Low-Complexity Hybrid ARQ Scheme for Polar Codes with Higher-Order Modulation
Kuangda Tian, Rongke Liu, Alexander Vardy, Runxin Wang · 2017
Combining the polar coded hybrid automatic repeat request (HARQ) with higher-order modulation has been proposed recently. To further improve the throughput of HARQ, a novel polar coded HARQ cheme with higher-order modulation is proposed. Wherein the proposed HARQ scheme, the unequal rror protection (UEP), caused by bit-mapping, in bit- interleaved polar coded modulation (BIPCM) is considered. Based on UEP, a non-linear integer programming (NLIP) problem is constructed to determine the optimal retransmitted sequence. Furthermore, a low-complexity suboptimal algorithm is proposed to solve the resulting NLIP problem. Simulation results show that the throughput of the proposed HARQ scheme outperforms the existing polar coded HARQ for higher-order modulation; in particular, our scheme easily accommodates arbitrarily puncturing methods. This makes it possible to use recently proposed puncturing methods for polar codes to further improve the performance of our HARQ scheme.