TCP Performance-Aware HARQ with AMC Scheme

This paper proposes a TCP performance-aware hybrid automatic repeat request (HARQ) with adaptive modulation and coding (AMC). The conventional scheme adapts the target packet error rate (PER) to improve the spectral efficiency at the expense of the average packet error rate when a packet is retransmitted. Unfortunately, this can cause the deterioration of TCP throughput. A TCP segment consists of several HARQ packets, thus the increase of error probability of a HARQ packet can exponentially increase the error probability of a TCP segment. For this reason, the conventional scheme may be inadequate from the TCP perspective. To solve this problem, this paper proposes the cross-layer MCS level selection method while referring to the TCP throughput. Compared with the conventional scheme, the proposed method improves the TCP throughput up to 89% over the poor signal quality.