Cross-Layer QoS-Constrained Optimization of Adaptive Multi-Rate Wireless Systems using Infrastructure-Based Cooperative ARQ

This research work aims at analyzing the effects of using cooperative-ARQ (CARQ) in wireless relay systems employing AMC at the physical layer and an infinitely persistent type-I Hybrid FEC/CARQ protocol at the DLC layer. To that end, a cross-layer multidimensional discrete-time Markov chain (DTMC)-based queuing model is developed to jointly exploit the capabilities of CARQ and AMC. Based on the stationary state probability distribution of the proposed multidimensional DTMC, closed-form analytical expressions for performance metrics such as average throughput, queue length, packet delay and packet loss rate are derived, and the impact of cooperative relaying on these performance parameters is analyzed. Numerical results confirm the validity of the presented AMC/CARQ cross-layer analytical framework and reveal that the proposed CARQ protocol consistently outperforms the classical Type-I Hybrid FEC/ARQ schemes and provides a noticeable improvement when facing correlated fading channel scenarios.