Research Of Space-Time Coding Technology In MIMO Mobile Communications Systems

Multiple Input Multiple Output (MIMO) technology is a great breakthrough in mobile communications, which can greatly increase the system capacity and spectrum efficiency without occupying any more bandwidth. It is the key technology in next generation of the mobile communications. Space-Time coding (STC) technology is a new coding technique which can combat with channel attenuation, obtain diversity gain against fading and enhance the capacity. MIMO combined with STC is the new development of communications. STC can be divided into two kinds: spatial multiplexing technology represented by vertical bell laboratory layered space time (V-BLAST); transmit diversity technology represented by space time block coding (STBC).This paper study on the above two schemes, evaluate system performance by simulation and theoretical results. The main content and innovation include:1. V-BLAST systems with zero-forcing (ZF) receiver is studied. On the basis of closed-form solutions for symbol error rate (SER) of independence Rayleigh fading channel, the closed-form solutions for SER of correlated channel is derived and verified by Monte Carlo simulations. The impact of spatial fading correlation on the system performance and capability is analyzed.2. Review the detection algorithms of V-BLAST, which includes ZF, minimum mean square error and successive interference cancellation. Simulate and analyze the impact of antenna numbers and algorithm on the system performance and complexity.3. Five coding schemes of STBC based on complex signal constellation is studied. The closed-form solutions for SER of independence Rayleigh fading channel is derived and verified by Monte Carlo simulations, analyzed the error performance and algorithm complexity, lay a theoretical foundation for evaluating those schemes.4. Multi-carrier CDMA (MC-CDMA) has frequency diversity and good performance. Combined the STBC based on real signal constellation with MC-CDMA technology, proposed the transmitter and receiver structure, derived the closed-form solutions for SER and verified by Monte Carlo simulations, analyze the impact of antenna, subcarrier and user number on the system performance and capability. The results show that the STBC MC-CDMA system get space, time and frequency gain and dramatically improve the system performance, capacity and spectrum efficiency.