Protograph-Based Raptor-Like LDPC Codes with Edge Addition for URLLC

For ultra-reliable low-latency communications (URLLC), low error floors are required for channel codes. In this paper, we propose a method of adding some edges to the protograph of the protograph-based raptor-like (PBRL) low-density parity-check (LDPC) codes. The added edges play a role of boosting up the reliability of weak variable nodes so that the code with edge addition can achieve low error floors. The edge addition is applied to an instance of 5G new radio (NR) LDPC code and it is shown that the edge addition lowers the error floor of the 5G NR LDPC code. Since the edge addition does not change the existing edge connections in the protograph, an adaptive use with/without edge addition have an effect of implementing two PBRL LDPC codes for enhanced mobile broadband (eMBB) and URLLC in an efficient way while keeping the system compatible with the original PBRL LDPC code.