Dynamic frequency allocation of femtocells for guaranteed macrocell throughput in OFDMA networks

Recently, femtocells have been introduced for indoor coverage extension and higher bandwidth services. However, the frequency allocation problem between the femtocells and the macrocell causes co-channel interference to be treated carefully. In this paper, we propose a dynamic frequency resource allocation scheme using Fractional Frequency Reuse (FFR) while satisfying the required macrocell throughput with a higher priority. The proposed scheme guarantees target macrocell throughput and allocates resource to femtocells in a dynamic manner by using the macrocell base station information. Assumpting that the macrocell users have priority over femtocell users, the macrocell users are pre-allocated by the 3-sectored FFR. The macrocell base station then informs femtocells of the reused sub-carriers with the allocation information of the macrocell users. In this way, the interference between the macrocell users and femtocells is greatly reduced and the target macrocell throughput is fulfilled. The simulation results show that proposed scheme enhances both macrocell/femtocell throughputs, and satisfies macrocell throughput in the overall network.