Performance Evaluation Of Wireless Relay For Lte-Advanced System

LTE-Advanced is enhanced technology based on LTE (Long Term Evolution). And it is also one of candidate technological standards for the next generation of mobile communication systems IMT-Advanced (International Mobile Telecommunication Advanced). LTE-Advanced system demands more on bandwidth, user data rate and spectral efficiency. In order to achieve requirements of LTE-Advanced system,3GPP proposed several key technologies including carrier aggregation, relay and multi-point cooperation. Relay technology can not only extend cell coverage, improve system throughput, eliminate or reduce communication blind zone, provide hotspots and indoor coverage, but also provide temporary and emergency network deployment, significantly reduce the cost of infrastructure through a wireless connection to the fixed network. Therefore, Relay technology got widespread attention and study.As a newly introduced node in cellular network, relay node adds access point for users and new data transmission links, which will inevitably lead to a complex interference structure and resource allocation problem. In the thesis, in order to achieve optimal system performance, resource allocation schemes and interference conditions are researched through system-level simulation of wireless relay system. In addition, capacity of backhaul link is an important factor determining system performance, so enhancement of backhaul link performance is a major study point.In the thesis, simulation platform of LTE-Advanced downlink relay system is built up according to3GPP protocols and proposals, and research and performance evaluation of relay technology in LTE-Advanced system is carried out. The main contents include:(1) Simulation platform of downlink relay system is designed and set up according to scenario assumptions and simulation parameters in3GPP TR36.814and other related protocols and proposals, including function modules such as network topology modeling, relay node deployment and user generation, radio propagation channel modeling, user access point selecting, traffic modeling, resource scheduling and interference calculation.(2) Resource allocation scheme in time and frequency domain is studied and a new user scheduling scheme based on relay buffer is put forward, which are verified to achieve performance enhancement by simulation.(3) Based on relay system simulation platform, we assess impact of the number and transmit power of relay on system performance, and analyze system performance by sector average throughput and edge user throughput.(4) Multi-user transmission scheme for improving backhaul link capacity is studied, since backhaul link capacity is the bottleneck limiting system performance improvement. We also verify the performance enhancement of system using the scheme by simulation.