Abstract: One of the effective techniques of improving the coverage and enhancing the capacity and data rate in cellular wireless networks is to reduce the cell size and transmission distances. Long Term Evolution (LTE) has developed small cellular base stations called femtocells that can dramatically improve voice and data coverage for the indoor subscribers. Therefore, the concept of deploying femtocells over macro cell has recently attracted growing interests in academia, industry, and standardization forums. Various technical challenges towards mass deployment of femtocells have been addressed in recent literature. However, the inter- and intra tier interferences in such systems can significantly reduce the capacity and cause an unacceptably high level of outage. In this paper we propose a scheme which mitigates co-tier as well as cross tier interference using cluster aware soft frequency reuse scheme. That assigns distinct set of Physical Resource Blocks (PRB)s to each interfering femtocells. The scheme first uses periodic messages from the femto-user (FUE) to identify the interfering femtocells. It then divides each femtocell area into cell-center and cell-edge. Finally, it uses the CASFR algorithm to assign un interfering sets of PRBs to the cell-center and cell-edge users of all the interfering femtocells Same process is followed by macrocells. The proposed interference mitigation scheme for femtocell networks offers significant performance improvement over the existing methods by substantially reducing the co-tier and cross-tier inferences in the system.

Keywords: Physical Resource Blocks (PRB), Femto-user (FUE), Inter-cell interference (ICI), PRB Swapping and Exchange (PSE).