关键词:认知无线电;协作中继;功率分配;功率控制;信道分配;中继选择 I 南京邮电大学硕士研究生学位论文 ABSTRACT ABSTRACT Cognitive radio (CR) is a new promising technology to improve the utilization of the limited spectral resources, which allows the primary users (PUs) and secondary users (SUs) to share the same spectrum. Spectrum availability of SUs is heterogeneous due to the location difference and opportunistic spectrum access nature of SUs, therefore the resource unbalance in cognitive radio networks (CRNs) is much more severe than traditional wireless networks. Cooperative relay can solve this problem by using relay nodes to bridge the transmitter and receiver exploiting channels common with them respectively. With the introduction of cooperative relay, the allocation of wireles