On Serially Concatenated Space-Time Codes

One of the most important topics in wireless communication system is to realize high speed and high quality communications under the limited transmit power and bandwidth. The multiple antennas system can equivalent the fading coefficients between transmit-receive antenna pairs to several parallel independent sub-channels, which can be utilized to transmit data as well as to improve the communication quality. Recently, the space-time codes designed for the multiple antennas system have inspired many attentions. And the serially concatenated space-time code (SCSTC) constructed by the binary error-correcting code and the space-time code is one of the practical techniques. Benefiting from the iterative decoding, SCSTC employs space-time code to provide the spatial-multiplexing gains and uses the binary error-correcting code to obtain coding gains, which make it possible for SCSTC to approach the channel capacity.In this dissertation, the space-time trellis code and the corresponding SCSTC are studied. Several results are obtained. They are1. The constrained capacity of orthogonal space-time block code is deduced. Then, the constrained capacities of several typical space-time codes, including layered space-time code, orthogonal space-time code and space-time trellis code, are systematically compared.2. A new optimization algorithm of space-time trellis code is presented. Firstly, the distance spectrum of space-time trellis code is analyzed. Then, a design criterion based on the distance spectrum is described and a simplified searching algorithm is given.3. The feasibility of non-full rank space-time code for serial concatenation is verified. Then, a kind of space-time code with parallel transitions (PT-STTC) is proposed. Using the proposed PT-STTC as the inner code, the SCSTC can significantly decrease the complexity without performance degradation.4. A kind of generalized recursive space-time trellis code (G-RSTTC) suitable for serial concatenation is designed. The basic encoder structure of G-RSTTC is first described. Then, the number of recursive convolutional codes and the coding rate of each code are determined. It is also verified that the minimum diversity gains that G-RSTTC based SCSTC can achieve is 2M, where M is the number of receive antennas. Based on this result, the generator matrices of G-RSTTC with different data rate are given. The constrained capacity of thedesigned G-RSTTC is also analyzed. Finally, the performance of G-RSTTC based SCSTC is compared with that of other available SCSTCs.5. Based on the extrinsic information transfer charts (EXIT Charts), a kind of serially concatenated space-time code with near channel capacity is designed. The analysis of EXIT Charts is generalized to the multiple antennas system. Then, several factors that affect the EXIT Charts of BLAST and recursive STTC are analyzed. The design of serial concatenation with near capacity is described and several examples are given.6. Using the constellation rotation method and the Almouti's scheme, a multiple space-time block code is proposed to utilize the time diversity inherent in the block fading channels. The design of MSTBC for both block and quasi-static fading channels are described. Then, the capacity of MSTBC is analyzed. A comparison with the Almouti's scheme is also conducted.