Distributed Optimal Relay Selection for Improving TCP Throughput in Cognitive Radio Networks: A Cross-Layer Design Approach
In Cognitive Radio (CR) networks, cooperative relaying is emerging as a key technology to improve the performance of Secondary Users (SUs), while ensuring the quality of service of primary users. Most previous work considers maximizing physical layer throughput as a design criterion. However, the end-to-end Transmission Control Protocol (TCP) performance perceived by SUs is largely ignored. In this paper, the authors take a cross-layer approach to jointly consider optimal relay selection strategy, adaptive modulation and coding and data-link layer frame size to maximize the TCP throughput in CR networks. Specifically, they formulate the CR relay network as a restless bandit system, where the finite-state Markov channel model is used to characterize the time-varying channel state.