An interference coordination scheme for dense femtocell environment

Femtocells applied in many existing systems, such as HSPA, 3GPP LTE, WiMAX, and etc, which cover a short range and offer an economically viable way to improve cellular system capacity, have caught world-wide researching interest nowadays. An interference coordination scheme is proposed for LTE downlink in this paper, which is split into three steps named as interference graph creation, orthogonal frequency distribution (OFD) algorithm and adaptive frequency reallocation (AFR) algorithm, respectively. The interference graph is created on the basis of the interference detection mechanism named as femtocell user measure-and-report (UMR). The OFD algorithm is used to allocate the orthogonal sub-bands with the goal of eliminating the inter-cell interference caused by neighbor femtocells. The AFR algorithm executes to improve the system capacity and imposes a limitation on the interference level. By extensive simulations, it has been proved that the proposed scheme can effectively mitigate the inter-cell interference and attain superior performance in terms of cell-edge and femtocell throughput compared to the reference schemes in the paper.