Research On Space-Time Coding And Precoding For MIMO Wireless Communication Systems

Because of its extraordinary capacity and diversity, multiple-input multiple-output (MIMO) system has become the direction of future development of wireless communication systems. In the past decade, techniques for MIMO system, such as space-time coding, spatial multiplexing, and space division multiple access (SDMA), have received extensive research and made significant progress. This thesis studies several techniques in the framework of MIMO, including differential space-time coding, single-carrier frequency domain equalization, multi-user downlink precoding, and user scheduling. The main contributions of the thesis are listed as follows:1. To increase the spectral efficiency of differential space-time coding, a scheme to deliver multiple bits by the amplitude component of transmit signal matrix is proposed. For the proposed scheme, a differential detection algorithm based on received signals in two adjacent coding intervals is derived, as well as a sequence detection algorithm for the amplitude component of transmit signal matrix. For differential space-time block code with differential encoding matrix constructed from QAM symbols, a differential detection algorithm which avoids channel power estimation is proposed.2. For the case when the number of transmit antennas is even, a differential unitary space-time modulation (DUSTM) scheme is proposed to reduce the computational complexity of the receiver. The proposed scheme exploits the orthogonal property of the Alamouti code and the design of cyclic group to construct differential encoding matrix, and achieves full antenna diversity. Compared with conventional DUSTM based on diagonal signals, the number of unitary matrices to be searched by the differential detector is significantly reduced. Furthermore, the proposed scheme reduces the dimensionality and cardinality of the cyclic group, thereby simplifying the design and improving the error performance.3. For MIMO channels with fading correlation, a scheme is proposed to design the initialization matrix of differential space-time block code by utilizing the information about fading correlation. The design is conducted by minimizing the upper bound on the average pairwise error probability of the differential detector. The optimal design takes into account fading correlation at both transmitter and receiver, but needs to be solved numerically. By ignoring fading correlation at the receiver, a suboptimal solution can be obtained, which has closed-form expression and performs close to the optimal design.4. For rapidly time-varying MIMO channels, a block differential space-time coding scheme is proposed by utilizing the basis expansion model (BEM) for time-varying channels. Relying on the fact that the coefficients of complex exponential basis of BEM are fixed for a block , the proposed scheme subdivide a block into multiple subblocks and performs differential encoding across the subblocks. By block interleaving at the transmitter and block deinterleaving at the receiver, signal detection does not need channel state information, and hence avoid estimation of the rapidly time-varying MIMO channel. By properly designing subblock length and differential encoding matrices, the proposed scheme can achieve full antenna diversity and Doppler diversity simultaneously.5. For single-carrier (SC) transmission over frequency-selective channels designed for frequency domain equalization (FDE), the equivalence between linear MMSE FDE and time-domain equalization is...