Send And Receive Multi-antenna System Anti-interference Study

Multi-antenna system means a communications system with multiple antennas at both transmitter and receiver. It has the ability to turn multipath propagation of the wireless channel, which causes fading, delay spread and other harmful factors for the signal transmission, into a benefit for the wireless communications systems. It promises many orders of magnitude improvement in spectrum efficiency and communication reliability. Multi-antenna system is one of the most significant breakthroughs in modern communications and a key technique for the next generation of wireless communications (3G and beyond).However, usually, there are various interferences in the wireless channel, which may degrade the multi-antenna system's performance or make the system fail to work. The problems with anti-interference for multi-antenna system are far from solved. Therefore, it is very important to study the issues on anti-interference techniques for multi-antenna system.This thesis describes the research results of anti-interference techniques for multi-antenna system by the author. It is organized as follows:Firstly, the thesis introduces the input-output relation for multi-antenna system, the transition and reception for space-time block coding scheme and the multi-antenna channel modeling techniques, both in the interference-free cases and in the interference cases.Then the thesis derives several capacity formulas for the multi-antenna system in the interference environments. Both the theoretical analysis and the simulation results show that, in the strong interference environments, in order to achieve the improvement of system capacity, the number of the antennas at the receiver must be larger than the number of interferences; otherwise, the system capacity would be closed to zero, which means that the system is unable to achieve reliable communication.Lastly, the thesis presents three interference suppression techniques for the multi-antenna system. These techniques are based on maximum likelihood criterion, noise subspace projection and minimum mean square error criterion, respectively. The thesis also offers the theoretical analysis for the presented anti-interference techniques. The simulation results verify the nice anti-interference performance. The simulation also analyzes the interferences parameters'effect on interference suppression techniques performances.