An Opportunistic Scheduling Scheme for Cognitive Wireless Networks with Cooperative Beamforming

Recent work has shown that distributed (or cooperative) beamforming can achieve cooperative gain, such as throughput gain and diversity gain, with no need for extra spectral holes in Cognitive Wireless Networks (CWNs). However, how to efficiently schedule cooperative beamforming to improve the quality of service of unlicensed secondary users has not been well addressed. In this paper, a simple opportunistic scheduling scheme is proposed to serve delay-sensitive traffics in CWNs with cooperative beamforming. After the probabilities of outages due to channel fading and random appearance of primary users are analyzed, respectively, the overall outage probability of our scheme is minimized by optimizing the scheduling parameter. The optimal scheduling scheme is then derived for the high-SNR regime. Simulation results show that compared to conventional schemes without cooperative beamforming, our scheduling scheme can significantly lower down the probability of message transmission failure within a given time period.