Win–win relationship between macrocell and femtocells for spectrum sharing in LTE-A

Heterogeneous networks (HetNets) are likely to provide a ubiquitous access to the mobile broadband services as they involve various small cells, each targeting a different environment in the network. However, the application of the advanced resource allocation techniques is highly needed in order to handle the inter-cell interference and fully exploit the benefits of such networks. In this study, the authors address the spectrum sharing problem in a HetNet composed of a macrocell and several femtocells. They propose a new approach in which macrocell and femtocells can simultaneously share the available bandwidth, while avoiding the intra-tier interference and helping the macrocell to offload by expanding the cell range of some femtocells. The author´s approach is formulated as a Stackelberg game, in which the macrocell is selling bandwidths to femtocells in exchange of some victim macro-users to serve, mainly the macro-users who undergo severe interference from the neighbouring femtocells. They demonstrated that their game theoretic reaches a stable state called Stackelberg equilibrium analytically and by simulations. More importantly, they show that overall network performance is improved in terms of total femtocells´ throughputs and spectral efficiency of the macro-users who are in the vicinity of the femtocells.