Optimal Joint Transmission Time and Power Allocation for Heterogeneous Cognitive Radio Networks

Abstract

The resource allocation in cognitive radio networks is one of the key issues to improve the spectrum efficiency. In most previous work, only one type of the secondary user (SU) network architecture is considered, i.e., it is always assumed that all SUs are centralized, or all are distributed. However, in heterogeneous cognitive radio networks, which takes both the centralized and distributed architectures into account, the resource allocation problem is largely ignored. In this paper, the joint transmission time and power allocation problem is considered for heterogeneous cognitive radio networks. The problem is formulated as a dual optimization problem with the optimization objective to be maximizing the total capacity of the SUs with the constraint of fairness. We first optimize the joint transmission time and power allocation for centralized SUs and propose a resource allocation scheme for centralized SUs in the time-frequency domain. Then for the heterogeneous case with both the centralized and distributed network architecture considered, we formulate the resource allocation problem as a cooperative game and propose an iterative power water-filling scheme to get to the Nash Equilibrium (NE). Based on the dual optimization, a dynamic optimal joint transmission time and power allocation scheme for heterogenous cognitive radio networks is proposed. Extensive simulation results are presented to illustrate the performance of the proposed scheme.