Generalized LDPC Codes for Ultra Reliable Low Latency Communication in 5G and Beyond

Generalized low-density parity-check (GLDPC) codes, where single parity-check constraints on the code bits are replaced with generalized constraints (an arbitrary linear code), are a promising class of codes for low-latency communication. In this paper, a practical construction of quasi-cyclic GLDPC codes is proposed, where the proportion of generalized constraints is determined by an asymptotic analysis. We analyze the complexity and performance of the message passing decoder with various update rules (including standard full-precision sum-product and min-sum algorithms) and quantization schemes for a GLDPC code over the additive white Gaussian noise (AWGN) channel and present a constraint-to-variable update rule based on the specific codewords of the component codes. The block error rate performance of the GLDPC codes, combined with a complementary outer code, is shown to outperform a variety of stateof-the-art code and decoder designs with suitable lengths and rates for the 5G ultra-reliable low-latency communication regime over an AWGN channel with quadrature PSK modulation.