Improvement And Simulation Of Coordinated Multipoint Joint Transmission With Non-ideal Backhaul

LTE-Advanced, the following evolution of LTE, has applied multiple key technologies, such as Carrier Aggregation, Enhanced UL/DL MIMO, Coordinated Multipoint(CoMP) Transmission and Reception, Small Cells Enhancements, which could improve the performance of bandwidth, peak transmission rate, average user throughput, cell edge user throughput in radio network system. CoMP technology, as a crucial part of LTE-Advanced technique, provides a good solution to problems of intercell interference and cell edge user throughput.By using Coordinated Scheduling/Beamforming(CS/CB) and(or) Joint Processing(JP) among several points, CoMP technology can reduce the inter-cell interference and enhance reception SINR of UEs, especially for the cell edge UEs of LTE-Advanced system, thereby increasing the throughput of UEs and improving the QoS of UEs. Although some work about the basic principle and implementation of CoMP technology has been done, there are still some problems to be solved in real system.Because of the smooth upgrade, LTE-Advanced system still has a large number of non-ideal backhaul networks. The delay of the non-ideal backhaul network is unstable and cannot be ignored. Thus it is impossible to ensure the CoMP coordinated points send data to one UE simultaneously, which would weaken the performance of Coordinated Scheduling/Beamforming and(or) Joint Processing, and finally reduce the throughput of the LTE-Advanced system.This paper focuses on the Joint Transmission technology, a part of CoMP technology, and proposes an improvement based on RAM and timestamp. First of all, the unstable delay of non-ideal backhaul has been transformed into the stable delay of the LTE-Advanced eNBs. Then, timestamp technology has been used to unify data transmission time of each base and to solve the error problem caused by the delay in data modem phrase. Finally this article propose a primary deployment method for the improvement in real application.To evaluate the performance of our proposal, some experiments have been conducted with LTE simulation model of NS-3 network simulator. The experiment result indicates that our method can efficiently solve the problem of throughput degradation in Joint Transmission technology with non-ideal backhaul.