| Multiple-input multiple-output (MIMO) technology can be utilized in order to accomplish a multiplexing gain and a diversity gain, thus enhancing the bit rate and the error performance, respectively. As a key coding scheme for MIMO system, space-time coding (STC) can provide transmit diversity, therefore decreasing the (bit error rate) BER without increasing the bandwidth or transmission power. By means of two-dimensional coding in space and time, the information symbols are transmitted over multiple antennas at different time slots.As one of the major schemes of STC, space-time block codes (STBC) are obtained vast attention in recent years. In this thesis, firstly, the coding and maximum-likelihood (ML) decoding of classic codes including orthogonal space-time block codes (OSTBC) and quasi-orthogonal space-time block codes (QOSTBC) are described. To reduce the decoding complexity of QOSTBC, an improved decoding algorithm is presented. The presented algorithm is with better BER performance than zero-forcing (ZF) algorithm under the same decoding complexity level. Secondly, space-time-polarization block codes (STPBC) are studied, and the BER performances of STPBC under various cross-polarization discrimination (XPD) scenarios are simulated. Finally, two coordinate interleaved coded spatial modulation schemes are proposed by applying the STC to spatial modulation. Both of these two schemes are with transmit diversity. The coding rule is designed for one of the schemes when the number of transmit antennas is not less than four. The other scheme is designed for two transmit antennas by exploiting temporal diversity and rotated constellation, and its spectral efficiency is the same with conventional spatial modulation. The conditional maximum-likelihood detection algorithm is used to reduce the decoding complexity. The simulation results demonstrate that the BER performances of the two schemes are better than that of conventional spatial modulation. |
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