| Multiple-input multiple-output (MIMO) technology and smart antenna technology are two effective approaches to improve the spectrum efficiency of wireless communication systems. A well-designed combination of MIMO and smart antenna can further upgrade the wireless transmission quality. Aiming at some existing problems of MIMO and smart antenna systems, two major contributions are made in this thesis.(1) To improve the fading-combating ability of Layered-Structure based Space-Time Coding, a Direct Sequence Spread Spectrum (DSSS) based Layered Space Time Coding approach is investigated. The focus is put on DSSS-VBLAST and DSSS-Double Space-Time Block Coding (DSTBC). Both analyses and simulation show that DSSS-VBLAST and DSSS-DSTBC outperform the corresponding Space-Time Coding approaches without DSSS, respectively. Moreover, DSSS based Layered Space Time Coding has a relative simple decoding algorithm and can be applied to the systems with only one receiving antenna.(2) A spatial diversity multiple-array antenna based Space-Time Eigenbeam Coding approach which combines MIMO and smart antenna is proposed. According to the requirements of complexity and QoS, several possible Space-Time Eigenbeam Coding schemes are presented and simulated for a two-array antenna system in an environment with one or two clusters. As a good tradeoff between the complexity and performance, eigenbeamforming based DSSS-DSTBC is suggested as the optimal scheme. |
PDF Full Text Request