Research On The Algorithm For Inter-Cell Interference Coordination In LTE-A Relay System

In order to meet the needs of IMT-Advanced and the higher demand for wireless communication market in the next few years,3GPP launched LTE-Advanced (LTE-A) research project. LTE-A is an evolution of LTE, which is proposed for providing a higher performance for the wireless communications system. It theoretically provides the uplink and downlink peak rates of up to500Mbps and1Gbps respectively, and the uplink and downlink peak spectrum efficiency of15bps/Hz and30bps/Hz, which allows the user to experience service with higher transmission rate and lower delay. LTE-A uses a series of technologies to improve the wireless communication system performance greatly including carrier aggregation, relay technology, multi-antenna enhancement technology and cooperative multi-point transmission. What LTE-A can achieve means that it will be the mainstream of wireless communications development in the following years.In LTE-A, inter-cell interference is an important factor of affecting the system performance, especially for cell edge users. While relay technology is used in LTE-A, which greatly improves the cell coverage and the effective transmission rate of the cell edge, it also increases the complexity of the interference scene, which makes the research of interference management in LTE-A relay system meaningful.Interference coordination is a key technology to solve inter-cell interference. By managing wireless resource and reducing interference between cellular, interference coordination improves system performance in a coordinated manner. In this paper, the interference coordination techniques in LTE-A relay system are studied. In the premise of studying a large number of related documents, a variety of LTE-A interference coordination algorithms are summarized and several schemes based on spectrum allocation are proposed according to FFR (Fractional Frequency Reuse) and SFR (Soft Frequency Reuse). Besides, the paper models resource allocation problem as a graph coloring problem and figures out a solution based on graph theory. The proposed schemes allow the system to get a performance gain which verifies the effectiveness of these schemes.