Research On Rate-compatible Polar Codes In 5G Communication Environment

Polar code,as a new channel coding technology which proposed by E.Arikan in 2009,is also the first error correction code that has been theoretically strictly proved to be capable of achieving arbitrary binary input discrete memoryless symmetrical channel(BI-DMC)capacity.Polar code has excellent decoding performance and low coding and decoding complexity and was adopted by 3GPP as the channel coding standard for the uplink and downlink of the 5G control channel in 2016.However,due to the limitation of the coding construction principle,the code length of the Polar code can only be a power of two,and it cannot well adapt to the channel conditions and the requirements of the system resources on the flexibility of the coding parameters.Therefore,it is necessary to introduce the rate-compatible technology in the application.This paper studies the rate-compatible scheme of Polar codes.The main research work and innovations include the following aspects:1.Research and analyze the encoding and decoding principles of Polar codes.In terms of coding,the channel polarization theory and common construction methods of Polar codes are studied,the phenomenon and coding steps of channel polarization are analyzed through experimental examples and specific data.In terms of decoding,the serial cancellation(SC)decoding,the serial cancellation list(SCL)decoding algorithm and the CA-SCL decoding algorithm with added cyclic redundancy check are studied.2.Analyze the coding scheme of Polar code in the enhanced mobile broadband(eMBB)scenario in 5G,and study the rate-compatible scheme of Polar code,including Repetition,Puncture and Shorten scheme.and its application scenarios.Based on this,the principle of rate-compatible based on puncturing and its three classic rate-compatible algorithms are emphasized.3.Based on the puncturing scheme,a puncturing design algorithm based on the periodic hierarchical rearrangement structure is proposed.This algorithm can easily obtain a flexible and adjustable rate-compatible punctured Polar code(RCPP)with code length and code rate.At the same time,the algorithm designed the number of puncturing positions of the left and right sub-graphs when performing the layer-by-level splitting operation,so that the final pattern of the hole has a uniform or quasi-uniform distribution(QUP)characteristics.In addition,the design can obtain more rich puncture patterns,simulation results show that the frame-error rate(BLER)performance of the rate-compatible puncturing scheme proposed in this paper is significantly better than the random puncturing scheme,compared with the classic QUP scheme,it also has about 0.1?0.2d B performance gain.4.On the basis of the traditional shortened code technology,this paper proposes a shortened rate-compatible algorithm based on Gaussian approximation to assist in the selection of puncturing positions,which can conveniently obtain rate-compatible Polar codes(RCPP).According to the constraints of shortened code,combined with Gaussian approximation technology,the puncturing positions that meet the conditions are selected and added to freeze set,thereby obtaining a more optimized freeze set.The simulation results show that the shortened rate-compatible scheme proposed in this paper can achieve a performance gain of about 0.1d B compared with the traditional shortening scheme in term of bit error rate(BER),compared with the classic QUP scheme,it also has about 0.25?0.4d B performance gain.