Multi-input Multi-output System, Key Technology Research

With the development of a communication technology, it is desired the mobile communication systems which can support very high rate data transmission. Because available radio spectrum is limited, higher data rates can be achieved only by enhancing spectral efficiency. MIMO(Multiple-Input-Multiple-Output) system adopts several antennas transmitting and receiving. The analysis indicates that MIMO technology is the important progress in wireless communications. It can enhance the capacity and spectral utilization efficiency of communication systems while no the increase of channel bandwidth. MIMO is one of the key technologies in the next generation mobile communication systems.In this dissertation, the author firstly analyzes the characteristic of the wireless channel, and establishes the channel model of the MIMO system. On the basis of it, the capacity of MIMO channel is discussed, the capacity of several typical systems is simulated, such as SISO, MISO, SIMO and MIMO, the difference among those are compared with each other. The key points are focused on the capacity of MIMO channel with Rayleigh Correlated Fading, and the effects of fading correlation on capacity of MIMO channel. Then, the capacity of MIMO channel with Rayleigh Correlated Fading is simulated by using water-pouring algorithm. Space-time coding is a set of practical signal design technique which is aimed at approaching the information theoretic capacity limit of MIMO channels. Therefore, in this article,we analyze the Alamouti's transmit diversity technique, do some research on the encoding and decoding algorithms of orthogonal space-time block coding, and present the simulation result of STBC utilizing a simple decoding algorithm. Finally, the performance of orthogonal space time block coding is evaluated by computer simulations.