Researches On Multi-Cell Jiont Processing In Lte-A System

The growing demand on better and faster communications in cellular network brings chanlleges to future mobile system. To satisfy the performance requirements of IMT-Advanced system,3GPP (3rd Generation Partnership Project) proposed the LTE-Advanced system, a smooth envolution from LTE, as a candidate approach. LTE-A considers some certain issues which are not concerned in LTE, such as CoMP (Coordinated Multiple Point Transmission and Reception) to improve the performance of users in cell edge. Performed through multi-cell coordinated bemaforming or joint processing, CoMP can effectively mitigate inter-cell interference and enlarge users' thoughput. In this thesis, inter-cell interference cacellation techniques in CoMP multi-cell joint processing are analyzed and simulated, and the major work is presented as follows:(1) Accoding to the evaluation guildences of IMT-Advanced system, the system simulation platform is modeled and implemented, which is composed of 5 main modules and the network topology involves 19 cells wrap-round. With the simulation parameters in urban macro-cell simulation enviroment, flow chart of system simulation is presented.(2) Joint precoding schemes in CoMP system are analyzed to cancel interference among coordinated users. According to the analysis of a few common precoding techniques, the THP method which is a non-linear precoding is choosen. Before simulating the CoMP system, coordinated scheme and set are determined on the basis of the statistic results of interference distribution among 19 cells. Two CoMP systems, SU-CoMP (Single-user CoMP) and MU-CoMP (Multi-user CoMP), are simulated and compared with the Non-CoMP system and the requirements of ITU.(3) A new multi-cell joint processing technique called interference alignment (IA) is considered in CoMP system. Compared with traditional IA, IA with CoMP is revised both in system model and algorithms. Analysis of BER (Bit Error Ratio) and sum rate performances is presented between traditional IA and CoMP IA, which shows that the CoMP IA is more powerful. The result also shows IA with Max-SINR distributed algorithm performs better than IA with prefect distributed algorithm. Then, CoMP IA is applied to the system simulation platform, to observe the cell spectral effiency and cell edge user spectral efficiency. Simulation results show that CoMP IA with Max-SINR can dramaticly improve the cell edge user spectral efficiency and adequately enhance cell spectral efficiency, compared with CoMP IA under perfect algorithm.