认知中继协同无线通信系统功率分配和混合频谱接入方案

文章首先对Underlay 认知-中继协作（cognitive radio relay cooperation, CR-RC）系统信源和中继的功率分配问题进行了研究，获得了Underlay CR-RC系统信源、中继独立功率分配(independent power allocation, IPA）和联合功率分配（joint power allocation, JPA）方案，并给出了基于IPA和JPA的CR-RC系统的中断概率和各态历经容量的封闭解析解；其次通过对Underlay CR-RC系统中断性能的比较分析，提出了高频谱效率、高能量效率的混合Interweave-Underlay CR-RC方案。在该方案中，定义了主、从用户中断概率约束，充分考虑了主、从系统的服务质量(quality of service, QoS)，当即使从用户的发射功率为零，主系统的QoS仍不能满足时，从用户以最大功率发送信号，无需考虑其对主用户的影响；当由于很强的主用户干扰，使得从用户的QoS不能得到满足时，从用户不再发射信号，发信功率为零；当主、从系统的QoS能够同时满足时，以Underlay模式工作。 

Power Allocation and Hybrid Spectrum Access Scheme of Cognitive Relay Cooperation Wireless Communication Systems

In this paper, we first investigate the power allocation for the source and relay of Underlay cognitive radio relay cooperation (CR-RC) systems, and present the independent power allocation (IPA) and joint power allocation (JPA) schemes. Then, with the IPA and JPA, the closed-form expressions of outage probability and ergodic capacity for Underlay CR-RC systems are achieved. Finally, through the comparison of outage performance, a hybrid Interweave-Underlay CR-RC schemes is presented. In the presented hybrid Interweave-Underlay CR-RC scheme, by considering the quality of service (QoS) of both the primary users (PUs) and secondary users (SUs), we define the constraint on the outage probability of primary and secondary systems. The main idea of the presented hybrid Interweave-Underlay CR-RC scheme is: 1) The SUs send its signals with maximum power under the case where the QoS of PUs is not guaranteed even if the transmit power of SUs is zero. 2) The SUs do not transmit signal under the case where the outage probability of SUs is very high due to the severe interference from PUs. 3) When the QoS of PUs and SUs is guaranteed simultaneously, the primary and secondary users work together by sharing spectrum.