Selective HARQ Transceiver Design for OFDM System

We present a novel selective Hybrid Automatic Repeat reQuest (HARQ) based transceiver design for orthogonal frequency division multiplexing (OFDM) system. The proposed method is bandwidth efficient and has lower complexity as compared to conventional HARQ method adopted by communication standards such as long-term evolution (LTE). Our transceiver design introduces an additional retransmission layer at OFDM modulation level, which is independent of conventional HARQ methods. Instead of calculating computationally expensive soft information and applying forward error correction (FEC) on the soft information, receiver requests retransmission of information symbols corresponding to the subcarriers that have signal-to-noise ratio (SNR) below a set threshold at modulation level. We also provide criteria for selective retransmission and throughput analysis with new selective retransmission approach. We demonstrate that with limited feedback at modulation layer level, the proposed method enhances throughput of the system in all SNR regimes. The proposed selective HARQ method provides great flexibility for an application to optimize throughput based on its bit error rate (BER) requirement.