Research On The Coding Technology Of MIMO-OFDM Systems For Wideband Wireless Communications

As a combination of MIMO and OFDM, MIMO-OFDM technique takes the advantages of both MIMO and OFDM and serves as a promising scheme for providing high data rate wireless service with good performance and affordable technique complexity in frequency selective fading channels for the future broadband wireless communications. As one of the core components of MIMO techniques, space-time coding constitutes stat-of-the-art transmission schemes based on multiple transmitters and receivers. This paper does not design new space-time codes or decoding algorithms. Rather, its goal is to provide system designers with a performance versus implementational complexity-type technology reference, the best choices at a given system complexity and throughput.To achieve the above goal, we began our investigation by studying the channel model of MIMO and the fundamental principles of space-time coding and analyzing the design criteria of space-time codes, which gave us the theoretical preparation for choosing the appropriate coding scheme.We continued our investigation with discussions of the three main space-time coding schemes, namely layered space-time (LST) coding, space-time trellis (STT) coding and space-time block (STB) coding. We analyzed the codec principles and the pros and cons of the three schemes.Finally, after studying the factors that will affect the performance of MIMO-OFDM systems, we built our simulation model to evaluate the performance of the STT coded OFDM system and the STB coded OFDM system. To improve the performance of the systems, turbo convolutional (TC) codes and Reed-Solomon codes were invoked for concatenation with Alamouti's unit-rate G₂ code and the various STT codes, respectively.