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Performance of frequency resource assignment schemes for cognitive radio based cooperative communication systems

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 resource allocation algorithms are presented and experimental results demonstrate that the proposed algorithms can not only enhance throughput, but also improve fairness and utility of users assuming available channels are known by base station.