Impact of User Collaboration on the Performance of Sensing-Based Opportunistic Spectrum Access

Spectrum scarcity is becoming a major issue for service providers interested in either deploying new services or enhancing the capacity for existing applications. On the other hand, recent measurements suggest that many portions of the licensed (primary) spectrum remain unused for significant periods of time. This has led the regulatory bodies to consider opening up under-utilized licensed frequency bands for opportunistic access by unlicensed (secondary) users. Among different options, sensing-based access incurs a very low infrastructure cost and is backward-compatible with the legacy primary systems. In this paper we investigate the effect of user collaboration on sensing- based secondary access in terms of critical parameters such as the spectrum utilization, the required signal-to-noise-ratio and the detection time. As suggested by our analysis and simulation results, collaboration may improve the opportunistic spectrum access significantly.