Multistage code modulation transmission method suitable for hybrid automatic repeat request system

Abstract

The invention discloses a multi-level coding modulation transmitting method suitable for a hybrid automatic repeat request system, which belongs to the wireless communication technology and comprises the following steps of: performing high-code-rate channel coding on a first information bit sequence of a transmitting end to obtain a first coding bit sequence, and performing low-bit-rate coding on the second information bit sequence to obtain a second coded bit sequence. In the first transmission, the first coded bit sequence and the second coded bit sequence are combined and pass through an interleaver to obtain a first transmission bit sequence, and the first transmission bit sequence is modulated to obtain a first transmission modulation symbol sequence; and if the first transmission fails, performing channel coding with a lower code rate on the second group of information bit sequences to obtain a first retransmission bit sequence, and modulating the first retransmission bit sequence to obtain a first retransmission modulation symbol sequence. Compared with a BICM scheme with the same spectrum efficiency, the transmitting method provided by the invention has the advantages that the demodulation and error correction code decoding complexity is greatly reduced, and meanwhile, the performance similar to that of an incremental redundancy HARQ is obtained.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a multi-level coding modulation transmission method suitable for a hybrid automatic repeat request system. Background Art

[0002] In mobile communication systems, forward error correction (FEC) and automatic repeat request (ARQ) technologies are usually used to ensure the reliability of data transmission. HARQ technology combines the advantages of ARQ and FEC technologies, improving the decoding capability of the receiving end at the cost of increasing less redundancy, which can improve the data transmission reliability of wireless networks, reduce delays, and increase throughput.

[0003] Traditional HARQ technology can be divided into two types: Chase Combining HARQ (CC-HARQ) and incremental redundancy HARQ (IR-HARQ). For CC-HARQ, the transmitter sends the same codeword for each transmission, and the receiver decodes all the received codewords by superposition and combination until the decoding is successful or the maximum number of retransmissions is reached. For IR-HARQ, the transmitter encodes the information bits to generate a low-rate codeword. First, a sub-codeword containing all the information is sent. Similarly, if the receiving end decodes incorrectly, a sub-codeword containing redundant information is sent to the receiving end. The receiving end combines all the previously received bits into a codeword with a lower code rate for combined decoding until the decoding is successful or the maximum number of retransmissions is reached. This coding method can obtain a greater coding gain, thereby achieving the purpose of incremental redundancy.

[0004] The Multi-Level Coded Modulation (MLCM) system divides data into multiple levels and assigns different coding and modulation schemes to each level. In the traditional Bit Interleaved Coded Modulation (BICM) system, all information bits need to pass through a highly complex code (such as LDPC code) to achieve better performance. The MLC modulation system is based on a layered coding framework, which can reduce the load of highly complex channel codes, thereby reducing the overall complexity and power consumption of FEC. Summary of the invention

[0005] The present invention provides a multi-level coding modulation transmission method suitable for a hybrid automatic repeat request system, which can obtain performance equivalent to or better than that of BICM while ensuring the lowest complexity.

[0006] The embodiment of the present invention provides a multi-level coding modulation transmission method applicable to a hybrid automatic repeat request system, comprising the following steps:

[0007] Step 1, dividing the information bit sequence of length k at the transmitting end into a first information bit sequence S1 of length k1 and a second information bit sequence S2 of length k2, where k=k1+k2;

[0008] Step 2: performing channel coding of a high code rate R1 on the first information bit sequence S1 to obtain a first coded bit sequence C1 with a bit length of n1, and performing channel coding of a low code rate R2 on the second information bit sequence S2 to obtain a second coded bit sequence C2 with a bit length of n2, where R1>R2;

[0009] Step 3, according to the modulation order M, based on m=log2M, obtain the number of bits m in a single M-order orthogonal amplitude modulation signal, and calculate the number of bits m1=m*n1 / (n1+n2) and m2=m*n2 / (n1+n2) corresponding to the two groups of codes in a modulation symbol respectively;

[0010] Step 4: In the first transmission, firstly, m1 bits are taken from the first coded bit sequence C1 with a bit length of n1, and then n2 bits are taken from the second coded bit sequence C2 with a bit length of n2, and the first transmission bit sequence C is obtained by interleaving. (1) ;

[0011] Step 5: Transmit the first bit sequence C (1) Square M for MLC mapping = 2 m The first transmission modulation symbol sequence X is obtained by QAM modulation (1) ;

[0012] Step 6: Send the first transmission modulation symbol sequence X to the receiving end (1) ;

[0013] Step 7: In the first transmission modulation symbol sequence X (1) When the receiving end detects that the decoding fails and cannot be received correctly, it feeds back a retransmission request to the transmitting end, so that the transmitting end performs a low-code R on the second information bit sequence S2 of length k2. ′ 2 channel coding, and obtain the coded bit sequence of length n1+n2 as the first retransmission bit sequence C (2) , R ′ 2 <R2;

[0014] Step 8: retransmit the first bit sequence C (2) Square M for global Gray mapping = 2 mThe first retransmission modulation symbol sequence X is obtained by QAM modulation (2) ;

[0015] Step 9: Send the first retransmission modulation symbol sequence X to the receiving end. (2) .

[0016] Optionally, in one embodiment of the present invention, in step 5, the square M of the MLC mapping is 2 m The constellation diagram corresponding to the QAM modulation is The number of constellation points in the partition is The partition Gray form, that is, the partition Among the constellation points, the bit labels of adjacent constellation points have only one bit difference; the bit labels of the constellation points are The partition index bit is used to determine the partition where the constellation point is located. The intra-region index bits are used to determine the constellation points within the partition.

[0017] Optionally, in one embodiment of the present invention, in step 8, the square M of the global Gray mapping is 2 m The constellation diagram corresponding to the QAM modulation of order 1 is in the form of a global Gray scale, that is, among the M constellation points, the bit labels of adjacent constellation points are different by one and only one bit.

[0018] Optionally, in one embodiment of the present invention, in step 6, the first transmission modulation symbol sequence X is sent to the receiving end. (1) After that, the following steps are also included:

[0019] Step 61: The receiving end receives the modulation symbol sequence Y after passing through the channel. (1) , square M=2 based on MLC mapping m According to the characteristics of the QAM modulation, firstly, the log likelihood ratio LLR1 corresponding to the first coded bit sequence is demodulated by partition, and a decoding algorithm is used to detect and correct errors. If the error correction is successful, step 62 is executed, otherwise step 63 is executed;

[0020] Step 62: based on the demodulation of the first coded bit sequence, demodulate the log likelihood ratio LLR2 corresponding to the second coded bit sequence in the region, and use a decoding algorithm to detect and correct errors. If the decoding is successful, the first transmission is successful, and an ACK signal is fed back to the transmitter. Otherwise, a NACK signal is fed back to the transmitter, and step 7 is executed;

[0021] Step 63, obtain the log-likelihood ratio value LLR of each bit through global demodulation, use a decoding algorithm to detect and correct errors for the log-likelihood ratio LLR2 corresponding to the second coded bit sequence, if the decoding is successful, execute step 64, if the decoding fails, the first transmission fails, and a NACK signal is fed back to the transmitter, and execute step 7;

[0022] Step 64, based on the demodulation of the second coded bit sequence, the auxiliary partition demodulates the log-likelihood ratio LLR1 corresponding to the first coded bit sequence, and uses a decoding algorithm to detect and correct errors. If the decoding is successful, the first transmission is successful, and an ACK signal is fed back to the transmitter. Otherwise, the first transmission fails, and a NACK signal is fed back to the transmitter, and step 7 is executed.

[0023] Optionally, in one embodiment of the present invention, in step 9, the first retransmission modulation symbol sequence X is sent to the receiving end. (2) After that, the following steps are also included:

[0024] Step 91: The receiving end receives the modulation symbol sequence Y after passing through the channel. (2) After that, the square M=2 based on the global Gray mapping m According to the characteristics of the QAM modulation of the first order, the LLR of the first retransmitted bit sequence is demodulated, and the LLR is combined with the log-likelihood ratio LLR2 corresponding to the second coded bit sequence demodulated during the first transmission, and a decoding algorithm is used to detect and correct errors. If the decoding is successful, step 92 is executed, otherwise the transmission fails;

[0025] Step 92: based on the demodulation of the second coded bit sequence, the auxiliary partition demodulates the log-likelihood ratio LLR1 corresponding to the first coded bit sequence, and uses a decoding algorithm to detect and correct errors. If the decoding is successful, the retransmission is successful, otherwise the transmission fails.

[0026] The multi-level coded modulation transmission method for a hybrid automatic repeat request system in an embodiment of the present invention is based on the MLCM architecture. Compared with the BICM scheme with the same spectrum efficiency, it reduces the coding length of the error correction code with higher complexity, thereby reducing the decoding complexity of the system; based on the characteristics of MLCM hierarchical reception and demodulation, it preferentially uses a lower-dimensional demodulation cascade instead of high-order constellation demodulation, thereby reducing the complexity of reception and demodulation. The first retransmission of the MLCM system adopts a combination of CCHARQ and IR HARQ, which can also achieve performance similar to that of a BICM system that fully adopts IR HARQ.

[0027] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0029] Figure 1 A flowchart of a multi-level coding modulation transmission method applicable to a hybrid automatic repeat request system provided according to an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of the first transmission interleaving process of the transmitting end according to an embodiment of the present invention;

[0031] Figure 3 This is a flow chart of the first transmission demodulation and decoding at the receiving end of an embodiment of the present invention;

[0032] Figure 4 This is a flowchart of the first retransmission demodulation and decoding at the receiving end of an embodiment of the present invention;

[0033] FIG5( a ) is a 64-QAM constellation diagram of an MLC-mapped square and corresponding bit labels for the first transmission generated in accordance with the first embodiment of the present invention;

[0034] FIG5( b ) is a square 64-QAM constellation diagram of global Gray mapping and corresponding bit labels for the first retransmission generated in accordance with the first embodiment of the present invention;

[0035] Figure 6 This is a performance comparison diagram of Embodiment 1 of the present invention;

[0036] Figure 7 This is a performance comparison diagram of the second embodiment of the present invention;

[0037] Figure 8 This is a performance comparison diagram of Example 3 of the present invention. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0039] Figure 1 The present invention is a flowchart of a multi-level coding modulation transmission method applicable to a hybrid automatic repeat request system provided in accordance with an embodiment of the present invention.

[0040] like Figure 1 As shown, the multi-level coding modulation transmission method applicable to the hybrid automatic repeat request system includes the following steps:

[0041] Step 1: divide the information bit sequence of length k at the transmitting end into a first information bit sequence S1 of length k1 and a second information bit sequence S2 of length k2, where k=k1+k2.

[0042] Step 2: Perform channel coding of the first information bit sequence S1 with a high code rate R1 to obtain a first coded bit sequence with a bit length of n1. The second information bit sequence S2 is channel-coded at a low code rate R2 to obtain a second coded bit sequence with a bit length of n2. R1>R2, where is the n1th bit of the first coded bit sequence C1, It is the n2th bit of the second coded bit sequence C2.

[0043] Step 3, according to the modulation order M, based on m=log2M, obtain the number of bits m in a single M-order orthogonal amplitude modulation signal, and calculate the number of bits m1=m*x1 / (n1+n2) and m2=m*n2 / (n1+n2) corresponding to the two groups of codes in a modulation symbol.

[0044] Step 4: In the first transmission, start with the first coded bit sequence with a bit length of n1. Take m1 bits from the second coded bit sequence with a bit length of n2 Take m2 bits from Figure 2 The process shown is interleaved and extracted to obtain the first transmission bit sequence

[0045] Step 5: For the first transmission bit sequence C (1) Square M for MLC mapping = 2 m The first transmission modulation symbol sequence X is obtained by QAM modulation (1) .

[0046] Step 6: Send a first transmission modulation symbol sequence X to the receiving end (1) .

[0047] Step 7: at the first transmission modulation symbol sequence X (1) When the receiving end detects that the decoding fails and cannot be received correctly, it feeds back a retransmission request to the transmitting end, so that the transmitting end performs a low-code R on the second information bit sequence S2 of length k2. ′ 2 channel coding, and obtain a coded bit sequence of length n1+n2 as the first retransmission bit sequence R ′ 2 <R2。

[0048] Step 8: retransmit the first bit sequence C (2)Square M for global Gray mapping = 2 m The first retransmission modulation symbol sequence X is obtained by QAM modulation (2) .

[0049] Step 9: Send the first retransmission modulation symbol sequence X to the receiving end (2) .

[0050] Optionally, in one embodiment of the present invention, in step 5, the square M of the MLC mapping is 2 m The constellation diagram corresponding to the QAM modulation is The number of constellation points in the partition is The partition Gray form, that is, the partition Among the constellation points, the bit labels of adjacent constellation points have only one bit difference; the bit labels of the constellation points are The partition index bit is used to determine the partition where the constellation point is located, which has higher reliability. The intra-zone index bit is used to determine the constellation point within the partition, and has lower reliability, where m1+m2=m.

[0051] Optionally, in one embodiment of the present invention, in step 8, the square M of the global Gray mapping is 2 m The constellation diagram corresponding to the QAM modulation of order 1 is in the form of a global Gray scale, that is, among the M constellation points, the bit labels of adjacent constellation points are different by one and only one bit.

[0052] Optionally, in one embodiment of the present invention, Figure 3 As shown, in step 6, a first transmission modulation symbol sequence X is sent to the receiving end. (1) After that, the following steps are also included:

[0053] Step 61: The receiving end receives the modulation symbol sequence Y after passing through the channel. (1) , square M=2 based on MLC mapping m According to the characteristics of the first-order QAM modulation, firstly, the log-likelihood ratio LLR1 corresponding to the first coded bit sequence is demodulated by partition, and a decoding algorithm is used to detect and correct errors. If the error correction is successful, step 62 is executed, otherwise step 63 is executed;

[0054] Step 62, based on the demodulation of the first coded bit sequence, demodulate the log likelihood ratio LLR2 corresponding to the second coded bit sequence in the region, and use the decoding algorithm to detect and correct errors. If the decoding is successful, the first transmission is successful, and an ACK signal is fed back to the transmitter. Otherwise, a NACK signal is fed back to the transmitter, and step 7 is executed;

[0055] Step 63, obtain the log-likelihood ratio value LLR of each bit through global demodulation, use the decoding algorithm to detect and correct the error of the log-likelihood ratio LLR2 corresponding to the second coded bit sequence, if the decoding is successful, execute step 64, if the decoding fails, the first transmission fails, and a NACK signal is fed back to the transmitter, and execute step 7;

[0056] Step 64, based on the demodulation of the second coded bit sequence, the auxiliary partition demodulates the log-likelihood ratio LLR1 corresponding to the first coded bit sequence, and uses a decoding algorithm to detect and correct errors. If the decoding is successful, the first transmission is successful, and an ACK signal is fed back to the transmitter. Otherwise, the first transmission fails, and a NACK signal is fed back to the transmitter, and step 7 is executed.

[0057] Optionally, in one embodiment of the present invention, Figure 4 As shown, in step 9, a first retransmission modulation symbol sequence X is sent to the receiving end. (2) After that, the following steps are also included:

[0058] Step 91: The receiving end receives the modulation symbol sequence Y after passing through the channel. (2) After that, the square M=2 based on the global Gray mapping m According to the characteristics of the QAM modulation, the LLR of the first retransmitted bit sequence is demodulated and combined with the log-likelihood ratio LLR2 corresponding to the second coded bit sequence demodulated during the first transmission, and a decoding algorithm is used to detect and correct errors. If the decoding is successful, step 92 is executed, otherwise the transmission fails.

[0059] Step 92, based on the demodulation of the second coded bit sequence, the auxiliary partition demodulates the log likelihood ratio LLR1 corresponding to the first coded bit sequence, and uses a decoding algorithm to detect and correct errors. If the decoding is successful, the retransmission is successful, otherwise the transmission fails.

[0060] It can be understood that the present invention divides the input information bit sequence into two groups, the first group of information bit sequences with a length of k1 are channel coded at a high code rate R1 to obtain the first group of coded bit sequences with a length of n1, and the second group of information bit sequences with a length of k2 are coded at a low code rate R2 to obtain the second group of coded bit sequences with a length of n2, R1>R2. In the first transmission, the first group of coded bit sequences with a length of n1 and the second group of coded bit sequences with a length of n2 are transmitted as follows Figure 2 The first transmission bit sequence is obtained after the interleaver shown. The first transmission sequence is modulated by MLC-mapped square M-order QAM to obtain the first transmission modulation symbol sequence; if the first transmission fails, the second group of information bit sequences with a length of k2 is modulated by a lower code rate R ′ 2 channel coding to obtain a coded bit sequence of length n1+n2, which is used as the first retransmission bit sequence. R2>R′ 2. Performing square M-order QAM modulation with global Gray mapping on the first retransmission bit sequence obtains the modulation symbol sequence for the first retransmission. Compared with the BICM scheme with the same spectrum efficiency, the transmission scheme of the present invention greatly reduces the complexity of demodulation and error correction code decoding, while obtaining performance similar to that of incremental redundancy HARQ.

[0061] like Figure 2 The specific steps of the interleaver shown are: first, according to the modulation order M=2 m , determine the number of bits m in a single M-order orthogonal amplitude modulation signal, and calculate the number of bits m1=m*n1 / (n1+n2) and m2=m*n2 / (n1+n2) corresponding to the two sets of channel coding parameters in a modulation symbol; then sequentially calculate the first set of coded bit sequences with a bit length of n1. Take m1 bits from the second group of coded bits of length n2 Take m2 bits and get the bit sequence of the first transmission The bit sequence Constitute a modulation symbol, Mapped to the partition index bit used to distinguish the interval where the constellation point is located, Mapped to the intra-region index bits used to determine the constellation points within the partition.

[0062] The multi-level coding modulation transmission method applicable to a hybrid automatic repeat request system of the present invention is described in detail below through specific embodiments.

[0063] Embodiment 1:

[0064] In the multi-level coded modulation transmission method designed by the present invention and applicable to the hybrid automatic repeat request system, the system modulation order M is set to 64.

[0065] like Figure 1 As shown, the information bit sequence of length k=1760 is divided into two groups of information bit sequences of length k1=654 and k2=1106. The first group of information bit sequences of length k1=654 is encoded by BCH with code rate R1=0.928 into the first group of coded bit sequences C1={c 1,1 ,c 1,2 ,…,c 1,704}, the second information bit sequence of length k2=1106 is encoded by LDPC with code rate R2=0.785 into the second coded bit sequence C2={c 2,1 ,c 2,2 ,…,c 2,1408}. By calculation, we can get m1 = m*n1 / (n1+n2) = 2 and m2 = m*n2 / (n1+n2) = 4. The interleaver sequentially takes 2 bits from the first group of coded bit sequences and 4 bits from the second group of coded bit sequences to form the first transmission codeword:

[0066] C (1) ={c 1,1 ,c 1,2 ,c 2,1 ,c 2,2 ,c 2,3 ,c 2,4 ,…,c 1,703 ,c 1,704 ,c 2,1405 ,c 2,1406 ,c 2,1407 ,c 2,1408};first

[0067] The 64-order QAM constellation diagram of the transmitted MLC mapping square is shown in Figure 5(a). The corresponding constellation diagram is a partitioned Gray form with 4 partitions and 16 constellation points in the partition. Among the 16 constellation points in the partition, the bit labels of adjacent constellation points have only one bit different; the bit label of each constellation point is defined as {b1b2b3b4b5b6}, the number of bits corresponding to the two groups of codes in a modulation symbol are m1=2 and m2=4, respectively, and b2} is the partition index bit used to distinguish the interval where the constellation point is located, with high reliability. The first transmission of codeword C (1) The first group of coded bits corresponding to the first transmission is mapped to {b1b2}, which is marked in red in the figure; {b3b4b5b6} is the index bit for determining the constellation point in the partition, which has a low reliability. (1) The corresponding second group of coded bits is mapped to {b3b4b5b6}.

[0068] When the first transmission fails, the second group of information bit sequence code rate R ′ 2=0.524 incremental redundancy LDPC coding to obtain the coded bit sequence C2={c 2,1 ,…,c 2,1408 ,…,c 2,2112} as the first retransmission bit sequence C (2) The square 64-QAM constellation diagram of the global Gray mapping of the first retransmission is shown in Figure 5(b), that is, among the 64 constellation points, the bit labels of adjacent constellation points have only one bit difference. The demodulated retransmission bit likelihood ratio is combined with the second group of codewords of the first transmission and input into the LDPC decoder.

[0069] Compared with the BICM system and IR-HARQ with the same spectrum efficiency, Figure 6As shown, the horizontal axis is SNR and the vertical axis is frame error rate (Frame Error Rate, FER). This scheme achieves performance comparable to that of traditional BICM while significantly reducing the overall complexity and power consumption of the error correction code FEC.

[0070] Embodiment 2:

[0071] In the multi-level coded modulation transmission method designed by the present invention and applicable to the hybrid automatic repeat request system, the system modulation order M is set to 1024.

[0072] like Figure 1 As shown, the information bit sequence of length k=3168 is divided into two groups of information bit sequences of length k1=1353 and k2=1815. The first group of information bit sequences of length k1=1353 is encoded by BCH with code rate R1=0.961 into the first group of coded bit sequences C1={c 1,1 ,c 1,2 ,…,c 1,1408}, the second group of information bit sequences of length k2=1815 are encoded by LDPC with code rate R2=0.859 into the second group of coded bit sequences C2={c 2,1 ,c 2,2 ,…,c 2,2112}. By calculation, we can get m1 = m*n1 / (n1+n2) = 4 and m2 = m*n2 / (n1+n2) = 6. The interleaver sequentially takes 4 bits from the first group of coded bit sequences and 6 bits from the second group of coded bit sequences to form the first transmission codeword C (1) ={c 1,1 ,c 1,2 ,c 1,3 ,c 1,4 ,c 2,1 ,c 2,2 ,c 2,3 ,c 2,4 ,c 2,5 ,c 2,6 ,…,c 1,1405 ,

[0073] c 1,1406 ,c 1,1407 ,c 1,1408 ,c 2,2107 ,c 2,2108 ,c 2,2109 ,c 2,2110 ,c 2,2111 ,c 2,2112}. The first transmitted bit sequence C (1) The square 1024-order QAM modulation after MLC mapping obtains the modulation symbol sequence X for the first transmission (1), where the corresponding constellation diagram is a partitioned Gray form with 16 partitions and 64 constellation points in the partition, that is, among the 64 constellation points in the partition, the bit labels of adjacent constellation points have only one bit different; the bit labels of the constellation points are {b1b2b3b4b5b6b7b8b9b 10}, {b1b2b3b4} is the partition index bit used to determine the partition where the constellation point is located, with higher reliability, {b5b6b7b8b9b 10} is the index bit in the zone, which is used to determine the constellation point in the zone, and has lower reliability; the first transmission codeword C (1) The first group of coded bits corresponding to the first transmission is mapped to {b1b2b3b4}, and the first transmission codeword C (1) The corresponding second group of coded bits is mapped to {b5b6b7b8b9b 10}.

[0074] When the first transmission fails, the second group of information bit sequences is transmitted through the code rate R ′ 2=0.516 incremental redundancy LDPC coding to obtain the coded bit sequence C2={c 2,1 ,…,c 2,2112 ,…,c 2,3520} as the first retransmission bit sequence C (2) The first retransmitted bit sequence C (2) The first retransmitted modulation symbol sequence X is obtained by square 1024-order QAM modulation after global Gray mapping. (2) , that is, among the 1024 constellation points, the bit labels of adjacent constellation points have only one bit different. The demodulated retransmission bit likelihood ratio is combined with the second group of codewords transmitted for the first time and input into the LDPC decoder.

[0075] Compared with the BICM system and IR-HARQ with the same spectrum efficiency, Figure 7 As shown, the horizontal axis is SNR and the vertical axis is FER. This scheme significantly reduces the overall complexity and power consumption of the error correction code FEC while achieving performance similar to that of the traditional BICM, and the retransmission performance is better than the traditional IR scheme.

[0076] Embodiment three:

[0077] In the multi-level coded modulation transmission method designed by the present invention and applicable to the hybrid automatic repeat request system, the system modulation order M is set to 4096.

[0078] like Figure 1As shown, the information bit sequence of length k = 2112 is divided into two groups of information bit sequences of length k1 = 1119 and k2 = 993. The first group of information bit sequences of length k1 = 1119 is encoded by BCH with code rate R1 = 0.971 into the first group of coded bit sequences C1 = {c 1,1 ,c 1,2 ,…,c 1,1152}, the second information bit sequence of length k2=993 is encoded by LDPC with R2=0.862 into the second coded bit sequence C2={c 2,1 ,c 2,2 ,…,c 2,1152}. By calculation, we can get m1 = m*n1 / (n1+n2) = 6 and m2 = m*n2 / (n1+n2) = 6. The interleaver sequentially takes 6 bits from the first group of coded bit sequences and 6 bits from the second group of coded bit sequences to form the first transmission codeword:

[0079] C (1) ={c 1,1 ,c 1,2 ,c 1,3 ,c 1,4 ,c 1,5 ,c 1,6 ,c 2,1 ,c 2,2 ,c 2,3 ,c 2,4 ,c 2,5 ,c 2,6 ,…,c 1,1147 ,c 1,1148 ,c 1,1149 ,c 1,1150 ,

[0080] c 1,1151 ,,c 1,1152 ,c 2,1147 ,c 2,1148 ,c 2,1149 ,c 2,1150 ,c 2,1151 ,c 2,1152}; The first transmitted bit sequence C (1) The square 4096-order QAM modulation after MLC mapping obtains the modulation symbol sequence X for the first transmission (1) , where the corresponding constellation diagram is a partitioned Gray form with 64 partitions and 64 constellation points in the partition, that is, among the 64 constellation points in the partition, the bit labels of adjacent constellation points have only one bit different; the bit labels of the constellation points are {b1b2b3b4b5b6b7b8b9b 10 b 11 b 12}, {b1b2b3b4b5b6} is the partition index bit used to determine the partition where the constellation point is located, with higher reliability, {b7b8b9b 10 b 11 b 12} is the index bit in the zone, which is used to determine the constellation point in the zone, and has lower reliability; the first transmission codeword C (1) The first group of coded bits corresponding to the first transmission is mapped to {b1b2b3b4b5b6}, and the first transmission codeword C (1) The corresponding second group of coded bits is mapped to {b7b8b9b 10 b 11 b 12}.

[0081] When the first transmission fails, the second group of information bit sequences is transmitted through the code rate R ′ 2=0.431 incremental redundancy LDPC coding to obtain the coded bit sequence C2={c 2,1 ,…,c 2,1152 ,…,c 2,2304} as the first retransmission bit sequence C (2) The first retransmitted bit sequence C (2) The first retransmitted modulation symbol sequence X is obtained by square 4096-order QAM modulation after global Gray mapping. (2) , that is, among the 4096 constellation points, the bit labels of adjacent constellation points have only one bit different; the demodulated retransmitted bit likelihood ratio is combined with the second group of codewords transmitted for the first time and input into the LDPC decoder.

[0082] Compared with the BICM system and IR-HARQ with the same spectrum efficiency, Figure 8 As shown, the horizontal axis is SNR and the vertical axis is FER. This scheme significantly reduces the overall complexity and power consumption of the error correction code FEC while achieving performance similar to that of the traditional BICM, and the retransmission performance is better than the traditional IR scheme.

[0083] The multi-level coded modulation transmission method for a hybrid automatic repeat request system proposed in an embodiment of the present invention greatly reduces the complexity of demodulation and error correction code decoding compared to a BICM scheme with the same spectrum efficiency, while achieving performance similar to that of incremental redundancy HARQ.

[0084] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0085] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0086] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

Claims

1. A multi-level coding modulation transmission method suitable for a hybrid automatic repeat request system, characterized in that: The following steps are involved: Step 1, dividing the information bit sequence of length k at the transmitting end into a first information bit sequence S1 of length k1 and a second information bit sequence S2 of length k2, where k=k1+k2; Step 2: performing channel coding of a high code rate R1 on the first information bit sequence S1 to obtain a first coded bit sequence C1 with a bit length of n1, and performing channel coding of a low code rate R2 on the second information bit sequence S2 to obtain a second coded bit sequence C2 with a bit length of n2, where R1>R2; Step 3, according to the modulation order M, based on m=log2M, obtain the number of bits m in a single M-order orthogonal amplitude modulation signal, and calculate the number of bits m1=m*n1 / (n1+n2) and m2=m*n2 / (n1+n2) corresponding to the two groups of codes in a modulation symbol respectively; Step 4: In the first transmission, firstly, m1 bits are taken from the first coded bit sequence C1 with a bit length of n1, and then m2 bits are taken from the second coded bit sequence C2 with a bit length of n2, and the first transmission bit sequence C is obtained by interleaving and extraction. (1) ; Step 5: Transmit the first bit sequence C (1) Square M for MLC mapping = 2 m The first transmission modulation symbol sequence X is obtained by QAM modulation (1) ; Step 6: Send the first transmission modulation symbol sequence X to the receiving end (1) ; Step 7: In the first transmission modulation symbol sequence X (1) When the receiving end detects that the decoding fails and cannot be received correctly, it feeds back a retransmission request to the transmitting end, so that the transmitting end performs a low-code R on the second information bit sequence S2 of length k2. ′ 2 channel coding, and obtain the coded bit sequence of length n1+n2 as the first retransmission bit sequence C (2) , R ′ 2 <R2; Step 8: retransmit the first bit sequence C (2) Square M for global Gray mapping = 2 m The first retransmission modulation symbol sequence X is obtained by QAM modulation (2) ; Step 9: Send the first retransmission modulation symbol sequence X to the receiving end. (2) .

2. The method according to claim 1, characterized in that In step 5, the MLC mapping square M = 2 m The constellation diagram corresponding to the QAM modulation is The number of constellation points in the partition is The partition Gray form, that is, the partition Among the constellation points, the bit labels of adjacent constellation points have only one bit difference; the bit labels of the constellation points are The partition index bit is used to determine the partition where the constellation point is located. The intra-region index bits are used to determine the constellation points within the partition.

3. The method according to claim 1, characterized in that In step 8, the square M of the global Gray map is 2 m The constellation diagram corresponding to the QAM modulation of order 1 is in the form of a global Gray scale, that is, among the M constellation points, the bit labels of adjacent constellation points are different by one and only one bit.

4. The method according to claim 1, characterized in that: In step 6, the first transmission modulation symbol sequence X is sent to the receiving end. (1) After that, the following steps are also included: Step 61: The receiving end receives the modulation symbol sequence Y after passing through the channel. (1) , square M=2 based on MLC mapping m According to the characteristics of the QAM modulation, firstly, the log likelihood ratio LLR1 corresponding to the first coded bit sequence is demodulated by partition, and a decoding algorithm is used to detect and correct errors. If the error correction is successful, step 62 is executed, otherwise step 63 is executed; Step 62: based on the demodulation of the first coded bit sequence, demodulate the log likelihood ratio LLR2 corresponding to the second coded bit sequence in the region, and use a decoding algorithm to detect and correct errors. If the decoding is successful, the first transmission is successful, and an ACK signal is fed back to the transmitter. Otherwise, a NACK signal is fed back to the transmitter, and step 7 is executed; Step 63, obtain the log-likelihood ratio value LLR of each bit through global demodulation, use a decoding algorithm to detect and correct errors for the log-likelihood ratio LLR2 corresponding to the second coded bit sequence, if the decoding is successful, execute step 64, if the decoding fails, the first transmission fails, and a NACK signal is fed back to the transmitter, and execute step 7; Step 64, based on the demodulation of the second coded bit sequence, the auxiliary partition demodulates the log-likelihood ratio LLR1 corresponding to the first coded bit sequence, and uses a decoding algorithm to detect and correct errors. If the decoding is successful, the first transmission is successful, and an ACK signal is fed back to the transmitter. Otherwise, the first transmission fails, and a NACK signal is fed back to the transmitter, and step 7 is executed.

5. The method according to claim 4, characterized in that In step 9, the first retransmission modulation symbol sequence X is sent to the receiving end. (2) After that, the following steps are also included: Step 91: The receiving end receives the modulation symbol sequence Y after passing through the channel. (2) After that, the square M=2 based on the global Gray mapping m According to the characteristics of the QAM modulation of the first order, the LLR of the first retransmitted bit sequence is demodulated, and the LLR is combined with the log-likelihood ratio LLR2 corresponding to the second coded bit sequence demodulated during the first transmission, and a decoding algorithm is used to detect and correct errors. If the decoding is successful, step 92 is executed, otherwise the transmission fails; Step 92: based on the demodulation of the second coded bit sequence, the auxiliary partition demodulates the log-likelihood ratio LLR1 corresponding to the first coded bit sequence, and uses a decoding algorithm to detect and correct errors. If the decoding is successful, the retransmission is successful, otherwise the transmission fails.

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