Research On Polar-Coded HARQ For Data Channel

Polar codes have excellent performance under finite-length and have been adopted as the coding scheme for 5G control channels by 5G mobile communication system.But there are no theoretical design and solution for its application in data channel.As an important means to improve the performance and throughput of the system,link adaptation technology is widely used in the data channel of digital communication system.In order to make polar codes the data channel coding scheme of future mobile communication systems such as beyond 5G(B5G)and 6G,polar codes must be combined with hybrid automatic repeat request(HARQ)technology.Aiming at the future mobile communication systems such as B5G and 6G,this paper deeply studies the characteristics of the polar codes,combines the polar codes with HARQ technology,and proposes the polar-coded HARQ technology for data channel.The innovative work of this paper mainly includes the following two aspects:Firstly,a rate-allocation(RA)method as a framework to study fast code construction of polar-coded hybrid automatic repeat request(HARQ)is proposed.We show that the active-bit relocation under masks(ARUM)polar-coded HARQ scheme can be efficiently constructed from determining the allocated rates for component polar codes while the ranking of bit indices within each component polar code can be obtained by fixed sequence(e.g.,the Polar sequence in the 5G standard).The key idea of the proposed RA method is finding out the equivalent channels whose average mutual information equals the target transmission rate.The total mutual information of each transmission block is calculated according to the polarization between transmission blocks based on the equivalent channels.Then the actual bit length of each transmission block is allocated according to the total mutual information of each transmission block.Finally,the bit channels on each transmission block can be sorted by the fixed sequence.Using RA method to construct ARUM-HARQ scheme is simple and robust for different configurations.It has general construction characteristics and is suitable for practical communication system.Simulation results show that the proposed method can achieve excellent decoding performance with low construction complexity.Secondly,we concern the self-decoding capability of polar-coded hybrid automatic repeat request(HARQ)schemes.The proposed self-decoding method enables the incremental redundancy(IR)based polar-coded HARQ to recover all source bits solely using the retransmission codewords.It provides an extra decoding chance when the joint decoding attempt fails.With this,the final decoding success probability increases such that the number of retransmissions can be reduced and the system latency goes down.We derive one necessary condition for the successful self-decoding,which can also guide the optimization of Polar-HARQ.Three mainstream Polar-HARQ schemes are compared from the perspective of self-decoding.Simulation results validate the analysis.The results show that RA-HARQ method can achieve excellent decoding performance with much lower construction complexity,and self-decoding can provide extra decoding chance when the joint decoding attempt fails.