The throughput of an LDPC-based incremental-redundancy scheme over block-fading channels

INcremental-Redundancy (INR) is a form of hybrid ARQ where the receiver asks the transmitter for additional parity bits when decoding is not successful. This technique is particularly useful in time-selective fading channels, since it implements variable-rate adaptive transmission with a very simple feedback binary channel, where the feedback messages are positive or negative acknowledgments (ACK and NACK, respectively). In this work an information-theoretic analysis of the achievable throughput and delay of INR over block-fading channels for random binary codes and for low-density parity-check (LDPC) binary linear codes.