Asymptotic performance of collaborative spectrum sensing under correlated log-normal shadowing

Collaborative spectrum sensing enables opportunistic unlicensed access to the unused portions of the licensed spectrum. We characterize the performance degradation of collaborative sensing due to correlated shadowing by deriving a lower-bound on the probability of missing the opportunities for unlicensed access. Moreover, we evaluate the effective number of collaborating users in terms of the distance spread of the sensing network and the characteristics of the propagation environment. This has practical implications in terms of protocol design as having a few number of users collaborate over a large distance may be more effective than a dense sensing network confined to a small area