The Research On Implementations Of Space-time Coding Echnology For MIMO System

With the development of multimedia applications such as social networking, voice and video, the demand for reliable high data rate wireless communication is growing. Researches have shown that multiple-input multiple-output (MIMO) systems can effectively improve the system capacity. Transmitting diversity and spatial division multiplexing can be achieved through space-time coding, and it's an effective way of making the channel capacity close to the theoretical capacity limit. The basic idea of space-time coding is introducing the correlation in both the space and time domains at the transmitter to obtain the coding gain and diversity gain, while improving the spectral efficiency.Based on the characteristics of wireless channel and Diversity theory,this article analyzes the channel model of MIMO system and give the derivation of the theoretical channel capacity. Three specific types of encoding schemes for MIMO system such as Space-Time Layered code,Space-Time Trellis Code and Space-Time Block Coding are analyzed in this paper, and the performance simulation results of those three types are presented for performance compare. Space-time Layered code is one of the earliest coding method, and its basic idea is dividing the source data into multiple low-speed data streams, coding and modulating the streams independently at parallel channels, then transmitting them from different multiple antennas. Space-Time Trellis Code combines the coding and modulation by inheriting the ideas of convolution code and trellis code. Information source is sent to different antennas after channel coding and serial to parallel converter, then it is transmitted by these antennas after a signal mapping and modulation. Space-Time block code turns the information source into code matrix by linear processing in the complex field, and the receiving end can detect the transmitted symbols by a relatively lower complexity decoding algorithm with the feature of linear. The thesis not only discusses the differential space-time block coding scheme that is suitable for the situation when the channel information is unknown but also stimulates for different numbers of transmitting antennas.