Opportunistic spectrum sharing in Poisson femtocell networks

In this paper, we propose a cognitive-based opportunistic spectrum sharing strategy for performance enhancement of a femtocell networks. This cognitive-based opportunistic spectrum access strategy aims to achieve better spectrum utilization with quality of service (QoS) protection for macrocell user equipments (MUEs) since the macrocell tier can be over-allocated spectrum resources. We analyze the performance of the two-tier network where the success probability with respect to the received signal to interference ratio (SIR) at each user and the total network throughput are derived under both closed and open access policies. In addition, we describe how to optimally choose the SIR threshold Q to maximize the total network throughput subject to QoS constraints for macrocell and femtocell users in terms of success probability. Via numerical studies, we show that our proposed opportunistic spectrum access scheme can achieve significant throughput gain compared to the conventional spectrum partitioning strategy.