Transmission latency minimization and energy efficiency improvement are two main challenges in multi-hop Cognitive Radio Networks (CRN), where the knowledge of topology and spectrum statistics are hard to obtain. For this reason, a cross-layer routing protocol based on quasi-cooperative multi-agent learning is proposed in this study. Firstly, to jointly consider the end-to-end delay and power efficiency, a comprehensive utility function is designed to form a reasonable tradeoff between the two measures. Then the joint design problem is modeled as a Stochastic Game (SG), and a quasi-cooperative multi-agent learning scheme is presented to solve the SG, which only needs information exchange with previous nodes. To further enhance performance, experience replay is applied to the update of conjecture belief to break the correlations and reduce the variance of updates. Simulation results demonstrate that the proposed scheme is superior to traditional algorithms leading to a shorter delay, lower packet loss ratio and higher energy efficiency, which is close to the performance of an optimum scheme.
Keywords: cognitive radio; cross-layer routing protocol; experience replay; quasi-cooperative multi-agent learning; stochastic game.