Typically, forward error correction (FEC) codes are designed based on the minimization of the error rate for a given code rate. However, for applications that incorporate hybrid automatic repeat request (HARQ) protocol and adaptive modulation and coding, the throughput is a more important performance metric than the error rate. Polar codes, a new class of FEC codes with simple rate matching, can be optimized efficiently for maximization of the throughput. In this paper, we aim to design HARQ schemes using multilevel polar codedmodulation (MLPCM). Thus, we first develop a method to determine a set-partitioning based bit-to-symbol mapping for high order QAM constellations. We simplify the LLR estimation of set-partitioned QAM constellations for a multistage decoder, and we introduce a set of algorithms to design throughputmaximizing MLPCM for the successive cancellation decoding (SCD). These codes are specifically useful for non-combining (NC) and Chase-combining (CC) HARQ protocols. Furthermore, since optimized codes for SCD are not optimal for SC list decoders (SCLD), we propose a rate matching algorithm to find the best rate for SCLD while using the polar codes optimized for SCD. The resulting codes provide throughput close to the capacity with low decoding complexity when used with NC or CC HARQ.

Additional Metadata
Keywords Chase-combining, Decoding, Forward error correction, HARQ, low complexity LLR estimation, multilevel coding, multistage decoding, Protocols, Quadrature amplitude modulation, Throughput, Throughput-based polar code design, Transmitters
Persistent URL dx.doi.org/10.1109/TCOMM.2018.2880204
Journal IEEE Transactions on Communications
Khoshnevis, H. (Hossein), Marsland, I, & Yanikomeroglu, H. (2018). Throughput-based Design for Polar Coded-Modulation. IEEE Transactions on Communications. doi:10.1109/TCOMM.2018.2880204