Inter-cell Interference Cancellation Based On Base Station Cooperation

In mobile communication systems, Inter-Cell Interference (ICI) is an inherent problem which is critical to system capacity. Cell-edge users in cellular systems suffer from the interferences of adjacent cells and their throughputs are typically very low. In order to improve the performance of cell-edge users, it is necessary to use the inter-cell interference cancellation technology. Traditional interference cancellation techniques include interleaved multiple access (IDMA) iterative interference cancellation technology, interference randomization, interference reconstruction. With the development of cooperation communication, in the LTE-Advance the cooperation communication has been put forward to eliminate the interference. As a kind of cooperation communication,CoMP(Coordinated Multi-Point transmission/reception) can eliminate inter-cell interference effectively by processing jointly among multiple base stations. CoMP can be divided into uplink and downlink CoMP. This thesis discusses both but the main research work focus on the uplink CoMP.Firstly, in the preliminary work of the thesis, a2X2OFDM-MIMO system model is established and several classical MIMO equalization algorithms are simulated and analyzed. Then the thesis discusses how the CoMP isused in the downlink to eliminate the interference with pre-coding techniques.The pre-coding algorithms used in CoMP are simulated and analyzed, including ZF, BD and BD-SVD algorithm.Secondly, the thesis focuses on the uplink interference cancellation with CoMP. Uplink interference can be divided into strong symmetric interference,weak symmetry interference and asymmetric interference.The subtraction of signal in uplink interference cancellation with CoMP can be divided into Distributed Interference Subtraction (DIS), CoMPressed Interference Forwarding (CIF),(Distributed Antenna System-Decentralized Decoding (DAS-D) and (Distributed Antenna System-Centralized Decoding (DAS-C).For the asymmetric interference scenario, the thesis discusses that the base stations can eliminate interference by grouping the strength of users’signals, The simulation results in a typical asymmetric interference scenario,shows that this scheme has good performance in interference cancellation.Finally, the thesis bulids a LTE system simulation model of3cells, simulates several different interference cancellation algorithms (ZF, MMSE, ZF-SIC, MMSE-SIC, ZF-OSIC, MMSE-OSIC) in DAS-C method. Also several uplink interference cancellation schemes (DIS, CIF, DAS-D) in the different interference scenarios are simulated and compared. The simulation results show that the dynamic program can guarantee better performance under the conditions of frequency reuse factor is1and balance load.