Joint spectrum allocation and scheduling in multi-radio multi-channel cognitive radio wireless networks

Cognitive radio can dynamically adapt to the available spectrum in the wireless network. Scheduling and spectrum allocation are tasks affecting the performance of cognitive radio wireless network. In [1], an iterative approach was proposed to efficiently compute the optimal scheduling for wireless mesh networks with single channel and single radio. The optimal scheduling problem is decomposed to a sequence of small optimization problems and maximum weighted independent set (MWIS) problems, and both of them can be computed quickly even for large networks. For example, the optimal scheduling can be computed for the mesh network with more than 2,000 links in less than one hour. Here, the iterative algorithm is extended to the cognitive radio wireless network with multi-channel and multi-radio. Allowing the schedule problem over multi-channel multi-radio results in higher dimension optimization problem. However, the proposed algorithm can obtain the optimal spectrum allocation and the schedule quickly for moderate size of networks. Numerical experiments show that the optimal throughput is achieved when the number of channels is one or two more than the number of interfaces.