| The data rate and reliability of communication systems can be greatly improved by spatial multiplexing and diversity gain, respectively provided by multiple-input multiple-output (MIMO). In MIMO systems, space-time coding combines channel coding and antenna diversity technologies so as to effectively utilize spatial multiplexing and diversity. And it is also to provide high-quality multimedia service .Space-time coding and hierarchical multimedia transmission in MIMO systems are researched in this thesis.At beginning, the thesis constructe transmission model of MIMO wireless communication system .Then space-time codes of diversity and multiplexing type are researched, respectively. Later, some researches have been done on the structure of multilayered space-time trellis codes (ML-STTC). The adaptive power allocation, the combination of ML-STTC and modified minimum mean square error (MMSE) group detection algorithms are proposed for ML-STTC. At last, the hierarchical multimedia transmission is researched and several hierarchical transmission schemes based on sub-stream allocation and power allocation are given. This thesis mainly consists of ML-STTC and hierarchical multimedia transmissions, and some conclusions have been drawn as follows.The nonuniform ML-STTC is researched. The system performance is simulated when different allocation schemes are applied to STTC encoders of different layers, and then the optimized allocation criteria is given. Then the group detection algorithm based on MMSE is proposed. In the thesis, an algorithm of searching the optimized power ratio is given, and the optimization results of different ML-STTC are analyzed and compared. Considering the difference of diversity gain in different layers of ML-STTC, a scheme integrating variable-rate channel coding with ML-STTC is proposed. Combined the characteristics of Turbo codes and embedded source code, two novel kinds of unequal error protection (UEP)schemes are proposed by optimizing channel coding and power allocation. Two hierarchical transmission schemes based on sub-stream allocation and power allocation are proposed for space-time coded multimedia transmission systems. Moreover, a closed form of MIMO space-time transmission scheme based on singular value decomposition (SVD) of channel matrix is given when the channel state information is known at the transmitter, and then a simple detection algorithm is drawn. At last, the transmission scheme is applied to multimedia transmission systems, and unequal error protection is achieved. |
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