The Research On Femtocell Uplink Interference Control Technology In LTE System

The rapid development of mobile communications technology and constantly increase of mobile users high-speed data traffic and multimedia traffic demand, promote the 3GPP’s evolution and research of UTRA and UTRAN, resulting in the emergence of the LTE which is a new wireless mobile communication technology. High frequency radio waves assigned in LTE macro base station have great penetrate loss in the building walls, so the indoor signal quality is poor, but the majority of data traffic request happen in the room, which causes the indoor mobile subscribers service experience have a serious decline. Femtocell is to appear to solve these problems, which is deployed in the indoor environment, through the IP backbual connection to the mobile core network, and is fully compatible with the LTE wireless spectrum and network architecture. So femtocell may effectively improve the indoor users received wireless signal quality and is the key technology of fixed-mobile convergence.Femtocell access point, also known as HeNB in LTE system, installed in room by the user, comprise LTE-Femtocell coexsitence wireless communication system with LTE system. Without planning and coordination in this coexistence system, a large number of serious interference will present, which will worsen LTE-Femtocell system overall performance. In this paper, on the primise that familiar with LTE system and femtocell norms, after reading lots of literatures about interference control technology in coexistence wireless communication system, the interference scenarios in the LTE-Femtocell system are classified and described, and then a detailed description is given to the general mechanism for uplink and downlink power control in LTE-Femtocell system. Focused on analysis of the interference that femtocell users transmit power to surrounding macro base station and its users and the influence in macro base station thruoghput in the uplink. Considering mitigating the adverse effects created by the femtocell users, this paper proposes two new algorithms based on LTE fractional power control to dynamically control femtocell users transmit power: based on path loss difference and based on network assistance.By Matlab to bulid LTE-Femtocell system-level simulation platform, using the Monte Carlo static simulation algorithm, On the basis of the femtocell suburban indoor model, these two proposed algorithms carry on simulation and analysis. The simulation results show the PLd algorithm weakens the impact generated by femtocell users in macro throughput, but reduces femtocell users performance; and the NA algorithm, ensuring the femtocell users performance, effectively reduces the degree of deterioration in its surrounding macro throughput performance.