Cross-layer optimization and analysis for overlay cognitive radio

Due to the spectrum-temporary challenges in the cognitive radio networks (CRNs), the pure divide-and-conquer strategies by layered principles strand. In this paper, our study presents a framework for cross-layer modeling design to jointly optimise the power and spectrum allocation, multi-path routing, data traffic, and QoS requirements in overlay CRNs. Because of the complexity of the optimization problem, vertical decomposition and distributed subgradient methods are applied. Firstly, the optimization problem is decoupled into two subproblems - a master problem related to QoS constrained flow control and routing selection, and a subproblem related to spectrum selection and physical power allocation - with dual decomposition method. Secondly, the master problem is further decomposed with the primal decomposition method, while the subproblem derived by a Lagrangian optimum with dual factors. Finally, simulation results show the implementability and efficiency of our proposed framework.