A hybrid automatic repeat request method for the Internet of Things based on system polarization code

Abstract

The present invention belongs to the field of wireless communication technology, and specifically discloses a hybrid automatic repeat request method for an Internet of Things based on a system polarization code, comprising the following steps: Polar‑NOMA system, design the system polarization code encoding scheme at the system transmitter; based on Polar‑NOMA The system is designed with a system polarization code decoding scheme at the system receiving end; according to the system polarization code encoding scheme and the system polarization code decoding scheme, the hybrid automatic retransmission request of the Internet of Things based on the system polarization code is completed. SNR It can still support the successful reception of data under high SNR Under the condition, the throughput can reach a maximum value of 1. The bit error rate of the present invention is low, which is conducive to the successful detection of errors by the check code, and solves the problem that the high reliability of transmission cannot be guaranteed due to the limitation of transmission delay in traditional communication.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications, and in particular relates to a design of an Internet of Things hybrid automatic repeat request method based on system polarization codes. Background Art

[0002] In modern wireless communication systems, how to detect and correct errors introduced during information transmission due to undesirable channel conditions is a very important issue. Commonly used error control strategies mainly include error detection, forward error correction, and automatic repeat request (ARQ). 自动重传请求 , 自动重传请求(ARQ) ). When a transmission error is detected, the traditional 自动重传请求(ARQ) The technology ensures the correct completion of the transmission process by retransmitting the original frame. 自动重传请求(ARQ) , Hybrid Automatic Repeat Request (HARQ) 混合自动重传请求(HARQ) ) In the scheme, the code length and code rate are flexible and variable. After an error frame is detected, the receiver does not discard the original error frame, but caches it and participates in the detection and decoding process after the subsequent retransmitted frame arrives, thereby indirectly improving the system signal-to-interference-noise ratio.

[0003] Since the 1970s and 1980s, 混合自动重传请求(HARQ) The technology has attracted widespread attention from the academic community. In 3G and later standards, 混合自动重传请求(HARQ) It has become an indispensable part of the communication system. According to the frame retransmission strategy, 混合自动重传请求(HARQ) Technologies can be divided into two main categories: 追逐 merge( 追逐合并 , CC ): 追逐 merge 混合自动重传请求(HARQ) plan( CC - HARQ ), the sender resends the same copy of the original frame each time it retransmits, and therefore the receiver also increases the "observation" of the original frame each time it receives the retransmitted frame, thereby improving the success rate of correct reception.

[0004] Incremental redundancy ( 增量冗余 , IR ): Different from 追逐 Combined, incremental redundancy hybrid automatic repeat request scheme ( 增量冗余 - HARQ , IR - HARQ ), each retransmitted frame sent by the transmitter contains an additional codeword. After the retransmitted frame reaches the receiving end, it participates in decoding together. The additional codeword it carries is used as an extension of the original frame, which increases the overall code length and reduces the code rate, ultimately achieving the effect of improving the system signal-to-interference-noise ratio.

[0005] In the design process of traditional communication systems, data transmission rate is the primary consideration. The code length of the transmission is often large, and the time limit for frame reception is relatively loose. Under this premise, the sender is allowed to repeatedly send frames that have not been successfully received to combat unsuccessful channel conditions, even though this process will inevitably bring delays.

[0006] In particular, in ultra-reliable low-latency communications ( 超可靠低延迟通信(URLLC) ), due to the strict restrictions on transmission delay, especially for the sender, the channel state information ( 信道状态信息(Channel State Information,CSI) ) in real time becomes very difficult, so in order to ensure high reliability of transmission, it is necessary to focus on the design of forward error correction code and retransmission strategy. In particular, in delay-sensitive systems, due to the CSI Lack of information, good design 混合自动重传请求(HARQ) Technology is particularly critical. Summary of the invention

[0007] The purpose of the present invention is to solve the problem that high reliability of transmission cannot be guaranteed due to the limitation of transmission delay in traditional communications, and proposes an Internet of Things hybrid automatic repeat request method based on system polarization code.

[0008] The technical solution of the present invention is: a hybrid automatic repeat request method for the Internet of Things based on system polarization code, comprising the following steps:

[0009] S1. Based on 极化码 - 非正交多址接入(NOMA) System, design the system polar code encoding scheme at the system transmitter;

[0010] S2. Based on 极化码 - NOMA System, design the system polar code decoding scheme at the system receiving end;

[0011] S3. According to the system polarization code encoding scheme and the system polarization code decoding scheme, complete the IoT hybrid automatic repeat request based on the system polarization code.

[0012] The beneficial effects of the present invention are:

[0013] The present invention is low 信噪比(SNR) It can still support the successful reception of data under high 信噪比(SNR) Under these conditions, the throughput can reach a maximum value of 1. Systematic codes are less affected by error propagation than non-systematic codes, so the bit error rate is lower, which is conducive to the successful detection of errors by the check code.

[0014] Preferably, the system transmitting end in step S1 includes a polar code encoder and 连续相位调制(CPM) modulator, the polar code encoder and 连续相位调制(CPM) The modulators are connected in series through an interleaving operation;

[0015] The polar code encoder is used to process the original sequence to obtain a codeword sequence;

[0016] Said 连续相位调制(CPM) The modulator is used to modulate the codeword sequence after the interleaving process to obtain a modulated signal.

[0017] Preferably, the system polar code encoding scheme in step S1 is designed using a two-step encoding method.

[0018] Preferably, the system polar code encoding scheme in step S1 specifically includes the following steps:

[0019] S11. Splitting the original sequence according to the information bits and the redundant bits to obtain the split original sequence;

[0020] S12. Calculate the split codeword sequence according to the split original sequence and the polar code generation matrix;

[0021] S13. Obtain a modulated signal according to the split codeword sequence, and complete the system polarization code encoding.

[0022] Preferably, the expression formula of the original sequence after splitting in step S11 is:

[0023]

[0024] in, represents the source sequence; represents a sequence of information bits; Indicates frozen bits; Represents a set of frozen bits; Represents a set of information bits; Indicates the row subscript of the source sequence.

[0025] Preferably, the expression formula of the split codeword sequence in step S12 is:

[0026]

[0027] in, represents a codeword sequence; Represents a codeword sequence The row subscript of ; represents a sequence of information bits; Represents a set of frozen bits; Represents a set of information bits; represents the polar code generator matrix; represents the polar code generator matrix The row subscript of .

[0028] Preferably, the expression formula of the modulated signal in step S13 is:

[0029]

[0030] in, Indicates a modulated signal; Indicates modulated signal The row subscript of ; Represents a set of information bits; represents the polar code generator matrix; represents the polar code generator matrix The row subscript of ; represents the polar code generation matrix Column subscripts of ; represents the identity matrix; Represents a sequence of information bits.

[0031] The beneficial effects of the above preferred solution are:

[0032] The system polarization code is realized at the system transmitting end through a two-step coding scheme, which is less affected by error propagation and has the advantage of low bit error rate.

[0033] Preferably, the receiving end in step S2 is provided with a receiver; the receiver processes, detects and finally determines the total received signal to obtain the original sequence.

[0034] Preferably, the system polar code decoding scheme in step S2 is specifically as follows: when the receiving end receives the subsequence for the first time At the same time, we get the original sequence Complete observation of each bit value; if continuous reception fails, Second retransmission sequence When it arrives, the receiver Second retransmission sequence The missing part is updated based on the observation value, the decoding is completed, and the hybrid automatic repeat request of the Internet of Things based on the system polarization code is realized.

[0035] The beneficial effects of the above preferred solution are:

[0036] At the receiving end, only one decoder is needed to meet the decoding needs when retransmitted frames arrive multiple times. 信噪比(SNR) The successful reception of data can still be supported under these conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure shows a flow chart of a hybrid automatic repeat request method for the Internet of Things based on system polarization code. DETAILED DESCRIPTION

[0038] Now, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the embodiments shown and described in the accompanying drawings are only exemplary and are intended to explain the principles and spirit of the present invention, rather than to limit the scope of the present invention.

[0039] like Figure 1 As shown, a multi-user joint decoding method for an Internet of Things downlink channel includes the following steps:

[0040] S1. Based on polarization code-non-orthogonal multiple access ( 极化码 - 非正交多址接入(NOMA) ) system, design the system polar code encoding scheme at the system transmitter;

[0041] S2. Based on 极化码 - NOMA System, design the system polar code decoding scheme at the system receiving end;

[0042] S3. According to the system polarization code encoding scheme and the system polarization code decoding scheme, complete the IoT hybrid automatic repeat request based on the system polarization code.

[0043] In this embodiment, the system transmitting end in step S1 includes a polar code encoder and 连续相位调制(CPM) modulator, the polar code encoder and 连续相位调制(CPM) The modulators are connected in series through an interleaving operation;

[0044] Said 连续相位调制(CPM) The modulator is used to modulate the codeword sequence after the interleaving process to obtain a modulated signal.

[0045] In this embodiment, the system polar code encoding scheme in step S1 is designed using a two-step encoding method.

[0046] In this embodiment, the system polar code encoding scheme in step S1 specifically includes the following steps:

[0047] S11. Splitting the original sequence according to the information bits and the redundant bits to obtain the split original sequence;

[0048] S12. Calculate the split codeword sequence according to the split original sequence and the polar code generation matrix;

[0049] S13. Obtain a modulated signal according to the split codeword sequence, and complete the system polarization code encoding.

[0050] In this embodiment, the expression formula of the original sequence after splitting in step S11 is:

[0051]

[0052] in, represents the source sequence; represents a sequence of information bits; Indicates frozen bits, ; Represents a set of frozen bits; Represents a set of information bits; Indicates the row subscript of the source sequence.

[0053] In this embodiment, the expression formula of the codeword sequence after the split in step S12 is:

[0054]

[0055] in, represents a codeword sequence; Represents a codeword sequence The row subscript of ; represents a sequence of information bits; Represents a set of frozen bits; Represents a set of information bits; represents the polar code generator matrix; represents the polar code generation matrix The row subscripts of , and then we get:

[0056]

[0057] in, represents the polar code generation matrix The column subscripts can be obtained and The conversion relationship between them is:

[0058] .

[0059] In this embodiment, the expression formula of the modulated signal in step S13 is:

[0060]

[0061] in, Indicates a modulated signal; Indicates modulated signal The row subscript of ; Represents a set of frozen bits; Represents a set of information bits; represents the polar code generator matrix; represents the polar code generation matrix The row subscript of ; represents the polar code generation matrix Column subscripts of ; is a lower triangular matrix, then The same is a lower triangular matrix, and then we get:

[0062]

[0063] in, represents the identity matrix; Represents a sequence of information bits.

[0064] In this embodiment, the receiving end in step S2 is provided with a receiver; the receiver processes, detects and finally determines the total received signal to obtain the original sequence.

[0065] In this embodiment, the system polar code decoding scheme in step S2 is specifically as follows: the receiving end receives the subsequence for the first time At the same time, we get the original sequence Complete observation of each bit value; if continuous reception fails, Second retransmission sequence When it arrives, the receiver Second retransmission sequence The missing part is updated with the observed value, thereby reducing the total bit rate and bringing additional coding gain. SC Decoding idea, when the nodes are all composed of frozen bits, the decoding process does not need to calculate the complete log-likelihood information. The punctured parts only contain frozen bits, and the actual codeword degenerates into a repeated code. Therefore, the missing part of the log-likelihood ratio can be filled with the existing observation value to complete the decoding process.

[0066] In this embodiment, the bit error rate curves of the polar code, the non-systematic code and the systematic code are compared, and it can be obtained that the systematic code and the non-systematic code have similar frame error rate curves, but under the same conditions, the bit error rate of the systematic code is lower than that of the non-systematic code, that is, when the probability of generating error frames is similar, the average number of bit errors of the systematic code in the error frames is lower than that of the non-systematic code, and this feature is conducive to the detection of error frames by the receiving end.

[0067] In this embodiment, the system throughput under the solution proposed by the present invention is analyzed.

[0068] for 自动重传请求(ARQ) System, throughput ( 吞吐量效率 ) is one of the most critical performance indicators. Throughput The calculation formula is:

[0069]

[0070] in, Indicates the number of information bits after each adaptive adjustment of the information; Indicates the number of information bits after each adaptive adjustment expectations; Indicates the code length after each adaptive adjustment; Indicates the code length after each adaptive adjustment expectations; record events Indicates that after After the first transmission, the frame still cannot be received successfully; Indicates an event complementary events, that is, After the first transmission, the original frame was successfully received.

[0071] Indicates an event The probability of occurrence is:

[0072]

[0073] in, Indicates the maximum number of retransmissions allowed; Indicates passing The total length of the sequence after transmission; Indicates the maximum number of retransmissions allowed The total length of the sequence after transmission; Indicates the maximum number of retransmissions allowed. The frame has been transmitted for several times but still cannot be received successfully; Indicates that the frame has not been successfully received after 1 transmission; Indicates passing After the first transmission, the frame still cannot be received successfully; Indicates passing After the first transmission, the frame still cannot be received successfully; Indicates intersection;

[0074] Further throughput The lower bound of is:

[0075]

[0076] With the channel 信噪比(SNR) To ensure that the throughput rate can eventually reach the maximum value, the solution proposed in the present invention sets There are no frozen bits in the bitstream, that is, the initial bit rate is 1, and it gradually decreases as the retransmitted frames continue to arrive.

[0077] The performance of the IoT hybrid automatic repeat request method based on system polarization code proposed in the present invention was simulated through a simulation program, and the situations with different retransmission times were compared.

[0078] Under the condition that the number of information bits is 40 and the total length of the codeword is 1024, as the number of retransmissions increases, the frame error rate of decoding ( 误帧率(FER) ) gradually decreases, that is, the reception failure rate gradually decreases. This shows that it is feasible to ensure the successful reception of frames by retransmitting frozen bits. With the help of low bit rate characteristics, at low signal-to-noise ratio ( 信噪比(SNR) ) condition, the proposed scheme can still ensure the successful transmission of data, and with the increase of the maximum number of retransmissions, the system throughput is improved by about 0.02 under -8dB conditions. As the channel conditions improve, retransmissions almost do not occur under 10dB conditions, so the throughput can be close to 1.

[0079] Under the condition of 200 information bits and 1024 total codeword length, as the number of retransmissions increases, the system 信噪比(SNR) The throughput performance of the area has been improved. When the maximum number of retransmissions is 4, the throughput is improved by about 0.2 compared with the maximum number of retransmissions 3 under -2dB conditions, and the throughput is improved by about 0.27 compared with the maximum number of retransmissions 2 under 0dB conditions. Compared with 40 information bits, due to the increase in code rate, on the one hand, when the number of information bits is 200, the 信噪比(SNR) Regional systems achieve higher throughput, but on the other hand successful reception of data frames in the -10dB to -5dB range cannot be guaranteed.

[0080] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A hybrid automatic repeat request method for the Internet of Things based on system polarization code, characterized in that: The following steps are involved: S1. Based on Polar-NOMA A system polarization code encoding scheme is designed at a system transmitting end. The system polarization code encoding scheme is designed by adopting a two-step encoding method, which specifically includes the following sub-steps: S11. Splitting the original sequence according to the information bits and the redundant bits to obtain the split original sequence; The expression formula of the original sequence after splitting in step S11 is: in, represents the source sequence; represents a sequence of information bits; Indicates frozen bits; Represents a set of frozen bits; Represents a set of information bits; Indicates the row subscript of the source sequence; S12. Calculate the split codeword sequence according to the split original sequence and the polar code generation matrix; The expression formula of the split codeword sequence is: in, represents a codeword sequence; Represents a codeword sequence The row subscript of ; represents a sequence of information bits; Represents a set of frozen bits; Represents a set of information bits; represents the polar code generator matrix; represents the polar code generation matrix The row subscript of ; S13. Obtain the modulated signal according to the split codeword sequence and complete the system polarization code encoding; The expression formula of the modulated signal is: in, Indicates a modulated signal; Indicates modulated signal The row subscript of ; Represents a set of information bits; represents the polar code generator matrix; represents the polar code generation matrix The row subscript of ; represents the polar code generation matrix Column subscripts of ; represents the identity matrix; represents a sequence of information bits; S2. Based on Polar-NOMA System, design the system polar code decoding scheme at the system receiving end; The receiving end is provided with a receiver; The receiver processes, detects and finally determines the total received signal to obtain the original sequence; The system polar code decoding scheme is specifically as follows: the receiving end receives the subsequence for the first time At the same time, we get the original sequence Complete observation of each bit value; if continuous reception fails, Second retransmission sequence When it arrives, the receiver Second retransmission sequence The missing part is updated with the observed value, the decoding is completed, and the hybrid automatic repeat request of the Internet of Things based on the system polarization code is realized; S3. According to the system polarization code encoding scheme and the system polarization code decoding scheme, complete the IoT hybrid automatic repeat request based on the system polarization code.

2. The hybrid automatic repeat request method for the Internet of Things based on system polarization code according to claim 1, characterized in that: The system transmitting end in step S1 includes a polar code encoder and CPM modulator, the polar code encoder and CPM The modulators are connected in series through an interleaving operation; The polar code encoder is used to process the original sequence to obtain a codeword sequence; Said CPM The modulator is used to modulate the codeword sequence after the interleaving process to obtain a modulated signal.

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