Research And Performance Analysis On The Efficient Decoding Algorithm Of LDPC Codes

With the increasing demand for bandwidth in modern communications,people have more stringent requirements on the reliability of information transmission.Low-Density Parity-Check?LDPC?codes have these following advantages:strong error correction,the possibility of approaching the Shannon'capacity limit and low encoding/decoding complexity.As a research hotspot in the field of channel coding,it has been widely used in communications fields and many others.The choice of decoding algorithm is essential to whether an LDPC codes can exert its excellent performance.Therefore,the research on the decoding algorithm of LDPC codes is extremely valuable.In this thesis,how to search for an efficient LDPC codes decoding algorithm is studied by analyzing the existing decoding algorithms.The main research work is as follows:1.By researching and analyzing the existing decoding algorithms of LDPC codes,it can be known that the existing decoding algorithms are mainly divided into hard-decision,hybrid decision and soft-decision decoding algorithms.The classical algorithms of the three categories decoding algorithms are simulated and analyzed,and the complexity of them is compared.The simulation results show that the complexity of the hard decision is low but its decoding performance is poor,and the soft decision is contrary to it,while the hybrid decision compromises both the complexity and the decoding performance.Generally,the advantages and disadvantages of the three types decoding algorithms vary.2.Considering that the Weighted Bit Flipping?WBF?decoding algorithm of LDPC codes produces the single-bit flipping phenomenon during the iteration in most cases and the phenomenon can result in the low decoding efficiency and may give rise to the endless loop of the bit flipping,a more Efficient WBF?EWBF?algorithm is proposed.The proposed EWBF algorithm has improved the flipping threshold so as to flip the multiple-bits in each iteration and improve the decoding efficiency while avoiding the endless loop phenomenon during the decoding.The simulation results show that the average decoding iteration number of the proposed decoding algorithm,compared with the WBF algorithm,the modified WBF?MWBF?algorithm and the Improved MWBF?IMWBF?algorithm,can be reduced 51.6%⁵6.2%,49.6%⁵4.2%and48.1%⁵1.3%,In terms of the decoding performance,the proposed algorithm performance is close to or even better than the IMWBF algorithm,when the maximum iteration number is set to 30 times,the net coding gain of the improved scheme is 0.92dB better than that of IMWBF algorithms at the BER of10^-4.3.In order to further improve the error-correction performance of the decoding algorithm for LDPC codes and accelerate the convergence speed of its decoding,an improved decoding algorithm based on the interlaced column row message-passing is proposed.In the proposed decoding algorithm,the residual value idea in the dynamic scheduling strategy decoding algorithm is introduced into the static serial scheduling strategy decoding algorithm so that the serial scheduling decoding algorithm performs an ordering calculation of the residual value before the message is updated in each iteration,and the original fixed update sequence of its node message is reordered.The simulation results show that the improved decoding algorithm,compared with the Interlaced Column Row Message-Passing?I-CRMP?algorithm,Column Message-Passing?CMP?algorithm,Column Message-Passing?CMP?algorithm,Belief Propagation?BP?algorithm,can achieve 0.13dB,0.23dB,0.24dB and 0.37dB net coding gain at the bit error rate10^-5.