Reliability parameter assisted low-complexity polarization code rate matching method

Abstract

The invention discloses a reliability parameter assisted low-complexity polarization code rate matching method, and belongs to the technical field of wireless communication. Aiming at the problem that a proper punching site is difficult to select during rate matching due to a recursive structure of a polar code, the invention provides a polar code punching site selection algorithm based on a reliability parameter. An information bit reliability parameter is defined to calculate the reliability of candidate punching bits, and the optimal punching position is selected by traversing and solving the minimum value of the maximum reliability parameter. In order to solve the problem of high complexity of the existing polar code rate matching method, an interleaving algorithm and a pruning serial offset list decoding algorithm based on rate matching parameter mapping are provided, secondary sorting calculation of an interleaver is avoided, and a calculation unit updating strategy of a decoder is simplified. The polarization code rate matching method provided by the invention not only can improve the rate matching coding gain, but also can effectively reduce the calculation complexity.

Description

Technical Field

[0001] The present invention relates to a polar code rate matching method, and in particular to a reliability parameter-assisted low-complexity polar code rate matching method, and belongs to the technical field of wireless communication. Background Art

[0002] In 2008, Arikan first proposed a new basic idea of ​​channel coding, namely the concept of channel polarization, at the International Information Theory (ISIT) Conference. He elaborated on this idea in more detail in a paper published in the Journal of Information Theory in 2009, and proposed a new coding method, named Polar Codes. The article provides an accurate construction method for polar codes, and for the first time proves that the Shannon limit channel capacity is "reached". Due to its excellent performance at medium to long block lengths and low decoding complexity, it has now been standardized for 5G eMBB data channels.

[0003] In the ideal error correction coding theory, the channel of the digital communication system is often an ideal channel without noise interference. The channel state information (CSI) can be accurately estimated at the transmitting end of these ideal channels. With the state information, the corresponding coding parameters can be set according to the current coding requirements. However, in actual communication, the real-time channel conditions and system resources may change at any time. For example, in places far away from the signal base station or when people are moving at high speed, the channel state information is usually not accurately estimated. In order to improve the reliability and transmission efficiency of communication, the parameters of channel coding (such as code length, code rate, information bit length) are required to be able to change continuously according to the actual situation during information transmission. This technology for adjusting coding parameters is called rate matching technology.

[0004] However, the rate matching technology of polar codes still faces challenges: polar codes are fixed-rate block codes. When the CSI is unknown at the transmitter, it is difficult to select a suitable code rate for transmission. If the selected code rate is too high, decoding will fail when the channel capacity is low; and if the code rate is too low, the transmission efficiency will be low. Therefore, how to select the most appropriate rate matching bit is particularly important, but the current rate matching scheme has a large performance loss and lacks indicators that describe the qualitative and quantitative description before and after rate matching. To address this problem, the present invention proposes a polar code rate matching method based on reliability parameters to quantify the above indicators. By analyzing the log-likelihood ratio information propagation from the channel output to the information bit, it is found that the LLR value reliability of the information bit through the direct path is strongly affected by the channel output. By analyzing the information propagation path in the decoding process, the direct path of the information bit is defined as the path with the least number of box addition operations (box addition operations lead to reduced output reliability) in the path from the information bit to the channel output. Considering the gain of the adjacent path to the direct path in the summation operation, a reliability evaluation metric for the information bit is introduced. The drilling positions are gradually found through the basis while maximizing the minimum reliability score in the reliability parameters. Summary of the invention

[0005] The present invention aims to solve the above problems of the prior art. A reliability parameter-assisted low-complexity polar code rate matching method is proposed. The technical solution of the present invention is as follows:

[0006] A reliability parameter-assisted low-complexity polar code rate matching method comprises the following steps:

[0007] 101. Initialization, obtaining polar code rate matching parameters, including information sequence length K, encoding code length N, target code length M, and code rate is defined as R=K / N;

[0008] 102. Construct an information sequence u, and add a CRC check bit before polarization coding;

[0009] 103. Polarization coding, outputting a coding sequence;

[0010] 104. Determine the puncturing position and puncturing parameters, calculate the code length according to the code rate required by the dynamic link, and thus determine the puncturing parameters of the adopted method, and record the puncturing number as P=MN;

[0011] 105. Puncture the coding sequence according to the puncturing parameters determined in 104. The process of determining the puncturing position is the design of the puncturing pattern. The puncturing pattern vector is defined as a vector p=(p1, p2, ..., p N ), where p i ∈{0,1}, i=1,2,…,N, p in the vector i =0 means that the i-th position corresponds to the perforation position;

[0012] 106. Reliability sorting sequence obtained by the punching algorithm Interleave the punctured sequence to obtain an interleaved sequence

[0013] 107. The transmitting end modulates the bit-interleaved sequence and then transmits it;

[0014] 108. The receiving end receives the modulated signal transmitted through the wireless channel and performs rate matching to obtain a coding sequence, which is recorded as y.

[0015] 109. Optimizing the decoder structure according to the puncturing pattern determined in 104, optimizing the update strategy of the check nodes and the variable nodes in the polar code serial cancellation column SCL decoding structure by using the mapping of the puncturing parameters, setting the log likelihood ratio of the virtual channel caused by the puncturing to 0 at the decoding end, and outputting the optimized SCL decoder;

[0016] 110. Use the SCL decoder optimized in 109 to perform polar code decoding, and pass the decoded candidate sequence through a CRC checker. If the check passes, the candidate sequence is output, otherwise, it returns to continue SCL decoding.

[0017] Furthermore, the step 103, polarization coding, outputting the coding sequence, is specifically as follows: first constructing a generator matrix Among them B N represents a bit reversal permutation matrix; represents the kernel matrix; It means to do n Kronecker products; then polarization coding is performed according to the generator matrix, and the output coding sequence is is the channel input sequence set (u1,u2,…,u N ).

[0018] Furthermore, the 104 determines the puncturing position and puncturing parameters, calculates the code length according to the code rate required by the dynamic link, and thus determines the parameters of the puncturing method, and the number of puncturing is recorded as P=MN. The specific steps include:

[0019] (1) Initialization

[0020] Input: Initial drilling pattern and the target drilling position number 0<P≤NK;

[0021] (2) Candidate Set

[0022] Constructing a candidate punctured bit set represents the frozen bit set, Π i-1 represents the puncturing pattern traversal list, i∈(1,2,…,N), the set contains all the unpunctured bits;

[0023] (3) Update reliability parameters

[0024] For each candidate bit Do the following:

[0025] a. Introduce reliability parameter update calculation and store reliability parameter sequence s b :=s(Π i-1 ∪{b})

[0026]

[0027] s k Represents the reliability parameter; r j The gain that the adjacent path brings to the current direct path; represents the set of adjacent paths that have a gain to the direct path through the summation operation; represents the information bit set; w H is the channel transition probability at that location; represents the i-th bit of the k-th stage; a is a weighting factor obtained by simulation calculation;

[0028] b. Sort the reliability parameter sequence in ascending order to obtain s b The sorting sequence

[0029] (4) Find a new drilling location

[0030] a. Find new puncturing positions by maximizing the minimum value in the reliability parameter sequence in turn; for j from 1 to K, select The largest candidate bit is put into the candidate set:

[0031]

[0032] b. If there is only one candidate bit in Σ, then the candidate bit becomes the new puncturing bit and jumps out of the loop, otherwise update the candidate set

[0033] (5) Update the drilling mode

[0034] a. If there is only one candidate bit in ∑, update the puncturing pattern Π i :=Π i-1 ∪Σ;

[0035] b. If there are multiple candidate positions and all candidate positions have been traversed, the position with the smallest index π = minΣ and the puncturing pattern Π is updated i :=Π i-1 ∪{π}.

[0036] Further, the 105 specifically includes the following steps: according to the puncturing position determined in 104, the reliability of each polarization sub-channel is estimated and sorted by using Gaussian approximation GA, K channels with the highest reliability are selected from N polarization sub-channels to place information bits, and the remaining NK sub-channels are placed with frozen bits, so as to construct an information sequence u, specifically including:

[0037] For AWGN channels, set the channel input to x , the output is set to y, and the system uses binary phase shift keying BPSK modulation, then

[0038] y=(-2x+1)+n (0.3)

[0039] The value range of information bit x is 0 or 1, n is the noise interference encountered during channel transmission, n~N(0,σ 2 ), then the log-likelihood ratios (LLRs) of the AWGN channel are expressed as,

[0040]

[0041] Output signal y~N(0,σ 2 ), then the log-likelihood ratio LLR(y) has a mean of 2 / σ 2 , with a variance of 4 / σ 2 Gaussian distribution of each polarization channel The probability density function of the LLR value is The distribution of To express it, then in the calculation process of the mean of LLRs, there is the following recursive relationship,

[0042]

[0043]

[0044] in, and Represent the mean and variance of the log-likelihood ratio in the AWGN channel;

[0045] The expression of the function is,

[0046]

[0047] Due to the analysis, When it is greater than 0, it is a monotonically decreasing function, and Will Simplified to,

[0048]

[0049] After recursive operation of equations (1.5) and (1.6), the mean of the target channel log-likelihood ratio is obtained: Then, according to the integral operation of formula (1.8), each polarization channel can be obtained The reliability measure P e (A i ).

[0050] Furthermore, the step 106 is specifically as follows: the reliability parameter of the sequence is obtained by using the reliability parameter-assisted puncturing algorithm. The reliability of any bit channel s i Uniquely corresponds to the coded bit x at the corresponding position in the codeword i , i=1,2,…,N, right Sort by size from small to large, and the resulting sequence is the index number of the polar code bit channel reliability sorting, so that Introduce an interleaving register to store reliability parameters; Arrange them in a head-to-tail staggered manner, that is, the one with the largest capacity value is placed in the first place, the smallest is placed in the second place, the second largest is placed in the third place, and so on and so forth, completing the alternation of the positions of the bit channel reliability parameters to obtain the interleaved target sequence For the first interleaved sequence, the correlation is determined according to the output of the minimum polarization operation unit in the polarization process, and the two symbols with the strongest correlation are placed at farther positions in the symbol sequence to obtain the second interleaved sequence.

[0051] Furthermore, the step 108 in which the receiving end receives the modulated signal transmitted through the wireless channel and performs rate matching to obtain a coding sequence, denoted as y, specifically includes:

[0052] In the decoding structure of the two-bit polarization unit, for the case where y1 is punctured, the log-likelihood ratios LLR of u1 and u2 can be directly obtained by LLR(u1)=LLR(y1) and LLR(u2)=LLR(y2).

[0053] Furthermore, the step 109 specifically includes: generating a matrix According to the puncturing bit selection method, puncturing is performed at the coding bit end in the order of index from small to large, F j,k and G j,k Represent the kth box operator and sum operator of the jth layer decoding structure, so that a group of F with the same input LLR value j,k and G j,k Computing modules form a computing unit.

[0054] Furthermore, the decoder optimization criterion is as follows: for the i-th puncturing position ui , i=1,2,…,M, let (b n ,b n-1 ,…,b1) represents the binary form of the position, then for any bit b k = 0, correspondingly, some computing units of the jth layer in the decoding structure can be omitted, that is, these omitted computing units can be directly replaced by registers. The decoding part first obtains the transfer probability of each sub-channel by separating the synthetic channel. Since multiple decoding paths are retained in the SCL decoding algorithm, a parameter is needed to measure and evaluate the performance of each path when the path storage is continuously updated and the decoding is finally judged and output. Therefore, a parameter is defined Represents the lth extended path when decoding to the i-th position The path metric is defined as

[0055]

[0056] in, is the polarization channel log likelihood ratio at the current location, is the output sequence after encoding; analysis shows that the larger the transfer probability, the smaller the metric value of the corresponding path, so L candidate paths with the smallest path metric values ​​are selected; the candidate sequence after decoding is subjected to CRC check, if the check result passes, the sequence is retained and output, otherwise it is decoded again.

[0057] The advantages and beneficial effects of the present invention are as follows:

[0058] 1. The present invention adopts a low-complexity polar code rate matching method assisted by a reliability parameter. By analyzing the direct path and adjacent path in the polar code decoding path, a reliability parameter is introduced, and the most suitable punching bit is found based on the parameter, which effectively reduces the performance loss problem caused by the rate matching technology. 2. By using the Gaussian approximation algorithm to construct the information bits and sort the punching bits, the applicable scenarios are improved and the coding complexity is effectively reduced. 3. By introducing an interleaving register to store the reliability parameters, secondary calculations are avoided to reduce the calculation complexity, and the secondary interleaving operation is added to improve the error correction performance. 4. By mapping the rate matching parameters to the SCL decoder, some calculation units in the decoding structure are omitted. These omitted calculation units can be directly replaced by registers, thereby reducing the space complexity and time complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 The present invention provides a low-complexity polar code rate matching method assisted by reliability parameters in a preferred embodiment.

[0060] Figure 2 FIG. 4 is a block diagram of a rate matching system of a polar code in an embodiment.

[0061] Figure 3 The figure is a schematic diagram of the structure of a polar code decoding unit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] The following will describe the technical solutions in the embodiments of the present invention in detail in conjunction with the accompanying drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention.

[0063] The technical solution of the present invention to solve the above technical problems is:

[0064] Figure 2 is a block diagram of the rate matching system of the polar code of the present invention, which consists of Figure 2 It can be seen that the polar code transmission model of the present invention includes a CRC encoder unit, a polar coding unit, a rate matching unit, a derate matching unit, an SCL decoding unit and a CRC check unit, wherein the rate matching unit determines the number of puncturing bits according to the estimated wireless channel state, and selects the optimal puncturing bit by the rate matching method proposed by the present invention;

[0065] The reliability parameter-assisted low-complexity polar code rate matching method proposed in the present invention is mainly based on the decoding path such as Figure 3 As shown in the figure, by analyzing the propagation of the log-likelihood ratio (LLR) information from the channel output to the information bit, it is found that there are certain paths (called direct paths) through which the reliability of the LLR value of the information bit is strongly affected by the channel output. By analyzing the information propagation path in the decoding process, the direct path of the information bit is defined as the path with the least number of box addition operations (box addition operations lead to reduced output reliability) in the path from the information bit to the channel output, and the gain of the adjacent path to the direct path in the summation operation is considered. Because the gain of the adjacent path with frozen bits is stronger than that of the path with information bits, a reliability evaluation metric for information bits is introduced - the reliability parameter:

[0066]

[0067] The puncturing bits are gradually found based on this basis, while maximizing the minimum reliability score in the reliability parameter sequence. The algorithm finds a new puncturing bit in the unpunctured coded bits to maximize the minimum reliability parameter in formula (1.17). The algorithm continues to search for new puncturing bits until the algorithm finds a target number of puncturing bits.

[0068] A reliability parameter-assisted low-complexity polar code rate matching method, characterized in that: the method assumes that the information sequence length is K, the encoding code length is N, the code rate is defined as R=K / N, and the target code length is M, and comprises the following steps:

[0069] 101. Initialization, obtaining polar code rate matching parameters, including information sequence length K, encoding code length N, and target code length M;

[0070] 102. Construct an information sequence u, and add a CRC check bit before polarization coding;

[0071] 103. Polarization coding, outputting the coding sequence, specifically: first construct the generator matrix Among them B N represents a bit reversal permutation matrix; represents the kernel matrix; It means to do n times Kronecker product. Then polarization coding is performed according to the generator matrix, and the output coding sequence is

[0072] 104. Determine the puncturing position and puncturing parameters, specifically: calculate the code length according to the code rate required by the dynamic link, thereby determining the puncturing parameters of the adopted method, the number of punctures is recorded as P=MN, and the selection of the puncturing position is determined according to the reliability parameter and the puncturing algorithm proposed by the present invention;

[0073] 105. Puncture the code sequence according to the puncturing parameters determined in 104. The process of determining the puncturing position is also called the design of the puncturing pattern. The puncturing pattern vector is defined as a vector p=(p1, p2, ..., p N ), where p i ∈{0,1}, i=1,2,…,N, p in the vector i =0 means that the i-th bit corresponds to the puncturing bit. For example, assuming the required code length M = 5, the mother code length N = 8, and the number of bits that need to be punctured is NM = 3. After reliability selection puncturing, the puncturing pattern is p = (0, 1, 0, 1, 0, 1, 1, 1), that is, the 1st, 3rd, and 5th bits of the codeword passing through the encoder are punctured bits. Before being transmitted into the channel, the message carried by these three bits needs to be discarded. Output the coded sequence after puncturing

[0074] 106. Reliability sorting sequence obtained by the punching algorithm Interleave the punctured sequence to obtain an interleaved sequence

[0075] 107. The transmitting end modulates the bit-interleaved sequence and then transmits it;

[0076] 108. The receiving end receives the modulated signal transmitted through the wireless channel and performs rate matching to obtain a coding sequence, which is recorded as y.

[0077] 109. Optimizing the decoder structure according to the puncturing pattern determined in 104, optimizing the update strategy of the check nodes and the variable nodes in the polar code SCL decoding structure by using the mapping of the puncturing parameters, setting the log likelihood ratio of the virtual channel caused by the puncturing to 0 at the decoding end, and outputting the optimized SCL decoder;

[0078] 110. Use the SCL decoder optimized in 109 to perform polar code decoding, and pass the decoded candidate sequence through a CRC checker. If the check passes, the candidate sequence is output, otherwise, it returns to continue SCL decoding.

[0079] Furthermore, in 101, the selected puncturing position is ensured to be optimal by maximizing the minimum reliability parameter. This method can effectively reduce the error performance loss of the punctured polarization code. The specific steps include:

[0080] (1) Initialization

[0081] Input: Initial drilling pattern and the target drilling position number 0<P≤NK

[0082] (2) Candidate Set

[0083] Constructing a candidate punctured bit set This set contains all the unpunched bits.

[0084] (3) Update reliability parameters

[0085] For each candidate bit Do the following:

[0086] a. Introduce reliability parameter update calculation and store reliability parameter sequence s b :=s(Π i-1 ∪{b})

[0087]

[0088] s k Represents the reliability parameter; r j The gain (information bits or frozen bits) brought by the adjacent path to the current direct path; represents the set of adjacent paths that have a gain to the direct path through the summation operation; represents the information bit set; w H is the channel transition probability at that location; represents the i-th bit of the k-th stage; a is a weighting factor obtained through simulation calculation.

[0089] b. Sort the reliability parameter sequence in ascending order to obtain s b The sorting sequence

[0090] (4) Find a new drilling location

[0091] a. Find new puncturing positions by maximizing the minimum value in the reliability parameter sequence in turn. For j from 1 to K, select The largest candidate is put into the candidate set:

[0092]

[0093] b. If there is only one candidate bit in ∑, then the candidate bit becomes the new puncturing bit and jumps out of the loop, otherwise update the candidate set

[0094] (5) Update the drilling mode

[0095] a. If there is only one candidate bit in ∑, update the puncturing pattern Π i :=Π i-1 ∪Σ

[0096] b. If there are multiple candidate positions and all candidate positions have been traversed, the position with the smallest index π = minΣ and the puncturing pattern Π is updated i :=Π i-1 ∪{π}.

[0097] Furthermore, step 105 is to estimate and sort the reliability of each polarization subchannel using Gaussian approximation (GA) according to the puncturing position determined in step 1, select K channels with the highest reliability from N polarization subchannels to place information bits, and place frozen bits in the remaining NK subchannels, thereby constructing an information sequence u. Specifically, the following steps are included:

[0098] For AWGN channels, set the channel input to x , the output is set to y, and the system uses binary phase shift keying (BPSK) modulation, then

[0099] y=(-2x+1)+n(0.13)

[0100] The value range of information bit x is 0 or 1, n is the noise interference encountered during channel transmission, n~N(0,σ 2 ). Then the log-likelihood ratios (LLRs) of the AWGN channel can be expressed as,

[0101]

[0102] In general, since the input is subject to independent Gaussian distribution, the output signal y~N(0,σ 2 ), then the log-likelihood ratio LLR(y) has a mean of 2 / σ2 , with a variance of 4 / σ 2 Since the Gaussian distribution can be completely determined only by the mean and variance, the probability density function only needs to obtain the mean and variance. When using the Gaussian approximation, due to the mathematical relationship between the mean and variance, we only need to calculate the mean in the log-likelihood ratio. In the AWGN channel, each polarization channel The probability density function of the LLR value is The distribution can be used To express it, then in the calculation process of the mean of LLRs, there is the following recursive relationship,

[0103]

[0104]

[0105] The expression of the function is,

[0106]

[0107] Due to the analysis, When it is greater than 0, it is a monotonically decreasing function, and In order to reduce the calculation and complexity, we can Simplified to,

[0108]

[0109] After recursive operation of equations (1.13) and (1.14), the mean of the target channel log-likelihood ratio can be obtained: Then, according to the integral operation of formula (1.16), each polarization channel can be obtained The reliability measure P e (A i ).

[0110] Furthermore, according to the reliability parameter-assisted low-complexity polar code rate matching method of claim 1, it is characterized in that: 106, specifically: the reliability parameter of the sequence obtained by the reliability parameter-assisted puncturing algorithm The reliability of any bit channel s i = (i = 1, 2, ..., N) uniquely corresponds to the coded bit x at the corresponding position in the codeword i =(i=1,2,…,N), right Sort by size from small to large, and the resulting sequence is the index number of the polar code bit channel reliability sorting, so that Introduce interleaving registers to store reliability parameters to avoid secondary calculations; Arrange them in a head-to-tail staggered manner, that is, the one with the largest capacity value is placed in the first place, the smallest is placed in the second place, the second largest is placed in the third place, and so on and so forth, completing the alternation of the positions of the bit channel reliability parameters to obtain the interleaved target sequence For the first interleaved sequence, the correlation is determined according to the output of the minimum polarization operation unit in the polarization process, and the two symbols with the strongest correlation are placed at farther positions in the symbol sequence to obtain the second interleaved sequence. The interleaving algorithm of the present invention is firstly based on the mapping relationship between the coded bit and the polarization sub-channel, the reliability of the polarization sub-channel is calculated, the high-reliability bit channel is interleaved with the low-reliability bit channel, and the high-reliability bit channel is used to assist in decoding the low-reliability bit channel, thereby improving the error correction performance of the polarization code while ensuring low complexity. Secondly, for the bit sequence obtained after interleaving, it can be sorted from large to small according to the size of the correlation, and the two bits with the strongest correlation are placed as far as possible in the sequence (that is, the sequence is interleaved according to the strength of the correlation), so as to avoid the situation where two bits with strong correlation have simultaneous errors due to experiencing the same channel fading.

[0111] Furthermore, according to the reliability parameter-assisted low-complexity polar code rate matching method of claim 1, it is characterized by: 108 and 109 are specifically: in the decoding structure of the two-bit polarization unit, for the case where y1 is punctured, the log likelihood ratio (LLR) of u1 and u2 can be directly obtained by LLR(u1)=LLR(y1) and LLR(u2)=LLR(y2). For the generation matrix According to the puncturing bit selection method, puncturing is performed at the coding bit end in the order of index from small to large, F j,k and G j,k The kth box operator and the sum operator represent the jth level decoding structure respectively. The decoder optimization criterion is as follows: for the i-th (i=1,2,…,M) puncturing position u i , let (b n ,b n-1 ,…,b1) represents the binary form of the position, then for any bit b k=0, correspondingly, some calculation units of the jth layer in the decoding structure can be omitted, that is, these omitted calculation units can be directly replaced by registers, thereby reducing space complexity and time complexity; the decoding part first obtains the transfer probability of each sub-channel by separating the synthetic channel, and then obtains the decoding result according to the corresponding decision formula, and retains multiple candidate path tables when selecting branches at each layer, using the principle of breadth-first search, and each decoding path is left for subsequent processing. The candidate sequence after decoding is subjected to CRC check, and if the check result passes, the sequence is retained and output, otherwise it is decoded again.

[0112] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions.

[0113] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0114] The above embodiments should be understood to be only used to illustrate the present invention and not to limit the protection scope of the present invention. After reading the contents of the present invention, technicians can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A reliability parameter-assisted low-complexity polar code rate matching method, characterized in that: The following steps are involved:

101. Initialization, obtaining polar code rate matching parameters, including information sequence length K, encoding code length N, target code length M, and code rate is defined as R=K / N; 102. Construct an information sequence u, and add a CRC check bit before polarization coding; 103. Polarization coding, outputting a coding sequence; 104. Determine the puncturing position and puncturing parameters, calculate the code length according to the code rate required by the dynamic link, and thus determine the puncturing parameters of the adopted method, and record the puncturing number as P=MN; 105. Puncture the coding sequence according to the puncturing parameters determined in 104. The process of determining the puncturing position is the design of the puncturing pattern. The puncturing pattern vector is defined as a vector p=(p1, p2, ..., p N ), where p i ∈{0,1}, i=1,2,…,N, p in the vector i =0 means that the i-th position corresponds to the perforation position; 106. Reliability sorting sequence obtained by the punching algorithm Interleave the punctured sequence to obtain an interleaved sequence 107. The transmitting end modulates the bit-interleaved sequence and then transmits it; 108. The receiving end receives the modulated signal transmitted through the wireless channel and performs rate matching to obtain a coding sequence, which is recorded as y.

109. Optimizing the decoder structure according to the puncturing pattern determined in 104, optimizing the update strategy of the check nodes and the variable nodes in the polar code serial cancellation column SCL decoding structure by using the mapping of the puncturing parameters, setting the log likelihood ratio of the virtual channel caused by the puncturing to 0 at the decoding end, and outputting the optimized SCL decoder; 110. Use the SCL decoder optimized in 109 to perform polar code decoding, and pass the decoded candidate sequence through a CRC checker. If the check passes, the candidate sequence is output, otherwise, it returns to continue SCL decoding.

2. The reliability parameter-assisted low-complexity polar code rate matching method according to claim 1, characterized in that: The step 103, polarization coding, outputting the coding sequence, is specifically as follows: first constructing a generator matrix Among them B N represents a bit reversal permutation matrix; represents the kernel matrix; It means to do n Kronecker products; then polarization coding is performed according to the generator matrix, and the output coding sequence is is the channel input sequence set (u1,u2,…,u N ).

3. The reliability parameter-assisted low-complexity polar code rate matching method according to claim 1, characterized in that: The step 104 determines the puncturing position and puncturing parameters, calculates the code length according to the code rate required by the dynamic link, and thus determines the puncturing parameters of the adopted method, and the number of puncturing is recorded as P=MN. The specific steps include: (1) Initialization Input: Initial drilling pattern and the target drilling position number 0<P≤NK; (2) Candidate Set Constructing a candidate punctured bit set represents the frozen bit set, Π i-1 represents the puncturing pattern traversal list, i∈(1,2,…,N), the set contains all the unpunctured bits; (3) Update reliability parameters For each candidate bit Do the following: a. Introduce reliability parameter update calculation and store reliability parameter sequence s b :=s(Π i-1 ∪{b}) s k Reliability parameter; r j The gain that the adjacent path brings to the current direct path; represents the set of adjacent paths that have a gain to the direct path through the summation operation; represents the information bit set; w H is the channel transition probability at that location; represents the i-th bit of the k-th stage; a is a weighting factor obtained by simulation calculation; b. Sort the reliability parameter sequence in ascending order to obtain s b The sorting sequence (4) Find a new drilling location a. Find new puncturing positions by maximizing the minimum value in the reliability parameter sequence in turn; for j from 1 to K, select The largest candidate bit is put into the candidate set: b. If there is only one candidate bit in ∑, then the candidate bit becomes the new puncturing bit and jumps out of the loop, otherwise update the candidate set (5) Update the drilling mode a. If there is only one candidate bit in ∑, update the puncturing pattern Π i :=Π i-1 ∪Σ; b. If there are multiple candidate positions and all candidate positions have been traversed, the position with the smallest index π = minΣ and the puncturing pattern Π is updated i :=Π i-1 ∪{π}.

4. The reliability parameter-assisted low-complexity polar code rate matching method according to claim 1, characterized in that: The 105 specifically includes the following steps: according to the puncturing positions determined in 104, the reliability of each polarization sub-channel is estimated and sorted by using Gaussian approximation GA, K channels with the highest reliability are selected from N polarization sub-channels to place information bits, and the remaining NK sub-channels are placed with frozen bits, so as to construct an information sequence u, specifically including: For AWGN channels, set the channel input to x , the output is set to y, and the system uses binary phase shift keying BPSK modulation, then y=(-2x+1)+n(0.3) where the value range of information bit x is 0 or 1, n is the noise interference encountered during channel transmission, n~N(0,σ 2 ), then the log-likelihood ratios (LLRs) of the AWGN channel are expressed as, Output signal y~N(0,σ 2 ), then the log-likelihood ratio LLR(y) has a mean of 2 / σ 2 , with a variance of 4 / σ 2 Gaussian distribution of each polarization channel The probability density function of the LLR value is The distribution of To express it, then in the calculation process of the mean of LLRs, there is the following recursive relationship, in, and Represent the mean and variance of the log-likelihood ratio in the AWGN channel; The expression of the function is, Due to the analysis, When it is greater than 0, it is a monotonically decreasing function, and Will Simplified to, After recursive operation of equations (1.5) and (1.6), the mean of the target channel log-likelihood ratio is obtained: Then, according to the integral operation of formula (1.8), each polarization channel can be obtained The reliability measure P e (A i ).

5. The reliability parameter-assisted low-complexity polar code rate matching method according to claim 1, characterized in that: The step 106 specifically includes: using a reliability parameter-assisted puncturing algorithm to obtain the reliability parameter of the sequence The reliability of any bit channel s i Uniquely corresponds to the coded bit x at the corresponding position in the codeword i , i=1,2,…,N, right Sort by size from small to large, and the resulting sequence is the index number of the polar code bit channel reliability sorting, so that Introduce an interleaving register to store reliability parameters; Arrange them in a head-to-tail staggered manner, that is, the one with the largest capacity value is placed in the first place, the smallest is placed in the second place, the second largest is placed in the third place, and so on and so forth, completing the alternation of the positions of the bit channel reliability parameters to obtain the interleaved target sequence For the first interleaved sequence, the correlation is determined according to the output of the minimum polarization operation unit in the polarization process, and the two symbols with the strongest correlation are placed at farther positions in the symbol sequence to obtain the second interleaved sequence.

6. The reliability parameter-assisted low-complexity polar code rate matching method according to claim 1, characterized in that: The step 108 in which the receiving end receives the modulated signal transmitted through the wireless channel and performs rate matching to obtain a coding sequence, denoted as y, specifically includes: In the decoding structure of the two-bit polarization unit, for the case where y1 is punctured, the log-likelihood ratios LLR of u1 and u2 can be directly obtained by LLR(u1)=LLR(y1) and LLR(u2)=LLR(y2).

7. The reliability parameter-assisted low-complexity polar code rate matching method according to claim 6, characterized in that: The step 109 specifically includes: generating a matrix According to the puncturing bit selection method, puncturing is performed at the coding bit end in the order of index from small to large, F j,k and G j,k Represent the kth box operator and sum operator of the jth layer decoding structure, so that a group of F with the same input LLR value j,k and G j,k Computing modules form a computing unit.

8. The reliability parameter-assisted low-complexity polar code rate matching method according to claim 6, characterized in that: The decoder optimization criterion is as follows: for the i-th puncturing position u i , i=1,2,…,M, let (b n ,b n-1 ,…,b1) represents the binary form of the position, then for any bit b k = 0, correspondingly, some computing units of the jth layer in the decoding structure can be omitted, that is, these omitted computing units can be directly replaced by registers. The decoding part first obtains the transfer probability of each sub-channel by separating the synthetic channel. Since multiple decoding paths are retained in the SCL decoding algorithm, a parameter is needed to measure and evaluate the performance of each path when the path storage is continuously updated and the decoding is finally judged and output. Therefore, a parameter is defined Represents the lth extended path when decoding to the i-th position The path metric is defined as in, is the polarization channel log likelihood ratio at the current location, is the output sequence after encoding; analysis shows that the larger the transfer probability, the smaller the metric value of the corresponding path, so L candidate paths with the smallest path metric values ​​are selected; the candidate sequence after decoding is subjected to CRC check, if the check result passes, the sequence is retained and output, otherwise it is decoded again.

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