Space-time Coding Technique In MIMO System

The technique of space-time coding and multiple input multiple output is an ideal candidate for improving wireless communication performance and increasing data rates in systems with bandwidth constraints. It has been received considerable attention.In this thesis, wireless channel model and the capacity of the MIMO channel are proposed firstly. Based on such model, we concretely discuss and analyze the principle of space-time code and two typical space-time coding algorithms and bit error rate performance. If the number of transmit antennas is more than two, the space-time block codes have to at a loss of code rate. The code rate can be made higher by constructing quasi-orthogonal codes. In this paper, we propose an improved space-time block code based on quasi-orthogonal design. Simulation results demonstrate that the new scheme can improve the performance not only at low SNR but also at high SNR, while the decoding complexity is the same as other quasi-orthogonal codes. The decoding of space-time block code also need exact knowledge of channel. In the end, a space-time coding without the knowledge of the channel is introduced, namely differential space-time coding.