interference effects and improve decoding reliability.

[0004] In high-speed mobile communication systems, when it is difficult to measure the channel signal-to-noise ratio and effectively predict the communication link between mobile devices through fixed instruments such as spectrum analyzers and signal analyzers, facing the situation of constantly changing channels in the communication link, channel coding technology, as a common error control method, plays a key role in improving the reliability of transmission. The key to channel coding lies in how to design and obtain efficient and reasonable codes. The current mainstream channel coding codewords include Turbo codes, LDPC codes, Polar codes, etc. Among the above codewords, Turbo codes are also called parallel cascade convolutional codes. They combine convolutional codes and random interleavers to achieve random coding. The encoding process of Polar codes is based on the channel polarization phenomenon. According to the Bhattacharyya parameters, bits with high reliability are selected as information bits, and bits with poor reliability are selected as useless bits. The encoding result is obtained through butterfly operation. LDPC codes are low-density parity-check codes. The check matrix and generator matrix are constructed according to certain rules. The encoding result can be obtained by multiplying the original information sequence with the generator matrix. In the decoding process, the decoding algorithm of LDPC code is called belief propagation algorithm. The decoder performs multiple iterative operations to obtain the maximum a posteriori probability of each bit, and judges the final decoding result according to the check equation. Among the above three codes, although Turbo code has excellent anti-interference ability similar to LDPC code, its decoding process is more complicated than binary LDPC code, and the decoding delay is larger. The code type used is also limited to short code length. Under medium and long code conditions, LDPC code can show performance that is closer to the Shannon limit than Turbo code, and the decoding complexity of Polar code also has certain disadvantages compared with binary LDPC code, and the decoding throughput is low. Although Polar code can theoretically polarize an absolutely clean channel, it does not have the error correction capability of LDPC code and has poor scalability. Compared with the first two code types, LDPC code relies on the structural advantages of sparse check matrix. It not only has the characteristics of simple hardware structure and easy implementation, but also can be processed in parallel, has a large throughput, and has good error correction and error detection capabilities. Therefore, the present invention selects LDPC code as an error control means;

[0005] High-speed communication systems such as 5G and 6G may utilize massive MIMO technology, which means that spectrum analyzers and signal analyzers need to be able to process signals received from multiple antennas, which gradually increases the complexity and cost of test equipment. At the same time, high-speed movement causes channel conditions to change rapidly, such as fast fading, multipath effects, and Doppler frequency shift, which require test equipment to be able to capture and analyze in real time or near real time. Faced with the rapid changes in channel conditions of communication links, it has become more difficult for fixed instruments (such as spectrum analyzers or signal analyzers) to directly measure the channel signal-to-noise ratio between mobile devices. In addition, in the traditional LDPC code encoding process, LDPC decoding based on preset fixed LDPC coding parameters can no longer meet the accuracy and efficiency requirements of channel coding in a mobile environment. How to solve the above technical problems to ensure the accuracy of data transmission and improve data transmission efficiency is an issue that we urgently need to solve. Summary of the invention

[0006] In order to solve the above technical problems, the object of the present invention is to provide a baseband signal encoding method based on LDPC code, comprising the following steps:

[0007] Step S1: According to the preset LDPC coding parameters of each communication link between the transmitting end and the receiving end, the original baseband signal to be sent is LDPC-encoded, and the coded signal is generated and distributed to the corresponding communication link for transmission;

[0008] Step S2: The receiving end decodes the codewords received by each communication link through a belief propagation algorithm to obtain a bit sequence of the original baseband data. The receiving end compares and analyzes the decoded bit sequences of each communication link to obtain an estimated bit sequence of the original baseband data, and obtains the bit error rate of the current feedback sliding window of each communication link according to the estimated bit sequence;

[0009] Step S3: pre-build a lookup table, the receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and the lookup table, and determines whether to generate the best LDPC coding parameter for the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link and the signal-to-noise ratio level, and encodes the generated best LDPC coding parameter to feed back to the generating end;

[0010] Step S4: The transmitting end decodes and analyzes the coding result fed back by the receiving end, obtains the optimal LDPC coding parameters of the next feedback sliding window of the communication link, and generates a new feedback sliding window of the communication link and the preset LDPC coding parameters of the feedback sliding window;

[0011] Step S5: The transmitter analyzes the preset LDPC coding parameters of the feedback sliding windows of each communication link in the current monitoring cycle, generates a prediction result, and obtains the preset LDPC coding parameters of the initial feedback sliding windows of each communication link in the next monitoring cycle according to the prediction result.

[0012] Further, according to the preset LDPC coding parameters of each communication link between the transmitting end and the receiving end, the process of performing LDPC coding on the original baseband signal to be transmitted, generating a coded signal and allocating it to the corresponding communication link for transmission includes:

[0013] All communication links between the transmitter and the receiver are obtained, a feedback sliding window is set for each communication link in the current monitoring period, preset LDPC coding parameters of the transmitter and the receiver of each communication link in the current feedback sliding window are obtained, the LDPC coding parameters include code rate, code length, number of decoding iterations and parity check matrix, the original baseband data that the transmitter needs to send at the current moment is obtained, the codewords of the original baseband data in each communication link are generated according to the preset LDPC coding parameters of each communication link, and each codeword is allocated to the corresponding communication link for transmission.

[0014] Furthermore, the receiving end decodes the codewords received by each communication link through a belief propagation algorithm, and the process of obtaining the bit sequence of the original baseband data includes:

[0015] After receiving the codewords transmitted by each communication link, the receiving end performs graph model decoding on the codewords received by each communication link through the belief propagation algorithm, constructs a graph model through the parity check matrix H, and each column of the parity check matrix H represents a variable node, and each row represents a check node. The information bits and check bits in the codewords are initialized for the variable nodes, and the variable nodes are connected to the check nodes according to the structure of the parity check matrix H. Then, the variable nodes and check nodes in the graph model are iteratively updated. When the number of iterations reaches the preset decoding iteration number of the receiving end, the iteration is stopped and the bit sequence of the decoded original baseband data is output.

[0016] Furthermore, the receiving end compares and analyzes the decoded bit sequences of each communication link to obtain the estimated bit sequence of the original baseband data, and obtains the bit error rate of the current feedback sliding window of each communication link according to the estimated bit sequence, including:

[0017] After obtaining the bit sequence of the current feedback sliding window of each communication link, construct an estimated bit sequence of the current feedback sliding window, obtain the bit value of the first bit of the bit sequence of the current feedback sliding window of each communication link, obtain the number of different bit values ​​corresponding to the first bit, select the bit value with a larger number as the bit value of the first bit of the estimated bit sequence, and so on, to obtain the bit value at each bit position of the estimated bit sequence;

[0018] The bit sequence of each communication link is compared with the estimated bit sequence, the number of error bits of each communication link is obtained, and the total number of bits of the estimated bit sequence is obtained, and the bit error rate of the current feedback sliding window of each communication link is obtained according to the number of error bits and the total number of bits.

[0019] Further, the receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and the lookup table, and determines whether to generate the best LDPC coding parameter of the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link and the signal-to-noise ratio level, and encodes the generated best LDPC coding parameter to feed back to the generating end. The process includes:

[0020] The bit error rate threshold allowed in the original baseband data of the transmitting end is obtained according to the estimated bit sequence, and the remaining bandwidth of each communication link in the current feedback sliding window is obtained, and the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters is obtained, and then the lookup table, preset LDPC coding parameters and bit error rates of each communication link of the receiving end in the current feedback sliding window are obtained, and the signal-to-noise ratio level of each communication link of the receiving end is obtained according to the lookup table, the preset LDPC coding parameters and the bit error rates of each communication link;

[0021] Determine whether to generate the best LDPC coding parameter for the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link, and the signal-to-noise ratio level; if the best LDPC coding parameter for the next feedback sliding window is generated, use the best LDPC coding parameter for the next feedback sliding window of the communication link as the preset LDPC coding parameter for the next feedback sliding window of the communication link at the receiving end;

[0022] Then, the sending timestamp of the codeword of the original baseband data of the transmitting end is obtained according to the estimated bit sequence, and the receiving timestamp of the codeword of the original baseband data of each communication link received by the receiving end is obtained at the same time, the transmission delay of each communication link is obtained according to the sending timestamp and the receiving timestamp of each communication link, and the feedback priority of each communication link is obtained according to the transmission delay and the bit error rate of each communication link, the first i communication links with the highest feedback priority are screened out as feedback links, and the optimal LDPC coding parameters of the next feedback sliding window of the communication link are encoded according to the preset LDPC coding parameters of the current feedback sliding window of each feedback link, and the codewords corresponding to each feedback link are generated, and the i codewords are allocated to the corresponding feedback links for transmission.

[0023] Further, the receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and the lookup table, and determines whether to generate the optimal LDPC coding parameter of the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link and the signal-to-noise ratio level. The process includes:

[0024] Construct a fuzzy control model, the input of the fuzzy control model is the signal-to-noise ratio level and the bit error rate threshold of the communication link, the output is the LDPC coding parameter of the communication link, the bit error rate continuous interval, the membership function and the membership threshold of the fuzzy control model are preset, and the bit error rate continuous interval is pre-divided into several fuzzy subsets, and the lookup table is used as the fuzzy adaptive rule table of the fuzzy control model;

[0025] The fuzzy control model uses the signal-to-noise ratio level and the bit error rate threshold of the current feedback sliding window of the communication link as evaluation indicators, selects a target fuzzy subset from a number of fuzzy subsets according to the bit error rate threshold, obtains the membership of each LDPC coding parameter to the target fuzzy subset under the current signal-to-noise ratio level through fuzzy comprehensive evaluation, obtains the LDPC coding parameters whose membership is greater than or equal to the membership threshold, and generates the first-layer LDPC coding parameter set of the communication link according to the LDPC coding parameters;

[0026] Obtaining the occupied bandwidth corresponding to the codeword generated by each LDPC coding parameter in the first-layer LDPC coding parameter set of the communication link and the remaining bandwidth of the communication link, comparing the occupied bandwidth corresponding to the codeword generated by each LDPC coding parameter in the first-layer LDPC coding parameter set of the communication link with the remaining bandwidth of the communication link, screening out the LDPC coding parameters whose occupied bandwidth corresponding to the codeword generated by the LDPC coding parameters in the first-layer LDPC coding parameter set of the communication link is less than or equal to the remaining bandwidth of the communication link, and generating a second-layer LDPC coding parameter set of the communication link according to the LDPC coding parameters;

[0027] Determine whether the preset LDPC coding parameters of the current feedback sliding window of the communication link are in the second-layer LDPC coding parameter set. If so, keep the preset LDPC coding parameters of the current feedback sliding window. If not, select an LDPC coding parameter from the second-layer LDPC coding parameter set and mark it as the optimal LDPC coding parameter.

[0028] Furthermore, the transmitting end decodes and analyzes the coding result fed back by the receiving end, obtains the optimal LDPC coding parameter of the next feedback sliding window of the communication link, and generates a new feedback sliding window of the communication link and a preset LDPC coding parameter of the feedback sliding window, including:

[0029] The trigger mechanism of the feedback sliding window of each communication link of the preset transmitting end is that when the transmitting end receives the best LDPC coding parameter of the communication link fed back by the receiving end, the communication link generates a new feedback sliding window, and uses the best LDPC coding parameter as the preset LDPC coding parameter of the new feedback sliding window;

[0030] After the transmitting end decodes and analyzes the i codewords fed back by the receiving end and obtains the optimal LDPC coding parameters of the next feedback sliding window of the communication link, the communication link generates a new feedback sliding window, and uses the optimal LDPC coding parameters as the preset LDPC coding parameters of the new feedback sliding window. The original baseband data that the transmitting end needs to send at the current moment is encoded according to the preset LDPC coding parameters of the new feedback sliding window of the communication link, and the generated codeword is transmitted through the communication link.

[0031] Furthermore, the transmitting end decodes and analyzes the i codewords fed back by the receiving end, which is consistent with the process in which the receiving end decodes the codewords received by each communication link through the belief propagation algorithm to obtain the bit sequence of the original baseband data, and compares and analyzes the decoded bit sequences of each communication link to obtain the estimated bit sequence of the original baseband data.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. In the actual process of LDPC decoding, due to the high error rate in mobile, even if the decoding process meets the parity check condition and the decoding algorithm correctly offsets the received error, erroneous decoding results may occasionally occur. Therefore, data is transmitted through multiple links, and the decoding results of the multiple links are compared and processed to generate an estimated bit sequence of the original baseband data that is almost impossible to make mistakes, so as to avoid obtaining erroneous decoding results of a single link decoding. At the same time, the bit error rate of the current feedback sliding window of each communication link is obtained according to the estimated bit sequence to judge the signal-to-noise ratio of the channel, and the signal-to-noise ratio is generated for feedback without the need for special measuring instruments to measure the channel conditions, which significantly improves the efficiency and accuracy of the subsequent dynamic adjustment of LDPC coding parameters according to the channel conditions.

[0034] 2. In the face of the development of advanced communication technologies such as 5G and 6G, and for highly dynamic environments and diversified service requirements, the present invention configures the LDPC coding parameters of the feedback sliding window of the communication link before the start of transmission, and dynamically adjusts the LDPC coding parameters according to the real-time channel state conditions, obtains the optimal LDPC coding parameters of the next feedback sliding window of the communication link, generates a new feedback sliding window of the communication link and preset LDPC coding parameters of the feedback sliding window, thereby maximizing the data throughput of mobile communications, while ensuring the reliability of data transmission, and meeting the higher requirements of speed, reliability and latency for future wireless communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of a baseband signal encoding method based on LDPC code according to an embodiment of the present application. DETAILED DESCRIPTION

[0036] The following is a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0037] like Figure 1 As shown, a baseband signal encoding method based on LDPC code includes the following steps:

[0038] Step S1: According to the preset LDPC coding parameters of each communication link between the transmitting end and the receiving end, the original baseband signal to be sent is LDPC-encoded, and the coded signal is generated and distributed to the corresponding communication link for transmission;

[0039] Step S2: The receiving end decodes the codewords received by each communication link through a belief propagation algorithm to obtain a bit sequence of the original baseband data. The receiving end compares and analyzes the decoded bit sequences of each communication link to obtain an estimated bit sequence of the original baseband data, and obtains the bit error rate of the current feedback sliding window of each communication link according to the estimated bit sequence;

[0040] Step S3: pre-build a lookup table, the receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and the lookup table, and determines whether to generate the best LDPC coding parameter for the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link and the signal-to-noise ratio level, and encodes the generated best LDPC coding parameter to feed back to the generating end;

[0041] Step S4: The transmitting end decodes and analyzes the coding result fed back by the receiving end, obtains the optimal LDPC coding parameters of the next feedback sliding window of the communication link, and generates a new feedback sliding window of the communication link and the preset LDPC coding parameters of the feedback sliding window;

[0042] Step S5: The transmitter analyzes the preset LDPC coding parameters of the feedback sliding windows of each communication link in the current monitoring cycle, generates a prediction result, and obtains the preset LDPC coding parameters of the initial feedback sliding windows of each communication link in the next monitoring cycle according to the prediction result.

[0043] It should be further explained that, in the specific implementation process, according to the preset LDPC coding parameters of each communication link between the transmitting end and the receiving end, the original baseband signal to be sent is LDPC encoded, and the coded signal is generated and allocated to the corresponding communication link for transmission. The process includes:

[0044] All communication links between a transmitter and a receiver are obtained, a feedback sliding window is set for each communication link in a current monitoring period, preset LDPC coding parameters of the transmitter and the receiver of each communication link in the current feedback sliding window are obtained, the LDPC coding parameters include code rate, code length, number of decoding iterations and parity check matrix, k bits of original baseband data that the transmitter needs to send at the current moment are obtained, and n-bit codewords of the original baseband data in each communication link are generated according to the preset LDPC coding parameters of each communication link, the n-bit codewords include original k information bits and (nk) check bits, the check bits are obtained by multiplying the original k information bits with the parity check matrix, and each codeword is allocated to a corresponding communication link for transmission.

[0045] It should be further explained that, in the specific implementation process, the receiving end decodes the codewords received by each communication link through the belief propagation algorithm, and the process of obtaining the bit sequence of the original baseband data includes:

[0046] After receiving the codewords transmitted by each communication link, the receiving end performs graph model decoding on the codewords received by each communication link through the belief propagation algorithm, constructs a graph model through the parity check matrix H, and each column of the parity check matrix H represents a variable node, and each row represents a check node. The information bits and check bits in the codewords are initialized for the variable nodes, and the variable nodes are connected to the check nodes according to the structure of the parity check matrix H. Then, the variable nodes and check nodes in the graph model are iteratively updated. When the number of iterations reaches the preset decoding iteration number of the receiving end, the iteration is stopped and the bit sequence of the decoded original baseband data is output.

[0047] It should be further explained that, in a specific implementation process, the receiving end compares and analyzes the bit sequences decoded by each communication link, obtains the estimated bit sequence of the original baseband data, and obtains the bit error rate of the current feedback sliding window of each communication link according to the estimated bit sequence, including:

[0048] After obtaining the bit sequence of the current feedback sliding window of each communication link, construct an estimated bit sequence of the current feedback sliding window, obtain the bit value of the first bit of the bit sequence of the current feedback sliding window of each communication link, obtain the number of different bit values ​​corresponding to the first bit, select the bit value with a larger number as the bit value of the first bit of the estimated bit sequence, and so on, to obtain the bit value at each bit position of the estimated bit sequence;

[0049] The bit sequence of each communication link is compared with the estimated bit sequence, the number of error bits of each communication link is obtained, and the total number of bits of the estimated bit sequence is obtained, and the bit error rate of the current feedback sliding window of each communication link is obtained according to the number of error bits and the total number of bits, wherein the bit error rate = number of error bits / total number of bits.

[0050] In practice, the decoded data may still contain erroneous decoding results due to high mobile error rates, even if the decoding process satisfies the parity check conditions and the decoding algorithm correctly offsets the received errors. Therefore, data is transmitted through multiple links, and the decoding results of the multiple links are compared to generate an estimated bit sequence of the original baseband data that is almost impossible to make mistakes, so as to avoid obtaining erroneous decoding results when decoding a single link. At the same time, the signal-to-noise ratio of the channel is determined by obtaining the bit error rate of the current feedback sliding window of each communication link based on the estimated bit sequence, and the signal-to-noise ratio is generated for feedback without the need for special measuring instruments to measure the channel conditions, which significantly improves the efficiency and accuracy of the subsequent dynamic adjustment of LDPC coding parameters according to the channel conditions.

[0051] It should be further explained that, in the specific implementation process, the receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and the lookup table, and determines whether to generate the best LDPC coding parameter of the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link and the signal-to-noise ratio level, and encodes the generated best LDPC coding parameter to feed back to the generating end. The process includes:

[0052] The bit error rate threshold allowed in the original baseband data of the transmitting end is obtained according to the estimated bit sequence, and the remaining bandwidth of each communication link in the current feedback sliding window is obtained, and the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters is obtained, and then the lookup table, preset LDPC coding parameters and bit error rates of each communication link of the receiving end in the current feedback sliding window are obtained, and the signal-to-noise ratio level of each communication link of the receiving end is obtained according to the lookup table, the preset LDPC coding parameters and the bit error rates of each communication link;

[0053] Determine whether to generate the best LDPC coding parameter for the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link, and the signal-to-noise ratio level; if the best LDPC coding parameter for the next feedback sliding window is generated, use the best LDPC coding parameter for the next feedback sliding window of the communication link as the preset LDPC coding parameter for the next feedback sliding window of the communication link at the receiving end;

[0054] Then, the sending timestamp of the codeword of the original baseband data of the transmitting end is obtained according to the estimated bit sequence, and the receiving timestamp of the codeword of the original baseband data of each communication link received by the receiving end is obtained at the same time, the transmission delay of each communication link is obtained according to the sending timestamp and the receiving timestamp of each communication link, and the feedback priority of each communication link is obtained according to the transmission delay and the bit error rate of each communication link, the first i communication links with the highest feedback priority are screened out as feedback links, and the optimal LDPC coding parameters of the next feedback sliding window of the communication link are encoded according to the preset LDPC coding parameters of the current feedback sliding window of each feedback link, and the codewords corresponding to each feedback link are generated, and the i codewords are allocated to the corresponding feedback links for transmission.

[0055] The calculation formula for obtaining the feedback priority of each communication link according to the transmission delay and bit error rate of each communication link is:

[0056]

[0057] Among them, ZD represents feedback priority; TD represents transmission delay; XC represents bit error rate; a1 and a2 represent weight factors.

[0058] It should be further explained that, in the specific implementation process, the process of pre-building the lookup table includes:

[0059] Pre-simulating communication links under different signal-to-noise ratio levels, different LDPC coding parameters, and pre-setting the same original baseband training data between the transmitter and the receiver, pre-simulating the transmitter to encode the original baseband training data according to different LDPC coding parameters to generate coded data, and transmitting the coded data through communication links under different signal-to-noise ratio levels, and after the receiver decodes the coded data under different LDPC coding parameters and signal-to-noise ratio levels, obtaining the bit error rate of the decoded original baseband training data and the preset original baseband training data, and after multiple simulation tests of the above process, obtaining the bit error rate range corresponding to the original baseband training data under different LDPC coding parameters and signal-to-noise ratio levels;

[0060] According to the bit error rate intervals corresponding to the original baseband training data under different LDPC coding parameters and signal-to-noise ratio levels, a lookup table of bit error rate intervals corresponding to different LDPC coding parameters under different signal-to-noise ratio levels is generated.

[0061] It should be further explained that, in the specific implementation process, the receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and the lookup table, and determines whether to generate the optimal LDPC coding parameter of the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link and the signal-to-noise ratio level. The process includes:

[0062] Construct a fuzzy control model, the input of the fuzzy control model is the signal-to-noise ratio level and the bit error rate threshold of the communication link, the output is the LDPC coding parameter of the communication link, the bit error rate continuous interval, membership function and membership threshold of the fuzzy control model are preset, the bit error rate continuous interval is [0,1], and the bit error rate continuous interval is pre-divided into several fuzzy subsets, and the lookup table is used as the fuzzy adaptive rule table of the fuzzy control model;

[0063] The fuzzy control model uses the signal-to-noise ratio level and the bit error rate threshold of the current feedback sliding window of the communication link as evaluation indicators, selects a target fuzzy subset from a number of fuzzy subsets according to the bit error rate threshold, obtains the membership of each LDPC coding parameter to the target fuzzy subset under the current signal-to-noise ratio level through fuzzy comprehensive evaluation, obtains the LDPC coding parameters whose membership is greater than or equal to the membership threshold, and generates the first-layer LDPC coding parameter set of the communication link according to the LDPC coding parameters;

[0064] Obtaining the occupied bandwidth corresponding to the codeword generated by each LDPC coding parameter in the first-layer LDPC coding parameter set of the communication link and the remaining bandwidth of the communication link, comparing the occupied bandwidth corresponding to the codeword generated by each LDPC coding parameter in the first-layer LDPC coding parameter set of the communication link with the remaining bandwidth of the communication link, screening out the LDPC coding parameters whose occupied bandwidth corresponding to the codeword generated by the LDPC coding parameters in the first-layer LDPC coding parameter set of the communication link is less than or equal to the remaining bandwidth of the communication link, and generating a second-layer LDPC coding parameter set of the communication link according to the LDPC coding parameters;

[0065] Determine whether the preset LDPC coding parameters of the current feedback sliding window of the communication link are in the second-layer LDPC coding parameter set. If so, keep the preset LDPC coding parameters of the current feedback sliding window. If not, select an LDPC coding parameter from the second-layer LDPC coding parameter set and mark it as the optimal LDPC coding parameter.

[0066] With the development of advanced communication technologies such as 5G and 6G, in response to highly dynamic environments and diversified service requirements, the present invention configures the LDPC coding parameters of the initial link before the start of transmission, and dynamically adjusts the LDPC coding parameters according to real-time channel state conditions, thereby maximizing the data throughput of the mobile communication system while ensuring the reliability of data transmission, meeting the higher requirements of speed, reliability and latency for future wireless communications.

[0067] It should be further explained that, in a specific implementation process, the transmitting end decodes and analyzes the coding result fed back by the receiving end, obtains the optimal LDPC coding parameter of the next feedback sliding window of the communication link, and generates a new feedback sliding window of the communication link and a preset LDPC coding parameter of the feedback sliding window, and the process includes:

[0068] The trigger mechanism of the feedback sliding window of each communication link of the preset transmitting end is that when the transmitting end receives the best LDPC coding parameter of the communication link fed back by the receiving end, the communication link generates a new feedback sliding window, and uses the best LDPC coding parameter as the preset LDPC coding parameter of the new feedback sliding window;

[0069] After the transmitting end decodes and analyzes the i codewords fed back by the receiving end and obtains the optimal LDPC coding parameters of the next feedback sliding window of the communication link, the communication link generates a new feedback sliding window, and uses the optimal LDPC coding parameters as the preset LDPC coding parameters of the new feedback sliding window. The original baseband data that the transmitting end needs to send at the current moment is encoded according to the preset LDPC coding parameters of the new feedback sliding window of the communication link, and the generated codeword is transmitted through the communication link.

[0070] It should be further explained that the decoding and analysis of the i codewords fed back by the receiving end by the transmitting end is consistent with the process in which the receiving end decodes the codewords received by each communication link through the belief propagation algorithm to obtain the bit sequence of the original baseband data, and compares and analyzes the decoded bit sequences of each communication link to obtain the estimated bit sequence of the original baseband data.

[0071] It should be further explained that, in the specific implementation process, the transmitter analyzes the preset LDPC coding parameters of the feedback sliding window of each communication link in the current monitoring period to generate a prediction result, and obtains the preset LDPC coding parameters of the initial feedback sliding window of each communication link in the next monitoring period according to the prediction result. The specific process is:

[0072] First, obtain the preset LDPC coding parameter sequences (M1, M2, ..., M j ), where M1 represents the preset LDPC coding parameter sequence of the initial feedback sliding window of the communication link, M2 represents the preset LDPC coding parameter sequence of the second feedback sliding window of the communication link, and M j represents the preset LDPC coding parameter sequence of the jth sliding window of the communication link, the preset weight factor δ,

[0073] δ = a3*j;

[0074] Wherein, a3 is a conversion coefficient, according to the LDPC coding parameter sequence (M1, M2, ..., M j ) and weight factor δ to obtain LDPC coding parameter prediction value MK;

[0075] MK=δM j +δ(1-δ) 2 M j-1 +...+δ(1-δ) t-1 M1;

[0076] In the above formula, if the j of the feedback sliding window of the communication link is larger, it proves that the channel condition of the communication link changes faster, then the preset LDPC coding parameter sequence of the feedback sliding window with larger j in the above formula has a greater influence on the preset LDPC coding parameter sequence of the initial feedback sliding window of the communication link in the next monitoring period, then the preset LDPC coding parameter sequence of the feedback sliding window with smaller j in the above formula has a smaller influence on the preset LDPC coding parameter sequence of the initial feedback sliding window of the communication link in the next monitoring period, that is, the preset LDPC coding parameter sequence of the initial feedback sliding window of the communication link in the next monitoring period has a higher correlation with the preset LDPC coding parameter sequences of the feedback sliding windows of the communication link in the most recent several times of the current monitoring period;

[0077] If the j of the feedback sliding window of the communication link is smaller, it proves that the channel condition of the communication link changes more slowly, then the preset LDPC coding parameter sequence of each feedback sliding window in the above formula has little effect on the preset LDPC coding parameter sequence of the initial feedback sliding window of the communication link in the next monitoring period, that is, the preset LDPC coding parameter sequence of the initial feedback sliding window of the communication link in the next monitoring period is more evenly correlated with the preset LDPC coding parameter sequence of each feedback sliding window of the communication link in the current monitoring period.

[0078] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A baseband signal encoding method based on LDPC code, characterized in that: The following steps are involved: Step S1: According to the preset LDPC coding parameters of each communication link between the transmitting end and the receiving end, the original baseband signal to be sent is LDPC-encoded, and the coded signal is generated and distributed to the corresponding communication link for transmission; Step S2: The receiving end decodes the codewords received by each communication link through a belief propagation algorithm to obtain a bit sequence of the original baseband data. The receiving end compares and analyzes the decoded bit sequences of each communication link to obtain an estimated bit sequence of the original baseband data, and obtains the bit error rate of the current feedback sliding window of each communication link according to the estimated bit sequence, including: After obtaining the bit sequence of the current feedback sliding window of each communication link, construct an estimated bit sequence of the current feedback sliding window, obtain the bit value of the first bit of the bit sequence of the current feedback sliding window of each communication link, obtain the number of different bit values ​​corresponding to the first bit, select the bit value with a larger number as the bit value of the first bit of the estimated bit sequence, and so on, to obtain the bit value at each bit position of the estimated bit sequence; Compare the bit sequence of each communication link with the estimated bit sequence, obtain the number of error bits of each communication link, obtain the total number of bits of the estimated bit sequence, and obtain the bit error rate of the current feedback sliding window of each communication link according to the number of error bits and the total number of bits; Step S3: pre-build a lookup table, the receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and the lookup table, and determines whether to generate the best LDPC coding parameter for the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link and the signal-to-noise ratio level, and encodes the generated best LDPC coding parameter to feed back to the generating end; Step S4: the transmitting end decodes and analyzes the coding result fed back by the receiving end, obtains the optimal LDPC coding parameter of the next feedback sliding window of the communication link, takes the optimal LDPC coding parameter as the preset LDPC coding parameter of the new feedback sliding window, and generates a new feedback sliding window of the communication link and the preset LDPC coding parameter of the feedback sliding window; Step S5: The transmitter analyzes the preset LDPC coding parameters of the feedback sliding windows of each communication link in the current monitoring cycle, generates a prediction result, and obtains the preset LDPC coding parameters of the initial feedback sliding windows of each communication link in the next monitoring cycle according to the prediction result.

2. The baseband signal encoding method based on LDPC code according to claim 1, characterized in that: The process of performing LDPC coding on the original baseband signal to be transmitted according to the preset LDPC coding parameters of each communication link between the transmitting end and the receiving end, generating a coded signal and allocating it to the corresponding communication link for transmission includes: All communication links between the transmitter and the receiver are obtained, a feedback sliding window is set for each communication link in the current monitoring period, preset LDPC coding parameters of the transmitter and the receiver of each communication link in the current feedback sliding window are obtained, the LDPC coding parameters include code rate, code length, number of decoding iterations and parity check matrix, the original baseband data that the transmitter needs to send at the current moment is obtained, the codewords of the original baseband data in each communication link are generated according to the preset LDPC coding parameters of each communication link, and each codeword is allocated to the corresponding communication link for transmission.

3. A baseband signal encoding method based on LDPC code according to claim 2, characterized in that: The receiving end decodes the codewords received by each communication link through the belief propagation algorithm to obtain the bit sequence of the original baseband data. The process includes: After receiving the codewords transmitted by each communication link, the receiving end performs graph model decoding on the codewords received by each communication link through the belief propagation algorithm, constructs a graph model through the parity check matrix H, and each column of the parity check matrix H represents a variable node, and each row represents a check node. The information bits and check bits in the codewords are initialized for the variable nodes, and the variable nodes are connected to the check nodes according to the structure of the parity check matrix H. Then, the variable nodes and check nodes in the graph model are iteratively updated. When the number of iterations reaches the preset decoding iteration number of the receiving end, the iteration is stopped and the bit sequence of the decoded original baseband data is output.

4. The baseband signal encoding method based on LDPC code according to claim 3, characterized in that: The receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and the lookup table, and determines whether to generate the best LDPC coding parameter of the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link and the signal-to-noise ratio level, and encodes the generated best LDPC coding parameter to feed back to the generating end. The process includes: The bit error rate threshold allowed in the original baseband data of the transmitting end is obtained according to the estimated bit sequence, and the remaining bandwidth of each communication link in the current feedback sliding window is obtained, and the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters is obtained, and then the lookup table, preset LDPC coding parameters and bit error rates of each communication link of the receiving end in the current feedback sliding window are obtained, and the signal-to-noise ratio level of each communication link of the receiving end is obtained according to the lookup table, the preset LDPC coding parameters and the bit error rates of each communication link; Determine whether to generate the best LDPC coding parameter for the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link, and the signal-to-noise ratio level; if the best LDPC coding parameter for the next feedback sliding window is generated, use the best LDPC coding parameter for the next feedback sliding window of the communication link as the preset LDPC coding parameter for the next feedback sliding window of the communication link at the receiving end; Then, the sending timestamp of the codeword of the original baseband data of the transmitting end is obtained according to the estimated bit sequence, and the receiving timestamp of the codeword of the original baseband data of each communication link received by the receiving end is obtained at the same time, the transmission delay of each communication link is obtained according to the sending timestamp and the receiving timestamp of each communication link, and the feedback priority of each communication link is obtained according to the transmission delay and the bit error rate of each communication link, the first i communication links with the highest feedback priority are screened out as feedback links, and the optimal LDPC coding parameters of the next feedback sliding window of the communication link are encoded according to the preset LDPC coding parameters of the current feedback sliding window of each feedback link, and the codewords corresponding to each feedback link are generated, and the i codewords are allocated to the corresponding feedback links for transmission.

5. A baseband signal encoding method based on LDPC code according to claim 4, characterized in that: The receiving end obtains the signal-to-noise ratio level of each communication link according to the bit error rate of each communication link and the lookup table, and determines whether to generate the optimal LDPC coding parameter of the next feedback sliding window of each communication link according to the lookup table, the bit error rate threshold, the occupied bandwidth corresponding to the codeword generated by different LDPC coding parameters, the remaining bandwidth of each communication link and the signal-to-noise ratio level. The process includes: Construct a fuzzy control model, the input of the fuzzy control model is the signal-to-noise ratio level and the bit error rate threshold of the communication link, the output is the LDPC coding parameter of the communication link, the bit error rate continuous interval, the membership function and the membership threshold of the fuzzy control model are preset, and the bit error rate continuous interval is pre-divided into several fuzzy subsets, and the lookup table is used as the fuzzy adaptive rule table of the fuzzy control model; The fuzzy control model uses the signal-to-noise ratio level and the bit error rate threshold of the current feedback sliding window of the communication link as evaluation indicators, selects a target fuzzy subset from a number of fuzzy subsets according to the bit error rate threshold, obtains the membership of each LDPC coding parameter to the target fuzzy subset under the current signal-to-noise ratio level through fuzzy comprehensive evaluation, obtains the LDPC coding parameters whose membership is greater than or equal to the membership threshold, and generates the first-layer LDPC coding parameter set of the communication link according to the LDPC coding parameters; Obtaining the occupied bandwidth corresponding to the codeword generated by each LDPC coding parameter in the first-layer LDPC coding parameter set of the communication link and the remaining bandwidth of the communication link, comparing the occupied bandwidth corresponding to the codeword generated by each LDPC coding parameter in the first-layer LDPC coding parameter set of the communication link with the remaining bandwidth of the communication link, screening out the LDPC coding parameters whose occupied bandwidth corresponding to the codeword generated by the LDPC coding parameters in the first-layer LDPC coding parameter set of the communication link is less than or equal to the remaining bandwidth of the communication link, and generating a second-layer LDPC coding parameter set of the communication link according to the LDPC coding parameters; Determine whether the preset LDPC coding parameters of the current feedback sliding window of the communication link are in the second-layer LDPC coding parameter set. If so, keep the preset LDPC coding parameters of the current feedback sliding window. If not, select an LDPC coding parameter from the second-layer LDPC coding parameter set and mark it as the optimal LDPC coding parameter.

6. A baseband signal encoding method based on LDPC code according to claim 5, characterized in that: The process in which the transmitting end decodes and analyzes the coding result fed back by the receiving end, obtains the optimal LDPC coding parameter of the next feedback sliding window of the communication link, and generates a new feedback sliding window of the communication link and the preset LDPC coding parameter of the feedback sliding window includes: The trigger mechanism of the feedback sliding window of each communication link of the preset transmitting end is that when the transmitting end receives the best LDPC coding parameter of the communication link fed back by the receiving end, the communication link generates a new feedback sliding window, and uses the best LDPC coding parameter as the preset LDPC coding parameter of the new feedback sliding window; After the transmitting end decodes and analyzes the i codewords fed back by the receiving end and obtains the optimal LDPC coding parameters of the next feedback sliding window of the communication link, the communication link generates a new feedback sliding window, and uses the optimal LDPC coding parameters as the preset LDPC coding parameters of the new feedback sliding window. The original baseband data that the transmitting end needs to send at the current moment is encoded according to the preset LDPC coding parameters of the new feedback sliding window of the communication link, and the generated codeword is transmitted through the communication link.

7. A baseband signal encoding method based on LDPC code according to claim 6, characterized in that: The process in which the transmitting end decodes and analyzes the i codewords fed back by the receiving end is consistent with the process in which the receiving end decodes the codewords received by each communication link through the belief propagation algorithm to obtain the bit sequence of the original baseband data, and compares and analyzes the decoded bit sequences of each communication link to obtain the estimated bit sequence of the original baseband data.

Images