Space-time Coding In MIMO System

Space–time coding technology improves spectral efficiency with multi-elements antenna array and has been a research hotspot in the telecommunication field recently.The generalized space-time coding technology deals with a wide range, which mainly includes the technique of transmit diversity gain and the technique of spatial multiplexing gain. The transmit diversity technique means that the same information was transmitted from different antennas, it can achieve the spatial diversity gain and have a strong ability of anti-fading. The spatial multiplexing technique means that the different information was transmitted from different antennas, it indeed indicates the essence of improving the capacity, BLAST from Bell Lab is a typical. However, layered space-time codes achieve high spectral efficiency at the cost of partial diversity gain and cannot obtain the maximum diversity gain. As a result, the detection algorithm of the receiver is the key factor to improve system performance. This thesis first analyses and compares the decoding algorithms of layered space-time codes without channel encoding, and then introduces iterative soft-decision decoding algorithm for layered space-time codes with channel encoding to acquire better system performance while keeping high data rate at the same time.Finally, a compromise scheme was proposed though combining STBC and BLAST to overcome the disadvantage of the lower coding efficiency of STBC and the poor anti-fading performance of BLAST. The final simulation results prove the theoretical analysis.