Study On Space-time Code Technology In Mobile Communication

Space-time coding(STC) technology has better spectral efficiency and better communication quality.It can satisfy the need of high speed data communication services. STC technology can divide into: Layered space-time coding (LSTC),space-time trellis code modulation (ST-TCM), Unitary space-time coding (USTC),differential space-time coding (DSTC).This paper studies LSTC and decode technology,and presents improved code and decode methods.we study and compare the analyse and design of STC in different channels,and have simulations for different algorithms.First,we introduce background of STC,and study three kinds of LSTC:LLST,VLST,DLST.We make elaborate studies for LST decode and compare ML decode algorithm with ZF detection algorithm.We present an algorithm based on MMSE and give computation method of improved weight vector.Equalization consider effects of channel characteristic matrix and noise to system. Simulation demonstrates that this algorithm improved system performance to some extent.At last through comparison of VLST decode and DLST decode we get their advantages and disadvantages.Then we present improved LSTC.We group the antennas at the transmit,each group encode independenty.We restrain noise at the improved end,and decode with SVD method.This method has better spectral efficiency and higher rate than STBC.Simulations verify that this method has better performance of anti-fading than BLAST.At the end,we analyze STC's performance in frequency selective fading channel and spatial relative fading channel. We design STC for both of them and have simulations at the same time.