Cooperative AF Relaying in Spectrum-Sharing Systems: Outage Probability Analysis under Co-Channel Interferences and Relay Selection
Cooperative AF Relaying in Spectrum-Sharing Systems: Outage Probability Analysis under Co-Channel Interferences and Relay Selection
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DOI：
10.1109/tcomm.2012.082712.120108
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发表时间：
2012-09
影响因子：
8.3
通讯作者：
Minghua Xia;S. Aïssa
中科院分区：
文献类型：
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作者：
Minghua Xia;S. Aïssa
对于频谱共享无线系统中的协作放大转发（AF）中继，次用户共享最初许可给主用户的频谱资源以彼此通信，并且因此，次发射机的发射功率严格地受到主接收机处的可容忍干扰功率的限制。此外，在中继器和次级接收器处接收的信号不可避免地受到来自初级发射器的信号的干扰。来自并发主传输的这些同信道干扰（CCI）会显著降低辅传输的性能。本文研究了频谱共享环境下，信道干扰对次链路中断概率的影响。特别地，为了补偿由于CCI引起的性能损失，次发射机及其中继节点的发射功率分别关于主接收机处的可容忍干扰功率和来自主发射机的CCI两者来优化。此外，当多个中继可用时，机会主义中继选择技术被利用以进一步提高系统性能，具有较低的实现复杂度。通过分析次系统中断概率的上下限，发现主接收端的可容忍干扰功率决定了系统性能，而不是主发射端的CCI。系统设计人员将受益于这一结果，在规划和设计下一代宽带频谱共享系统。
For cooperative amplify-and-forward (AF) relaying in spectrum-sharing wireless systems, secondary users share spectrum resources originally licensed to primary users to communicate with each other and, thus, the transmit power of secondary transmitters is strictly limited by the tolerable interference powers at primary receivers. Furthermore, the received signals at a relay and at a secondary receiver are inevitably interfered by the signals from primary transmitters. These co-channel interferences (CCIs) from concurrent primary transmission can significantly degrade the performance of secondary transmission. This paper studies the effect of CCIs on outage probability of the secondary link in a spectrum-sharing environment. In particular, in order to compensate the performance loss due to CCIs, the transmit powers of a secondary transmitter and its relaying node are respectively optimized with respect to both the tolerable interference powers at the primary receivers and the CCIs from the primary transmitters. Moreover, when multiple relays are available, the technique of opportunistic relay selection is exploited to further improve system performance with low implementation complexity. By analyzing lower and upper bounds on the outage probability of the secondary system, this study reveals that it is the tolerable interference powers at primary receivers that dominate the system performance, rather than the CCIs from primary transmitters. System designers will benefit from this result in planning and designing next-generation broadband spectrum-sharing systems.