Joint optimization of polar codes and STBCs

Abstract

Space-time block codes (STBCs) have been designed and used to achieve the diversity and multiplexing gains in multiple antenna systems. STBCs have been typically designed based on rank and determinant criteria which can provide good performance at high signal-tonoise ratios (SNRs). Later, STBCs are designed based on mutual information to provide good performance at a specific SNR corresponding to the forward error correction (FEC) code rate. However, once the FEC code and STBC are concatenated, to achieve the best performance, STBC should be designed by considering the structure of the FEC code and the corresponding decoder in addition to the code rate. Polar codes are a new class of FEC codes that benefit from a variety of low complexity decoders and simple rate matching. Polar codes can be efficiently designed for a specific channel and STBC. Therefore, by changing the parameters of a specific STBC and optimizing the polar code for each new STBC, the best match between polar codes and STBCs can be found. Throughout this paper, we introduce a simple method for joint optimization of polar codes and STBCs and show that it can substantially improve the performance of the concatenated scheme.