Cross-layer combination of cooperative HARQ with AMC in wireless ad-hoc networks

This paper proposes a cross-layer design which combines adaptive modulation and coding (AMC), cooperative diversity at physical layer (PHY) and hybrid automatic repeat request (HARQ) at data link layer (LL) for wireless ad-hoc networks. First, we provide theoretical analyses of conventional direct transmission scheme and cooperative transmission scheme with AMC and HARQ that include analytical expressions for the packet error rate (PER) and spectral efficiency. Then we propose a novel hybrid transmission scheme which invokes cooperation based on the feedback AMC information. Numerical results demonstrate that the performance of the hybrid transmission scheme is equivalent to the cooperative transmission scheme while its cooperation cost is kept much lower compared with that of the cooperative transmission scheme.