Energy-Efficient Spectrum Allocation In Two-Tier Femtocell Networks

Femtocell is a promising option for the mobile operators to improve the network coverage. However, the mass deployment of femtocell faces a number of challenges.In this paper, we focus on interference management and green communication technology, and propose an interference mitigation spectrum allocation for energy efficient OFDMA femtocell networks. We first propose an inter-tier interference mitigation strategy by forcing the macro-interfering femtocells to use the dedicated sub-channels. The non-interfering femtocells, on the other hand, will use the shared sub-channels which are also used by the macrocell. We then present the sub-channels allocation scheme based on the Firefly algorithm to mitigate the intra-tier interference. Finally, we reassign the ratio between the dedicated and shared sub-channels to maximize the efficient utilization. The propose interference mitigation scheme offers significant performance improvement by substantially reducing the inference and improving fairness and energy efficiency of utilization in the system. At last, we have analyzed the interference in the two-tier femtocell network and establish the system model through MATLAB. Extensive simulation results have demonstrated that the proposed interference mitigation framework can effectively mitigate both inter-tier and intra-tier interference and improve the fairness and energy efficiency significantly.