LDPC design for 5G NR URLLC & mMTC

Low density parity check (LDPC) code in the fifth generation (5G or New Radio, NR) was mainly designed for the enhanced Mobile Broadband (eMBB) scenario, and specific optimization has not been considered for both scenarios of Ultra-Reliable and Low Latency Communications (URLLC) and massive Machine Type Communications (mMTC), especially for small transport block sizes (TBSs). Therefore, we introduce a specific optimized design method of LDPC code for small TBSs of the latter two scenarios. According to the proposed method, a new LDPC code is designed and its performance is better than the LDPC code in 5G. Furthermore, an improved algorithm combining belief propagation (BP) and ordered statistic decoding (OSD) is considered in this paper. Compared with traditional BP+OSD algorithm, although there is slight performance loss, the number of OSD decoding implemented in the improved algorithm can be reduced to 1 or 2. Simulation results indicate that the performance of the improved BP+OSD decoding algorithm is obviously better than that of the popular BP decoding and also better than that of the polar code in 5G.