Efficient Design of Multi-Packet Hybrid ARQ Transmission Scheme Based on Polar Codes

Abstract

In this paper, a new polar coded hybrid automatic repeat request (HARQ) strategy combining multiple packets (MP) of transmission rounds is proposed to improve the throughput, which is called MP-HARQ. In our scheme, first, part of message bits in previous packet and the new source packet are jointly encoded in the retransmission round. Then, backtrack-freezing decoding is implemented at the receiver. To maximize throughput and achieve rate adaptation, we optimize the parameters of the proposed scheme by dynamic programming algorithm on the basis of estimated packet error rate and calculation of throughput. Finally, numerical simulation results suggest that the proposed three-level MP-HARQ could attain similar throughput to the conventional incremental redundancy HARQ of rate-compatible punctured polar codes (RCPP IR-HARQ) and ensure a significant gain over the HARQ scheme with Chase combining, using a low-complexity HARQ control and less transmission times in contrast to RCPP IR-HARQ.

Keywords

• Polar codes
• hybrid ARQ
• multiple-packet
• backtrack-freezing decoding
• throughput
• rate adaptation