Distributed energy-efficient cross-layer design for cognitive radio networks

In this paper, we jointly consider power control, channel assignment, and routing to minimize network energy consumption while maintaining data rate requirements on each radio link in the multi-hop cognitive radio network. This problem is formulated as a Mixed Integer Non-linear Programming (MINP). Due to the NP-hard property of the MINP, the MINP is decomposed into |N| (the number of nodes in the network) problems so that each problem can be distributedly and locally solved at each node. Furthermore, a Lagrangean Relaxation based Heuristic (LRH) was proposed to approximate the solution of each problem. Through the technique of Lagrangean relaxation, each problem is transformed into its relaxed form and solved iteratively. Numerical results demonstrate that the proposed scheme can efficiently save network energy consumption up to 90%.