WO2022247082A1 - Transmission method in which pseudo-random sequence and sparse concatenated code are superimposed in bit field - Google Patents

Transmission method in which pseudo-random sequence and sparse concatenated code are superimposed in bit field Download PDF

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WO2022247082A1
WO2022247082A1 PCT/CN2021/121021 CN2021121021W WO2022247082A1 WO 2022247082 A1 WO2022247082 A1 WO 2022247082A1 CN 2021121021 W CN2021121021 W CN 2021121021W WO 2022247082 A1 WO2022247082 A1 WO 2022247082A1
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sequence
sparse
information
pseudo
coding
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PCT/CN2021/121021
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French (fr)
Chinese (zh)
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陈为刚
何亚龙
韩昌彩
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天津大学
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2647Arrangements specific to the receiver only
    • H04L27/2655Synchronisation arrangements
    • H04L27/2656Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2647Arrangements specific to the receiver only
    • H04L27/2655Synchronisation arrangements
    • H04L27/2662Symbol synchronisation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2647Arrangements specific to the receiver only
    • H04L27/2655Synchronisation arrangements
    • H04L27/2668Details of algorithms
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02DCLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00Reducing energy consumption in communication networks
    • Y02D30/70Reducing energy consumption in communication networks in wireless communication networks

Definitions

  • the invention relates to the field of digital communication, in particular to a transmission method of superimposing pseudo-random sequences and sparse concatenated coding in bit domains.
  • a frame When data information is transmitted in the communication system, a frame is generally composed of several symbols as the basic unit of data transmission. The position of each digital time slot can be identified according to the frame positioning signal. Therefore, in the digital communication network, frame Synchronization is an indispensable prerequisite for subsequent data processing.
  • the conventional frame synchronization method has a high probability of false locking and cannot achieve stable tracking synchronization.
  • the frame synchronization detection performance can be effectively improved by increasing the length of the frame synchronization word, but this will bring additional spectrum overhead and destroy the original frame structure of the system.
  • the traditional synchronous detection method is difficult to implement, and the accuracy will be greatly limited.
  • Short burst signal duration is short, difficult to capture and detect, and has strong anti-interference and anti-capture capabilities. This excellent characteristic makes short burst signals widely used in communication systems that require strong concealment, such as: military Communication and the emergency life-saving communication that appeared in recent years.
  • short-burst communication Under low signal-to-noise ratio, short-burst communication generally requires less information to be transmitted, and uses an extremely low bit rate coding scheme and configures an extremely low information transmission rate to achieve stronger anti-interference capabilities.
  • the combination of extremely low rate and extremely low bit rate can achieve reliable transmission under extremely low signal-to-noise ratio, but at the same time, it also makes the duration of the data segment longer. If the frame header is also longer, the duration of the entire burst is longer.
  • the method of inserting a special code group to achieve frame synchronization mainly includes the coherent insertion method and the interval insertion method.
  • the coherent insertion method is to insert the frame synchronization code group at the beginning of each frame.
  • this frame synchronization method it is The transmitted data is compiled into frames, each frame contains one or more code groups, and a special character is added to the head of the frame to indicate the beginning of a frame.
  • the receiving end searches the received bit stream, and once this special character is detected, the starting position of the frame is obtained, and the code groups in the frame are divided accordingly.
  • the frame synchronization code group is not inserted in the information code stream, but a frame synchronization code is inserted every certain number of information symbols, and the receiving end can search and detect the received symbols. Determine the position of the frame synchronization code.
  • the search and detection of the frame synchronization position can generally use the external synchronization method or the self-synchronization method. Specifically, after the receiving end receives the data from the sending end, it performs a sliding correlation between the local sequence and the receiving sequence. If it is at the boundary position of the synchronous capture frame , the correlation function of the two sequences will have a sharp peak, and the synchronization position information can be obtained by using the correlation peak.
  • the external synchronization method often inserts a pilot sequence with good autocorrelation characteristics before each frame, that is, frame synchronization codes, such as Barker codes, m sequences, and so on. Then, sliding detection is performed on the received signal at the receiving end, and the position of the frame header is calculated according to the correlation characteristics of the frame synchronization code, so as to realize frame synchronization. Since the magnitude of the received signal may be smaller than the noise magnitude under low SNR, the frame synchronization code is generally detected by correlation accumulation and threshold judgment.
  • the autocorrelation of the frame synchronization code is characterized by a large difference between the main lobe and the side lobe. The sharper the peak of the main lobe, the higher the accuracy of the decision. This difference can be improved by increasing the length of the frame synchronization code. When the frame synchronization The longer the code, that is, the longer the pilot sequence, the higher the effective gain of correlation accumulation will be.
  • autocorrelation or differential coherent detectors are often used in OFDM systems, and detection methods based on the correlation between the inserted pilot sequence and the received signal are also widely used, and the performance of this method is better than that of non- Coherent detection and autocorrelation detectors, but cross-correlation detectors consume a lot of resources.
  • the research results show that under the same signal-to-noise ratio, the optimal criterion algorithm has nearly 3dB gain than the simple correlation criterion algorithm.
  • the correlation value at a certain time is greater than the decision threshold, it can be judged as was successfully captured, and the offset phase at which this correlation peak is located is the estimated value of frame sync detection.
  • the traditional window search peak detection algorithm also uses a threshold judgment method. If the correlation peak value exceeds the threshold, it is judged that the frame header capture is successful. However, the performance of this detection method is very sensitive to the threshold setting.
  • the present invention provides a transmission method and device for superimposing pseudo-random sequences and sparse concatenated coding in the bit field.
  • the receiver of the present invention can also realize accurate signal capture and synchronization under low signal-to-noise ratio, so as to complete effective signal transmission.
  • Receive; the sending end performs sparse coding processing on the information sequence to be transmitted, so that after the pseudo-random sequence is superimposed on it, the frame synchronization accuracy under a certain signal-to-noise ratio can still be guaranteed, and compared with the traditional coding transmission method, it can Reliable transmission of information is achieved under low signal-to-noise ratio, see the following description for details:
  • a transmission method for superimposing pseudo-random sequences and sparse concatenated coding in bit fields comprising the following steps:
  • channel coding is first performed on the information sequence to be transmitted, and each channel coded symbol is converted into a sparse sequence with a small proportion of symbol "1" according to the sparse coding scheme, and then the sparse sequence and the pseudo-random sequence are one by one
  • the sequence to be transmitted is obtained by bit XOR superposition, and finally modulated and sent;
  • the received signal and the local pseudo-random sequence are subjected to sliding correlation judgment to realize frame synchronization and transmission symbol synchronization, further remove the pseudo-random sequence in the signal, and then calculate each bit in the demodulator
  • the hard decision and soft decision information are sent to the decoder for decoding and the hard output and soft output information of each sparsely coded codeword are calculated, and finally the channel coding corresponding to each codeword is obtained according to the same mapping rules as the sending end Symbol hard-decision information and soft-decision information are channel-decoded to obtain the original information sequence.
  • the concatenated coding transmission method of superimposing pseudo-random sequences proposed by the present invention can realize two functions of frame synchronization and information transmission simultaneously with one code stream and carrier;
  • the present invention performs sparse coding processing on the information sequence to be transmitted at the sending end, so that after the pseudo-random sequence is superimposed on it, the accuracy of frame synchronization under a certain signal-to-noise ratio can still be guaranteed;
  • the present invention can realize reliable transmission of information at a lower signal-to-noise ratio.
  • Fig. 1 is the system block diagram that the scheme of the present invention realizes
  • Fig. 2 is a schematic diagram of the structure of the sequence to be transmitted after superimposing the pseudo-random sequence in the present invention
  • Fig. 3 is the implementation flowchart of the sending end based on the low-heavy sequence mapping of the present invention
  • Fig. 4 is the schematic representation of the waveform of the sequence set V 4 corresponding to 2 coded bits w fixed to 1 in the present invention
  • Fig. 5 is the schematic representation of the waveform of the sequence set V 8 corresponding to 3 code bits w fixed to 1 in the present invention
  • FIG. 6 is a schematic representation of a waveform of a sequence set constructed with w fixed as 1 in the present invention.
  • Fig. 7 is a schematic representation of a waveform of a sequence set with w not fixed structure in the present invention.
  • Fig. 8 is the implementation flow chart of the sending end based on the low repetition code word mapping of the present invention.
  • Fig. 9 is a flow chart of decoding at the receiving end based on low-heavy sequence mapping in the present invention.
  • Fig. 10 the present invention is based on the decoding flow chart of the receiving end of low repetition codeword mapping
  • FIG. 11 is a simulation diagram of frame synchronization detection performance in Embodiment 1 of the present invention.
  • Fig. 12 is the specific embodiment 1 of the present invention under AWGN channel, RS code and LDPC code are respectively used as the decoding bit error rate performance figure of outer code;
  • Fig. 13 is the frame synchronization detection error rate curve under the AWGN channel of Embodiment 2 of the present invention.
  • Fig. 14 is the frame synchronization detection error rate curve under the AWGN channel of the specific embodiment 3 of the present invention.
  • Fig. 15 is a performance diagram of the decoding bit error rate of the specific embodiments 2 and 3 of the present invention under the AWGN channel.
  • Table 1 is the corresponding relationship between the coding symbol composed of 3 bits and the sequence set V8 in the specific embodiment of the present invention, and 8 groups of binary sparse sequences;
  • Table 2 is a schematic diagram of the corresponding relationship between each group of binary sparse sequences and coded symbols in the sequence set V 64 with a length of 8 chips corresponding to 6 coded bits, which is constructed w indefinitely in the present invention.
  • the embodiment of the present invention proposes a bit-field superimposed pseudo-random sequence and sparse coding Sequential low signal-to-noise ratio communication methods.
  • channel coding is first performed on the information sequence to be transmitted, and then each channel coding symbol is converted into a sparse sequence with a small proportion of symbol "1" according to a specially designed sparse coding scheme, and then the sparse sequence is combined with the pseudo-random sequence
  • the sequence to be transmitted is obtained by bit-by-bit XOR superposition, and finally modulated and sent; at the receiving end, firstly, the received signal and the local pseudo-random sequence are subjected to sliding correlation judgment to achieve frame synchronization and transmission symbol synchronization, and further remove the pseudo-random sequence in the signal , and then calculate the hard decision and soft decision information of each bit in the demodulator, and send it to the decoder for decoding and calculate the hard output and soft output information of each sparse codeword, and finally according to the same
  • the mapping rule the hard-decision information and soft-decision information of the channel coding symbols corresponding to each codeword are obtained, and the original information sequence is obtained through channel decoding.
  • the method proposed by the invention can ensure high accuracy of frame synchronization and realize reliable transmission of information under low signal-to-noise ratio, and can realize interference-free separation of transmission data under certain synchronization code related performance loss.
  • the method proposed by the present invention can flexibly select the correlation length according to channel conditions, the maximum length is the same as the frame length, and has good channel adaptability, thereby realizing the trade-off between complexity and performance in the sliding correlation detection algorithm.
  • the present invention proposes a cascaded coding transmission method of superimposing pseudo-random sequences, selects pseudo-random sequences with good correlation as the carrier of information transmission, and still has good autocorrelation characteristics after being superimposed with sparse coding sequences, And there is no need to allocate time slots for the training sequence, which effectively improves the frequency band utilization.
  • the sliding correlation acquisition method is used for signal acquisition, and the frame synchronization and transmission can be accurately realized without loss of transmission resources.
  • the present invention can use one code stream to simultaneously realize two functions of frame synchronization and information transmission.
  • the communication solution in the present invention will be described in detail below in conjunction with the accompanying drawings.
  • channel coding is first performed on the information sequence to be transmitted, and then each channel coding symbol is converted into a sparse sequence with a small proportion of symbol "1" according to a specially designed sparse coding scheme, and then the sparse sequence is combined with
  • the pseudo-random sequence is XOR-superposed bit by bit to obtain the sequence to be transmitted, as shown in Figure 2, and finally modulated and sent;
  • the received signal and the local pseudo-random sequence are subjected to sliding correlation judgment to realize frame synchronization and transmission symbol synchronization, further remove the pseudo-random sequence in the signal, and then calculate each bit in the demodulator
  • the hard decision and soft decision information are sent to the decoder to decode and calculate the hard output and soft output information of each sparsely coded codeword.
  • the channel corresponding to each codeword is obtained according to the same mapping rules as the sending end. Encode symbol hard-decision information and soft-decision information, and obtain the original information sequence through channel decoding.
  • the local pseudo-random sequence is specifically the same pseudo-random sequence m as that of the sender, and the receiver can select the sliding window length of the correlator according to the channel conditions, where the maximum length is the same as the frame length, and correspondingly, the correlation operation is performed within the sliding window
  • the local sequence of is a binary sequence of the same length intercepted from the pseudo-random sequence m from its head to the rear.
  • step (1) is specifically:
  • each p-bit encoded codeword for c is a group, and the i-th group of bit streams can be expressed as [c ip ,c ip+1 , ...,c ip+p-1 ] to form the corresponding encoding symbols, denoted as e i ,
  • c ip+1 is the second chip of the i-th bit stream
  • c ip+j is the j-th chip of the i-th bit stream
  • N is the bit length of the codeword c
  • p is the number of symbols in each group of bit streams.
  • mapping sequence set V for realizing the sparseness of channel coding codewords, and design a special sparse coding scheme according to the mapping sequence set V, and obtain a binary sparse sequence s after sparse coding;
  • step (2) is specifically:
  • the receiving end receives the transmission signal, first realizes signal capture through the cross-correlation detector according to the known pseudo-random sequence, and completes frame synchronization and transmission symbol synchronization;
  • the generation of the binary sparse sequence s in the above step (1.2) specifically has two sparse coding implementation methods, which are:
  • the weight w of each sequence in the constructed sequence set may not be completely equal.
  • w can be arbitrarily smaller than the sequence
  • the value of half the length is shown in Figures 4, 5, 6, 7, 8 and Table 1.
  • the mapping relationship between the channel coding symbols and the sparse sequence set is established to obtain the sparse coding codeword sequence.
  • the sequence in which the density of the symbol "1" in the binary sequence is less than 1/2 is called a low-heavy sequence; specifically, the implementation steps are as follows:
  • the second method use low-repetition codeword mapping to realize sparse coding, as shown in Figure 8, first, use the information bits of some low-repetition codewords of the error-correcting code to construct a sequence set, which can make each group of sequences in the sequence set undergo error-correcting coding
  • the obtained codewords are all low-weight codewords, and then the mapping relationship between the channel coding symbols and the information bits of the low-weight codewords is established, and finally the low-heavy error correction coding is performed on the mapped sequence to obtain the sparse code sequence of words.
  • the code word whose symbol "1" density is less than 1/2 in the binary code word sequence is called low repetition code word.
  • mapping rules select the binary sequence corresponding to the position number and the encoding symbol value in the sequence set V as the transmission sequence, that is, when the encoding symbol is c i , select the binary sequence whose position number is c i in the sequence set V As the corresponding transmission sequence, complete the mapping;
  • step (2.1) is specifically:
  • N k is the length of the sliding window of the correlator
  • y(n+g) is the sequence after the received signal is shifted by g bits
  • m(n) is the pseudo-random sequence in the sliding window
  • k represents the sequence number output by the correlator
  • n is the serial number of the digital sample.
  • each symbol uses the l-dimensional Gaussian distribution density function to calculate the soft information according to the sequence set V, expressed as:
  • ⁇ 2 is the noise variance
  • jth chip of the nth group of received signals is the j-th chip of the sequence numbered a in the sequence set V.
  • ri ⁇ s i represents the product of the i-th chip of the two sequences, ri is the i-th chip of the received sequence, and s i is the i-th chip of the sparse sequence in the mapping table.
  • a low signal-to-noise ratio communication method designed by the present invention in which a pseudo-random sequence and a sparse coded sequence are superimposed in a bit field, can realize two functions of frame synchronization and information transmission at the same time with one code stream and a carrier, without allocating additional time slots for pilots .
  • Three specific embodiments are given below, all under the AWGN channel, adopting the BPSK modulation method to illustrate the feasibility of the method of the present invention, and to further understand the purpose, characteristics and advantages of the invention.
  • the channel coding used in this embodiment is the RS(511, k) code defined on the GF(512) domain, the code rate is k/511, the length of the information sequence is 511 symbols, and each symbol has 9 bits.
  • the pseudo-random sequence adopts an m-sequence with a series number of 14 and a feedback coefficient of 42103 (octal).
  • mapping table select the information bits corresponding to the codewords with weights of 7 or 8 in 511 Golay (23,12) codes, and add all 0 codewords to form a mapping table, corresponding to GF each element of (512);
  • the sequence to be transmitted is actually a pseudo-random sequence with 33% chip inversion, and the overall transmission code rate is 9k/(511 ⁇ 23).
  • the RS decoder adopts a hard-decision decoding algorithm to complete RS decoding according to the obtained hard-decision information of the channel coded symbols to obtain the original information sequence.
  • the performance of frame synchronization detection increases with the increase of the length of the sliding correlation window.
  • the m-sequence has the optimal frame synchronization Detection performance
  • the error rate reaches 10 -4
  • the correlation length is only 1023
  • the frame synchronization detection error rate reaches 10 -4 when the signal-to-noise ratio is -5dB, which verifies the proposed
  • the scheme has excellent frame synchronization detection performance under low signal-to-noise ratio.
  • the error performance of this embodiment is simulated, as shown in Figure 12, in this embodiment, the RS code is used as the outer code, and when the overall code rate of the concatenated code is 0.192, when the signal-to-noise ratio is -3.2dB, the system's translation
  • the code error bit error rate (BER) can reach 10 -5 .
  • the NB-LDPC code with a code rate of 1/2 is used as the outer code.
  • the decoding bit error rate (BER) of the system can be 10 -5 ; with the NB-LDPC code of 1/3 code rate as the outer code, when the overall code rate of the concatenated code is 0.131, and the signal-to-noise ratio is -7.8dB, the system's decoding bit error rate (BER ) can reach 10 -5 .
  • the channel coding adopted in this embodiment is an LDPC code defined on the GF(8) domain
  • the adopted parity check matrix H has a code length of 384 symbols, a code rate of 1/2, and an information sequence length of 192 symbols, corresponding to,
  • the code length is 1152 bits
  • the information sequence is 576 bits long.
  • the 4 non-zero elements in each row of the parity check matrix are randomly selected from the non-zero element set ⁇ 1,2,...,7 ⁇ corresponding to the finite field.
  • the pseudo-random sequence adopts an m-sequence with a series number of 12 and a feedback coefficient of 10123 (octal).
  • the sequence set used for sparse coding contains 8 groups of binary sparse sequences with a length of 8 chips, expressed as:
  • V 8 ⁇ v 0 , v 1 ,...,v 7 ⁇
  • the codeword with a symbol length of 384 is sparsely orthogonally encoded to obtain 384 groups of transmission symbols with a length of 8 chips, and the sparse sequence composed of these transmission symbols XOR with the pseudo-random sequence m with a length of 3072 chip by chip to obtain the sequence t to be transmitted;
  • sequence to be transmitted is actually a pseudo-random sequence with 12.5% chip inversion, and the overall transmission code rate is 3/16.
  • each group of received signals uses an 8 -dimensional Gaussian distribution density function to calculate the symbol likelihood information of the corresponding data according to the sequence set V8, and the calculation method is shown in formula (4);
  • the Fast Fourier Transform-Confidence Propagation (FFT-BP) algorithm on the GF(8) domain is used for decoding.
  • Statistics and compared with the frame synchronization detection error rate of the frame header in the traditional frame structure, where the frame header is also composed of m-sequence.
  • the frame synchronization detection performance of this embodiment is optimal, that is, when the signal-to-noise ratio is -17dB, the detection error rate reaches 10 -5 , which is close to the length Frame synchronization detection performance for 2047 frame headers.
  • the local sequences in the sliding window are the first 1023 chips and the first 2047 chips of the pseudo-random sequence, and the detection error rates are -12dB and -15dB respectively It reaches 10 -5 , which is close to the frame synchronization detection performance of the frame header composed of m-sequences with lengths of 511 and 1023 respectively.
  • the specific implementation process of the embodiment is as follows.
  • the channel coding adopted in this embodiment is an LDPC code defined on the GF(64) domain
  • the adopted parity check matrix H has a code length of 384 symbols, a code rate of 1/2, and an information sequence length of 192 symbols, corresponding to,
  • the code length is 2304 bits
  • the information sequence is 1152 bits long.
  • the 4 non-zero elements of each row of the parity check matrix are randomly selected from the set of non-zero elements of the corresponding finite field.
  • the pseudo-random sequence used is the same as that of the specific embodiment 1, and the implementation process of the scheme is similar to that of the specific embodiment 2.
  • the FFT-BP algorithm on the GF(64) domain is used for decoding.
  • the frame synchronization detection error rate of this embodiment is counted under the AWGN channel, and compared with the frame header in the traditional frame structure Frame sync detection error rates are compared.
  • this embodiment achieves the optimal frame synchronization detection performance, that is, when the signal-to-noise ratio is -9dB, the error rate reaches 10 -5 , which is close to the length of 255 Frame synchronization detection performance of frame headers composed of m-sequences.
  • the correlation length is 2047
  • the detection error rate reaches 10 -5 when the signal-to-noise ratio is -dB, which is better than the frame synchronization detection performance of the frame header whose length is 127.
  • the scheme of the present invention can ensure the accuracy of burst capture and frame synchronization detection under low signal-to-noise ratio, and can adapt to different channel conditions by selecting different correlation lengths. At the same time, compared with the traditional transmission scheme, it also has a certain error performance gain, which is suitable for short burst communication.
  • the models of the devices are not limited, as long as they can complete the above functions.

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Abstract

Disclosed in the present invention is a transmission method in which a pseudo-random sequence and a sparse concatenated code are superimposed in a bit field. The method comprises: (1) at a sending end, firstly, performing channel coding on an information sequence to be transmitted, according to a sparse coding scheme, converting each channel coded symbol into a sparse sequence having a small proportion of code elements "1", then, performing bit-by-bit exclusive OR superimposition on the sparse sequence and a pseudo-random sequence, so as to obtain a sequence to be transmitted, and finally, modulating and sending same; and (2) at a receiving end, firstly, performing a sliding correlation decision on a received signal and a local pseudo-random sequence, so as to realize frame synchronization and transmission symbol synchronization, further removing the pseudo-random sequence from the signal, then, calculating, in a demodulator, hard decision information and soft decision information of each bit, sending same to a decoder for decoding and calculating hard output information and soft output information of each sparse coded codeword, according to a mapping rule the same as that at the sending end, obtaining hard decision information and soft decision information of the channel coded symbol corresponding to each coded codeword, and obtaining an original information sequence by means of channel decoding.

Description

比特域叠加伪随机序列与稀疏级联编码的传输方法Transmission method of superimposed pseudo-random sequence and sparse concatenated coding in bit field 技术领域technical field
本发明涉及数字通信领域,尤其涉及一种比特域叠加伪随机序列与稀疏级联编码的传输方法。The invention relates to the field of digital communication, in particular to a transmission method of superimposing pseudo-random sequences and sparse concatenated coding in bit domains.
背景技术Background technique
数据信息在通信系统中传输时,一般总是以若干个码元组成一帧作为数据传输的基本单元,各个数字时隙的位置可以根据帧定位信号加以识别,因此在数字通信网中,实现帧同步是对后续数据处理不可或缺的前提。然而随着现代纠错编译码技术的发展,通信系统的帧同步锁定跟踪门限面临着更高的要求,常规的帧同步方法存在着很高的假锁概率,不能实现稳定的跟踪同步。通过增加帧同步字的长度可以有效改善帧同步检测性能,但这会带来额外的频谱开销且会破坏系统原本的帧结构。尤其当接收机工作在低信噪比下,如突发通信,传统同步检测方法实现困难,准确性会受到很大的限制。When data information is transmitted in the communication system, a frame is generally composed of several symbols as the basic unit of data transmission. The position of each digital time slot can be identified according to the frame positioning signal. Therefore, in the digital communication network, frame Synchronization is an indispensable prerequisite for subsequent data processing. However, with the development of modern error correction coding and decoding technology, the frame synchronization locking and tracking threshold of the communication system is facing higher requirements. The conventional frame synchronization method has a high probability of false locking and cannot achieve stable tracking synchronization. The frame synchronization detection performance can be effectively improved by increasing the length of the frame synchronization word, but this will bring additional spectrum overhead and destroy the original frame structure of the system. Especially when the receiver works under low signal-to-noise ratio, such as burst communication, the traditional synchronous detection method is difficult to implement, and the accuracy will be greatly limited.
短突发信号持续时间短,捕获和检测困难,具有较强的抗干扰、抗捕获能力,这一优良的特性使短突发信号广泛应用于对隐蔽性要求较强的通信系统,例如:军事通信及近年来出现的应急救生通信。低信噪比下短突发通信一般所需传输的信息量较少,采用极低码率的编码方案以及配置极低的信息传输速率,以此来实现更强的抗干扰能力。极低速率和极低码率相结合,可以实现极低信噪比下的可靠传输,但同时也使得数据段持续时间变长,若帧头也较长,则整个突发持续时间更长,极大的降低了其隐蔽性,因此突发通信的高隐蔽性和高可靠性难以同时实现。因此对突发通信的信号捕获及同步方法进行研究,提升其接收机在低信噪比环境下的同步检测性能非常重要,这也是完成对数据帧的接收、发挥编码调制方案优异性能以及实现在低信噪比下的可靠通信的必要条件。为了实现帧同步,通常有两类方法,一种是在传输信息流中插入一些特殊码组作为每帧的头尾标记,接收端根据这些特殊码组的位置就可以实现帧同步,另一种是利用码组本身之间彼此不同的特性来实现自同步,无需借助外部特殊码组。Short burst signal duration is short, difficult to capture and detect, and has strong anti-interference and anti-capture capabilities. This excellent characteristic makes short burst signals widely used in communication systems that require strong concealment, such as: military Communication and the emergency life-saving communication that appeared in recent years. Under low signal-to-noise ratio, short-burst communication generally requires less information to be transmitted, and uses an extremely low bit rate coding scheme and configures an extremely low information transmission rate to achieve stronger anti-interference capabilities. The combination of extremely low rate and extremely low bit rate can achieve reliable transmission under extremely low signal-to-noise ratio, but at the same time, it also makes the duration of the data segment longer. If the frame header is also longer, the duration of the entire burst is longer. It greatly reduces its concealment, so it is difficult to achieve high concealment and high reliability of burst communication at the same time. Therefore, it is very important to study the signal acquisition and synchronization method of burst communication and improve the synchronization detection performance of the receiver in the low SNR environment. Necessary for reliable communication at low signal-to-noise ratios. In order to achieve frame synchronization, there are usually two types of methods, one is to insert some special code groups in the transmission information stream as the head and tail marks of each frame, and the receiving end can realize frame synchronization according to the positions of these special code groups; Self-synchronization is realized by using the different characteristics of the code groups themselves, without the need for external special code groups.
插入特殊码组实现帧同步的方法主要有连贯式插入法和间隔式插入法,其中连贯式插入法就是在每帧的开头集中插入帧同步码组的方法,在这种帧同步方式中,被传输的数据被编成帧,每帧包含一个或多个码组,帧的头部加一个特殊字符来指明一帧的开始。接收 端对接收到的比特流进行搜索,一旦检测到这种特殊字符,就得到了帧起始位置,并据此划分帧内的码组。但在某些情况下,帧同步码组并非集中插入在信息码流中,而是每隔一定数量的信息码元,插入一段的帧同步码,收端可以通过对接收码元进行搜索检测来确定帧同步码的位置。帧同步位置的搜索和检测一般可以采用外同步法或者自同步法,具体而言,接收端收到发送端的数据后,将本地序列与接收序列进行滑动相关,若处于同步捕获帧的边界位置时,两个序列的相关函数会出现尖锐峰值,利用相关峰就可得到同步位置信息。外同步法常在每一帧前插入一段具有良好自相关特性的导频序列,即帧同步码,如巴克码,m序列等。然后在接收端对接收信号进行滑动检测,根据帧同步码的相关特性计算出帧头的位置,从而实现帧同步。由于在低信噪比下接收信号的幅度会出现小于噪声幅度的情况,因此帧同步码的检测方式一般都是相关积累与门限判决。帧同步码的自相关性的特点是主瓣和旁瓣差异较大,主瓣峰值越尖锐,判决的准确性就会越高,这个差异可以通过增加帧同步码的长度来提高,当帧同步码越长,即导频序列越长,相关积累的有效增益就会越高。The method of inserting a special code group to achieve frame synchronization mainly includes the coherent insertion method and the interval insertion method. The coherent insertion method is to insert the frame synchronization code group at the beginning of each frame. In this frame synchronization method, it is The transmitted data is compiled into frames, each frame contains one or more code groups, and a special character is added to the head of the frame to indicate the beginning of a frame. The receiving end searches the received bit stream, and once this special character is detected, the starting position of the frame is obtained, and the code groups in the frame are divided accordingly. However, in some cases, the frame synchronization code group is not inserted in the information code stream, but a frame synchronization code is inserted every certain number of information symbols, and the receiving end can search and detect the received symbols. Determine the position of the frame synchronization code. The search and detection of the frame synchronization position can generally use the external synchronization method or the self-synchronization method. Specifically, after the receiving end receives the data from the sending end, it performs a sliding correlation between the local sequence and the receiving sequence. If it is at the boundary position of the synchronous capture frame , the correlation function of the two sequences will have a sharp peak, and the synchronization position information can be obtained by using the correlation peak. The external synchronization method often inserts a pilot sequence with good autocorrelation characteristics before each frame, that is, frame synchronization codes, such as Barker codes, m sequences, and so on. Then, sliding detection is performed on the received signal at the receiving end, and the position of the frame header is calculated according to the correlation characteristics of the frame synchronization code, so as to realize frame synchronization. Since the magnitude of the received signal may be smaller than the noise magnitude under low SNR, the frame synchronization code is generally detected by correlation accumulation and threshold judgment. The autocorrelation of the frame synchronization code is characterized by a large difference between the main lobe and the side lobe. The sharper the peak of the main lobe, the higher the accuracy of the decision. This difference can be improved by increasing the length of the frame synchronization code. When the frame synchronization The longer the code, that is, the longer the pilot sequence, the higher the effective gain of correlation accumulation will be.
此外,自相关或差分相干检测器在正交频分复用系统中经常使用,基于插入的导频序列和接收信号之间相关性的检测方法也具有广泛应用,这种方法的性能优于非相干检测和自相关检测器,但互相关检测器会消耗大量的资源。研究结果表明,在相同的信噪比下,最优准则算法比简单相关准则算法具有将近3dB的增益。有研究者以匹配滤波器为基础,提出了一种并行搜索方案,该方案利用匹配滤波器计算同步码在每个采样时刻的相关值,若某一时刻相关值大于判决门限,即可判定为成功捕获,而此相关峰值所在的偏移相位即为帧同步检测的估计值。传统的窗搜索峰值检测算法也采用门限判决方法,相关峰值超过门限则判定为帧头捕获成功,但该检测方法的性能对门限的设置非常敏感,为避免峰值检测器对预设门限的依赖,有人提出了一种无需设置门限的峰值检测器,将峰值搜索限定在一个有限长的窗内,作为一段,然后在段内搜索最大值位置作为备选项,接下来判断下一窗口内最大值位置是否与此位置相符,若相符,则帧头搜索成功,完成帧同步,但是该算法计算量较大且需借助于导频,大大增加了复杂度。为进一步降低算法复杂度,基于连续搜索算法的思想,有人提出了滑动相关检测窗口法,从多个样点中抽取一个样点,将抽取出每组样点数据与本地码字进行相关性分析,证明了该方法实现信号捕获的可行性,并且在一定程度上能够节省搜索时间。In addition, autocorrelation or differential coherent detectors are often used in OFDM systems, and detection methods based on the correlation between the inserted pilot sequence and the received signal are also widely used, and the performance of this method is better than that of non- Coherent detection and autocorrelation detectors, but cross-correlation detectors consume a lot of resources. The research results show that under the same signal-to-noise ratio, the optimal criterion algorithm has nearly 3dB gain than the simple correlation criterion algorithm. Some researchers proposed a parallel search scheme based on matched filters. This scheme uses matched filters to calculate the correlation value of the synchronization code at each sampling time. If the correlation value at a certain time is greater than the decision threshold, it can be judged as was successfully captured, and the offset phase at which this correlation peak is located is the estimated value of frame sync detection. The traditional window search peak detection algorithm also uses a threshold judgment method. If the correlation peak value exceeds the threshold, it is judged that the frame header capture is successful. However, the performance of this detection method is very sensitive to the threshold setting. In order to avoid the dependence of the peak detector on the preset threshold, Someone proposed a peak detector without setting a threshold, limiting the peak search to a finite window as a segment, and then searching for the maximum position in the segment as an alternative, and then judging the maximum position in the next window Whether it matches this position, if it matches, the frame header search is successful and frame synchronization is completed, but this algorithm has a large amount of calculation and needs to rely on pilots, which greatly increases the complexity. In order to further reduce the complexity of the algorithm, based on the idea of continuous search algorithm, someone proposed the sliding correlation detection window method, which extracts a sample point from multiple sample points, and performs correlation analysis between the extracted sample point data and the local codeword , which proves the feasibility of this method to achieve signal capture, and can save search time to a certain extent.
为了降低硬件实现所需的码片资源,现有技术中又提出了利用本地序列和接收信号的硬判决结果进行互相关操作实现检测的简化方法,但是其不如根据软判决信息进行相关检 测方法的性能,且在低信噪比环境下,当信号被噪声严重破坏时,这类数据辅助的检测器需要更长的帧头数据来维持信号捕获和同步检测的准确性,导致了数据传输效率的下降,使得突发的隐蔽性和抗截获性降低,同时也带来了更大的带宽需求,降低了频谱利用率。In order to reduce the chip resources required for hardware implementation, a simplified method of using the local sequence and the hard decision results of the received signal to perform cross-correlation operations for detection is proposed in the prior art, but it is not as good as the correlation detection method based on soft decision information. performance, and in a low signal-to-noise ratio environment, when the signal is severely damaged by noise, this type of data-assisted detector needs longer frame header data to maintain the accuracy of signal capture and synchronization detection, resulting in a decrease in data transmission efficiency The decrease reduces the concealment and anti-interception of bursts, and also brings greater bandwidth requirements and reduces spectrum utilization.
发明内容Contents of the invention
本发明提供了一种比特域叠加伪随机序列与稀疏级联编码的传输方法及装置,本发明的接收机在低信噪比下也可实现准确的信号捕获和同步,以完成对信号的有效接收;发送端对待传输信息序列进行稀疏化编码处理,使得伪随机序列与之叠加后,仍能保证一定信噪比下的帧同步准确性,且与传统的编码传输方法相比,可在更低的信噪比下实现信息的可靠传输,详见下文描述:The present invention provides a transmission method and device for superimposing pseudo-random sequences and sparse concatenated coding in the bit field. The receiver of the present invention can also realize accurate signal capture and synchronization under low signal-to-noise ratio, so as to complete effective signal transmission. Receive; the sending end performs sparse coding processing on the information sequence to be transmitted, so that after the pseudo-random sequence is superimposed on it, the frame synchronization accuracy under a certain signal-to-noise ratio can still be guaranteed, and compared with the traditional coding transmission method, it can Reliable transmission of information is achieved under low signal-to-noise ratio, see the following description for details:
一种比特域叠加伪随机序列与稀疏级联编码的传输方法,所述方法包括以下步骤:A transmission method for superimposing pseudo-random sequences and sparse concatenated coding in bit fields, said method comprising the following steps:
(1)在发送端,首先对待传输信息序列进行信道编码,将每个信道编码符号按照稀疏编码方案转换为码元“1”的比例较少的稀疏序列,接着将稀疏序列与伪随机序列逐比特异或叠加得到待传输序列,最后调制发送;(1) At the sending end, channel coding is first performed on the information sequence to be transmitted, and each channel coded symbol is converted into a sparse sequence with a small proportion of symbol "1" according to the sparse coding scheme, and then the sparse sequence and the pseudo-random sequence are one by one The sequence to be transmitted is obtained by bit XOR superposition, and finally modulated and sent;
(2)在接收端,首先将接收信号与本地伪随机序列进行滑动相关判决,以实现帧同步和传输符号同步,进一步移除信号中的伪随机序列,然后在解调器中计算每一比特的硬判决和软判决信息,送入译码器进行译码并计算每个稀疏编码码字的硬输出和软输出信息,最后根据与发送端相同的映射规则得到每个码字对应的信道编码符号硬判决信息和软判决信息,经信道译码得到原始信息序列。(2) At the receiving end, firstly, the received signal and the local pseudo-random sequence are subjected to sliding correlation judgment to realize frame synchronization and transmission symbol synchronization, further remove the pseudo-random sequence in the signal, and then calculate each bit in the demodulator The hard decision and soft decision information are sent to the decoder for decoding and the hard output and soft output information of each sparsely coded codeword are calculated, and finally the channel coding corresponding to each codeword is obtained according to the same mapping rules as the sending end Symbol hard-decision information and soft-decision information are channel-decoded to obtain the original information sequence.
本发明提供的技术方案的有益效果是:The beneficial effects of the technical solution provided by the invention are:
1、本发明提出的叠加伪随机序列的级联编码传输方法可用一个码流与载波同时实现帧同步和信息传输两个功能;1. The concatenated coding transmission method of superimposing pseudo-random sequences proposed by the present invention can realize two functions of frame synchronization and information transmission simultaneously with one code stream and carrier;
2、本发明通过在发送端对待传输信息序列进行稀疏化编码处理,使得伪随机序列与之叠加后,仍能保证一定信噪比下的帧同步准确性;2. The present invention performs sparse coding processing on the information sequence to be transmitted at the sending end, so that after the pseudo-random sequence is superimposed on it, the accuracy of frame synchronization under a certain signal-to-noise ratio can still be guaranteed;
3、本发明与传统的编码传输方法相比,可在更低的信噪比下实现信息的可靠传输。3. Compared with the traditional coded transmission method, the present invention can realize reliable transmission of information at a lower signal-to-noise ratio.
附图说明Description of drawings
图1为本发明方案实现的系统框图;Fig. 1 is the system block diagram that the scheme of the present invention realizes;
图2为本发明中叠加伪随机序列后的待传输序列结构示意图;Fig. 2 is a schematic diagram of the structure of the sequence to be transmitted after superimposing the pseudo-random sequence in the present invention;
图3为本发明基于低重序列映射的发送端实现流程图;Fig. 3 is the implementation flowchart of the sending end based on the low-heavy sequence mapping of the present invention;
图4为本发明中与2编码比特对应的w固定为1的序列集V 4的波形表示示意图; Fig. 4 is the schematic representation of the waveform of the sequence set V 4 corresponding to 2 coded bits w fixed to 1 in the present invention;
图5为本发明中与3编码比特对应的w固定为1的序列集V 8的波形表示示意图; Fig. 5 is the schematic representation of the waveform of the sequence set V 8 corresponding to 3 code bits w fixed to 1 in the present invention;
图6为本发明w固定为1构造的序列集的波形表示示意图;FIG. 6 is a schematic representation of a waveform of a sequence set constructed with w fixed as 1 in the present invention;
图7为本发明w不固定构造的序列集的波形表示示意图;Fig. 7 is a schematic representation of a waveform of a sequence set with w not fixed structure in the present invention;
图8为本发明基于低重码字映射的发送端实现流程图;Fig. 8 is the implementation flow chart of the sending end based on the low repetition code word mapping of the present invention;
图9本发明基于低重序列映射的接收端译码流程图;Fig. 9 is a flow chart of decoding at the receiving end based on low-heavy sequence mapping in the present invention;
图10本发明基于低重码字映射的接收端译码流程图;Fig. 10 the present invention is based on the decoding flow chart of the receiving end of low repetition codeword mapping;
图11为本发明具体实施例1帧同步检测性能仿真图;FIG. 11 is a simulation diagram of frame synchronization detection performance in Embodiment 1 of the present invention;
图12为本发明具体实施例1在AWGN信道下,RS码和LDPC码分别作为外码的译码误比特率性能图;Fig. 12 is the specific embodiment 1 of the present invention under AWGN channel, RS code and LDPC code are respectively used as the decoding bit error rate performance figure of outer code;
图13为本发明具体实施例2在AWGN信道下的帧同步检测错误率曲线;Fig. 13 is the frame synchronization detection error rate curve under the AWGN channel of Embodiment 2 of the present invention;
图14为本发明具体实施例3在AWGN信道下的帧同步检测错误率曲线;Fig. 14 is the frame synchronization detection error rate curve under the AWGN channel of the specific embodiment 3 of the present invention;
图15为本发明具体实施例2和3在AWGN信道下的译码误比特率性能图。Fig. 15 is a performance diagram of the decoding bit error rate of the specific embodiments 2 and 3 of the present invention under the AWGN channel.
表1为本发明具体实施例3比特组成的编码符号与序列集V 8中8组二进制稀疏序列的对应关系; Table 1 is the corresponding relationship between the coding symbol composed of 3 bits and the sequence set V8 in the specific embodiment of the present invention, and 8 groups of binary sparse sequences;
表2为本发明w不固定构造的与6编码比特对应的长度为8码片的序列集V 64的各组二进制稀疏序列与编码符号的对应关系示意图。 Table 2 is a schematic diagram of the corresponding relationship between each group of binary sparse sequences and coded symbols in the sequence set V 64 with a length of 8 chips corresponding to 6 coded bits, which is constructed w indefinitely in the present invention.
具体实施方式Detailed ways
为使本发明的目的、技术方案和优点更加清楚,下面对本发明实施方式作进一步地详细描述。In order to make the purpose, technical solution and advantages of the present invention clearer, the implementation manners of the present invention will be further described in detail below.
针对短突发通信在低信噪比环境中传输存在的困难,为保证其突发检测的准确性和数据传输的可靠性,本发明实施例提出了一种比特域叠加伪随机序列与稀疏编码序列的低信噪比通信方法。Aiming at the difficulties of short-burst communication transmission in low signal-to-noise ratio environment, in order to ensure the accuracy of burst detection and the reliability of data transmission, the embodiment of the present invention proposes a bit-field superimposed pseudo-random sequence and sparse coding Sequential low signal-to-noise ratio communication methods.
在发送端,首先对待传输信息序列进行信道编码,然后将每个信道编码符号按照专门设计的稀疏编码方案转换为码元“1”的比例较少的稀疏序列,接着将稀疏序列与伪随机序列逐比特异或叠加得到待传输序列,最后调制发送;在接收端,首先将接收信号与本地伪随机序列进行滑动相关判决,以实现帧同步和传输符号同步,进一步移除信号中的伪随机序列,然后在解调器中计算每一比特的硬判决和软判决信息,并送入译码器进行译码并计算每个稀疏编码码字的硬输出和软输出信息,最后根据与发送端相同的映射规则得到每 个码字对应的信道编码符号硬判决信息和软判决信息,经信道译码得到原始信息序列。At the sending end, channel coding is first performed on the information sequence to be transmitted, and then each channel coding symbol is converted into a sparse sequence with a small proportion of symbol "1" according to a specially designed sparse coding scheme, and then the sparse sequence is combined with the pseudo-random sequence The sequence to be transmitted is obtained by bit-by-bit XOR superposition, and finally modulated and sent; at the receiving end, firstly, the received signal and the local pseudo-random sequence are subjected to sliding correlation judgment to achieve frame synchronization and transmission symbol synchronization, and further remove the pseudo-random sequence in the signal , and then calculate the hard decision and soft decision information of each bit in the demodulator, and send it to the decoder for decoding and calculate the hard output and soft output information of each sparse codeword, and finally according to the same According to the mapping rule, the hard-decision information and soft-decision information of the channel coding symbols corresponding to each codeword are obtained, and the original information sequence is obtained through channel decoding.
本发明提出的方法可在低信噪比下保证帧同步的高准确性以及实现信息的可靠传输,在一定的同步码相关性能损失下,可实现传输数据的无干扰分离。另外,本发明提出的方法可根据信道状况灵活选择相关长度,最大长度与帧长相同,有较好的信道适应性,从而实现滑动相关检测算法中复杂度与性能的权衡。The method proposed by the invention can ensure high accuracy of frame synchronization and realize reliable transmission of information under low signal-to-noise ratio, and can realize interference-free separation of transmission data under certain synchronization code related performance loss. In addition, the method proposed by the present invention can flexibly select the correlation length according to channel conditions, the maximum length is the same as the frame length, and has good channel adaptability, thereby realizing the trade-off between complexity and performance in the sliding correlation detection algorithm.
本发明面向数字通信领域,提出一种叠加伪随机序列的级联编码传输方法,选取相关性良好的伪随机序列作为信息传输的载体,与稀疏编码序列叠加后,仍具有良好的自相关特性,且无需专门为训练序列分配时隙,有效提高了频带利用率,同时利用伪随机序列的相关性,采用滑动相关捕获法进行信号捕获,在没有传输资源损失的情况下能精确实现帧同步和传输符号同步,并结合级联码实现低信噪比下信息的可靠传输,与传统的编码传输方法相比,本发明可以用一个码流同时实现帧同步与信息传输两个功能。下面结合附图对本发明中的通信方案做出详细说明。Facing the field of digital communication, the present invention proposes a cascaded coding transmission method of superimposing pseudo-random sequences, selects pseudo-random sequences with good correlation as the carrier of information transmission, and still has good autocorrelation characteristics after being superimposed with sparse coding sequences, And there is no need to allocate time slots for the training sequence, which effectively improves the frequency band utilization. At the same time, using the correlation of the pseudo-random sequence, the sliding correlation acquisition method is used for signal acquisition, and the frame synchronization and transmission can be accurately realized without loss of transmission resources. Symbol synchronization, combined with concatenated codes to achieve reliable transmission of information under low signal-to-noise ratio, compared with traditional coding transmission methods, the present invention can use one code stream to simultaneously realize two functions of frame synchronization and information transmission. The communication solution in the present invention will be described in detail below in conjunction with the accompanying drawings.
本发明方案的系统实现框图如图1所示,本发明方案应包括以下步骤:The system realization block diagram of the scheme of the present invention is as shown in Figure 1, and the scheme of the present invention should comprise the following steps:
(1)在发送端,首先对待传输信息序列进行信道编码,然后将每个信道编码符号按照专门设计的稀疏编码方案转换为码元“1”的比例较少的稀疏序列,接着将稀疏序列与伪随机序列逐比特异或叠加得到待传输序列,如图2所示,最后调制发送;(1) At the sending end, channel coding is first performed on the information sequence to be transmitted, and then each channel coding symbol is converted into a sparse sequence with a small proportion of symbol "1" according to a specially designed sparse coding scheme, and then the sparse sequence is combined with The pseudo-random sequence is XOR-superposed bit by bit to obtain the sequence to be transmitted, as shown in Figure 2, and finally modulated and sent;
(2)在接收端,首先将接收信号与本地伪随机序列进行滑动相关判决,以实现帧同步和传输符号同步,进一步移除信号中的伪随机序列,然后在解调器中计算每一比特的硬判决和软判决信息,并送入译码器进行译码并计算每个稀疏编码码字的硬输出和软输出信息,最后根据与发送端相同的映射规则得到每个码字对应的信道编码符号硬判决信息和软判决信息,经信道译码得到原始信息序列。(2) At the receiving end, firstly, the received signal and the local pseudo-random sequence are subjected to sliding correlation judgment to realize frame synchronization and transmission symbol synchronization, further remove the pseudo-random sequence in the signal, and then calculate each bit in the demodulator The hard decision and soft decision information are sent to the decoder to decode and calculate the hard output and soft output information of each sparsely coded codeword. Finally, the channel corresponding to each codeword is obtained according to the same mapping rules as the sending end. Encode symbol hard-decision information and soft-decision information, and obtain the original information sequence through channel decoding.
其中,本地伪随机序列具体是与发送端相同的伪随机序列m,接收机可根据信道状况选择相关器的滑动窗口长度,其中最大长度与帧长相同,相应地,位于滑动窗口内进行相关运算的本地序列为从伪随机序列m由其首向后截取的相同长度的二进制序列。Among them, the local pseudo-random sequence is specifically the same pseudo-random sequence m as that of the sender, and the receiver can select the sliding window length of the correlator according to the channel conditions, where the maximum length is the same as the frame length, and correspondingly, the correlation operation is performed within the sliding window The local sequence of is a binary sequence of the same length intercepted from the pseudo-random sequence m from its head to the rear.
其中,上述步骤(1)具体为:Wherein, the above step (1) is specifically:
(1.1)K信息比特经过信道编码后得到N比特长的编码码字c,c以每p比特编码码字为一组,其中第i组比特流可表示为[c ip,c ip+1,…,c ip+p-1],组成对应的编码符号,表示为e i(1.1) After K information bits are channel-coded, an N-bit-long encoded codeword c is obtained. Each p-bit encoded codeword for c is a group, and the i-th group of bit streams can be expressed as [c ip ,c ip+1 , …,c ip+p-1 ] to form the corresponding encoding symbols, denoted as e i ,
Figure PCTCN2021121021-appb-000001
Figure PCTCN2021121021-appb-000001
其中i∈{0,1,…,N/P-1},c ip+1为第i组比特流的第二个码片,c ip+j为第i组比特流的第j个码片,N为码字c的比特长度,p为每组比特流的码元个数。 Where i∈{0,1,…,N/P-1}, c ip+1 is the second chip of the i-th bit stream, c ip+j is the j-th chip of the i-th bit stream , N is the bit length of the codeword c, and p is the number of symbols in each group of bit streams.
(1.2)构建用以实现信道编码码字稀疏化的映射序列集V,并根据映射序列集V设计专门的稀疏编码方案,经稀疏编码后得到二进制稀疏序列s;(1.2) Construct a mapping sequence set V for realizing the sparseness of channel coding codewords, and design a special sparse coding scheme according to the mapping sequence set V, and obtain a binary sparse sequence s after sparse coding;
(1.3)将二进制稀疏序列s与伪随机序列m进行逐码片异或得到待传输序列t,
Figure PCTCN2021121021-appb-000002
调制并发送。
(1.3) Perform chip-by-chip XOR of the binary sparse sequence s and the pseudo-random sequence m to obtain the sequence t to be transmitted,
Figure PCTCN2021121021-appb-000002
Modulate and send.
其中,上述步骤(2)具体为:Wherein, the above-mentioned step (2) is specifically:
(2.1)接收端收到传输信号,首先根据已知的伪随机序列通过互相关检测器实现信号捕获,完成帧同步和传输符号同步;(2.1) The receiving end receives the transmission signal, first realizes signal capture through the cross-correlation detector according to the known pseudo-random sequence, and completes frame synchronization and transmission symbol synchronization;
(2.2)移除接收信号中的伪随机序列,根据本地已知的伪随机序列的脉冲位置对接收信号进行符号翻转,从而恢复出叠加的稀疏序列,并送入解调器;(2.2) Remove the pseudo-random sequence in the received signal, and flip the sign of the received signal according to the pulse position of the locally known pseudo-random sequence, thereby recovering the superimposed sparse sequence and sending it to the demodulator;
(2.3)在解调器中计算每一比特的硬判决和软判决信息,接着根据与发送端稀疏编码方案中相应的映射规则得到每条稀疏序列对应的信道编码符号硬信息和软信息,经信道译码得到原始信息序列。(2.3) Calculate the hard decision and soft decision information of each bit in the demodulator, and then obtain the hard information and soft information of the channel coding symbols corresponding to each sparse sequence according to the corresponding mapping rules in the sparse coding scheme at the sending end, and then pass Channel decoding obtains the original information sequence.
其中,上述步骤(1.2)中的二进制稀疏序列s的生成,具体有两种稀疏编码实现方式,分别为:Among them, the generation of the binary sparse sequence s in the above step (1.2) specifically has two sparse coding implementation methods, which are:
第一种:利用低重序列映射实现稀疏编码,如图3所示,首先,构建的序列集中每组序列的重量w可不完全相等,在保证序列稀疏性的前提下,w可为任意小于序列长度一半的值,如图4、5、6、7、8及表1所示,然后,建立信道编码符号与稀疏序列集之间的映射关系,得到稀疏编码码字序列。The first one: use low-heavy sequence mapping to implement sparse coding, as shown in Figure 3. First, the weight w of each sequence in the constructed sequence set may not be completely equal. On the premise of ensuring the sparsity of the sequence, w can be arbitrarily smaller than the sequence The value of half the length is shown in Figures 4, 5, 6, 7, 8 and Table 1. Then, the mapping relationship between the channel coding symbols and the sparse sequence set is established to obtain the sparse coding codeword sequence.
其中,将二进制序列中符号“1”的密度小于1/2的序列称为低重序列;具体的,其实现步骤如下:Among them, the sequence in which the density of the symbol "1" in the binary sequence is less than 1/2 is called a low-heavy sequence; specifically, the implementation steps are as follows:
(3.1)序列集包括2 p组不同的二进制稀疏序列,表示为
Figure PCTCN2021121021-appb-000003
其中每组序列的长度为l码片,位置编号为a的一组二进制稀疏序列可表示为
Figure PCTCN2021121021-appb-000004
l≤2 p,α=0,1,…,2 p-1;
(3.1) The sequence set includes 2 p groups of different binary sparse sequences, expressed as
Figure PCTCN2021121021-appb-000003
The length of each group of sequences is l chips, and a group of binary sparse sequences whose position number is a can be expressed as
Figure PCTCN2021121021-appb-000004
l≤2 p , α=0,1,...,2 p -1;
(3.2)选择序列集V中位置编号与编码符号值对应的二进制稀疏序列作为传输符号,即当编码符号为e i,选择序列集V中位置编号为e i的二进制稀疏序列
Figure PCTCN2021121021-appb-000005
作为对应的传输符号,稀疏编码完成;
(3.2) Select the binary sparse sequence corresponding to the position number in the sequence set V and the encoding symbol value as the transmission symbol, that is, when the encoding symbol is e i , select the binary sparse sequence whose position number is e i in the sequence set V
Figure PCTCN2021121021-appb-000005
As the corresponding transmission symbol, sparse coding is completed;
(3.3)针对低重序列映射实现稀疏编码的方案设计相应的译码算法。(3.3) Design the corresponding decoding algorithm for the low-weight sequence mapping scheme to realize sparse coding.
第二种:利用低重码字映射实现稀疏编码,如图8所示,首先,利用纠错码的部分低重码字的信息位来构建序列集,这可使得序列集中每组序列经纠错编码后得到的码字均为低码重的码字,然后建立信道编码符号与低重码字的信息位之间的映射关系,最后对映射完成后的序列进行低重纠错编码,得到稀疏编码码字序列。The second method: use low-repetition codeword mapping to realize sparse coding, as shown in Figure 8, first, use the information bits of some low-repetition codewords of the error-correcting code to construct a sequence set, which can make each group of sequences in the sequence set undergo error-correcting coding The obtained codewords are all low-weight codewords, and then the mapping relationship between the channel coding symbols and the information bits of the low-weight codewords is established, and finally the low-heavy error correction coding is performed on the mapped sequence to obtain the sparse code sequence of words.
其中,将二进制编码码字序列中符号“1”的密度小于1/2的码字称为低重码字。Wherein, the code word whose symbol "1" density is less than 1/2 in the binary code word sequence is called low repetition code word.
具体的,其实现步骤如下:Specifically, the implementation steps are as follows:
(4.1)以Golay(23,12)码为例,映射序列集V由Golay(23,12)码中码重为0、7和8的编码码字的12比特信息位组成,其中
Figure PCTCN2021121021-appb-000006
表示位置编号为a的一组二进制序列,α=0,1,…,N/P-1;
(4.1) Taking the Golay(23,12) code as an example, the mapping sequence set V is composed of the 12-bit information bits of the encoded codewords with code weights 0, 7 and 8 in the Golay(23,12) code, where
Figure PCTCN2021121021-appb-000006
Represents a set of binary sequences whose position number is a, α=0,1,...,N/P-1;
(4.2)根据映射规则选择序列集V中位置编号与编码符号值对应的二进制序列作为传输序列,即当编码符号为c i,选择序列集V中位置编号为c i的二进制序列
Figure PCTCN2021121021-appb-000007
作为对应的传输序列,完成映射;
(4.2) According to the mapping rules, select the binary sequence corresponding to the position number and the encoding symbol value in the sequence set V as the transmission sequence, that is, when the encoding symbol is c i , select the binary sequence whose position number is c i in the sequence set V
Figure PCTCN2021121021-appb-000007
As the corresponding transmission sequence, complete the mapping;
(4.3)对映射得到的传输序列执行Golay编码,即每12比特为一组编码为23比特长的重量为0、7或8的二进制稀疏序列s;(4.3) Golay encoding is performed on the mapped transmission sequence, that is, every 12 bits is a binary sparse sequence s encoded as a 23-bit long binary sparse sequence s with a weight of 0, 7 or 8;
(4.4)针对低重码字映射实现稀疏编码的方案设计相应的译码算法。(4.4) Design a corresponding decoding algorithm for the low-repetition codeword mapping scheme to realize sparse coding.
其中,上述步骤(2.1)具体为:Wherein, the above-mentioned step (2.1) is specifically:
(5.1)将接收信号y和本地伪随机序列m送入互相关检测器,进行滑动相关,其输出R(k,g)即为互相关值,可表示为:(5.1) Send the received signal y and the local pseudo-random sequence m into the cross-correlation detector for sliding correlation, and the output R(k, g) is the cross-correlation value, which can be expressed as:
Figure PCTCN2021121021-appb-000008
Figure PCTCN2021121021-appb-000008
其中,N k为相关器滑动窗口长度,y(n+g)为接收信号移位g位后的序列,m(n)为处于滑动窗口内的伪随机序列,k表示相关器输出的序号,n为数字样值序号。 Among them, N k is the length of the sliding window of the correlator, y(n+g) is the sequence after the received signal is shifted by g bits, m(n) is the pseudo-random sequence in the sliding window, k represents the sequence number output by the correlator, n is the serial number of the digital sample.
(5.2)检测任何时刻的相关结果,搜索相关峰位置,其判决准则为:(5.2) Detect the correlation results at any time, search for the correlation peak position, and the judgment criterion is:
Figure PCTCN2021121021-appb-000009
Figure PCTCN2021121021-appb-000009
其中,
Figure PCTCN2021121021-appb-000010
表示搜索到的相关峰位置,代表数据帧的到达。
in,
Figure PCTCN2021121021-appb-000010
Indicates the searched correlation peak position, representing the arrival of the data frame.
(5.3)成功完成码捕获后,根据相关峰位置,确定帧同步估计值,找到接收信号一帧的起始位置,建立与发送端起止时刻一致的脉冲序列,实现帧同步;(5.3) After successfully completing the code capture, determine the estimated value of frame synchronization according to the position of the correlation peak, find the starting position of one frame of the received signal, establish a pulse sequence consistent with the start and end times of the sending end, and realize frame synchronization;
(5.4)将接收信号进行划分,以每l码片为一组作为接收符号,实现传输符号同步, 并依次送入解调器计算每一符号的软信息。(5.4) Divide the received signal into a group of 1 chip as the received symbol to realize the synchronization of the transmitted symbols, and send them to the demodulator to calculate the soft information of each symbol in turn.
参见图9,上述步骤(3.3)中针对低重序列映射实现稀疏编码的方案设计的译码算法的具体步骤为:Referring to Fig. 9, in the above step (3.3), the specific steps of the decoding algorithm designed for the low-heavy sequence mapping to realize the sparse coding scheme are as follows:
(6.1)每l码片的接收信号组成一个符号,送入解调器,其中第n组接收信号表示为
Figure PCTCN2021121021-appb-000011
(6.1) The received signal of every l chip forms a symbol and is sent to the demodulator, where the nth group of received signal is expressed as
Figure PCTCN2021121021-appb-000011
(6.2)在解调器中,每个符号根据序列集V利用l维高斯分布密度函数计算软信息,表示为:(6.2) In the demodulator, each symbol uses the l-dimensional Gaussian distribution density function to calculate the soft information according to the sequence set V, expressed as:
Figure PCTCN2021121021-appb-000012
Figure PCTCN2021121021-appb-000012
其中,
Figure PCTCN2021121021-appb-000013
为该接收符号对应v a在序列集V的位置编号a的符号似然信息,σ 2为噪声方差,
Figure PCTCN2021121021-appb-000014
为第n组接收信号的第j个码片,
Figure PCTCN2021121021-appb-000015
为序列集V中的位置编号为a的序列的第j个码片。
in,
Figure PCTCN2021121021-appb-000013
is the symbol likelihood information of the received symbol corresponding to the position number a of v a in the sequence set V, σ 2 is the noise variance,
Figure PCTCN2021121021-appb-000014
is the jth chip of the nth group of received signals,
Figure PCTCN2021121021-appb-000015
is the j-th chip of the sequence numbered a in the sequence set V.
(6.3)将得到的符号似然信息进行归一化后作为没有译码时的初始概率直接送入多进制译码器进行译码,或将其转为比特软信息后送入二进制译码器进行译码,将第n组信息比特对应符号a的初始符号概率表示为
Figure PCTCN2021121021-appb-000016
计算方式为:
(6.3) Normalize the obtained symbol likelihood information as the initial probability without decoding and directly send it to the multi-ary decoder for decoding, or convert it into bit soft information and send it to binary decoding The device decodes, and the initial symbol probability of the nth group of information bits corresponding to the symbol a is expressed as
Figure PCTCN2021121021-appb-000016
The calculation method is:
Figure PCTCN2021121021-appb-000017
Figure PCTCN2021121021-appb-000017
参见图10,上述步骤(4.4)中针对低重码字映射实现稀疏编码的方案设计的译码算法的具体步骤为:Referring to Fig. 10, in the above-mentioned step (4.4), the specific steps of the decoding algorithm for the scheme design of realizing sparse coding for the low-repetition codeword mapping are:
(7.1)在解调器中计算每一比特对数似然信息r i并得到相应的硬判决结果u i,其中, (7.1) Calculate the logarithmic likelihood information r i of each bit in the demodulator and obtain the corresponding hard decision result u i , where,
Figure PCTCN2021121021-appb-000018
Figure PCTCN2021121021-appb-000018
(7.2)根据得到的比特对数似然信息和硬判决结果,以相关差作为译码度量进行Golay译码,其中相关差
Figure PCTCN2021121021-appb-000019
相关差最小的码字即为Golay译码结果;
(7.2) According to the obtained bit log likelihood information and hard decision results, Golay decoding is performed with the correlation difference as the decoding metric, where the correlation difference
Figure PCTCN2021121021-appb-000019
The codeword with the smallest correlation difference is the Golay decoding result;
其中,r i·s i表示两个序列第i个码片的乘积,r i为接收序列的第i个码片,s i为映射表 中的稀疏序列的第i个码片。 Among them, ri · s i represents the product of the i-th chip of the two sequences, ri is the i-th chip of the received sequence, and s i is the i-th chip of the sparse sequence in the mapping table.
(7.3)Golay译码完成后,按照与发送端相同的映射规则得到每个码字对应的信道编码符号硬判决和软判决信息,并输出到信道译码器;(7.3) After the Golay decoding is completed, the hard decision and soft decision information of the channel coding symbols corresponding to each codeword are obtained according to the same mapping rules as the sending end, and are output to the channel decoder;
(7.4)根据得到的信道编码符号的硬判决和软判决信息,完成信道译码,恢复传输信息。(7.4) According to the obtained hard decision and soft decision information of the channel coding symbols, complete channel decoding and restore transmission information.
本发明设计的一种比特域叠加伪随机序列与稀疏编码序列的低信噪比通信方法,可用一个码流与载波同时实现帧同步和信息传输两个功能,无需为导频分配额外的时隙。下面给出三个具体的实施例,均在AWGN信道下,采用BPSK调制方法,说明本发明方法的可行性,进一步了解发明的目的、特征和优点。A low signal-to-noise ratio communication method designed by the present invention, in which a pseudo-random sequence and a sparse coded sequence are superimposed in a bit field, can realize two functions of frame synchronization and information transmission at the same time with one code stream and a carrier, without allocating additional time slots for pilots . Three specific embodiments are given below, all under the AWGN channel, adopting the BPSK modulation method to illustrate the feasibility of the method of the present invention, and to further understand the purpose, characteristics and advantages of the invention.
实施例1Example 1
本实施例采用的信道编码为定义在GF(512)域上的RS(511,k)码,码率为k/511,信息序列长度为511个符号,每个符号9个比特。伪随机序列采用级数为14,反馈系数为42103(八进制)的m序列。The channel coding used in this embodiment is the RS(511, k) code defined on the GF(512) domain, the code rate is k/511, the length of the information sequence is 511 symbols, and each symbol has 9 bits. The pseudo-random sequence adopts an m-sequence with a series number of 14 and a feedback coefficient of 42103 (octal).
如附图1系统模型所示,方案具体过程如下:As shown in the system model in Figure 1, the specific process of the scheme is as follows:
(1)随机信源以每9比特信息为一组,得到符号长度为k的信息序列后送入RS编码器,进行编码得到符号长度为511的512进制RS码字e=[e 0,e 1,…,e 510]; (1) The random information source takes every 9 bits of information as a group, obtains an information sequence with a symbol length of k, and sends it to the RS encoder for encoding to obtain a 512-ary RS code word e=[e 0 , with a symbol length of 511 e 1 ,...,e 510 ];
(2)构造映射表,选择511个Golay(23,12)码中重量分别为7或8的码字所对应的信息位,另外加上全0码字,以此构成映射表,分别对应GF(512)的每一个元素;(2) Construct a mapping table, select the information bits corresponding to the codewords with weights of 7 or 8 in 511 Golay (23,12) codes, and add all 0 codewords to form a mapping table, corresponding to GF each element of (512);
(3)选择映射序列集中位置编号与编码符号值对应的二进制序列作为传输符号,即若编码符号为e i,则选择序列集V中的二进制稀疏序列
Figure PCTCN2021121021-appb-000020
作为传输符号,符号映射完成;
(3) Select the binary sequence corresponding to the position number in the mapping sequence set and the encoding symbol value as the transmission symbol, that is, if the encoding symbol is e i , then select the binary sparse sequence in the sequence set V
Figure PCTCN2021121021-appb-000020
As a transmission symbol, the symbol mapping is completed;
(4)比特长度为4599的序列经过映射并执行Golay(23,12)编码,得到511组23码片长的传输符号,将这些传输符号组成的该稀疏序列s与处理为长度为11753的m序列m逐码片异或后得到待传输序列x;(4) A sequence with a bit length of 4599 is mapped and Golay(23,12) encoded to obtain 511 groups of transmission symbols with a length of 23 chips, and the sparse sequence s composed of these transmission symbols is processed into m with a length of 11753 After the sequence m is XORed chip by chip, the sequence x to be transmitted is obtained;
其中,m序列超过11753的部分进行截断操作。Among them, the part of the m-sequence exceeding 11753 is truncated.
其中,待传输序列实际是33%码片翻转的伪随机序列,整体传输码率为9k/(511×23)。Wherein, the sequence to be transmitted is actually a pseudo-random sequence with 33% chip inversion, and the overall transmission code rate is 9k/(511×23).
(5)将待传输序列x进行BPSK调制后依次发送;(5) carry out BPSK modulation to the sequence x to be transmitted and send it sequentially;
(6)信号经过AWGN信道后,到达接收端的信号为y,然后将y和本地序列m送入滑 动相关检测器中,连续地进行相关处理,其输出R(k,g)即为互相关值,计算方式参见公式(2);(6) After the signal passes through the AWGN channel, the signal arriving at the receiving end is y, and then y and the local sequence m are sent to the sliding correlation detector for continuous correlation processing, and the output R(k,g) is the cross-correlation value , see formula (2) for the calculation method;
(7)检测任何时刻的相关结果,搜索相关峰位置,其判决准则参见公式(3);(7) Detect the correlation results at any time, and search for the correlation peak position, the judgment criterion is shown in formula (3);
(8)成功完成码捕获后,根据相关峰位置,确定帧同步估计值,找到接收信号一帧的起始位置,建立与发送端起止时刻一致的脉冲序列,实现帧同步;(8) After successfully completing the code capture, determine the estimated frame synchronization value according to the correlation peak position, find the starting position of one frame of the received signal, set up a pulse sequence consistent with the start and end times of the sending end, and realize frame synchronization;
(9)将接收信号进行划分,以23码片为一组作为接收符号,实现传输符号同步,并将符号依次送入解调器计算每一比特的硬判决信息和软判决信息。在解调器中计算每一比特对数似然信息r i并得到相应的硬判决结果u i,硬判决方式参见公式(6); (9) Divide the received signal into a group of 23 chips as the received symbols to realize the synchronization of the transmitted symbols, and send the symbols to the demodulator in turn to calculate the hard decision information and soft decision information of each bit. Calculate the logarithmic likelihood information r i of each bit in the demodulator and obtain the corresponding hard decision result u i , see formula (6) for the hard decision method;
(10)利用已知的伪随机序列,对解调器得到的硬判决和软判决信息进行处理,移除叠加的伪随机序列;(10) Utilize the known pseudo-random sequence to process the hard decision and soft decision information obtained by the demodulator, and remove the superimposed pseudo-random sequence;
(11)根据得到的比特对数似然信息和硬判决结果,以相关差作为译码度量进行Golay译码,其中相关差
Figure PCTCN2021121021-appb-000021
相关差最小的码字即为Golay译码结果,直接进行硬判决;
(11) According to the obtained bit log likelihood information and hard decision results, Golay decoding is performed with the correlation difference as the decoding metric, where the correlation difference
Figure PCTCN2021121021-appb-000021
The codeword with the smallest correlation difference is the result of Golay decoding, and the hard decision is directly made;
(12)按照与发送端相同的映射规则得到Golay译码硬判决结果对应的RS编码符号,并输出到RS译码器;(12) Obtain the RS coding symbols corresponding to the Golay decoding hard decision results according to the same mapping rules as the sending end, and output them to the RS decoder;
(13)RS译码器采用硬判决译码算法,根据得到的信道编码符号的硬判决信息,完成RS译码,得到原始的信息序列。(13) The RS decoder adopts a hard-decision decoding algorithm to complete RS decoding according to the obtained hard-decision information of the channel coded symbols to obtain the original information sequence.
首先,对本实施例的帧同步检测错误率进行了统计,如图11所示,帧同步检测性能随滑动相关窗口长度的增大而提高,相关长度为11753时,m序列有最优的帧同步检测性能,在信噪比为-22dB时,错误率达到10 -4,当相关长度仅为1023时,帧同步检测错误率在信噪比为-5dB下可达10 -4,验证了所提方案在低信噪比下出色的帧同步检测性能。 First, statistics are made on the error rate of frame synchronization detection in this embodiment. As shown in Figure 11, the performance of frame synchronization detection increases with the increase of the length of the sliding correlation window. When the correlation length is 11753, the m-sequence has the optimal frame synchronization Detection performance, when the signal-to-noise ratio is -22dB, the error rate reaches 10 -4 , when the correlation length is only 1023, the frame synchronization detection error rate reaches 10 -4 when the signal-to-noise ratio is -5dB, which verifies the proposed The scheme has excellent frame synchronization detection performance under low signal-to-noise ratio.
然后,对本实施例的错误性能进行仿真,如图12所示,本实施例中以RS码为外码,级联码整体码率为0.192时在信噪比为-3.2dB时,系统的译码误比特错误率(BER)可达到10 -5。本方案中以1/2码率的NB-LDPC码为外码,级联码整体码率为0.196时,在信噪比为-6.2dB时,系统的译码误比特错误率(BER)可达到10 -5;以1/3码率的NB-LDPC码为外码,级联码整体码率为0.131时,在信噪比为-7.8dB时,系统的译码误比特错误率(BER)可达到10 -5Then, the error performance of this embodiment is simulated, as shown in Figure 12, in this embodiment, the RS code is used as the outer code, and when the overall code rate of the concatenated code is 0.192, when the signal-to-noise ratio is -3.2dB, the system's translation The code error bit error rate (BER) can reach 10 -5 . In this scheme, the NB-LDPC code with a code rate of 1/2 is used as the outer code. When the overall code rate of the concatenated code is 0.196, and the signal-to-noise ratio is -6.2dB, the decoding bit error rate (BER) of the system can be 10 -5 ; with the NB-LDPC code of 1/3 code rate as the outer code, when the overall code rate of the concatenated code is 0.131, and the signal-to-noise ratio is -7.8dB, the system's decoding bit error rate (BER ) can reach 10 -5 .
实施例2Example 2
本实施例采用的信道编码为定义在GF(8)域上的LDPC码,所采用的校验矩阵H码长为384符号,码率为1/2,信息序列长度为192符号,对应为,码长1152比特,信息序列长576比特。校验矩阵每行的4个非零元素随机取自对应有限域的非零元素集合{1,2,…,7}。伪随机序列采用级数为12,反馈系数为10123(八进制)的m序列。The channel coding adopted in this embodiment is an LDPC code defined on the GF(8) domain, the adopted parity check matrix H has a code length of 384 symbols, a code rate of 1/2, and an information sequence length of 192 symbols, corresponding to, The code length is 1152 bits, and the information sequence is 576 bits long. The 4 non-zero elements in each row of the parity check matrix are randomly selected from the non-zero element set {1,2,...,7} corresponding to the finite field. The pseudo-random sequence adopts an m-sequence with a series number of 12 and a feedback coefficient of 10123 (octal).
稀疏编码所用序列集包含8组长度为8个码片的二进制稀疏序列,表示为:The sequence set used for sparse coding contains 8 groups of binary sparse sequences with a length of 8 chips, expressed as:
V 8={v 0,v 1,…,v 7} V 8 ={v 0 , v 1 ,...,v 7 }
序列集中位置编号为a的稀疏序列表示为
Figure PCTCN2021121021-appb-000022
其中α∈{0,1,…,7}。附图5所示为序列集V 8的波形表示,表1所示为序列集V 8中子序列与编码符号的对应关系。
The sparse sequence whose position number is a in the sequence set is expressed as
Figure PCTCN2021121021-appb-000022
where α∈{0,1,...,7}. Figure 5 shows the waveform representation of the sequence set V8 , and Table 1 shows the correspondence between subsequences and coding symbols in the sequence set V8 .
表1Table 1
Figure PCTCN2021121021-appb-000023
Figure PCTCN2021121021-appb-000023
如附图1系统模型所示,方案具体过程如下:As shown in the system model in Figure 1, the specific process of the scheme is as follows:
(1)随机信源产生576比特的信息序列,以每3比特信息为一组,得到符号长度为192的信息序列f=[f 0,f 1,…,f 191]后送入LDPC编码器,根据其校验矩阵H进行编码得到符号长度为384的8进制LDPC码字e=[e 0,e 1,…,e 383]; (1) A random information source generates a 576-bit information sequence, and each 3-bit information is used as a group to obtain an information sequence f=[f 0 ,f 1 ,…,f 191 ] with a symbol length of 192 and send it to the LDPC encoder , encode according to its check matrix H to obtain an octal LDPC codeword e=[e 0 , e 1 ,..., e 383 ] whose symbol length is 384;
(2)选择序列集V 8中位置编号与编码符号值对应的二进制稀疏序列作为传输符号,即若编码符号为e i,则选择序列集V中的二进制稀疏序列
Figure PCTCN2021121021-appb-000024
作为传输符号,稀疏编码完成;
(2) Select the binary sparse sequence corresponding to the position number and coded symbol value in the sequence set V 8 as the transmission symbol, that is, if the coded symbol is e i , then select the binary sparse sequence in the sequence set V
Figure PCTCN2021121021-appb-000024
As a transmission symbol, sparse coding is completed;
(3)符号长度为384的码字经过稀疏正交编码,得到384组8码片长的传输符号,将这 些传输符号组成的该稀疏序列
Figure PCTCN2021121021-appb-000025
与长度为3072的伪随机序列m逐码片异或后得到待传输序列t;
(3) The codeword with a symbol length of 384 is sparsely orthogonally encoded to obtain 384 groups of transmission symbols with a length of 8 chips, and the sparse sequence composed of these transmission symbols
Figure PCTCN2021121021-appb-000025
XOR with the pseudo-random sequence m with a length of 3072 chip by chip to obtain the sequence t to be transmitted;
其中,待传输序列实际是12.5%码片翻转的伪随机序列,整体传输码率为3/16。Wherein, the sequence to be transmitted is actually a pseudo-random sequence with 12.5% chip inversion, and the overall transmission code rate is 3/16.
(4)将待传输序列t进行BPSK调制后依次发送;(4) carry out BPSK modulation to the sequence t to be transmitted and send it sequentially;
(5)信号捕获与同步的实际执行步骤参见实施例1中的步骤(6)-(8);(5) For the actual execution steps of signal capture and synchronization, refer to steps (6)-(8) in Embodiment 1;
(6)将接收信号进行划分,每8码片的接收信号
Figure PCTCN2021121021-appb-000026
组成一个符号,送入解调器;
(6) Divide the received signal, the received signal of every 8 chips
Figure PCTCN2021121021-appb-000026
Form a symbol and send it to the demodulator;
(7)在解调器中,每组接收信号根据序列集V 8利用8维高斯分布密度函数计算对应数据的符号似然信息,计算方式参见公式(4); (7) In the demodulator, each group of received signals uses an 8 -dimensional Gaussian distribution density function to calculate the symbol likelihood information of the corresponding data according to the sequence set V8, and the calculation method is shown in formula (4);
(8)将符号似然信息进行归一化后作为没有译码时的初始概率直接送入8进制LDPC译码器进行译码。第n组信息比特对应符号为a的初始符号概率,表示为
Figure PCTCN2021121021-appb-000027
计算方式参见公式(5);
(8) After the symbol likelihood information is normalized, it is directly sent to the octal LDPC decoder for decoding as the initial probability without decoding. The initial symbol probability of the nth group of information bits corresponding to the symbol a is expressed as
Figure PCTCN2021121021-appb-000027
See formula (5) for the calculation method;
在本实施例中,采用GF(8)域上的快速傅里叶变换-置信度传播(FFT-BP)算法进行译码,首先,在AWGN信道下对本实施例的帧同步检测错误率进行了统计,并与传统帧结构中帧头的帧同步检测错误率进行了对比,其中,该帧头也由m序列组成。如附图14所示,当相关器滑动窗口长度为3072时,本实施例的帧同步检测性能为最优,即在信噪比为-17dB时,检测错误率达到10 -5,接近于长度为2047的帧头的帧同步检测性能。而当相关长度分别为1023和2047时,处于滑动窗口内的本地序列分别为伪随机序列的前1023个码片和前2047个码片,检测错误率分别在信噪比为-12dB和-15dB时达到10 -5,分别接近于长度为511和1023的m序列构成的帧头的帧同步检测性能。 In this embodiment, the Fast Fourier Transform-Confidence Propagation (FFT-BP) algorithm on the GF(8) domain is used for decoding. Statistics, and compared with the frame synchronization detection error rate of the frame header in the traditional frame structure, where the frame header is also composed of m-sequence. As shown in Figure 14, when the correlator sliding window length is 3072, the frame synchronization detection performance of this embodiment is optimal, that is, when the signal-to-noise ratio is -17dB, the detection error rate reaches 10 -5 , which is close to the length Frame synchronization detection performance for 2047 frame headers. When the correlation lengths are 1023 and 2047 respectively, the local sequences in the sliding window are the first 1023 chips and the first 2047 chips of the pseudo-random sequence, and the detection error rates are -12dB and -15dB respectively It reaches 10 -5 , which is close to the frame synchronization detection performance of the frame header composed of m-sequences with lengths of 511 and 1023 respectively.
然后,对本实施例在AWGN信道下的系统差错性能进行了仿真。如附图16所示,本实施例在信噪比为-0.8dB时,译码误比特错误率(BER)可达到10 -6,相比采用BPSK调制结合相同LDPC码的传统编码调制传输方案,有约1.3dB的性能增益。。 Then, the system error performance of this embodiment under the AWGN channel is simulated. As shown in Figure 16, when the signal-to-noise ratio is -0.8dB in this embodiment, the decoding bit error rate (BER) can reach 10 -6 . , there is a performance gain of about 1.3dB. .
实施例3Example 3
在发送端以6比特码字为一组进行稀疏编码,采用的序列集V 64如表2所示,表示为V 64=[v 0,v 1,…,v 63],包含64组长度为8个码片的二进制稀疏序列,其中重量w=1的序列有8个,重量w=3的序列有56个,序列集中位置编号为a的稀疏序列表示为
Figure PCTCN2021121021-appb-000028
其中α∈{0,1,…,63}。实施例的具体实现过程如下。
At the sending end, a group of 6-bit codewords is used as a group for sparse coding, and the sequence set V 64 used is shown in Table 2, expressed as V 64 =[v 0 ,v 1 ,…,v 63 ], including 64 groups of length It is a binary sparse sequence of 8 chips, wherein there are 8 sequences with weight w=1, and 56 sequences with weight w=3, and the sparse sequence whose position number is a in the sequence set is expressed as
Figure PCTCN2021121021-appb-000028
where α∈{0,1,...,63}. The specific implementation process of the embodiment is as follows.
表2Table 2
Figure PCTCN2021121021-appb-000029
Figure PCTCN2021121021-appb-000029
本实施例采用的信道编码为定义在GF(64)域上的LDPC码,所采用的校验矩阵H码长为384符号,码率为1/2,信息序列长度为192符号,对应为,码长2304比特,信息序列长1152比特。校验矩阵每行的4个非零元素随机取自对应有限域的非零元素集合。所采用的伪随机序列与具体实施例1相同,方案实现过程与具体实施例2类似。The channel coding adopted in this embodiment is an LDPC code defined on the GF(64) domain, the adopted parity check matrix H has a code length of 384 symbols, a code rate of 1/2, and an information sequence length of 192 symbols, corresponding to, The code length is 2304 bits, and the information sequence is 1152 bits long. The 4 non-zero elements of each row of the parity check matrix are randomly selected from the set of non-zero elements of the corresponding finite field. The pseudo-random sequence used is the same as that of the specific embodiment 1, and the implementation process of the scheme is similar to that of the specific embodiment 2.
在本实施例中,采用GF(64)域上的FFT-BP算法进行译码,首先,在AWGN信道下对本实施例的帧同步检测错误率进行了统计,并与传统帧结构中帧头的帧同步检测错误率进行了对比。如图13所示,相关器滑动窗口长度为3072时,该实施例达到最优的帧同步检 测性能,即在信噪比为-9dB时,错误率达到10 -5,接近于长度为255的m序列构成的帧头的帧同步检测性能。而当相关长度2047时,检测错误率分别在信噪比为-dB时达到10 -5,优于长度为127的帧头的帧同步检测性能。 In this embodiment, the FFT-BP algorithm on the GF(64) domain is used for decoding. First, the frame synchronization detection error rate of this embodiment is counted under the AWGN channel, and compared with the frame header in the traditional frame structure Frame sync detection error rates are compared. As shown in Figure 13, when the correlator sliding window length is 3072, this embodiment achieves the optimal frame synchronization detection performance, that is, when the signal-to-noise ratio is -9dB, the error rate reaches 10 -5 , which is close to the length of 255 Frame synchronization detection performance of frame headers composed of m-sequences. When the correlation length is 2047, the detection error rate reaches 10 -5 when the signal-to-noise ratio is -dB, which is better than the frame synchronization detection performance of the frame header whose length is 127.
然后,对本实施例在AWGN信道下的系统差错性能进行了仿真。如图15所示,本实施例在信噪比为-2.2dB时,BER可达到10 -6,相比采用BPSK结合相同LDPC码的传输方案,有约1dB的性能增益。 Then, the system error performance of this embodiment under the AWGN channel is simulated. As shown in FIG. 15 , in this embodiment, when the SNR is -2.2dB, the BER can reach 10 -6 . Compared with the transmission scheme using BPSK combined with the same LDPC code, there is a performance gain of about 1dB.
由实施例仿真结果可知,本发明方案在低信噪比下能够保证突发捕获及帧同步检测的准确性,且可通过选择不同的相关长度适应不同的信道状况。同时,相比传统传输方案也有一定的错误性能增益,适合应用于短突发通信。It can be seen from the simulation results of the embodiment that the scheme of the present invention can ensure the accuracy of burst capture and frame synchronization detection under low signal-to-noise ratio, and can adapt to different channel conditions by selecting different correlation lengths. At the same time, compared with the traditional transmission scheme, it also has a certain error performance gain, which is suitable for short burst communication.
本发明实施例对各器件的型号除做特殊说明的以外,其他器件的型号不做限制,只要能完成上述功能的器件均可。In the embodiments of the present invention, unless otherwise specified, the models of the devices are not limited, as long as they can complete the above functions.
本领域技术人员可以理解附图只是一个优选实施例的示意图,上述本发明实施例序号仅仅为了描述,不代表实施例的优劣。Those skilled in the art can understand that the accompanying drawing is only a schematic diagram of a preferred embodiment, and the serial numbers of the above-mentioned embodiments of the present invention are for description only, and do not represent the advantages and disadvantages of the embodiments.
以上所述仅为本发明的较佳实施例,并不用以限制本发明,凡在本发明的精神和原则之内,所作的任何修改、等同替换、改进等,均应包含在本发明的保护范围之内。The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (9)

  1. 一种比特域叠加伪随机序列与稀疏级联编码的传输方法,其特征在于,所述方法包括以下步骤:A kind of transmission method of superimposed pseudo-random sequence and sparse concatenated coding in bit field, it is characterized in that, described method comprises the following steps:
    (1)在发送端,首先对待传输信息序列进行信道编码,将每个信道编码符号按照稀疏编码方案转换为码元“1”的比例较少的稀疏序列,接着将稀疏序列与伪随机序列逐比特异或叠加得到待传输序列,最后调制发送;(1) At the sending end, channel coding is first performed on the information sequence to be transmitted, and each channel coded symbol is converted into a sparse sequence with a small proportion of symbol "1" according to the sparse coding scheme, and then the sparse sequence and the pseudo-random sequence are one by one The sequence to be transmitted is obtained by bit XOR superposition, and finally modulated and sent;
    (2)在接收端,首先将接收信号与本地伪随机序列进行滑动相关判决,以实现帧同步和传输符号同步,进一步移除信号中的伪随机序列,然后在解调器中计算每一比特的硬判决和软判决信息,送入译码器进行译码并计算每个稀疏编码码字的硬输出和软输出信息,最后根据与发送端相同的映射规则得到每个码字对应的信道编码符号硬判决信息和软判决信息,经信道译码得到原始信息序列。(2) At the receiving end, firstly, the received signal and the local pseudo-random sequence are subjected to sliding correlation judgment to realize frame synchronization and transmission symbol synchronization, further remove the pseudo-random sequence in the signal, and then calculate each bit in the demodulator The hard decision and soft decision information are sent to the decoder for decoding and the hard output and soft output information of each sparsely coded codeword are calculated, and finally the channel coding corresponding to each codeword is obtained according to the same mapping rules as the sending end Symbol hard-decision information and soft-decision information are channel-decoded to obtain the original information sequence.
  2. 根据权利要求1所述的一种比特域叠加伪随机序列与稀疏级联编码的传输方法,其特征在于,所述步骤(1)具体为:A kind of transmission method of superimposed pseudo-random sequence and sparse concatenated coding in bit field according to claim 1, it is characterized in that, described step (1) is specifically:
    (1.1)K信息比特经信道编码后得到N比特长的编码码字c,c以每p比特编码码字为一组,其中第i组可表示为[c ip,c ip+1,…,c ip+p-1],组成对应的编码符号,表示为e i
    Figure PCTCN2021121021-appb-100001
    (1.1) K information bits are channel-coded to obtain an N-bit codeword c, c is a group of codewords of p bits each, and the i-th group can be expressed as [c ip , c ip+1 ,..., c ip+p-1 ] to form the corresponding encoding symbols, expressed as e i ,
    Figure PCTCN2021121021-appb-100001
    (1.2)构建用以实现信道编码码字稀疏化的映射序列集V,并根据映射序列集设计专门的稀疏编码方案,经稀疏编码后得到二进制稀疏序列s;(1.2) Construct the mapping sequence set V used to realize the sparseness of channel coding code words, and design a special sparse coding scheme according to the mapping sequence set, and obtain the binary sparse sequence s after sparse coding;
    (1.3)将二进制稀疏序列s与伪随机序列m进行逐码片异或得到待传输序列t,
    Figure PCTCN2021121021-appb-100002
    调制并发送。
    (1.3) Perform chip-by-chip XOR of the binary sparse sequence s and the pseudo-random sequence m to obtain the sequence t to be transmitted,
    Figure PCTCN2021121021-appb-100002
    Modulate and send.
  3. 根据权利要求1所述的一种比特域叠加伪随机序列与稀疏级联编码的传输方法,其特征在于,所述步骤(2)具体为:A kind of transmission method of superimposed pseudo-random sequence and sparse concatenated coding in bit field according to claim 1, it is characterized in that, described step (2) is specifically:
    (2.1)接收端收到传输信号,根据已知的伪随机序列通过互相关检测器实现信号捕获,完成帧同步和传输符号同步;(2.1) The receiving end receives the transmission signal, realizes signal capture through a cross-correlation detector according to a known pseudo-random sequence, and completes frame synchronization and transmission symbol synchronization;
    (2.2)移除接收信号中的伪随机序列,根据本地已知的伪随机序列的脉冲位置对接收信号进行符号翻转,恢复出叠加的稀疏序列,并送入解调器;(2.2) Remove the pseudo-random sequence in the received signal, flip the received signal according to the pulse position of the locally known pseudo-random sequence, recover the superimposed sparse sequence, and send it to the demodulator;
    (2.3)在解调器中计算每一比特的硬判决和软判决信息,接着根据与发送端稀疏编码方案中相应的映射规则得到每条稀疏序列对应的信道编码符号硬信息和软信息,经信道译码得到原始信息序列。(2.3) Calculate the hard decision and soft decision information of each bit in the demodulator, and then obtain the hard information and soft information of the channel coding symbols corresponding to each sparse sequence according to the corresponding mapping rules in the sparse coding scheme at the sending end, and then pass Channel decoding obtains the original information sequence.
  4. 根据权利要求2所述的一种比特域叠加伪随机序列与稀疏级联编码的传输方法,其特征在于,所述步骤(1.2)具体为:The transmission method of a kind of bit field superposition pseudo-random sequence and sparse concatenated coding according to claim 2, it is characterized in that, described step (1.2) is specifically:
    (1.2.1)利用低重序列映射实现稀疏编码,首先,构建的序列集中每组序列的重量w不完全相等,在保证序列稀疏性的前提下,w为任意小于序列长度一半的值,然后,建立信道编码符号与稀疏序列集之间的映射关系,得到稀疏编码码字序列;(1.2.1) Use low-heavy sequence mapping to realize sparse coding. First, the weight w of each group of sequences in the constructed sequence set is not completely equal. Under the premise of ensuring sequence sparsity, w is any value less than half the sequence length, and then , establish the mapping relationship between the channel coding symbols and the sparse sequence set, and obtain the sparse coding codeword sequence;
    (1.2.2)利用低重码字映射实现稀疏编码,首先,利用纠错码的部分低重码字的信息位来构建序列集,使得序列集中每组序列经纠错编码后得到的码字均为低码重的码字,然后建立信道编码符号与低重码字的信息位之间的映射关系,最后对映射完成后的序列进行低重纠错编码,得到稀疏编码码字序列。(1.2.2) Use the low-repetition codeword mapping to realize sparse coding. First, use the information bits of some low-repetition codewords of the error-correcting code to construct a sequence set, so that the codewords obtained after error-correcting coding for each sequence in the sequence set are The low-weight codeword, and then establish the mapping relationship between the channel coding symbols and the information bits of the low-weight codeword, and finally perform low-heavy error correction coding on the mapped sequence to obtain a sparsely coded codeword sequence.
  5. 根据权利要求1所述的一种比特域叠加伪随机序列与稀疏级联编码的传输方法,其特征在于,在接收端,将接收信号与本地伪随机序列进行滑动相关判决,以实现帧同步和传输符号同步,具体步骤为:According to claim 1, a kind of transmission method of superimposing pseudo-random sequence and sparse concatenated coding in bit field, it is characterized in that, at the receiving end, the sliding correlation judgment is carried out between the received signal and the local pseudo-random sequence, so as to realize frame synchronization and Transmission symbol synchronization, the specific steps are:
    (3.1)将接收信号y和本地伪随机序列m送入互相关检测器,进行滑动相关,其输出R(k,g)表示为:(3.1) Send the received signal y and the local pseudo-random sequence m to the cross-correlation detector for sliding correlation, and the output R(k,g) is expressed as:
    Figure PCTCN2021121021-appb-100003
    Figure PCTCN2021121021-appb-100003
    其中,N k为相关器滑动窗口长度,y(n+g)为接收信号移位g位后的序列,m(n)为处于滑动窗口内的伪随机序列,k表示相关器输出的序号,n为数字样值序号; Among them, N k is the length of the sliding window of the correlator, y(n+g) is the sequence after the received signal is shifted by g bits, m(n) is the pseudo-random sequence in the sliding window, k represents the sequence number output by the correlator, n is the serial number of the digital sample;
    (3.2)检测任何时刻的相关结果,搜索相关峰位置,其判决准则为:(3.2) Detect the correlation results at any time, search for the correlation peak position, and the judgment criterion is:
    Figure PCTCN2021121021-appb-100004
    Figure PCTCN2021121021-appb-100004
    其中,
    Figure PCTCN2021121021-appb-100005
    表示搜索到的相关峰位置,代表数据帧的到达;
    in,
    Figure PCTCN2021121021-appb-100005
    Indicates the searched correlation peak position, representing the arrival of the data frame;
    (3.3)成功完成码捕获后,根据相关峰位置,确定帧同步估计值,找到接收信号一帧的起始位置,建立与发送端起止时刻一致的脉冲序列,实现帧同步;(3.3) After successfully completing the code capture, determine the estimated frame synchronization value according to the correlation peak position, find the starting position of a frame of the received signal, establish a pulse sequence consistent with the start and end times of the sending end, and realize frame synchronization;
    (3.4)将接收信号进行划分,以每l码片为一组作为接收符号,实现传输符号同步, 并依次送入解调器计算每一符号的软信息。(3.4) Divide the received signal into a group of 1 chip as the received symbol to realize the synchronization of the transmitted symbols, and send them to the demodulator to calculate the soft information of each symbol in turn.
  6. 根据权利要求4所述的一种比特域叠加伪随机序列与稀疏级联编码的传输方法,其特征在于,所述步骤(1.2.1)具体为:The transmission method of a kind of bit field superposition pseudo-random sequence and sparse concatenated coding according to claim 4, it is characterized in that, described step (1.2.1) is specifically:
    序列集包括2 p组不同的二进制稀疏序列,表示为
    Figure PCTCN2021121021-appb-100006
    其中每组序列的长度为l码片,位置编号为a的一组二进制稀疏序列可表示为
    Figure PCTCN2021121021-appb-100007
    Figure PCTCN2021121021-appb-100008
    α=0,1,…,2 p-1;
    The sequence set consists of 2 p sets of distinct binary sparse sequences denoted as
    Figure PCTCN2021121021-appb-100006
    The length of each group of sequences is l chips, and a group of binary sparse sequences whose position number is a can be expressed as
    Figure PCTCN2021121021-appb-100007
    Figure PCTCN2021121021-appb-100008
    α=0,1,..., 2p -1;
    选择序列集V中位置编号与编码符号值对应的二进制稀疏序列作为传输符号,即当编码符号为e i,选择序列集V中位置编号为e i的二进制稀疏序列
    Figure PCTCN2021121021-appb-100009
    作为对应的传输符号,稀疏编码完成;
    Select the binary sparse sequence corresponding to the position number in the sequence set V and the encoding symbol value as the transmission symbol, that is, when the encoding symbol is e i , select the binary sparse sequence whose position number is e i in the sequence set V
    Figure PCTCN2021121021-appb-100009
    As the corresponding transmission symbol, sparse coding is completed;
    针对低重序列映射实现稀疏编码的方案设计相应的译码算法。A corresponding decoding algorithm is designed for the sparse coding scheme of low-weight sequence mapping.
  7. 根据权利要求5所述的一种比特域叠加伪随机序列与稀疏级联编码的传输方法,其特征在于,所述步骤(1.2.2)具体为:A kind of transmission method of superimposed pseudo-random sequence and sparse concatenated coding in bit field according to claim 5, it is characterized in that, described step (1.2.2) is specifically:
    根据映射规则选择序列集V中位置编号与编码符号值对应的二进制序列作为传输序列;Select the binary sequence corresponding to the position number and the coded symbol value in the sequence set V as the transmission sequence according to the mapping rule;
    对映射得到的传输序列执行Golay编码,针对低重码字映射实现稀疏编码的方案设计相应的译码算法。Golay encoding is performed on the mapped transmission sequence, and a corresponding decoding algorithm is designed for the sparse coding scheme realized by low-repetition codeword mapping.
  8. 根据权利要求6所述的一种比特域叠加伪随机序列与稀疏级联编码的传输方法,其特征在于,所述针对低重序列映射实现稀疏编码的方案设计相应的译码算法,具体步骤为:According to claim 6, a bit-field superimposed pseudo-random sequence and sparse concatenated coding transmission method is characterized in that, the corresponding decoding algorithm is designed for the scheme of low-heavy sequence mapping to realize sparse coding, and the specific steps are as follows :
    (6.1)每l码片的接收信号组成一个符号,送入解调器,每个符号根据序列集V利用l维高斯分布密度函数计算软信息,表示为:(6.1) The received signal of each 1 chip forms a symbol, which is sent to the demodulator, and each symbol calculates the soft information by using the 1-dimensional Gaussian distribution density function according to the sequence set V, expressed as:
    Figure PCTCN2021121021-appb-100010
    Figure PCTCN2021121021-appb-100010
    其中,
    Figure PCTCN2021121021-appb-100011
    为该接收符号对应v a在序列集V的位置编号a的符号似然信息;
    in,
    Figure PCTCN2021121021-appb-100011
    The received symbol corresponds to the symbol likelihood information of the position number a of v a in the sequence set V;
    (6.2)将得到的符号似然信息进行归一化后作为没有译码时的初始概率直接送入多进制译码器进行译码,或将其转为比特软信息后送入二进制译码器进行译码,将第n组信息比特对应符号a的初始符号概率表示为
    Figure PCTCN2021121021-appb-100012
    计算方式为:
    (6.2) Normalize the obtained symbol likelihood information as the initial probability without decoding and directly send it to the multi-ary decoder for decoding, or convert it into bit soft information and send it to binary decoding The device decodes, and the initial symbol probability of the nth group of information bits corresponding to the symbol a is expressed as
    Figure PCTCN2021121021-appb-100012
    The calculation method is:
    Figure PCTCN2021121021-appb-100013
    Figure PCTCN2021121021-appb-100013
  9. 根据权利要求7所述的一种比特域叠加伪随机序列与稀疏级联编码的传输方法,其特征在于,所述针对低重码字映射实现稀疏编码的方案设计相应的译码算法,具体步骤为:According to claim 7, a bit-field superimposed pseudo-random sequence and sparse concatenated coding transmission method, characterized in that, the corresponding decoding algorithm is designed for the scheme of implementing sparse coding for low-heavy code word mapping, and the specific steps are as follows :
    (7.1)在解调器中计算每一比特对数似然信息r i并得到相应的硬判决结果u i(7.1) Calculate the logarithmic likelihood information r i of each bit in the demodulator and obtain the corresponding hard decision result u i ;
    (7.2)根据得到的比特对数似然信息和硬判决结果,以相关差作为译码度量进行Golay译码,相关差最小的码字即为Golay译码结果;(7.2) According to the obtained bit logarithmic likelihood information and hard decision results, Golay decoding is carried out with the correlation difference as the decoding measure, and the codeword with the smallest correlation difference is the Golay decoding result;
    (7.3)Golay译码完成后,按照与发送端相同的映射规则得到每个码字对应的信道编码符号硬判决和软判决信息,并输出到信道译码器;(7.3) After the Golay decoding is completed, the hard decision and soft decision information of the channel coding symbols corresponding to each codeword are obtained according to the same mapping rules as the sending end, and are output to the channel decoder;
    (7.4)根据得到的信道编码符号的硬判决和软判决信息,完成信道译码,得到原始信息序列。(7.4) Complete channel decoding according to the obtained hard decision and soft decision information of channel coding symbols, and obtain the original information sequence.
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