Coverage Radius Bounds and Impact on SINR in Blindly Placed LTE Femtocells

An important issue affecting cellular networks is to make services available to regions of bad or no reception. Femtocells are considered to be the solution to meet the future needs for better indoor coverage, high data rates and capacity in the cellular networks. Since femtocell access points (FAPs) are usually user deployed, thus blind placement of FAPs is inevitable leading to problems of power spillage causing severe co and cross-tier interference and subsequent performance degradation. Even though femtocells are discovering an important role, the issue of interference as a result of blindly placed FAPs needs to be addressed. This paper presents performance analysis of a coverage radius based power control scheme to circumvent the problems caused by blind placement of FAPs. Our coverage radius based power control scheme does not require FAPs to be relocated to optimal positions for interference mitigation; rather a self-update algorithm is implemented by FAPs to reduce their cell radius by adaptive adjustment of power values for interference management. Using system level simulations, the performance of the scheme has been analysed for densely deployed single and multi cell femtocell scenarios. Compared to existing schemes, our scheme provides improved interference mitigation and throughput results. The results reveal that coverage radius of FAPs has considerable effect on both co and cross-tier signal to interference plus noise ratio (SINR) values. It is also shown that there are coverage radius bounds which provide balanced co and cross-tier SINR values. These bounds provide valuable information for effective distribution of Femtocell User Equipments to avoid performance degradation in blindly placed densely deployed femtocells.