Bhuvan Modi, O. Olabiyi and A. Annamalai
Center of Excellence for Communication Systems Technology Research, Department of
Electrical and Computer Engineering, Prairie View A & M University, TX 77446 United
States of America
This paper analyzes the efficiency of a joint-design of an 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 nonregenerative
relay networks under prescribed delay and/or error performance constraints. Particularly, we
generalize the existing design model/results for cross-layer combining of AMC along with truncated ARQ
in non-cooperative diversity networks 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 nonidentically
distributed (i.n.d) fading statistics among the spatially distributed nodes; (iii) analysis of the
effectiveness of joint-adaptation of the maximum retransmission limit Rmax of ARQ protocol and
cooperative diversity order N for delay-insensitive applications. Our insightful numerical results reveal
that the average throughput can be increased significantly by judiciously combining two additional degrees
of freedom (N and Rmax) that are available in cooperative amplify-and-forward (CAF) relay networks
besides employing AMC at the PHY layer, especially in the most challenging low signal-to-noise ratio
(SNR) regime.
KEYWORDS
cross-layer design, adaptive retransmission, cooperative relay diversity, adaptive modulation and coding
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