Optimal distributed cooperative node selection for multimedia transmission improvement in cognitive radio networks

In this paper, we take a cross-layer design approach to jointly consider distributed optimal relay selection, adaptive modulation and coding (AMC) at the physical layer and intra-refreshing rate at the application layer to improve multimedia transmissions over underlay CR networks. Specifically, we formulate the CR cooperative network as a restless bandit system, where the finite-state Markov channel (FSMC) model is used to characterize the time-varying channel state. The objective is to minimize multimedia distortion and increase spectral efficiency. With this stochastic optimization formulation, the optimal cooperative node selection policy has indexability property that dramatically reduces the computation and implementation complexity. Simulation results are presented to show the effectiveness of the proposed scheme.