Method for transmitting multi-level coded modulation suitable for hybrid automatic repeat request system

Abstract

The application discloses a multi-stage coding modulation transmitting method suitable for a hybrid automatic repeat request system and belongs to wireless communication technology. The method comprises the following steps: performing high-rate channel coding on a first information bit sequence of a transmitting end to obtain a first coded bit sequence, and performing low-rate channel coding on a second information bit sequence to obtain a second coded bit sequence. In a first transmission, the first coded bit sequence and the second coded bit sequence are combined and passed through an interleaver to obtain a first transmission bit sequence, and modulation is performed on the first transmission sequence to obtain a first transmission modulation symbol sequence; if the first transmission fails, a second group of information bit sequences are subjected to lower-rate channel coding to obtain a first retransmission bit sequence, and modulation is performed on the first retransmission bit sequence to obtain a first retransmission modulation symbol sequence. The transmitting method of the application greatly reduces the demodulation and error correction code decoding complexity compared with a BICM scheme with the same spectral efficiency, and obtains a performance close to that of incremental redundancy HARQ.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a multi-level coded modulation transmission method suitable for hybrid automatic repeat request systems. Background Technology

[0002] In mobile communication systems, Forward Error Correction (FEC) and Automatic Repeat Request (ARQ) technologies are commonly used to ensure data transmission reliability. HARQ technology combines the advantages of both ARQ and FEC, improving the decoding capability of the receiver with minimal redundancy. This enhances data transmission reliability in wireless networks, reduces latency, and increases throughput.

[0003] Traditional HARQ techniques 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 in each transmission. The receiver then decodes all received codewords by superimposing and combining them until successful decoding or the maximum retransmission count is reached. For IR-HARQ, the transmitter encodes the information bits to generate a low-rate codeword. First, it sends a sub-codeword containing all the information. Similarly, if the receiver fails to decode, it sends a sub-codeword containing redundant information. The receiver then combines all previously received bits to form a lower-rate codeword and decodes it until successful decoding or the maximum retransmission count is reached. This encoding / decoding method can achieve greater coding gain, thus achieving incremental redundancy.

[0004] Multi-Level Coded Modulation (MLCM) systems divide data into multiple layers and assign different coding and modulation schemes to each layer. In traditional Bit Interleaved Coded Modulation (BICM) systems, all information bits require highly complex codes (such as LDPC codes) to achieve good performance. MLC modulation systems, based on a layered coding framework, can reduce the load of highly complex channel codes, thereby reducing the overall complexity and power consumption of FEC. Summary of the Invention

[0005] This invention provides a multi-level coding modulation transmission method suitable for hybrid automatic repeat request systems, which achieves performance comparable to or better than BICM while ensuring minimal complexity.

[0006] This invention provides a multi-level coding and modulation transmission method suitable for a hybrid automatic repeat request system, comprising the following steps:

[0007] 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;

[0008] Step 2: Perform high-rate channel coding on the first information bit sequence S1 to obtain a first coded bit sequence C1 with a bit length of n1; perform low-rate channel coding 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: Based on the modulation order M, and according to 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 sets of codes in a modulation symbol, respectively.

[0010] Step 4: In the first transmission, first take m1 bits from the first coded bit sequence C1 with a bit length of n1, then take n2 bits from the second coded bit sequence C2 with a bit length of n2. Through interleaving and extraction, obtain the first transmission bit sequence C. (1) ;

[0011] Step 5, for the first transmitted bit sequence C (1) Square M=2 for MLC mapping m QAM modulation yields the first transmission modulation symbol sequence X. (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 receiver detects a decoding failure and cannot receive data correctly, it sends a retransmission request to the transmitter, causing the transmitter to process the second information bit sequence S2 of length k2 at a low code rate R. ′ Channel coding of length 2 yields a coded bit sequence of length n1+n2, which serves as the first retransmission bit sequence C. (2) R ′ 2 <R2;

[0014] Step 8, process the first retransmitted bit sequence C (2) The square M=2 for global Gray mapping mFirst-order QAM modulation yields the first retransmission modulation symbol sequence X. (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 first-order QAM modulation has a number of partitions. The constellation points within the partition are The partitioning gray form, that is, within the partition In a constellation of constellations, adjacent constellation points have exactly one different bit in their bit labels; the bit label of a constellation point is... The partition index bits are used to determine the partition where the constellation point is located. The index bits within the partition are used to determine the constellation point within the partition.

[0017] Optionally, in one embodiment of the present invention, in step 8, the square M of the global Gray map is 2. m The constellation diagram corresponding to the QAM modulation is in the form of a global Gray, that is, among the M constellation points, the bit tags of adjacent constellation points are different by exactly 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) 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 The characteristics of QAM modulation are as follows: First, the log likelihood ratio LLR1 corresponding to the first encoded bit sequence is demodulated by partitioning, 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 (LLR) of each bit through global demodulation. Use a decoding algorithm to detect and correct errors for the LLR2 corresponding to the second encoded bit sequence. If the decoding is successful, proceed to step 64. If the decoding fails, the first transmission fails. Feed back a NACK signal to the transmitter and proceed to step 7.

[0022] Step 64: Based on the demodulation of the second encoded bit sequence, the log-likelihood ratio LLR1 corresponding to the first encoded bit sequence is demodulated by auxiliary partition, and a decoding algorithm is used 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. Then, 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) The following steps are also included:

[0024] Step 91, the receiving end receives the modulation symbol sequence Y after passing through the channel. (2) Then, based on the global Gray map, the square M=2 m The characteristics of QAM modulation are used to demodulate the LLR of the first retransmitted bit sequence and combine it with the log likelihood ratio LLR2 corresponding to the second encoded bit sequence demodulated during the first transmission. 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 demodulated second encoded bit sequence, the log-likelihood ratio (LLR1) corresponding to the first encoded bit sequence is demodulated by auxiliary partitioning, and a decoding algorithm is used 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 hybrid automatic repeat request (HRM) systems, based on the MLCM architecture, reduces the coding length of the more complex error correction codes compared to the BICM scheme with the same spectral efficiency, thereby reducing the decoding complexity of the system. Furthermore, leveraging the hierarchical reception and demodulation characteristics of MLCM, it prioritizes the use of lower-dimensional demodulation concatenation instead of higher-order constellation demodulation, further reducing the complexity of reception and demodulation. The first retransmission of the MLCM system employs a combination of CCHARQ and IR HARQ, achieving performance similar to that of a BICM system using only IR HARQ.

[0027] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

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

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

[0030] Figure 2 This is a schematic diagram of the first transmission interleaving process at the transmitter in an embodiment of the present invention;

[0031] Figure 3 This is a flowchart of the first transmission demodulation and decoding process at the receiving end according to an embodiment of the present invention.

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

[0033] Figure 5(a) shows the 64-QAM constellation diagram and corresponding bit tags of the MLC mapping square generated in the first transmission according to Embodiment 1 of the present invention.

[0034] Figure 5(b) shows the square 64-QAM constellation diagram of the global Gray map generated in the first retransmission of the present invention and the corresponding bit tags.

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

[0036] Figure 7 This is a performance comparison chart of Embodiment 2 of the present invention;

[0037] Figure 8 This is a performance comparison chart of Embodiment 3 of the present invention. Detailed Implementation

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

[0039] Figure 1 This is a flowchart of a multi-level coding modulation transmission method for a hybrid automatic repeat request system provided according to an embodiment of the present invention.

[0040] like Figure 1 As shown, the multi-level coded modulation transmission method applicable to a 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 high-rate channel coding (R1) on the first information bit sequence S1 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 of R2 to obtain a second coded bit sequence with a bit length of n2. R1>R2, where, For the n1th bit of the first encoded bit sequence C1, It is the n2th bit of the second encoded bit sequence C2.

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

[0044] Step 4: In the first transmission, start with the first encoded bit sequence of bit length n1. Take m1 bits from the first bit, and then take the second encoded bit sequence of length n2. Take m2 bits from the middle, and then... Figure 2 The process shown involves interleaving and extraction to obtain the first transmitted bit sequence.

[0045] Step 5, for the first transmitted bit sequence C (1) Square M=2 for MLC mapping m QAM modulation yields the first transmission modulation symbol sequence X. (1) .

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

[0047] Step 7, in the first transmission modulation symbol sequence X (1) When the receiver detects a decoding failure and cannot receive data correctly, it sends a retransmission request to the transmitter, causing the transmitter to process the second information bit sequence S2 of length k2 at a low code rate R. ′ Channel coding of length 2 yields a coded bit sequence of length n1+n2, which serves as the first retransmission bit sequence. R ′ 2 <R2。

[0048] Step 8, process the first retransmitted bit sequence C (2)The square M=2 for global Gray mapping m First-order QAM modulation yields the first retransmission modulation symbol sequence X. (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 first-order QAM modulation has a number of partitions. The constellation points within the partition are The partitioning gray form, that is, within the partition In a constellation of constellations, adjacent constellation points have exactly one different bit in their bit labels; the bit label of a constellation point is... The partition index bits are used to determine the partition where the constellation point is located, resulting in higher reliability. The intra-region index bits are used to determine constellation points within the partition, which 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 map is 2. m The constellation diagram corresponding to the QAM modulation is in the form of a global Gray, that is, among the M constellation points, the bit tags of adjacent constellation points are different by exactly one bit.

[0052] Optionally, in one embodiment of the invention, such as Figure 3 As shown, in step 6, the first transmission modulation symbol sequence X is sent to the receiving end. (1) 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 The characteristics of QAM modulation are as follows: First, the log likelihood ratio LLR1 corresponding to the first coded bit sequence is demodulated in the partition, and the 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 encoded bit sequence, demodulate the log-likelihood ratio LLR2 corresponding to the second encoded bit sequence within 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.

[0055] Step 63: Obtain the log-likelihood ratio (LLR) of each bit through global demodulation. Use a decoding algorithm to detect and correct errors for the LLR2 corresponding to the second encoded bit sequence. If the decoding is successful, proceed to step 64. If the decoding fails, the first transmission fails. Feed back a NACK signal to the transmitter and proceed to step 7.

[0056] Step 64: Based on the demodulation of the second encoded bit sequence, the log-likelihood ratio LLR1 corresponding to the first encoded bit sequence is demodulated by auxiliary partitioning, and a decoding algorithm is used 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. Then, proceed to step 7.

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

[0058] Step 91, the receiving end receives the modulation symbol sequence Y after passing through the channel. (2) Then, based on the global Gray map, the square M=2 m The characteristics of QAM modulation are used to demodulate the LLR of the first retransmitted bit sequence and combine it with the log-likelihood ratio LLR2 corresponding to the second coded bit sequence demodulated during the first transmission. 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 encoded bit sequence, the log-likelihood ratio LLR1 corresponding to the first encoded bit sequence is demodulated by auxiliary partitioning, and a decoding algorithm is used to detect and correct errors. If the decoding is successful, the retransmission is successful; otherwise, the transmission fails.

[0060] Understandably, this invention divides the input information bit sequence into two groups. The first group of information bit sequences, with a length of k1, is channel-coded at a high code rate R1 to obtain a first group of coded bit sequences of length n1. The second group of information bit sequences, with a length of k2, is encoded at a low code rate R2 to obtain a second group of coded bit sequences of length n2, where R1 > R2. In the first transmission, the first group of coded bit sequences of length n1 and the second group of coded bit sequences of length n2 are processed as follows... Figure 2 The first transmission bit sequence is obtained after the interleaver shown. Square M-order QAM modulation with MLC mapping is then applied to the first transmission sequence to obtain the first transmission modulation symbol sequence. If the first transmission fails, the second group of information bit sequences of length k2 is processed at a lower code rate R. ′ Channel coding of 2 yields a coded bit sequence of length n1+n2, which serves as the first retransmission bit sequence, where R2>R.′ 2. The first retransmitted bit sequence is modulated using a square M-order QAM with global Gray mapping to obtain the first retransmitted modulation symbol sequence. Compared with the BICM scheme of the same spectral efficiency, the transmission scheme of this invention achieves performance similar to incremental redundancy HARQ while significantly reducing the complexity of demodulation and error correction code decoding.

[0061] like Figure 2 The specific steps of the interleaver shown are as follows: First, based on 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 codes in a modulation symbol based on the parameters of the two sets of channel codes; then, sequentially start from the first set of coded bit sequences with a bit length of n1. Take m1 bits and encode the second group of bits of length n2. Take m² bits to obtain the bit sequence of the first transmission. Bit sequence To form a modulation symbol, Mapped to partition index bits used to distinguish the intervals where constellation points are located. Mapped to the intra-zone index bits used to determine constellation points within the partition.

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

[0063] Example 1:

[0064] In the multi-level coding modulation transmission method designed for hybrid automatic repeat request systems according to the present invention, 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 into a first group of encoded bit sequences C1 = {c} using a BCH with a code rate R1 = 0.928. 1,1 ,c 1,2 ,…,c 1,704 The second group of information bit sequences of length k2 = 1106 is encoded into a second group of encoded bit sequences C2 = {c} using LDPC with a code rate R2 = 0.785, resulting in a second group of encoded bit sequences C2 = {c}. 2,1 ,c 2,2 ,…,c 2,1408}. Calculations show that 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 transmitted 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 transmitted MLC mapping square 64-order QAM constellation diagram is shown in Figure 5(a). The corresponding constellation diagram is a partitioned Gray form with 4 partitions and 16 constellation points within each partition. Among the 16 constellation points in a partition, adjacent constellation points have exactly one different bit in their bit tags. The bit tags of each constellation point are defined as {b1b2b3b4b5b6}. The two sets of codes in a modulation symbol correspond to the number of bits m1 = 2 and m2 = 4 respectively. {b2} is the partition index bit used to distinguish the interval where the constellation point is located. The reliability is high. The codeword C of the first transmission is shown in Figure 5(a). (1) The first group of coded bits corresponding to this is mapped to {b1b2}, marked in red in the diagram; {b3b4b5b6} are the intra-area index bits used to determine the constellation points within the partition, which have lower reliability. The first transmitted codeword C (1) The corresponding second group of encoded bits is mapped to {b3b4b5b6}.

[0068] If the first transmission fails, the second group of information bit sequence code rate R will be used. ′ The incremental redundancy LDPC encoding with 2 = 0.524 yields the encoded 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 map for the first retransmission is shown in Figure 5(b), meaning that among the 64 constellation points, adjacent constellation points have exactly one different bit in their bit tags. The demodulated retransmission bit likelihood ratio is combined with the second group of codewords from the first transmission and input into the LDPC decoder.

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

[0070] Example 2:

[0071] In the multi-level coding modulation transmission method designed for hybrid automatic repeat request systems according to the present invention, 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 into the first group of encoded bit sequences C1 = {c} using a BCH with a code rate R1 = 0.961. 1,1 ,c 1,2 ,…,c 1,1408 The second group of information bit sequences of length k2 = 1815 is encoded into a second group of encoded bit sequences C2 = {c} using LDPC with a code rate R2 = 0.859. 2,1 ,c 2,2 ,…,c 2,2112}. Calculations show that 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 transmitted 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 bit sequence C transmitted in the first transmission. (1) The square 1024-order QAM modulation after MLC mapping yields the modulation symbol sequence X for the first transmission. (1)The corresponding constellation diagram is in the form of a partitioned Gray diagram with 16 partitions and 64 constellation points within each partition. This means that among the 64 constellation points within a partition, adjacent constellation points have exactly one different bit in their bit labels. The bit labels of the constellation points are {b1b2b3b4b5b6b7b8b9b}. 10 {b1b2b3b4} are partition index bits used to determine the partition where the constellation point is located, which has higher reliability. {b5b6b7b8b9b} 10 The index bits within the partition are used to determine the constellation point within the partition, resulting in lower reliability; the first transmitted codeword C (1) The first group of coded bits corresponding to this is mapped to {b1b2b3b4}, and the first transmitted codeword C (1) The corresponding second group of encoded bits is mapped to {b5b6b7b8b9b} 10}

[0074] If the first transmission fails, the second set of information bit sequences will be transmitted via code rate R. ′ The incremental redundancy LDPC encoding with 2 = 0.516 yields the encoded bit sequence C2 = {c 2,1 ,…,c 2,2112 ,…,c 2,3520} as the first retransmission bit sequence C (2) The bit sequence C of the first retransmission (2) The modulation symbol sequence X for the first retransmission is obtained by square 1024-order QAM modulation after global Gray mapping. (2) That is, among the 1024 constellation points, adjacent constellation points have exactly one different bit in their bit tags. The demodulated retransmission bit likelihood ratio is combined with the second group of codewords from the first transmission and input into the LDPC decoder.

[0075] Compared with BICM systems and IR-HARQ systems with the same spectral efficiency, such as Figure 7 As shown, the horizontal axis represents SNR and the vertical axis represents 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 its retransmission performance is superior to that of the traditional IR scheme.

[0076] Example 3:

[0077] In the multi-level coding modulation transmission method for hybrid automatic repeat request systems designed in this invention, 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 into the first group of encoded bit sequences C1 = {c} using a BCH with a code rate R1 = 0.971. 1,1 ,c 1,2 ,…,c 1,1152 The second group of information bit sequences of length k2 = 993 is encoded by LDPC with R2 = 0.862 into a second group of encoded bit sequences C2 = {c 2,1 ,c 2,2 ,…,c 2,1152}. Calculations show that 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 transmitted 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 bit sequence C of the first transmission (1) The square 4096th order QAM modulation after MLC mapping yields the modulation symbol sequence X for the first transmission. (1) The corresponding constellation diagram is in the form of a partitioned Gray diagram with 64 partitions and 64 constellation points within each partition. This means that among the 64 constellation points within a partition, adjacent constellation points have exactly one different bit in their bit labels. The bit labels of the constellation points are {b1b2b3b4b5b6b7b8b9b}. 10 b 11 b 12{b1b2b3b4b5b6} are partition index bits used to determine the partition where the constellation point is located, which has higher reliability. {b7b8b9b} 10 b 11 b 12 The index bits within the partition are used to determine the constellation point within the partition, resulting in lower reliability; the first transmitted codeword C (1) The first group of coded bits corresponding to this is mapped to {b1b2b3b4b5b6}, and the first transmitted codeword C (1) The corresponding second group of encoded bits is mapped to {b7b8b9b} 10 b 11 b 12}

[0081] If the first transmission fails, the second set of information bit sequences will be transmitted via code rate R. ′ The incremental redundancy LDPC encoding with 2 = 0.431 yields the encoded bit sequence C2 = {c 2,1 ,…,c 2,1152 ,…,c 2,2304} as the first retransmission bit sequence C (2) The bit sequence C of the first retransmission (2) The first retransmission modulation symbol sequence X is obtained by square 4096-order QAM modulation using global Gray mapping. (2) That is, among the 4096 constellation points, the bit tags of adjacent constellation points are different by exactly one bit; the retransmission bit likelihood ratio after demodulation is combined with the second group of codewords from the first transmission and input into the LDPC decoder.

[0082] Compared with BICM systems and IR-HARQ systems with the same spectral efficiency, such as Figure 8 As shown, the horizontal axis represents SNR and the vertical axis represents 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 its retransmission performance is superior to that of the traditional IR scheme.

[0083] The multi-level coding modulation transmission method for hybrid automatic repeat request systems proposed in this invention significantly reduces the complexity of demodulation and error correction code decoding compared to the BICM scheme with the same spectral efficiency, while achieving performance similar to incremental redundancy HARQ.

[0084] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0085] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0086] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

Claims

1. A multi-level coded modulation transmission method suitable for a hybrid automatic repeat request system, characterized in that, Includes the following steps: 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; Step 2: Perform high-rate channel coding on the first information bit sequence S1 to obtain a first coded bit sequence C1 with a bit length of n1; perform low-rate channel coding 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: Based on the modulation order M, and according to 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 sets of codes in a modulation symbol, respectively. Step 4: In the first transmission, first take m1 bits from the first coded bit sequence C1 with a bit length of n1, then take m2 bits from the second coded bit sequence C2 with a bit length of n2. Through interleaving and extraction, obtain the first transmitted bit sequence C. (1) ; Step 5, for the first transmitted bit sequence C (1) Square M=2 for MLC mapping m QAM modulation yields the first transmission modulation symbol sequence X. (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 receiver detects a decoding failure and cannot receive data correctly, it sends a retransmission request to the transmitter, causing the transmitter to process the second information bit sequence S2 of length k2 at a low code rate R. ′ Channel coding of length 2 yields a coded bit sequence of length n1+n2, which serves as the first retransmission bit sequence C. (2) R ′ 2 <R2; Step 8, process the first retransmitted bit sequence C (2) The square M=2 for global Gray mapping m First-order QAM modulation yields the first retransmission modulation symbol sequence X. (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 square M of the MLC mapping is 2. m The constellation diagram corresponding to the first-order QAM modulation has a number of partitions. The constellation points within the partition are The partitioning gray form, that is, within the partition In a constellation of constellations, adjacent constellation points have exactly one different bit in their bit labels; the bit label of a constellation point is... The partition index bits are used to determine the partition where the constellation point is located. The index bits within the partition are used to determine the constellation point 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 is in the form of a global Gray, that is, among the M constellation points, the bit tags of adjacent constellation points are different by exactly 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) 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 The characteristics of QAM modulation are as follows: First, the log likelihood ratio LLR1 corresponding to the first encoded bit sequence is demodulated by partitioning, 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 (LLR) of each bit through global demodulation. Use a decoding algorithm to detect and correct errors for the LLR2 corresponding to the second encoded bit sequence. If the decoding is successful, proceed to step 64. If the decoding fails, the first transmission fails. Feed back a NACK signal to the transmitter and proceed to step 7. Step 64: Based on the demodulation of the second encoded bit sequence, the log-likelihood ratio LLR1 corresponding to the first encoded bit sequence is demodulated by auxiliary partition, and a decoding algorithm is used 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. Then, 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) The following steps are also included: Step 91, the receiving end receives the modulation symbol sequence Y after passing through the channel. (2) Then, based on the global Gray map, the square M=2 m The characteristics of QAM modulation are used to demodulate the LLR of the first retransmitted bit sequence and combine it with the log likelihood ratio LLR2 corresponding to the second encoded bit sequence demodulated during the first transmission. 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 demodulated second encoded bit sequence, the log-likelihood ratio (LLR1) corresponding to the first encoded bit sequence is demodulated by auxiliary partitioning, and a decoding algorithm is used to detect and correct errors. If the decoding is successful, the retransmission is successful; otherwise, the transmission fails.

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