An adaptive sub-band allocation scheme for dense femtocell environment

Femtocells are designed to cover a short range of area and improve the cellular system capacity in an economically viable way. In this paper, we propose an adaptive sub-band allocation (ASA) scheme for the downlink transmission of the LTE system, which consists of orthogonal sub-band assignment (OSA) algorithm and adaptive sub-band reuse (ASR) algorithm based on the interference graph. The interference graph is used to model the interference relationships between femtocells and femtocell users, while it could be simplified as the interference relationships of adjacent femtocells in this paper. The OSA algorithm is performed to eliminate the inter-cell interference, while the ASR algorithm is operated to increase with spectral reuse and suppress the interference level of the network. An instance of our ASA scheme is described in detail, which considers the mobility of the serving users and the operation complexity. By extensive simulations, it has been proved that our proposed scheme effectively mitigates the interference level in the femtocell networks and obtains superior performance in terms of cell-edge and femtocell throughput compared with the reference schemes available in the paper.