Rate-maximization Channel Assignment Scheme in Cognitive Radio Networks

In this paper, we consider the coordinated spectrum access problem in a multiuser single-transceiver cognitive radio network (CRN). Our objective is to maximize the sum-rate achieved by all contending CR users with respect to both spectrum assignment and transmission rate. The problem is posed as a utility maximization problem subject to hardware and interference constraints. Specifically, we show that this problem can be formulated as an integer linear programming problem (ILP) with unimodular constraint matrix, which can be optimally solved in polynomial time using linear programming (LP). Unlike previous research, our formulation is not restricted to the information-theoretic capacity, and can be applied to any arbitrarily given rate-SINR function. We also develop a distributed CSMA/CA-based MAC protocol for CRNs to realize the optimal assignment in a distributed manner. The performance of our protocol is compared to a reference CSMA/CA CRN MAC protocol. Simulation results show that the proposed protocol significantly improves network throughput and preserves fairness.