Frequency Reuse And Handover Scheme In Cellular Relay Network Under Lte System

Nowadays, due to the advantage in network performance, the long term evolution (LTE) system is developing rapidly, and is becoming the leading edge in the research of wireless communication. Meanwhile, relay technology is one of the effect ways to increase cell coverage and transmission rate. Therefore the further improvement in network performance based on LTE relay networks is very popular in the communication field.The cellular relay network adopting Orthogonal Frequency Division Multiple (OFDM) technique has advantage in cell coverage and transmission rate. In order to improve the performance of cell edge users, especially to avoid inter cell and intra cell interference, this paper adopts an enhanced soft frequency reuse scheme to assure inter cell coordination. The algorithm proposed in the paper considers interference coordination and is load-adaptive. During the variable traffic load, this algorithm dynamically assigns available frequency resources among users, and uses interference indicator to reduce interference. It can improve signal-to-interference plus noise ratio (SINR) of the UE in each sub channel thus enable the system achieve better throughput and blocking probability performance. Simulation results prove that the proposed scheme may achieve desirable performance on throughput, blocking probability and spectral utilization in the sector under different traffic load compared with other schemes.Besides, In order to optimize handover target selection and achieve better handover performance in cellular relay networks under LTE system, a novel handover measurement and decision scheme based on cost function is proposed in the paper. The proposed scheme adopts reference signal receiving quality (RSRQ) in the measurement stage and uses a modified signal cost function considering signal overhead in different handover types and expected long-term throughput of UE. Besides, UE fairness and sector resource utilization are taken into account as well. Theory analysis and simulation results prove that the proposed scheme can enhance cell throughput, decrease handover delay and signal overhead, and improve UE fairness. LTE relay multicast and broadcast NS2 simulation platform is also established to provide platform for theory research and algorithm design. The simulation platform optimizes protocol stack, implements relay selection algorithm, inter cell interference coordination and handover function. Besides, it completes the construction and establishment of multicast service, network and accumulative broadcast algorithm.