Research On Space Time Coding In MIMO System

With the application of multimedia in next generation wireless communications, the demand for wide-band high data rate communication services is growing. As the available radio spectrum is limited, higher data rates can be achieved only by designing more efficient signaling techniques. Recent research in information theory has shown that large gains in capacity of communication over wireless channels are feasible in multiple-input multiple output (MIMO) systems. The MIMO channel is constructed with multiple antennas at both ends of the wireless link. Space-time coding is a set of practical signal design techniques aimed at approaching the information theoretic capacity limit of MIMO channels. Space-time coding is based on introducing joint correlation in transmitted signals in both the space and time domains. Through this approach, simultaneous diversity and coding gains can be obtained, as well as high spectral efficiency. The fundamentals of space-time coding have been established by Tarokh etc in 1998. Space-time coding and related MIMO signal processing soon evolved into a most vibrant research area in wireless communications.There are two kinds of space-time coding, one is based on transmit diversity and the other is spatial multiplexing schemes. With regard to space-time coding based on transmit diversity ,we discuss space-time block coding(STBC),differential space-time block coding(Differential STBC) and space time trellis coding (STTC) .The classical mathematical framework of orthogonal designs is applied to construct space-time block codes and it made STBC can achieve the maximum diversity gain and have a simple decoding algorithm. Differential STBC can decode without channel estimation and simplify the receiver. STTC can achieve both coding gain and diversity gain and have good performance, but its complexity is high. V-BLAST is a classical application of spatial multiplexing schemes and has spectral efficiencies of 20-40 bps/Hz, but...