Adaptive constellation mapping method and system based on joint coding system

Abstract

An adaptive constellation mapping method and system based on a joint coding system, relating to the field of wireless communication technology, are disclosed. The method includes: performing joint source-channel coding on the source data to be transmitted; obtaining a non-uniformly distributed bit sequence using residual redundancy information retained during coding, and dividing the bit sequence into delayed bits and non-delayed bits according to a preset delay scheme; modulating the non-uniformly distributed bit sequence using an adaptive constellation mapping scheme based on the dual criteria of maximizing system channel capacity and maximizing the average Euclidean distance between constellation points corresponding to the same delayed bits, generating a modulated signal; transmitting the modulated signal; receiving the transmitted noisy signal, using the likelihood information of delayed bits from joint decoding feedback to assist demodulation, obtaining the likelihood information of the bit sequence before delay, and sequentially deinterleaving and performing joint source-channel decoding on the bit sequence likelihood information to recover the original source data.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and more specifically, to an adaptive constellation mapping method and system based on a joint coding system. Background Technology

[0002] Against the backdrop of wireless communication technology continuously evolving towards higher speed, lower latency, and higher reliability, Bit Interleaved Coding and Modulation (BICM) technology, with its high spectral efficiency and flexible coding and modulation structure, has become one of the core technologies of modern communication systems.

[0003] To further improve the system's bit error rate performance, the Delayed Bit Interleaved Coding and Modulation (DBICM) system introduces a delay module and a decode-demodulation feedback mechanism to feed back the decoded delayed bit information to the demodulator to assist in subsequent demodulation, which significantly enhances the system's reliability.

[0004] However, most existing research on DBICM systems is based on separate source-channel coding design, which assumes that source coding can completely eliminate source redundancy. This does not make full use of the residual redundant information still retained after source coding in actual systems, resulting in a bottleneck in the performance improvement of the system under non-uniform source or time-varying channel conditions.

[0005] In terms of constellation mapping design, traditional DBICM systems generally adopt fixed mapping methods, such as Gray mapping. This type of mapping scheme does not take into account the non-uniform distribution characteristics of the output bit sequence of the Joint Source-Channel Coding (JSCC) system during the design, and cannot adaptively adapt to the source statistical characteristics to optimize the constellation point distribution, thus limiting the further exploitation of the system's channel capacity.

[0006] Meanwhile, under the feedback mechanism of the DBICM system, the demodulator needs to filter the constellation point set based on the delay bit information of the decoding feedback. However, the average Euclidean distance between constellation points with the same delay bit value in the fixed mapping scheme is often small, which leads to a decrease in the reliability of demodulation decision in noisy environments and affects the overall bit error rate performance of the system.

[0007] To address the aforementioned issues, existing technologies employ schemes that adapt to non-uniform sources by introducing distributed matchers; however, this approach increases the system's implementation complexity and hardware overhead. Other studies have attempted to optimize channel capacity or constellation point geometry individually, but these have failed to achieve synergistic improvement, resulting in limited performance gains in DBICM systems with joint source-channel coding.

[0008] Therefore, designing a constellation mapping method that can simultaneously maximize channel capacity and demodulation reliability without adding extra system modules has become a pressing technical challenge for the current JSC-DBICM system. Summary of the Invention

[0009] This invention provides an adaptive constellation mapping method and system based on a joint coding system to improve at least one of the above-mentioned technical problems.

[0010] In a first aspect, the present invention provides an adaptive constellation mapping method based on a joint coding system, which includes steps S1 to S4.

[0011] S1. Obtain the source data to be transmitted, along with preset compression rate, power constraints, and modulation scheme. Perform joint source-channel coding on the source data. Utilize the residual redundancy information retained during the coding process to obtain a non-uniformly distributed bit sequence, and divide the bit sequence into delayed bits and non-delayed bits according to a preset delay scheme.

[0012] S2. Based on the dual criteria of maximizing the system channel capacity and maximizing the average Euclidean distance between constellation points corresponding to the same delay bits, an adaptive constellation mapping scheme matching the modulation method is constructed, and the adaptive constellation mapping scheme is used to modulate the non-uniformly distributed bit sequence to generate a modulated signal.

[0013] S3. The modulated signal is transmitted through an additive white Gaussian noise channel.

[0014] S4. Receive the noisy signal transmitted through the additive white Gaussian noise channel, use the delayed bit likelihood information from the joint decoding feedback to assist demodulation, obtain the bit sequence likelihood information before the delay, and sequentially deinterleave and perform joint source-channel decoding on the bit sequence likelihood information to recover the original source data.

[0015] Secondly, the present invention provides an adaptive constellation mapping system based on a joint coding system, which includes a transmitter and a receiver that are communicatively connected.

[0016] The transmitter is used to execute steps S1 to S3 in any segment of the first aspect.

[0017] The receiving end is used to execute steps S3 to S4 in any segment of the first aspect.

[0018] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0019] This invention introduces a joint source-channel coding framework, which, without the need for additional distribution matchers or shaping modules, fully utilizes the statistical redundancy information remaining after source coding, making the modulation symbols exhibit non-uniform distribution characteristics. This improves the statistical matching degree with the additive white Gaussian noise channel, effectively enhancing the system's spectral efficiency and power utilization.

[0020] Meanwhile, based on the dual criteria of maximizing system channel capacity and maximizing the average Euclidean distance between constellation points with the same delay, this invention designs an adaptive constellation mapping scheme. This scheme dynamically optimizes the constellation point layout under different modulation orders, source statistical characteristics, and delay configurations, ensuring both the approximation performance of system capacity and enhancing the decision reliability in the decoding feedback-assisted demodulation process, significantly reducing the bit error rate. Furthermore, this invention maintains high compatibility with existing coding and modulation architectures at both the transmitter and receiver ends, avoiding complex hardware modifications or additional signal processing overhead. It possesses good engineering feasibility and generalization capabilities, making it suitable for future wireless communication scenarios characterized by low latency, high reliability, and limited resources. Attached Figure Description

[0021] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the specific embodiments of the present invention will be briefly introduced below. It should be understood that the following drawings only show some specific embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a system architecture diagram of an adaptive constellation mapping method based on a joint coding system. Figure 1 The core modules and information flow of the transmitter and receiver were clearly defined, supporting the design logic of "source-channel-mapping" collaborative optimization.

[0023] Figure 2 This is a comparison diagram between the ordinary mapping and the mapping after introducing prior information from the decoding feedback. It is used to verify the mechanism that "the demodulator selects constellation points based on the delayed bits of the feedback," providing visual support for the design principle of "maximizing the average Euclidean distance between constellation points with the same delayed bits."

[0024] Figure 3 for Figure 2 Under the two mapping schemes, after filtering by decoder feedback information, the distribution map of the constellation point subsets corresponding to the same delay bits is shown. This is used to verify the rationality of the design principle of "maximizing the average Euclidean distance of constellation points with the same delay bits" and to provide intuitive support for the adaptive mapping scheme.

[0025] Figure 4This is a schematic diagram of bit allocation and constellation point layout for three traditional mapping schemes under 16QAM modulation. Figure 4 As a performance benchmark for the adaptive mapping of this invention, it supports the effectiveness verification of the dual criteria of "maximizing channel capacity" and "maximizing the average Euclidean distance between bit constellation points with the same delay".

[0026] Figure 5 This diagram illustrates the adaptive mapping schemes for four source codes under 16QAM modulation. It shows the bit allocation and constellation layout of each scheme, and the matching delay scheme. It supports the design logic of "maximizing channel capacity" and "maximizing the average Euclidean distance between points in the same delay bit constellation".

[0027] Figure 6 This diagram shows the bit allocation and constellation layout for three traditional mapping schemes under 64QAM modulation. It serves as a performance benchmark for the adaptive mapping scheme of this invention, supporting the validity verification of the dual criteria of "maximizing channel capacity" and "maximizing the average Euclidean distance between constellation points with the same delay."

[0028] Figure 7 This diagram illustrates the adaptive mapping schemes for four source codes under 64QAM modulation. It shows the bit allocation and constellation layout of each scheme, and the matching delay scheme. It supports the design logic of "maximizing the average Euclidean distance between points in the same delay bit constellation" and "maximizing channel capacity".

[0029] Figure 8 Source code basis matrix In 16QAM (corresponding to adaptive mapping) ) and 64QAM (corresponding to adaptive mapping) The diagram illustrates the channel capacity differences between the adaptive mapping scheme and three traditional mapping schemes under different modulation methods. This demonstrates the effectiveness of adaptive mapping in unlocking the channel's transmission potential.

[0030] Figure 9 The source code base matrix with a code rate of one-third In 16QAM (corresponding to adaptive mapping) ) and 64QAM (corresponding to adaptive mapping) The diagram illustrates the channel capacity differences between the adaptive mapping scheme and three traditional mapping schemes under different modulation methods. This demonstrates the effectiveness of adaptive mapping in unlocking the channel's transmission potential.

[0031] Figure 10 The source code basis matrix for P-LDPC codes In 16QAM (corresponding to adaptive mapping) ) and 64QAM (corresponding to adaptive mapping) The diagram illustrates the channel capacity differences between the adaptive mapping scheme and three traditional mapping schemes under different modulation methods. This demonstrates the effectiveness of adaptive mapping in unlocking the channel's transmission potential.

[0032] Figure 11 The source code basis matrix is ​​not precoded. In 16QAM (corresponding to adaptive mapping) ) and 64QAM (corresponding to adaptive mapping) The diagram illustrates the channel capacity differences between the adaptive mapping scheme and three traditional mapping schemes under different modulation methods. This demonstrates the effectiveness of adaptive mapping in unlocking the channel's transmission potential.

[0033] Figure 12 Source code basis matrix In 16QAM (corresponding to adaptive mapping) ) and 64QAM (corresponding to adaptive mapping) The graph shows the BER performance differences between the three traditional mapping schemes under the modulation scheme.

[0034] Figure 13 The source code base matrix with a code rate of one-third In 16QAM (corresponding to adaptive mapping) ) and 64QAM (corresponding to adaptive mapping) The graph shows the BER performance differences between the three traditional mapping schemes under the modulation scheme.

[0035] Figure 14 The source code basis matrix for P-LDPC codes In 16QAM (corresponding to adaptive mapping) ) and 64QAM (corresponding to adaptive mapping) The graph shows the BER performance differences between the three traditional mapping schemes under the modulation scheme.

[0036] Figure 15 The source code basis matrix is ​​not precoded. In 16QAM (corresponding to adaptive mapping) ) and 64QAM (corresponding to adaptive mapping) The graph shows the BER performance differences between the three traditional mapping schemes under the modulation scheme.

[0037] The four types of source codes include: the basic source code basis matrix. The source code base matrix with a code rate of one-third. . is the source code basis matrix used for P-LDPC codes. . is the non-precoded source code basis matrix. .

[0038] Three traditional mapping schemes include: 16QAM and Mapping Mapping Mapping comparison, 64QAM and Mapping Mapping Mapping comparison. Detailed Implementation

[0039] As future mobile communication systems face increasingly stringent constraints regarding latency, complexity, and implementation costs, the traditional design approach that assumes source coding can completely eliminate source redundancy is unlikely to hold true in practical systems. Especially under conditions of low latency and limited computing resources, some residual redundant information inevitably remains after source coding. Ignoring this redundancy not only wastes system resources but may also limit the improvement of overall transmission performance.

[0040] Based on this, the present invention fully considers the objective existence of residual redundant information under non-ideal source coding conditions, and introduces it as an information resource that the system can utilize. By combining source channel coding and bit interleaving modulation, the transmitted signal presents statistical characteristics that are more conducive to channel transmission without adding additional system modules.

[0041] The purpose of this invention is to provide an adaptive constellation mapping method and system based on Joint Source-Channel Delay Bit-Interleaved Coded Modulation (JSC-DBICM) system. While reducing the system implementation complexity, it fully explores the potential gains of residual redundant information in the source coding, so as to improve the transmission reliability and resource utilization efficiency of the system and meet the needs of future mobile communication systems for efficient and low-complexity transmission schemes.

[0042] Example 1, please refer to Figures 1 to 15 The first embodiment of the present invention provides an adaptive constellation mapping method based on a joint coding system, which can be executed by an adaptive constellation mapping system based on a joint coding system to implement steps S1 to S4. The method includes a transmitter processing procedure and a receiver processing procedure.

[0043] The transmitting end first acquires the source data to be transmitted, as well as the system's target transmission rate, power constraints, and modulation scheme. The target transmission rate comprehensively considers the source coding rate, channel coding rate, and modulation order. Based on these system parameters, the probability distribution of the modulated signal is determined. Then, while satisfying the power constraints, the modulated signal is amplitude normalized or scaled according to the statistical characteristics of the jointly coded bit sequence to achieve better statistical matching characteristics in an additive white Gaussian noise channel.

[0044] Based on this, the transmitting end processes the source data using a joint source-channel coding method according to the preset source code fundamental matrix and channel code fundamental matrix. Specifically, source coding maps the source data into an information bit sequence, retaining some source statistical characteristics during the coding process to make the information bit sequence exhibit a non-uniform distribution. Subsequently, channel coding is performed on the information bit sequence based on the channel code fundamental matrix, introducing parity bits to enhance noise immunity. The source code fundamental matrix and channel code fundamental matrix undergo matching analysis and parameter selection using a system performance threshold analysis method to ensure the stability and convergence performance of the joint decoding process.

[0045] Subsequently, the bit sequences obtained by source coding and channel coding are subjected to bit interleaving. The parity bits generated by channel coding are used as the symbol bits of the modulation symbols, while the information bit sequences generated by source coding are mapped to the amplitude bits of the modulation symbols according to a preset rule, thereby constructing a bit-interleaved modulation structure.

[0046] Based on the bit interleaving result, a modulation mapping operation is performed to generate a modulated signal. The modulated signal is then transmitted to the receiving end through an additive white Gaussian noise channel.

[0047] After receiving the received signal transmitted through an additive white Gaussian noise channel, the receiving end first demodulates the received signal to obtain the likelihood information of the corresponding bits. Then, it sequentially deinterleaves the demodulated bit likelihood information to recover the structural relationship of the bit sequence before interleaving. Based on this, the receiving end employs a joint source-channel decoding method, performing coordinated iterative decoding processes for the source encoder and channel encoder. By alternately exchanging soft information between source decoding and channel decoding, the bit likelihood information is gradually updated until a preset iteration termination condition is met, thereby recovering the original source data.

[0048] This embodiment uses an additive white Gaussian noise channel as the transmission environment and 16QAM and 64QAM modulation methods as examples to illustrate the entire process of the system's transmitter processing, adaptive constellation mapping design, receiver feedback-assisted demodulation, and joint decoding.

[0049] This embodiment is based on Figure 1 The architecture shown is implemented as follows. The transmitter completes signal modulation sequentially through source coding, channel coding, interleaving, delay module, and adaptive constellation mapping. The receiver recovers the source data through demodulation, de-delay, deinterleaving, and joint decoding. The decoder and demodulator form a closed loop through the feedback of delay bit likelihood information.

[0050] The adaptive constellation mapping method of the present invention includes steps S1 to S4.

[0051] S1. Obtain the source data to be transmitted, along with preset compression rate, power constraints, and modulation scheme. Perform Joint Source-Channel Coding (JSCC) on the source data. Utilize the residual redundancy information retained during the coding process to obtain a non-uniformly distributed bit sequence, and divide the bit sequence into delayed bits and non-delayed bits according to a preset delay scheme.

[0052] Preferably, S1 includes S11 to S13.

[0053] S11. Obtain the source data, the prior probability that the source bit value is 1, the target transmission rate, the power constraint, and the modulation order. The target transmission rate is determined by combining the source coding rate, the channel coding rate, and the modulation order.

[0054] Specifically, the first step is to acquire source data and initialize system parameters. At any given moment, an independent and identically distributed sequence of binary information. The input source encoder performs source compression, assuming the given source basis matrix... The size is Simply put Copy-Interweave Next, making This allows the information source to be compressed. Let be the number of rows in the source code base matrix.

[0055] S12. Based on the preset source code base matrix and the preset channel code base matrix, perform source coding and channel coding on the source data in sequence to obtain a joint coded bit sequence containing information bits and check bits.

[0056] Joint Source-Channel Coding (JSCC) processing includes source coding and channel coding.

[0057] The source coding employs a copy-interleaving method to construct a source code verification matrix, and compresses and encodes the source data based on the source code verification matrix. Specifically, this involves: compressing and encoding the source data using a preset source code base matrix. Perform copy-interleaving expansion to construct the source code verification matrix. According to the aforementioned source code verification matrix For source data Compress and encode to obtain the source codeword. The source codeword retains its source statistical characteristics after compression, resulting in a non-uniform distribution of bits corresponding to the source codeword.

[0058] .

[0059] .

[0060] In the formula, This indicates transpose. The length of the source data. The number of copy-interleaving operations during source coding. Let be the number of columns in the source code base matrix.

[0061] Specifically, source coding: based on a preset source code base matrix. Through "copy-interweaving" Secondary construction of the source verification matrix Using formulas For source data Compress and encode to obtain the source codeword. .in . The number of copy-interleaving operations during source coding. Let be the number of columns in the source code base matrix. The length of the source data. This indicates transpose.

[0062] The channel coding constructs a channel check matrix based on a preset channel code base matrix, and performs protective coding on the source codewords. Specifically, this involves encoding the preset channel code base matrix... Perform copy-interleaving spread and construct the channel check matrix. According to the channel verification matrix Constructing the channel generation matrix Based on the channel generation matrix Source code of the message Compress and encode to obtain the joint coded codewords. The jointly encoded codeword includes information bits and parity bits for modulation mapping to enhance noise immunity during subsequent transmission.

[0063] .

[0064] .

[0065] In the formula, To verify the sequence matrix. It is an identity matrix.

[0066] Specifically, channel coding: based on a preset channel code base matrix. Through "copy-interweaving" Secondary construction of channel verification matrix .Depend on Constructing the channel generation matrix ( To verify the sequence matrix, (The identity matrix). Using the formula Channel coding is performed on the source codeword.

[0067] Among them, subscript Indicates the source. Subscript Indicates the channel. Subscript For time indexing.

[0068] The four basis matrices used in this example are as follows: .

[0069] .

[0070] .

[0071] .

[0072] In the formula, The source code base matrix is ​​denoted as . The source code base matrix is ​​based on this. It is the source code base matrix with a code rate of one-third. This is the source code basis matrix used for P-LDPC codes. It is the source code basis matrix without precoding.

[0073] The four basis matrices above can be used to generate four source check matrices, which can compress the source data. The compressed data can then be fed into the channel encoder to complete the source-channel coding.

[0074] S13. Perform bit interleaving and delay configuration on the joint coded bit sequence, so that the check bits generated by channel coding are used as the symbol bits of the modulation symbol, and the information bits generated by source coding are used as the amplitude bits of the modulation symbol, and configure a portion of the bits as delayed bits and the remaining bits as non-delayed bits.

[0075] Preferably, the preset delay scheme corresponds one-to-one with the modulation method, and includes: When 16QAM modulation is used, the pre-configured 16QAM delay scheme is invoked. The multiple bit positions corresponding to each modulation symbol are divided into delayed bit positions and non-delayed bit positions.

[0076] When 64QAM modulation is used, the pre-configured 64QAM delay scheme is invoked. The multiple bit positions corresponding to each modulation symbol are divided into delayed bit positions and non-delayed bit positions, and the maximum delay is controlled within a preset upper limit. .

[0077] In the formula, This indicates the delay scheme. This indicates the maximum delay.

[0078] The delayed bits are used to form feedback prior information after decoding at the receiving end. The non-delayed bits are used to perform candidate constellation point selection and auxiliary demodulation under the constraints of the feedback prior information.

[0079] Specifically, the preset delay scheme matches the modulation method: when using 16QAM modulation, the delay scheme... When using 64QAM modulation, the delay scheme... And maximum delay .

[0080] S2. Based on the dual criteria of maximizing the system channel capacity and maximizing the average Euclidean distance between constellation points corresponding to the same delay bits, an adaptive constellation mapping scheme matching the modulation method is constructed, and the adaptive constellation mapping scheme is used to modulate the non-uniformly distributed bit sequence to generate a modulated signal.

[0081] Specifically, an adaptive constellation mapping scheme is designed based on the dual criteria of "maximizing system channel capacity + maximizing the average Euclidean distance between constellation points with the same delay". Then, the adaptive constellation mapping scheme is used to modulate the non-uniformly distributed bit sequence to generate a modulated signal adapted to the statistical characteristics of the source.

[0082] Preferably, S2 includes S21 to S24.

[0083] S21. Based on the non-uniform distribution characteristics of the bit sequence after joint encoding, calculate the occurrence probability of each constellation point, and use the occurrence probability of the constellation point as the statistical input for constellation mapping design.

[0084] Specifically, after the joint coding process, the compressed source sequence still contains residual redundant information. Therefore, the 0 and 1 bits in the transmitted codeword do not follow a uniform distribution, and the probability of constellation points does not follow an equal probability distribution. To quantify this statistical characteristic, it is possible to traverse the preset source code basis matrix. The elements of each row determine the row weight of the matrix.

[0085] .

[0086] In the formula, Represents the source code basis matrix The The line is heavy. This is the row index of the matrix. This is the column index of the matrix. Let be the number of columns in the source code base matrix. Source code basis matrix The Middle Line number The values ​​of the elements in the column.

[0087] For line weight The prior probability that a given bit sub-block is bit 1 in the original source is: Under the condition of joint coding, the first The probability that the bit in the sub-block corresponding to a row is 0 or 1 is: .

[0088] .

[0089] .

[0090] In the formula, For the first The probability that the bit in the sub-block corresponding to the row is 0. For the first The probability that the bit in the sub-block corresponding to the row is 1. These are intermediate parameters used to simplify calculations. It is the prior probability that a bit in the original binary information source is 1.

[0091] Under ideal interleaving conditions, the bits in a modulation symbol are independent of each other. For using... In a system using a first-order modulation scheme, each modulation symbol is composed of... Composed of bits, any constellation point The probability of a constellation point appearing can be determined by the joint probability of its corresponding bit combination. That is, the probability of a constellation point appearing is calculated based on the non-uniform distribution of bits after joint encoding.

[0092] The probability of any constellation point appearing is: .

[0093] In the formula, This represents the probability of occurrence. For constellations. for The probability of its occurrence. The source code base matrix is ​​denoted as . This is a constellation mapping scheme. express Under given conditions hour The probability of its occurrence. This is the bit index within the modulation symbol. This represents the number of bits in the modulation symbol. It is the prior probability that a bit in the original binary information source is 1. For the interleaved and mapped modulation symbols within the first 1 bit. For the first The probability of a sub-block of bits.

[0094] The above method can obtain the non-uniform probability distribution of each constellation point, which serves as an important basis for subsequent adaptive constellation mapping design and channel capacity calculation.

[0095] S22. Given a delay scheme, calculate the system channel capacity corresponding to the candidate mapping schemes, and select the set of mapping schemes that maximizes the system channel capacity.

[0096] In this embodiment, to fully utilize the non-uniform bit distribution characteristics introduced by joint coding and the delayed bit feedback information, an adaptive constellation mapping design method based on dual optimization criteria is proposed. The dual optimization criteria include: maximizing the system channel capacity and maximizing the average Euclidean distance between constellation points with the same delayed bit duration.

[0097] Rule 1: Maximize system channel capacity.

[0098] Under ideal interleaving conditions, the modulation system can be equivalent to multiple parallel bit sub-channels, and its total channel capacity can be expressed as the sum of the capacities of each sub-channel. Under ideal interleaving conditions, the JSC-DBICM system can be equivalent to multiple independent parallel bit sub-channels, and the total channel capacity of the system is defined as the sum of the capacities of each bit sub-channel.

[0099] For the given delay scheme The system channel capacity is: .

[0100] In the formula, To provide a given delay scheme Under the condition of joint source-channel coding, the delayed bit-interleaved coding modulation system Total channel capacity. This is the index of the delayed sub-channel. This is the set of delayed sub-channels. For the first Capacity of each delayed sub-channel. This is a set of indices for undelayed sub-channels. This is the index of the undelayed sub-channel. For the first Channel capacity of an undelayed subchannel under the condition of using delayed bits to feed back prior information.

[0101] For the For each delayed subchannel, due to the feedback information from the decoder, its channel capacity can be expressed by the mutual information between the input bits and the channel output: .

[0102] In the formula, For transmission to the first The bits of the delayed sub-channel (i.e. the first) (delay bits). This is the channel output. This represents information entropy. This is the standard function symbol used in information theory to calculate the "mutual information" between two random variables.

[0103] Preferred, For input information entropy, Let be the conditional entropy.

[0104] For an undelayed subchannel, the decoded delayed bit feedback information is introduced as a priori constraint during demodulation, and its channel capacity is expressed as: .

[0105] In the formula, For the first Bits of an undelayed subchannel. This indicates the delayed bit information that has been fed back by the decoder.

[0106] This formula shows that demodulation of the undelayed bits utilizes known delay bit information as a condition, thereby improving the effective capacity of the sub-channel. Through this feedback mechanism, the candidate constellation point set of the undelayed sub-channel is constrained, thus effectively improving the channel capacity of the corresponding sub-channel. Based on the above analysis, the total channel capacity of the system will be maximized. This serves as the primary optimization criterion for adaptive constellation mapping design.

[0107] S23. In the set of mapping schemes, the average Euclidean distance between constellation points with the same delay bit value is further calculated, and the mapping scheme with the largest average Euclidean distance is preferentially selected as the adaptive constellation mapping scheme.

[0108] Rule 2: Maximize the average Euclidean distance between points in a constellation with the same delay.

[0109] In this embodiment, in the joint coding delayed bit interleaving coding modulation system, an information feedback path is established between the decoder and the demodulator. After receiving the delayed bit decoding result output by the decoder, the demodulator uses the delayed bit as prior constraint information to assist in the demodulation decision process for the non-delayed bits. During demodulation, based on the delayed bit value fed back by the decoder, the complete constellation point set is divided, and only constellation points that meet the delayed bit value condition are retained as the candidate constellation point set. The remaining constellation points that do not meet the condition do not participate in the decision of the current symbol. The demodulator only makes decisions within the subset of constellation points that meet the delayed bit value constraint.

[0110] Under the constellation point selection conditions described above, although the number of candidate constellation points is significantly reduced, the geometric distribution among the retained constellation points still differs under different mapping schemes. The Euclidean distance between the remaining constellation points directly affects the reliability of the demodulation soft decision; the larger the Euclidean distance, the stronger the robustness to noise interference. Therefore, in the adaptive constellation mapping design process, maximizing the average Euclidean distance between constellation points with the same delay bit value is taken as the second optimization criterion.

[0111] For a given combination of delay bits Define the set of constellation points that satisfy the condition for the value of this delay bit as follows: Within this set, the average Euclidean distance between bit constellation points with the same delay is: .

[0112] In the formula, This is the weighted average Euclidean distance. This represents the total number of constellation points. Index for the first constellation point. Index for the second constellation point. For the first constellation points The probability of its occurrence. For the first constellation points The probability of its occurrence. For a collection of all and Having the same delay bit information A set of. This represents the average energy of each symbol in the constellation chart. This represents the Euclidean distance.

[0113] The average energy of each symbol in the constellations is: .

[0114] In the formula, It represents the absolute value.

[0115] S24. When multiple candidate mapping schemes simultaneously satisfy the aforementioned dual criteria, the mapping scheme with a larger number of adjacent constellation points that satisfy the Gray mapping characteristics shall be given priority.

[0116] Preferably, when multiple constellation mapping schemes simultaneously satisfy the system channel capacity maximization criterion, the mapping scheme that maximizes the average Euclidean distance between constellation points with the same delay bits is selected first. If multiple candidate mapping schemes still exist, the mapping scheme with a larger number of constellation points that satisfy the Gray mapping characteristics is further selected to reduce the risk of error propagation during decoding.

[0117] The adaptive constellation mapping scheme is determined through iterative updates of constellation point positions, specifically including: Obtain the prior probability of the source bit being 1, the target transmission rate, the delay scheme, the source code base matrix, the modulation order, and the initial constellation mapping scheme, and calculate the initial system channel capacity and the initial average Euclidean distance based on the initial constellation mapping scheme.

[0118] Select at least two different constellation points from the constellation point set, and exchange the spatial positions of the at least two different constellation points to generate candidate mapping schemes.

[0119] The candidate mapping schemes are evaluated for performance. When the system channel capacity corresponding to the candidate mapping scheme is not lower than the system channel capacity corresponding to the current mapping scheme, the average Euclidean distance corresponding to the candidate mapping scheme is calculated.

[0120] When the system channel capacity and average Euclidean distance corresponding to the candidate mapping scheme are not lower than those of the current mapping scheme, the candidate mapping scheme is used to update the current mapping scheme; otherwise, a new constellation point combination is selected to continue the iterative search.

[0121] When the number of iterations reaches a preset threshold or the mapping performance converges, the final adaptive constellation mapping scheme is output.

[0122] Specifically, to achieve the aforementioned dual-criteria adaptive constellation mapping design, a mapping determination method based on iterative updates of constellation point positions is proposed. This method, while maintaining the system channel capacity, further improves the average Euclidean distance between constellation points with the same delay bit by adjusting the geometric distribution of constellation points. First, relevant system parameters are obtained, including the prior probability that the source bit value is 1. System target transmission rate Delay scheme Source code base matrix Modulation order and initial constellation mapping scheme Based on the aforementioned source statistical characteristics and the system target rate, the corresponding system Shannon limit is calculated to determine the theoretical performance reference benchmark under the current source conditions.

[0123] Simultaneously, based on the non-uniform bit distribution obtained after joint coding, the occurrence probability of each constellation point under the initial mapping scheme is calculated. Under the initial mapping scheme, the system's probability under a given delay scheme is calculated respectively. The channel capacity under the given conditions, and the average Euclidean distance between constellation points with the same delay, are used as initial evaluation metrics for the subsequent mapping update process. Any two different constellation points are selected from the constellation point set, and their spatial positions are swapped to obtain new candidate mapping schemes. The performance of these candidate mapping schemes is evaluated, and their corresponding system channel capacity is calculated.

[0124] When the system channel capacity of a candidate mapping scheme is not lower than that of the current mapping scheme, it is considered to meet the system channel capacity maximization criterion. Under this premise, the average Euclidean distance between the same delay bit constellation points under the candidate mapping scheme is further calculated.

[0125] Based on the candidate mapping scheme satisfying the channel capacity constraint, a new mapping scheme is formed by introducing a third different constellation point for position swapping. The performance indicators of different mapping schemes in terms of the average Euclidean distance between constellation points with the same delay and the system channel capacity are compared. If the new mapping scheme is no less than the current mapping scheme in both system channel capacity and the average Euclidean distance between constellation points with the same delay, the current mapping scheme is updated to the new mapping scheme. Otherwise, a new constellation point combination is selected for iterative search. The above constellation point swapping and performance evaluation process is repeated until a preset termination condition is met, and the final determined adaptive constellation mapping scheme is output. The termination condition may include the number of iterations reaching a preset threshold or the mapping performance converging.

[0126] S3. The modulated signal is transmitted to the receiving end through an additive white Gaussian noise (AWGN) channel. Specifically, the modulation signal is subjected to amplitude normalization or scaling processing, and the normalized or scaled modulation signal is transmitted to the additive white Gaussian noise channel under the condition of satisfying the power constraint.

[0127] S4. Receiver processing: Receive the noisy signal transmitted through the Additive White Gaussian Noise (AWGN) channel, use the delayed bit likelihood information from the joint decoding feedback to assist demodulation, obtain the bit sequence likelihood information before the delay, and sequentially deinterleave and perform joint source-channel decoding on the bit sequence likelihood information to recover the original source data.

[0128] Preferably, S4 specifically includes S41 to S46.

[0129] S41. Receive the noisy signal transmitted through the additive white Gaussian noise channel, and use the delayed bit likelihood information from the joint decoding feedback to assist in demodulation, thereby obtaining the bit sequence likelihood information before the delay.

[0130] S42. Feed back the likelihood information corresponding to the delay bits to the demodulator.

[0131] S43. The demodulator, based on the feedback delay bit value, filters out a subset of candidate constellation points from the complete constellation point set that match the delay bit value, and calculates the initial likelihood information of non-delay bits only within the subset of candidate constellation points. The filtering rule for the subset of candidate constellation points is: if the value corresponding to the feedback delay bit is the target value, then only constellation points in the tag whose corresponding delay bit value matches the target value are retained.

[0132] S44. Deinterleave the bit likelihood information obtained from demodulation to restore the structural relationship of the bit sequence before interleaving.

[0133] S45. Input the deinterleaved soft information into the channel decoder and the source decoder, and alternately exchange the soft information between the channel decoder and the source decoder.

[0134] S46. The channel decoder transmits the likelihood information of the channel variable nodes to the corresponding verification node of the source decoder. The source decoder generates likelihood information fed back to the channel decoder based on the source statistical constraints to gradually update the posterior probability of each bit and recover the original source data.

[0135] The specific process of joint source-channel decoding is as follows: the source decoder and the channel decoder iterate together. The channel decoder transmits the likelihood information of the channel variable node to the verification node of the source decoder. The source decoder generates likelihood information that is fed back to the channel decoder. The two alternately update the likelihood information until the number of iterations reaches a preset threshold or the likelihood information converges, and then outputs the recovered source data.

[0136] The specific process of using the likelihood information of delayed bits from the joint decoder to assist demodulation is as follows: After the joint decoder completes the decoding of the delayed sub-block, it feeds back the likelihood information corresponding to the delayed bits to the demodulator. Based on the likelihood information of the delayed bits, the demodulator selects a subset of candidate constellation points "consistent with the value of the delayed bits" from the complete constellation point set, and calculates the initial likelihood information of the bits of the non-delayed sub-block only within this subset. The selection rule for the candidate constellation point subset is: if the bit value corresponding to the feedback likelihood information of the delayed bits is... Then only the "delay bit value" in the constellation point set is retained. The constellation points are defined as follows. The initial likelihood information of the undelayed sub-block bits is the percentage of the matching degree between each constellation point in that subset and the received signal.

[0137] The iteration termination conditions for the joint source-channel decoding include: the number of iterations reaching a preset threshold, or the change in likelihood information between two consecutive iterations being less than a preset convergence threshold. After satisfying the iteration termination conditions, the recovered source data and the corresponding delayed bit decoding results are output, and the delayed bit decoding results are used for subsequent feedback-assisted demodulation.

[0138] like Figures 8 to 15 As shown, the adaptive constellation mapping method based on the Joint Source-Channel Delay Bit-Interleaved Coded Modulation (JSC-DBICM) system proposed in this invention exhibits stable and significant performance advantages under different source statistical characteristics, different source code structures, and different modulation orders.

[0139] Specifically, under 16QAM and 64QAM modulation schemes, for various non-uniform information sources and their corresponding source LDPC codes, the constellation mapping schemes obtained by the adaptive mapping determination method can effectively increase the average Euclidean distance between constellation points corresponding to the same delay bit without reducing the system channel capacity, thereby improving the reliability of demodulation decision.

[0140] Simulation results show that, compared with traditional Gray mapping, DBICM-ID mapping, and contrastive mapping schemes combined with probabilistic shaping, the adaptive mapping scheme proposed in this invention can get closer to the Shannon limit in terms of channel capacity performance, significantly reduce the signal-to-noise ratio gap between the system and the Shannon limit at the target transmission rate, and obtain stable capacity gain under various source conditions.

[0141] Meanwhile, in terms of bit error rate performance, the adaptive mapping scheme shows a significant improvement in decoding performance under medium and high-order modulation conditions. The required signal-to-noise ratio at the same bit error rate level is significantly lower than that of the existing comparative mapping scheme, further verifying the effectiveness of the mapping design criterion in the joint source-channel coding system.

[0142] In summary, the adaptive constellation mapping method proposed in this invention can adaptively optimize constellation mapping relationships under different modulation schemes and source statistics without changing the existing coding structure and decoding algorithm, taking into account both maximizing system channel capacity and optimizing geometric distance. It has good versatility, stability and engineering application value.

[0143] The adaptive constellation mapping method transforms residual redundant information from source coding into usable statistical characteristics of the system without introducing additional distribution matchers or modules, thereby improving the overall resource utilization efficiency of the system. It can fully utilize the residual redundant information from source coding.

[0144] By jointly designing the source code base matrix, the channel code base matrix, and the bit interleaving modulation structure, complex additional signal processing is avoided while ensuring system performance. This approach is suitable for low-latency, low-complexity communication scenarios and reduces system implementation complexity.

[0145] The generated modulated signal is closer to a Gaussian distribution in terms of statistical characteristics, which is beneficial for transmission through additive white Gaussian noise channels. Under the same power constraint, it can improve the system transmission rate and bit error rate performance, as well as improve transmission reliability and transmission efficiency.

[0146] In summary, the data transmission method and system of joint coding delay bit interleaving coding modulation proposed in this invention can achieve efficient and reliable data transmission under complexity-constrained conditions, and has good engineering application value and promotion prospects.

[0147] Example 2: The present invention provides an adaptive constellation mapping system based on a joint coding system, which includes a transmitter and a receiver that are communicatively connected.

[0148] The transmitter is used to execute steps S1 to S3 in any segment of Embodiment 1.

[0149] The receiving end is used to execute steps S3 to S4 in any segment of Embodiment 1.

[0150] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An adaptive constellation mapping method based on a joint coding system, characterized in that, Include: S1. Obtain the source data to be transmitted, as well as the preset compression rate, power constraints, and modulation scheme; perform joint source-channel coding on the source data; use the residual redundant information retained during the coding process to obtain a non-uniformly distributed bit sequence, and divide the bit sequence into delayed bits and non-delayed bits according to a preset delay scheme. S2. Based on the dual criteria of maximizing the system channel capacity and maximizing the average Euclidean distance between constellation points corresponding to the same delay bits, an adaptive constellation mapping scheme matching the modulation method is constructed, and the adaptive constellation mapping scheme is used to modulate the non-uniformly distributed bit sequence to generate a modulated signal. S3. The modulated signal is transmitted through an additive white Gaussian noise channel; S4. Receive the noisy signal transmitted through the additive white Gaussian noise channel, use the delayed bit likelihood information from the joint decoding feedback to assist demodulation, obtain the bit sequence likelihood information before the delay, and sequentially deinterleave and perform joint source-channel decoding on the bit sequence likelihood information to recover the original source data.

2. The adaptive constellation mapping method based on a joint coding system according to claim 1, characterized in that, S2 include: Based on the non-uniform distribution characteristics of the bit sequence after joint encoding, the occurrence probability of each constellation point is calculated, and the occurrence probability of the constellation point is used as the statistical input for constellation mapping design. Given a delay scheme, calculate the system channel capacity corresponding to the candidate mapping schemes, and select the set of mapping schemes that maximize the system channel capacity. In the set of mapping schemes, the average Euclidean distance between constellation points with the same delay bit value is further calculated, and the mapping scheme with the largest average Euclidean distance is preferentially selected as the adaptive constellation mapping scheme. When multiple candidate mapping schemes simultaneously satisfy the aforementioned dual criteria, the mapping scheme with a larger number of adjacent constellation points that satisfy the Gray mapping characteristics is further prioritized.

3. The adaptive constellation mapping method based on a joint coding system according to claim 2, characterized in that, The probability of constellation points appearing is calculated based on the non-uniform distribution of bits after joint coding, specifically including: The probability of any constellation point appearing is: ； In the formula, The probability of occurrence; For the constellations; for The probability of its occurrence; The source code basis matrix; A constellation mapping scheme; express Under given conditions hour The probability of its occurrence; Bit index within the modulation symbol; The number of bits in the modulation symbol; It is the prior probability that a bit is 1 in the original binary information source; For the interleaved and mapped modulation symbols within the first 1 bit; For the first The probability of a sub-block of bits; The row weights of the source code basis matrix are: ； In the formula, Represents the source code basis matrix The The line of line is heavy; This represents the row index of the matrix; For column indices of the matrix; The number of columns in the source code base matrix; Source code basis matrix The Middle Line number The values ​​of the elements in the column; The prior probability of bit 1 in the original source is: Under the conditions, the first The probability of a bit value in the sub-block corresponding to a row is: ； ； ； In the formula, For the first The probability that a bit in the sub-block corresponding to a row is 0; For the first The probability that a bit in the sub-block corresponding to a row is 1; These are intermediate parameters used to simplify calculations.

4. The adaptive constellation mapping method based on a joint coding system according to claim 2, characterized in that, The system channel capacity is: ； In the formula, To provide a given delay scheme Under the condition of joint source-channel coding, the delayed bit-interleaved coding modulation system Total channel capacity; This is the index for the delayed sub-channel; For a set of delayed sub-channels; For the first Capacity of each delayed sub-channel; A set of indices for undelayed sub-channels; This is the index of the undelayed sub-channel; For the first Channel capacity of an undelayed subchannel under the condition of using delayed bits to feed back prior information; The capacity of the delayed subchannel is: ； In the formula, For transmission to the first The bits of the delayed sub-channel (i.e. the first) (one delay bit) For channel output; Represents information entropy; This is the standard function symbol used in information theory to calculate the "mutual information" between two random variables; The non-delayed subchannel capacity is: ； In the formula, For the first Bits of an undelayed subchannel; This indicates the delayed bit information that has been fed back by the decoder; The average Euclidean distance between points in a constellation with the same delay is: ； In the formula, The weighted average Euclidean distance; This represents the total number of constellation points. Index the first constellation point; Index for the second constellation point; For the first constellation points The probability of its occurrence; For the first constellation points The probability of its occurrence; For a collection of all and Having the same delay bit information A set; The average energy of each symbol in the constellation chart; Indicates Euclidean distance; The average energy of each symbol in the constellations is: ； In the formula, It represents the absolute value.

5. The adaptive constellation mapping method based on a joint coding system according to claim 2, characterized in that, The adaptive constellation mapping scheme is determined through iterative updates of constellation point positions, including: Obtain the prior probability of the source bit value being 1, the target transmission rate, the delay scheme, the source code base matrix, the modulation order, and the initial constellation mapping scheme, and calculate the initial system channel capacity and the initial average Euclidean distance based on the initial constellation mapping scheme; Select at least two different constellation points from the constellation point set, and exchange the spatial positions of the at least two different constellation points to generate candidate mapping schemes; The candidate mapping schemes are evaluated for performance. When the system channel capacity corresponding to the candidate mapping scheme is not lower than the system channel capacity corresponding to the current mapping scheme, the average Euclidean distance corresponding to the candidate mapping scheme is calculated. When the system channel capacity and average Euclidean distance corresponding to the candidate mapping scheme are not lower than the current mapping scheme, the candidate mapping scheme is used to update the current mapping scheme; otherwise, a new constellation point combination is selected to continue the iterative search. When the number of iterations reaches a preset threshold or the mapping performance converges, the final adaptive constellation mapping scheme is output.

6. The adaptive constellation mapping method based on a joint coding system according to claim 1, characterized in that, S1 includes: S11. Obtain source data, the prior probability that the source bit value is 1, the target transmission rate, the power constraint, and the modulation order; wherein, the target transmission rate is determined by combining the source coding rate, the channel coding rate, and the modulation order. S12. Based on the preset source code base matrix and the preset channel code base matrix, perform source coding and channel coding on the source data in sequence to obtain a joint coded bit sequence containing information bits and check bits; S13. Perform bit interleaving and delay configuration on the joint coded bit sequence, so that the check bits generated by channel coding are used as the symbol bits of the modulation symbol, and the information bits generated by source coding are used as the amplitude bits of the modulation symbol, and configure a portion of the bits as delayed bits and the remaining bits as non-delayed bits.

7. The adaptive constellation mapping method based on a joint coding system according to claim 6, characterized in that, The source coding employs a copy-interleaving method to construct a source code verification matrix, and compresses and encodes the source data based on the source code verification matrix, specifically as follows: By using the preset source code base matrix Perform copy-interleaving expansion to construct the source code verification matrix. ; According to the source code verification matrix For source data Compress and encode to obtain the source codeword. The source codeword retains its source statistical characteristics after compression, resulting in a non-uniform distribution of bits corresponding to the source codeword. ； ； In the formula, Indicates transpose; The length of the source data; The number of copy-interleaving operations during source coding; The number of columns in the source code base matrix; The channel coding constructs a channel check matrix based on a preset channel code base matrix, and performs protective coding on the source codewords, specifically as follows: By using the preset channel code base matrix Perform copy-interleaving spread and construct the channel check matrix. ; According to the channel verification matrix Constructing the channel generation matrix ; Based on the channel generation matrix Source code of the message Compress and encode to obtain the joint coded codewords. The joint coded codeword includes information bits and parity bits for modulation mapping to enhance noise immunity during subsequent transmission. ； ； In the formula, To verify the sequence matrix; It is the identity matrix; Among them, subscript Indicates the source; subscript Indicates channel; subscript For time indexing; The preset delay scheme corresponds one-to-one with the modulation method, and includes: When 16QAM modulation is used, the pre-configured 16QAM delay scheme is invoked. The multiple bit positions corresponding to each modulation symbol are divided into delayed bit positions and non-delayed bit positions; When 64QAM modulation is used, the pre-configured 64QAM delay scheme is invoked. The multiple bit positions corresponding to each modulation symbol are divided into delayed bit positions and non-delayed bit positions, and the maximum delay is controlled within a preset upper limit. ; In the formula, Indicate the delay scheme; Indicates the maximum delay; Among them, the delayed bits are used to form feedback prior information after decoding at the receiving end; the non-delayed bits are used to perform candidate constellation point screening and auxiliary demodulation under the constraints of the feedback prior information.

8. An adaptive constellation mapping method based on a joint coding system according to any one of claims 1 to 7, characterized in that, S4 specifically includes: The noisy signal transmitted through an additive white Gaussian noise channel is received, and the delayed bit likelihood information from the joint decoding feedback is used to assist demodulation to obtain the bit sequence likelihood information before the delay. The likelihood information corresponding to the delayed bits is fed back to the demodulator; The demodulator selects a subset of candidate constellation points that match the value of the delayed bit in the feedback from the complete constellation point set, and calculates the initial likelihood information of the non-delayed bits only within the subset of candidate constellation points; wherein, the selection rule for the subset of candidate constellation points is: if the value corresponding to the delayed bit in the feedback is the target value, then only constellation points in the tag whose corresponding delayed bit value matches the target value are retained; The bit likelihood information obtained from demodulation is deinterleaved to restore the structural relationship of the bit sequence before interleaving; The deinterleaved soft information is input into the channel decoder and the source decoder, and the soft information is alternately exchanged between the channel decoder and the source decoder; The channel decoder transmits the likelihood information of the channel variable nodes to the corresponding verification node of the source decoder. The source decoder generates likelihood information fed back to the channel decoder based on the source statistical constraints, so as to gradually update the posterior probability of each bit and recover the original source data.

9. An adaptive constellation mapping method based on a joint coding system according to any one of claims 1 to 7, characterized in that, S3 specifically involves performing amplitude normalization or scaling on the modulated signal, and then transmitting the normalized or scaled modulated signal to the additive white Gaussian noise channel while satisfying power constraints.

10. An adaptive constellation mapping system based on a joint coding system, characterized in that, This includes the transmitting and receiving ends capable of communication connections; The transmitter is used to execute steps S1 to S3 in the adaptive constellation mapping method based on a joint coding system as described in any one of claims 1 to 9; The receiving end is used to execute steps S3 to S4 in the adaptive constellation mapping method based on a joint coding system as described in any one of claims 1 to 9.

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