Research On LDPC Decodiing Algorithm And Performance Analysis Of LDPC Code And Polarized Code

Low-density parity-check code(LDPC)is a coding scheme proposed by Gallager in 1962 that approaches the Shannon limit.Compared with Turbo code,LDPC code have better decoding performance,flexible construction,and Low error leveling,etc.Especially under long codes,LDPC decoding performance is more excellent.Polar code,as an emerging channel coding scheme,is currently the only channel coding scheme that can be strictly proven theoretically to reach the Shannon limit,and the decoding complexity is relatively low.At present,LDPC code and Polar code have been respectively selected as the data channel and control channel coding standards in the 5G-e MBB scenario.Firstly,this paper studies the LDPC decoding algorithm,and proposes two non-binary LDPC decoding algorithms based on symbol flipping,and analyzes their performance?complexity?decoding convergence speed and energy consumption,etc.Secondly,this paper analyzes and compares the performance of the two channel coding schemes used in 5G at different code lengths/bit rates.The main contents are as follows:1.On the decoding algorithm based on the symbol flipping prediction mechanism(D-SFDP),an improved ID-SFDP algorithm based on the flipping function design is proposed.In this algorithm,we redefine the flipping rule and design a flipping function so that It can realize multi-bit flipping at each iteration,so as to avoid falling into an infinite loop in the iterative process and improve the decoding performance and convergence speed.The simulation results show that the average number of iterations of the ID-SFDP algorithm proposed in this paper is about 17.4 times less than the D-SFDP algorithm aroundE_b/N₀=4.8d B;In terms of decoding performance,ID-SFDP decoding algorithm has about 0.49d B performance gain compared with D-SFDP algorithm aroundBER=2×10^-5.2.An improved(T)ID-SFDP algorithm based on the voting truncation criterion is proposed based on the ID-SFDP algorithm.The(T)ID-SFDP decoding algorithm uses a voting mechanism to count the number of check nodes whose current bit does not meet the syndrome,so as to judge whether the bit is reliable.By setting a truncation threshold,some variable nodes that meet the conditions can participate in the operation,which can reduce the decoding complexity at each iteration.So the(T)ID-SFDP algorithm can trade-off between decoding comple-xity and performance effectively.The simulation results show that the number of galois field addition operations of the(T)ID-SFDP decoding algorithm is about53%of the ID-SFDP algorithm.The number of integer/real addition operations is about 52%of the ID-SFDP algorithm.The number of integer/real comparison operations is about 58%of the ID-SFDP algorithm.3.The energy consumption analysis of the ID-SFDP and(T)ID-SFDP decoding algorithms proposed in this paper is carried out.The traditional comple-xity analysis is to calculate the various operations at each iteration.This paper quantitatively analyzes the complexity of the algorithm by defining the energy generated by each algorithm operation.Experimental data shows that compared with the D-SFDP algorithm,the ID-SFDP algorithm reduces energy consumption by about 782.5(m W/MHz).4.The performance of LDPC code and Polar code is compared and analyzed under different parameters.The binary LDPC code is constructed based on the IEEE802.16e standard(1/2,2/3,3/4,5/6 code rate)and uses the SPA decoding algorithm.The non-binary LDPC code is constructed based on the finite field,and uses QSPA and the decoding algorithm proposed in this paper.Polar code uses SCL/CA-SCL decoding algorithm.In order to compare under the same conditions and parameters,the Polar code is punctured.The simulation results show that under the medium and short code length,when the code rate is the same,SC/SCL-Polar has a certain gap in performance with the LDPC code,while CA-SCL-Polar has more obvious advantages in performance when the number of paths is large(for example,L?8).