A tailored fractional frequency reuse scheme for Heterogeneous Networks

Enhancing the cell coverage and the network capacity is an urgent need in the future wireless communications. In this context, Heterogeneous Networks (HetNets), where traffic is offloaded to the small cells coexisting with the macro cells, are considered as an efficient solution. However, due to its multi-layer structure, interference is a major performance bottleneck for HetNets. Therefore, the spectrum has to be optimally assigned to the different network layers. In this paper, the inter-cell interference of the macro-pico deployment in a dense area case is investigated. We study some existing static Fractional Frequency Reuse (FFR) schemes and we propose a new one in order to alleviate both the co-tier and cross-tier interferences. The proposed solution is simple to implement and aims at maximizing the number of satisfied users given their required data rates. A planning study is first done and a heurestic approach is proposed to estimate the optimal parameters for the proposed scheme under different number of picocells. Then, a comparison with other FFR schemes is performed. Simulation results show that the proposed solution can boost significantly the overall system throughput (Mbps/k²) and reduce the outage probability.