Performance of power allocation of relay stations for cognitive radio based cooperative communication systems

Abstract

Cognitive radio (CR) allows unauthorized users to access authorized band without interfering the authorized user, thereby improving the bandwidth efficiency. In addition, cooperative communications with relay stations (RSs) can be used to improve throughput performance of 4G downlink network. In this study a cognitive radio assisted cooperation (CRAC), which combines advantages of CR and cooperative communications with RSs, is considered for resources allocation in the downlink orthogonal frequency division multiple access (OFDMA) networks. Two adaptive power allocation schemes, throughput based power allocation of RS (Thr-RS) and utility based power allocation of RS (Uti-RS) are presented. Simulation results demonstrate that the proposed Uti-RS allocation schemes can not only enhance throughput, but also improve fairness and utility of users for CRAC communication systems.