Conditional error rate and combining schemes for hybrid automatic repeat request with M‐pulse amplitude modulation
Hang Long, Wei Xiang, Jing Wang, Yueying Zhang, Yuanan Liu, Wenbo Wang · International Journal of Communication Systems · 2012
SUMMARY In hybrid automatic repeat request (HARQ), maximum ratio combining (MRC) is usually employed at the receiver if the retransmitted signal is the same as that of the first transmission. However, it is proved that MRC is not the optimum combining scheme with binary phase shift keying modulation in terms of the conditional error rate. In this paper, the conditional error rate of HARQ with M‐pulse amplitude modulation (M‐PAM) and arbitrary combining schemes at the receiver is analyzed. Then, the optimum combining scheme with M‐PAM is proposed with the aim of minimizing the conditional error rate.Copyright © 2012 John Wiley & Sons, Ltd.