Joint-design of adaptive modulation and coding with adaptive ARQ for cooperative relay networks
A. Annamalai, Bhuvan Modi, Oluwatobi Olabiyi · 2011
This article investigates the efficacy of a joint-design of adaptive modulation and coding (AMC) at the physical (PHY) layer with an adaptive Rmax-truncated selective-repeat automatic repeat request (ARQ) protocol at the medium access control (MAC) layer to maximize the throughput of cooperative amplify-and-forward (CAF) relay networks under prescribed delay and/or error performance constraints. Specifically, we generalize the existing design/results for cross-layer combining of AMC with truncated ARQ in non-cooperative diversity systems in three-folds: (i) extension of the cross-layer PHY/MAC design or optimization to cooperative diversity systems; (ii) generalization/unification of analytical expressions for various network performance metrics to generalized block fading channels with independent but non-identically distributed (i.n.d) fading statistics among the spatially distributed nodes; (iii) investigation of the effectiveness of joint-adaptation of the maximum retransmission limit Rmaxin ARQ protocol and cooperative diversity order N for delay-insensitive applications. Our numerical results reveal that the average throughput can be increased considerably by judiciously combining two additional degrees of freedom (N and Rmax) that are available in CAF relay networks besides employing AMC at the PHY layer, especially in the most challenging low signal-to-noise ratio (SNR) regime.