Research On Space-Time Coding Technology Of MIMO Systems

The major driver for broadband wireless communications has been reliable high-data-rate services. This, together with the scarcity of bandwidth resources, motivates research toward developing efficient coding and modulation schemes. Multiple-input multiple-output systems, which deploy multiple antennas at both ends of the wireless link, explore the extra spatial dimension, to significantly increase the spectral efficiency, and to improve the link reliability relative to single antenna systems. It has been widely acknowledged that the space-time coding techniques can effectively exploit the spatial diversity created by multiple transmit antennas. Although the performance of MIMO space-time coding system is fine, limited by movable termination's volume and power, it could not establish the multi-receiving antenna, but cooperation diversity technology solve this problem.Firstly, the paper introduced the developing history and the present situation of mobile communications as well as MIMO space-time coding technology, on the basis of analyzed the code and encoded scheme and BER property of OSTBC and QOSTBC, we make the improvement to it about the diversity gain and BER property of OSTBC is not ideal under the frequency selectivity fading channel. The fundamental research and the simulation result indicated that this corrective method can also obtain the high diversity gain and BER property under the frequency selectivity fading channel.Secondly, studied the differential space-time coding which circumvents the need for channel estimation. In some cases, it is difficult to estimate the channels, the more effective method is to use the differential space-time coding. However, most differential coding schemes are designed only for time-selective channels or only for frequency-selective channels. In view of this problem, this article researched in detail about differential space-time coding under double selectivity fading channel. The theoretical research demonstrated that this method could obtain the greatest union space-multipath and the Doppler diversity gain, the simulation result further confirmed the correctness of the theoretical research.Finally, the differential space-time coding and decoding programs and cooperative diversity combining techniques proposed differential space-time cooperative diversity fusion algorithm. Cooperative diversity antenna technology enables single-antenna mobile terminals to share with each other, so as to constitute a virtual MIMO multi-antenna system, MIMO technology toward utility provides a new way.