Performance Enhancement of LDPC Codes Based on Protograph Construction in 5G-NR Standard

Abstract

To meet the high throughput demands, the 3rd Generation Partnership Project has specified the low-density parity check (LDPC) codes in the fifth generation-new radio 5G-NR standard with rate and length compatibility and scalability. This paper presents an extensive performance evaluation and enhancement of LPDC using the protograph-based construction defined in the 5G-NR standard. Firstly, the protograph-LDPC with layered offset min-sum (OMS) decoding, polar with successive cancellation list (SCL), and block turbo code are implemented and compared. Puncturing and shortening are applied to maintain block length at 1024 and code rate at 1/2 for all codes for comparison fairness. The results showed that P-LDPC outperforms its counterparts in terms of bit/ frame error rate (BER/ FER) behavior for given signal-to-noise ratios. Then, different P-LDPC settings were realized to study the effects of base graph selection (Graph1 or Graph2), code rate change (1/3 - 2/3), and block lengths increase (260 – 4160 bits). The simulation outcomes proved that BER performed better for lower coding rates or higher block lengths. Furthermore, P-LDPC behavior was examined over a Rayleigh flat-fading channel to achieve a 12.5 dB coding gain at 0.001 BER compared with uncoded transmission.