Research On Antenna Selection Algorithm In Multiple Input Multiple Output System

Multiple input multiple output (MIMO) technique as a great breakthrough in wireless communication system can obtain high spectral efficiencies and MIMO-related topics also occupy a considerable part of today's academic communications research. However, among the implications of employing multiple antennas is the associated increase in the cost of the additional hardware required in the form of radio frequency (RF) chains. To count for these problems, while utilizing the advantages of multiple antennas, the technique of antenna selection was developed. The idea behind antenna selection is to use only a subset of the transmit and /or receive antennas with better performance in MIMO systems.Note that when instantaneous channel realization varies fast or the feedback capacity of channel is limited, it is difficult for receiver to send channel information accurately to transmitter and so that the transmit can't make an accurate selection. In the thesis, a multi-mode antenna selection algorithm based on partial channel state information is proposed, in which the number of active transmitters is determined dynamically according to the channel state and the signal is precoded with the vectors feedbacked from the receiver. The algorithm has less complexity and can run in real time.Antenna selection algorithm based on modified Gram-Schmidt QR decomposition is presented which doesn't need a mass of searches over all possible subsets. The vector signal error rate is chosen as the performance target and the optimal antenna subset is determined in the process of QR decomposition of channel matrix.At last a transmit antenna selection algorithm based on correlation matrix is developed according to the characters of downlink transmission as well as the distribution of singular value. It utilizes the correlation matrix varied slowly instead of the whole channel matrix and can achieve excellent performance in the case of fast-varied channel.