Study On The Space-Time Coding Based On Array Processing Techniques

Space-Time Coding (STC) based on the MIMO can achieve high speed data ratewith limited transmit power and frequency bandwidth, and it has been adopted by the3rd generation mobile standards (CDMA-2000&W-CDMA). The current researches onSpace-Time Coding are focused on the following areas, construction and optimizationof Space-Time Codes, combination STC with other channel coding techniques, STC inimperfect channels and combination STC with two-dimensioned Spatial-temporaltechniques (for example, array signal processing) et. al Based on the broad study of Space-Time Coding and array signal processing,researches on the orthogonal information which is choose as the weight of STC transmitarray are performed in this dissertation. A new BLAST based on RAKE receiving is proposed in this project, whichchooses a group of orthogonal spreading sequences as the weight of the STC transmitarray. The receiver suppresses interferences from other antennas by the orthogonality ofthe transmitted signals. The information from the corresponding 'layer' is extractedfrom every receive antenna by RAKE receiver to form efficient statistic decision.Simulation results show that the proposed BLAST can achieve good performance. A new layered architecture based on OFDM is proposed in this project, whichchooses IFFT as the weight of the STC transmit array. OFDM can greatly suppress ISIwhich is caused by multi-path domino effect. In frequency domain, OFDM can offer agroup of orthogonal sub-channels to carry information. This new system combinesfrequency diversity and space diversity, and performs very well. Coded eigen-beams is studied in this project when a group of eigenvector from thespatial matrix is introduced as the weight of the STC transmit array. In multi-pathenvironment, eigen-beamforming can channel the transmit power in the directions withthe biggest gains. It works very well with Downlink and TDD modes. In nature,Space-Time coded eigen-beams technique combines diversity techniques andbeamforming techniques, is one of the most important research directions in the area ofSTC.