Research On Decoding Algorithm Of Polar Codes And Its Application

Polar code is currently the only kind of channel code that has been proved to be able to reach the Shannon limit in binary discrete memoryless channels.Due to its superior performance and low coding and decoding complexity,it has attracted widespread attention in the industry.In November 2016,the polar code was determined as the channel coding scheme for the control channel under the enhanced mobile bandwidth scenario in the fifth generation mobile communication.The new multiple access technologies SCMA and Massive MIMO are also key technologies in future 5G mobile communications.In this paper,the basic principle of polar code and its polarization process are introduced firstly.Based on this,the coding structure and coding process of polar code are given.This paper simulates several existing mainstream decoding algorithms of polar code with comparative analysis.In addition,the Belief Propagation(BP)decoding algorithm of the polar code is mainly studied.Based on the original BP decoding algorithm,the BP decoding algorithm based on min-sum and the BP decoding algorithm in the probability domain are deduced.The stochastic calculation of the probability tracking structure TFM was introduced into the BP decoding algorithm of the polar code,and a new type of BP decoding algorithm based on the stochastic calculation was proposed.It realized iterative decoding with single probability bit and reduced the hardware consumption.At the same time,a post-processing method is proposed to improve the original BP decoding algorithm.Under the condition of increasing the number of iterations,the performance of BP decoding algorithm is significantly improved.Then,this paper studies the SCMA system based on polar code encoding.Aiming at the problem of slow convergence and high complexity for traditional iterative detection decoding algorithms,this paper combines the factor graph of MPA detection algorithm of SCMA with the factor graph of BP decoding algorithm of polar code to form a joint factor graph.Based on this,a joint detection decoding algorithm is proposed,and the joint detection decoding algorithm is compared with the traditional iterative detection decoding algorithm.The results show that the joint detection algorithm not only outperforms the traditional iterative detection decoding algorithm in performance,but also lower than the traditional iterative detection decoding algorithm in computational complexity.Finally,this paper proposed a high-performance and low-complexity layered iterative sampling detection algorithm in Massive MIMO system.The traditional MMSE detection algorithm,MMSE detection algorithm based on Jacobi,MMSE detection algorithm based on conjugate gradient and ISD detection algorithm recently published is compared with the proposed algorithm.In addition,this paper also deduced the calculation process of the proposed algorithm in the soft input soft output system,and simulated with polar code encoded.Next,we can study the joint detection and decoding of the entire receiver of the Massive MIMO system with SCMA-based multiple access technology encoded by polar code.