Mimo Communication Systems, Adaptive Equalization

In this thesis, the channel equalization,one of the most important anti-fading techniques,is researched. The focus is the equalization for the MIMO (Multiple Input & Multiple Output) systems. Nowadays, MIMO has been paid much attention to. With multiple antennas both at the transmitting and receiving ends, it can increase the capacity of the system and the efficiency of the spectrum a lot. However, high-speed data transmission causes time-variant multi-path fading and inter-symbol interference (ISI). Adaptive equalization can effectively combat ISI and its basic task is to compensate for the channel aberration. The wireless propagation environment is described first: analyzing the small-scaled fading, including amplitude fading, multi-path time delay and Doppler spectrum spread. Then the characters of mobile channel of MIMO are analyzed.In this thesis, different adaptive equalization algorithms to overcome the ISI are researched, for example LMS, RLS, GALE, LSALE and CMA. The lattice filter equalization is not widely implemented due to its high complexity. In this sense, adaptive lattice algorithm is still an open topic. Then this article researches the combination of fractionally spaced equalizer (FSE) and decision feedback equalizer (DFE). This kind of equalizer has low sensitivity to the receiver's sampling phase, and it can eliminate the ISI without adding noise gain. At last, different adaptive equalization algorithms applied in MIMO system are simulated. The research shows that adaptive equalization decreases ISI and BER effectively and improves the performance of MIMO system.