Cell edge detection based interference avoidance scheme for closed mode LTE femtocells

Femtocells have come up as a promising solution for indoor coverage and Quality of Service, QoS of the users. One of the major challenges in the wide deployment of the femtocells is the cross-tier interference among the users at the cell edges. A typical high interference case is the uplink interference caused by the non subscribed cell edge users at the closed mode femtocells. In dense urban scenarios this interference may occur frequently resulting in the high deterioration of the femtocell capacity and QoS of the users; thus affecting the over all cell throughput. Fractional Frequency Reuse, FFR based schemes are a common option to cater the problem. Although efficient in interference avoidance, FFR results in lower cell throughput. The proposed scheme is an effective threshold based interference avoidance scheme working on the principles of Universal Frequency Reuse, UFR to obtain higher cell throughput. The information of femtocells location or their power settings are not required in the approach. Consequently it requires minimum backhaul signalling between the macrocell and the femtocells. Simulation results show significant improvement of the proposed scheme in terms of macrocell throughput, spectral efficiency and SINR of the femtocell user.