Hybrid spectrum arrangement and interference mitigation for coexistence between LTE macrocellular and femtocell networks

When deploying two-tier LTE cellular networks with coexistence of macrocells and underlaid femtocells, the strategies of spectrum arrangement need to be investigated to efficiently utilize the scarce spectrum resource. Co-channel spectrum usage and dedicated-channel spectrum usage are two traditional strategies of spectrum arrangement. Nevertheless, there are pros and cons of them from the perspective of achievable network capacity in two-tier LTE network as they result in different amounts of available spectrum at each tier and disparate cross-tier interferences. To improve overall spectrum utilization, we propose a novel approach of spectrum arrangement, which is called hybrid spectrum arrangement, to take advantage of their merits. In our proposal, an underlaid femtocell can select its spectrum usage mode according to a criterion aiming to benefit both macrocell and femtocell in terms of achieved capacities. Consequently, the femtocells embedded in macrocell are self-organized as inner and outer femtocells, which operate in dedicated-channel spectrum usage and co-channel spectrum usage, respectively. Then, we examine distinct characteristics of cross-tier interferences in the context of hybrid spectrum arrangement and present corresponding schemes to mitigate the residual significant interferences. Analysis and system level simulation are given to validate the effectiveness of our proposed methods for two-tier LTE cellular network.