Distributed Hybrid Spectrum Sharing for OFDMA-based Cognitive Femtocells in 5G Networks

Abstract:
The femto access points (FAPs) with cognitive capabilities are seen as an efficient way to cope with interference between the FAPs and the macrocells (MBSs). This interference should be properly addressed in emerging 5G mobile networks to enable dense deployment of the FAPs. The cognitive FAPs may access the spectrum by means of overlay or underlay mode. The main drawback of the overlay mode is that its efficiency fully depends on the activity of the macrocell users (MUEs) and insufficient resources can remain for the FAPs’ users (FUEs). The main drawback of the underlay mode is that it can result in low transmission efficiency due to low power level. In this paper, we propose a distributed hybrid spectrum sharing that dynamically selects the mode currently more beneficial in terms of FUEs’ throughput. The results show that the proposed scheme is able to significantly outperform both overlay and underlay modes in terms of FUEs’ throughput while the performance of MUEs is intact.