Packet Superposition HARQ Scheme Enabled by LDPC Coupled Codes

In this paper, we propose an improved Hybrid Automatic Repeat reQuest (HARQ) scheme based on cross-packet superposition retransmission by employing dedicated low-density parity-check (LDPC) matrices. Simulation results demonstrate that the scheme improves Bit Error Rate (BER) and Packet Error Rate (PER) performance up to 0.4 dB at the cost of increased packet handling complexity. The key element of our system is the combination of the systematic part of a codeword with the parity part of another codeword without any reductions in the code rate. Thus, to some extent, retransmission can be performed without any need to send additional parity bits.