Multi-cell Interference Coordination Research In LTE System

The trends in Broadband of Mobile Communication and mobility of Broadband Access promoted3GPP to initiate LTE Project in2004. As the dominant customized wireless communication technology of3GPP, the peak date rate of LTE system can reach326Mbit/s, it can significantly improve the spectrum efficiency and reduce the delay, improve the performance of the district edge users and increase the capacity of the community. However, this OFDMA access mode in LTE system can not reduce inter-cell interference effectively, so inter-cell interference become the major factors that limit LTE system performance. In order to solve the above problems, in this paper we use several key techniques including frequency reuse and coordinated multi-point to study multi-cell interference coordination in LTE system.With the introduction of power ratio, the scheme of static fractional frequency reuse could dynamically adjust the frequency reuse factor according to the change of user distribution, the scheme of semi-static fractional frequency reuse could avoid wasting resources after introducing subcarrier priority, the use of frequency resources of the system is more reasonable, simulation results show the two methods could greatly improve the cell edge throughput, edge user interference is greatly reduced. The scheme of pre-coding matrix index feedback based on multi-point cooperation requires user to give the service cell not only PMI feedback itself needed but also the interference cell PMI feedback through collaboration and data sharing between cells, the scheme is divided into single pre-coding matrix index feedback and multiple pre-coding matrix index feedback according to the number of PMI, the analysis shows that the scheme brings the system a large performance improvement.In this paper we propose a scheme of pre-coding matrix index feedback based on round robin, this scheme is based on single pre-coding matrix index feedback, then the scheduling rights will transfer between cells to ensure the fairness, the performance simulation show that this scheme could not only solve the problem of interference between cells and improve system performance but also ensure the fairness between cells in the cooperation. Finally, the joint interference mitigation technology combining the technology of frequency reuse and pre-coding matrix index feedback based on multi-point cooperation is studied, we analyze the joint interference mitigation scheme based on different ideas, the results show that the system performance can be greatly improved.