Study On Coordinated Radio Resource Management Technique In Distributed Wireless Network

The next generation wireless communication network is evolving towards a heterogeneous, wideband and flat direction. Distributed wireless network is becoming an important support of future mobile communication network with its special characteristics such as cheap cost, rapid deployment and so on. In order to resolve the contradiction between scarce wireless resources and increasing requirements of data and multimedia, radio resource management techniques as efficient as possible are taken as one of the key research topics. Furthermore, coordinated communication technology makes high transmission efficiency and transmission reliability and therefore more comprehensive attention have been taken to the coordinated radio resource management techniques. Coordinated multiple points transmission as one of the key aspect from LTE-A could decrease the interference between base stations. There is no center control unit in distributed network and all transmission points have the same function with the center control unit, through the interconnection and sharing users’data between transmission points, coordinated transmission could be realized by turning interference signals of the adjacent transmission points into useful signals. The whole system performance could be enhanced with the interference decreases especially for the cell-edge users.In respect to the distributed wireless network radio resource management technology of CoMP, this thesis analyzes its theory, application background, transmission scheme and key steps, including the determination of edge users and coordinated node selection. Due to the backhaul link between base stations is not ideal in practical application and therefore the information exchange between coordinated points will introduce the backhaul delay, which will decrease the performance of CoMP. So this thesis mainly researches on the effect of delay to the performance of CoMP and coordinated transmission based on delay.In respect to the effect of delay to the performance of CoMP, first of all, this paper researches on the composition of the delay in CoMP system and makes an analysis of factors that affect delay, including the selection of CoMP transmission scheme, method of coordinated base station’s user data acquisition, precoding scheme and X2 interface performance. Secondly, by building corresponding system model, theoretically analyzes the system performance under ideal and non-ideal backhaul and obtains the system performance degradation due to delay by comparing two situations. Finally, through adding the delay module to the LTE system level simulation platform and simulations verifies the system performance degradation.In respect to the coordinated transmission based on delay, this thesis proposes a coordinated multiple base stations transmission scheme based on delay in distributed network. According to different delays from coordinated base stations to users, the delay compensation of each user is realized by phase rotation of transmitted signals at the base station side in frequency domain. Furthermore, through the backhaul latency between base stations to select apposite coordinated base station and achieve synchronous collaboration. Decreasing the backhaul latency which coordinated base stations bring through exchange mutual coordinated information to reduces the coordinated transmission that the latency has an effect on. Simulation results shows that the proposed scheme could reduce interface and improve both the edge users’ throughput and the overall throughput of the system.