[0037] The present invention will be further explained in detail with reference to the drawings and specific examples below. For the step numbers in the following examples, they are only set for convenience of explanation, and there is no restriction on the order of steps. The execution order of each step in the examples can be adjusted adaptively according to the understanding of those skilled in the art.
[0038] BCJR decoding algorithm of convolutional codes is the maximum a posteriori probability decoding (MAP). When iterative decoding is used in concatenated codes, the prior probability of information bits changes every iteration, which can make MAP decoder give the best performance. Considering the shortcomings of the existing polarization code and convolution code in the cascade decoding design, this design improves the cascade design mode, proposes an improved polarization code cascade system with polarization code as outer code and convolution code as inner code, and gives the coding and decoding methods realized by this system.
[0039] The invention also provides a serial cascade system of polarization code and convolution code for realizing a polarization code decoding method based on right information processing, specifically, a cascade code with a code rate of 1/2 is formed by using polarization code with a code rate of 2/3 as an outer code and convolution code with a code rate of 3/4 as an inner code through an interleaver.
[0040] such as Figure 1 As shown, the present invention provides a polarization code decoding method based on right information processing, which combines the right information processing at the source end of polarization code BP decoder with the code design of cascade polarization code, and is suitable for the decoding method of serial cascade polarization code design. The method includes the following steps:
[0041] S1, initializing the prior information of convolutional code decoder and polarization code decoder, and setting the threshold and iteration times of right information processing;
[0042] S2, after soft demodulation, the information vector output by the channel is sent to a convolutional code decoder for decoding, so as to obtain information outside the convolutional decoding;
[0043] Specifically, the channel output information vector y = {y 1 ,y 2 …y N }(N is the length of the code word transmitted in the channel) is sent to the convolutional code decoder after soft demodulation, and the convolutional code BCJR or max-log-map algorithm is used for decoding to obtain the information outside the convolutional decoding.
[0044] S3, that information outside the convolution decode is sent to an interleaver to obtain the interleave information;
[0045] Specifically, the obtained additional information Sending into an interleaver to obtain the interleaved information. Send it to polarization code decoder.
[0046] S4, that interleave information is sent to the polarization code decoder for BP decode until the polarization code information sequence passes the CRC check, and the decision codeword is output to complete the decoding.
[0047] Specifically, the BP decoding is performed in the polarization code decoder. When the iterative decoding is completed, since the polarization code information sequence has been added with CRC codes in sections during encoding, the segmented CRC check can be performed at this time. Let the information sequence u = {u1, U2 ... um} (m is the number of segments divided). If all sub-segments of the polarization code information sequence pass the CRC check, the iteration is stopped, and the decision codeword u is output to announce the end of decoding. If all sub-segments fail the CRC check, the iteration is continued and step S4 is repeated.
[0048] Further, as a preferred embodiment of this method, it further includes assigning the right information of the source end of the polarization code decoder, specifically including:
[0049] S5, judging that the polarization code information sequence still fails the CRC check after iteration to the maximum number of iterations, performing segmented right information processing and re-CRC check, and outputting the decoded information sequence.
[0050] Further, as a preferred embodiment of this method, the step of sending the interleaved information to the polarization code decoder for BP decoding until the polarization code information sequence passes CRC check, and outputting the decision codeword to complete the decoding specifically includes:
[0051] Sen that interleaved information to a polarization code decode for BP decoding, and performing segmented CRC check aft judging that the iterative decoding is completed once;
[0052] Iterative decoding is performed until all sub-segments of polarization code information sequence pass CRC check or reach the maximum number of iterations, and decoding is completed.
[0053] As a further preferred embodiment of the method, the cyclic iterative decoding is performed until all sub-segments of the polarization code information sequence pass CRC check or reach the maximum number of iterations, and the decoding step is completed, which specifically includes:
[0054] It is judged that all sub-segments of the polarization code information sequence fail the CRC check, and iterative decoding is continued until the maximum number of iterations is reached;
[0055] It is judged that all sub-segments of the polarization code information sequence have passed CRC check, and the iteration is stopped and the judgment code word is output to complete decoding.
[0056] As a further preferred embodiment of the method, the step of initializing the prior information of the convolutional code decoder and the polarization code decoder and setting the threshold and iteration times of the right information processing specifically includes:
[0057] The prior information of that convolutional code decode and the prior information of the polarization code decoder are set to 0;
[0058] According to the preset rules, the threshold value and the maximum iteration number of right information processing are set.
[0059] Specifically, the prior information of convolutional code decoder and the prior information of polarization code decoder at the source end are set to 0, and the threshold sum of right information processing is set. The threshold value is set according to experience, and the maximum iteration times Iter_max between concatenated code component codes and T max of polarization code BP decoding are set.
[0060] Further, as a preferred embodiment of this method, the decoding sent to the convolutional code decoder is specifically decoding by using convolutional code BCJR.
[0061] Particularly, max-log-map algorithm is adopted for decoding.
[0062] Further, as a preferred embodiment of this method, the step of judging that the polarization code information sequence still fails CRC check after the maximum iteration times, processing segmented right information, re-CRC checking, and outputting decoded information sequence specifically includes:
[0063] Judging that all sub-segments of the polarization code information sequence still fail the CRC check at the maximum iteration times;
[0064] Setting the right information of the sub-segment decoding sequence of the polarization code through CRC check;
[0065] According to the absolute value of the decision likelihood information, setting the threshold value of the right information processing of the sub-segment decoding sequence of which the polarization code failed CRC check;
[0066] Specifically, if all sub-segments still fail to pass the CRC check at the maximum number of iterations, the segmented right information processing is performed, specifically for the sub-segment decoding sequence that has passed the CRC check, such as U. k ＝{u 1 ，u 2 …u m }(m is the length of the sub-segment sequence, 1≤k≤M), if u i = 0 (1 ≤ I ≤ m), then the right information corresponding to the source end of the polarization code BP decoder is set to R. i，1 ＝∞； Ruou i = 1 (1 ≤ I ≤ m), then the corresponding right information is set to R.i，1 ＝-∞。 At the same time, for the subsegment sequence that fails CRC check, threshold processing is performed according to the absolute value of decision likelihood information, and for the information bits whose absolute value is greater than the set threshold, such as | L. i，1 |＞Ω threshold , then r i，1 ＝L i，1; If |L i，1 |＜T threshold , then r i，1 ＝-L i，1.
[0067] Acquiring a factor diagram of a polarization code decoder and performing BP decoding in the factor diagram;
[0068] After judging that one iteration decoding is completed, CRC check is performed on the information sequence;
[0069] Circulate the CRC check step until all sub-segments of the information sequence pass the CRC check or the iteration times reach the maximum value, and output the decoded information sequence.
[0070] Specifically, the BP decoding is performed in the factor graph again, and the operations of steps S4 and S5 are performed. If all the sub-Duan Yiran can't pass the CRC check by the maximum number of iterations T_max, the left information of the last layer node will be And right information And the sum is used as the output information of the node bits. And sending the external information into an interleaver to obtain the interleaved information. Go to step S2, information As the prior information of convolutional decoder, BCJR or max-log-map decoding is performed.
[0071] In addition, when the number of iterations reaches Iter_max, the decoding information sequence is output (whether CRC check is passed or not).
[0072] As a further preferred embodiment of the method, the obtaining of the factor graph of the polarization code decoder further comprises clearing the node information of the remaining layers except the first layer and the last layer in the factor graph of the polarization code decoder.
[0073] Specifically, the node information of the other layers in the factor graph except the node information of the first layer (source end) and the last layer (input end of information to be decoded) in the polarization code BP decoder is cleared, so as to clear the trap set caused by the error loop in the factor graph.
[0074] A device for realizing polarization code decoding method based on right information processing;
[0075] At least one processor;
[0076] At least one memory for storing at least one program;
[0077] When that at least one program is execute by the at least one processor, the at least one processor realizes a polarization code decode method based on right information processing as described above.
[0078] In order to verify the performance improvement of the proposed algorithm compared with the existing cascade design, we give the Block Error Rate (BLER) performance chart of the proposed cascade coding in additive white Gaussian noise channel (AWGN). Experimental conditions are different SNR e in AWGN channel. b /N 0 Under the condition of BPSK modulation, the modulation mode adopted is bpsk modulation. As for the polarization code as the outer code, its code rate is R. 1 = 2/3, the information sequence to be encoded is protected by segmented CRC-4 code, and the segmentation mode is uniform segmentation, and the polarization code is constructed by density evolution method. The maximum number of iterations of polarization code BP decoding is set to 60, and the maximum number of iterations between polarization code and convolution code is set to 10.
[0079] The performance of concatenated codes with code length of 1024 and code rate of 0.5 is investigated. such as Figure 2 As shown in, we list the decoding performance comparison between the proposed design scheme of concatenated code and the existing polarization code decoding algorithm. at Figure 2 Among them, the decoding performance of concatenated codes under the proposed design scheme is better than the latest polarization code soft in soft out (SISO) decoding algorithm, and the performance exceeds that of CA-SCL (L = 6). In particular, when compared with SCL (L = 32), the decoding performance of the concatenated code under the proposed design scheme is BLER = 10. -6 0.8dB better than SCL decoding algorithm.
[0080] The preferred embodiment of the present invention has been specifically described above, but the invention is not limited to the described embodiment. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention, and these equivalent modifications or substitutions are included in the scope defined in the claims of this application.
