Research On Polar Coding And Decoding Algorithm For URLLC Scene In 5g Environment

Polar code is a channel coding scheme proposed in 2008,which has been theoretically proved to achieve the Shannon channel capacity.Compared with Polar codes in the u RLLC scenario,the two coding schemes of LDPC code and Turbo code,Polar codes have lower complexity and better performance,so Polar codes are more suitable for u RLLC(ultra-reliable,lowlatency communication)in 5G Scenes.In the URLLC scenario,the end-to-end delay requirement is less than 1ms,so the application of the Polar code in the URLLC scenario is faced with the following challenges: one is ultra-low delay,and the other is high reliability.The general way to reduce the delay is to use short packets to reduce the delay,but this will in turn lead to a serious loss of coding gain.In order to improve reliability,strong channel coding needs to be used,which is finally adapted to the retransmission technology,which increases the delay to a certain extent.In order to meet the requirements of low latency and high reliability in u RLLC scenarios,the following researches are carried out in this paper:1.The u RLLC scenario has relatively high requirements on reliability and delay.Therefore,based on the existing low-complexity construction algorithm,in order not to increase the complexity,but also to improve the reliability of coding,this paper proposes a Polar code and Convolutional code concatenation for constructing coding schemes.A construction algorithm of dynamically freezing bits is added to the concatenated coding scheme,so that the concatenated coding scheme has lower complexity and better performance than the classical construction algorithm.2.The decoding algorithm in the u RLLC scenario needs to have the lowest possible complexity to ensure that the decoding delay is not too high.While reducing the complexity,it may reduce the reliability.In order to solve this problem,this paper proposes a SC-Fano decoding algorithm.In this algorithm,each decoding node needs to compare the path metric value with the threshold value to select the direction of decoding movement.Without increasing the complexity of the algorithm,a good decoding performance can be obtained.At last,the CRC check bit is added on the basis of the algorithm,which further improves the decoding performance of the Polar code.3.Finally,combined with the proposed encoding algorithm and decoding algorithm,the proposed encoding and decoding algorithm is simulated and verified by the joint encoding and decoding scheme.The scheme gain is improved by about 0.5d B.