Research Of Space-time Coding And Space-time-frequency Expansion Of CDMA

Space-time coding, which employs multiple transmit and multiple receiveantennas and introduces temporal and spatial correlation into signals transmitted, is a new coding and signal processing technology of wireless communication systems. It can dramatically improve the bandwidth efficiency of traditional single-antenna systems. This technique is in tended to provide new solutions to the problem of limited bandwidth.MIMO-OFDM system is considered as a promising physical layer technology for high-data-rate downlink of4G system. Most of current works in MIMO-OFDM technology focus on single-user systems. However, most of practical wireless system may be multiuser systems, where some special issues, e.g., inferences, multiuser detection, should be considered.In this thesis, the author makes the following contributions:Give a summary of the basic detection algorithms of V-BLAST systems, andpropose a processing method in which splits the processing steps of the channematrix from the whole detection algorithm.Give a method to get the suboptimal detection which based on the channel energy for the successive interference cancellation (SIC) detection.A class of fast SIC detection algorithms which is based on the Sherman-Morrison formula are developed based an exiting algorithm.Proposed a method to combine the STBC and the BALST.Proposed space-time-frequency spreading (STFS) scheme, a new downlink code division multiple access scheme based on MIMO-OFDM technology, and proposed Coupled-Hadamard code (CHC) for this scheme.