| Multiple input multiple output (MIMO) technique as a great breakthrough in wireless communication system can obtain high channel capacities and spectral efficiencies. Distributed MIMO combining the merits of MIMO and distributed antenna system is drawing intensive attention due to its unique merits such as larger system ergodic capacity, better coverage and lower transmit power. The performance of MIMO and distributed MIMO benefits from the antenna number of transmitter and receiver. However, the complexity and the cost of additional hardware grow significantly with the number of antennas which need more radio frequency (RF) chains. Antenna selection technique is developed to solve these problems. It only uses a subset of transmit and/or receive antenna with better channel performance to communicate, and it decreases the complexity and hardware cost of MIMO and distributed MIMO significantly.This thesis focuses on studying and analyzing the channel capacity and downlink transmit antenna selection algorithms of distributed MIMO system. Firstly, the channel capacity of MIMO system in Rayleigh fading channel is studied, and then we analyze the channel capacity of distributed MIMO system where the channel model considered the influences of path fading, small-scale fading and lognormal shadowing. Through the channel capacity comparison of MIMO and distributed, it is found that the distributed MIMO system could achieve a better ergodic capacity than MIMO system. Secondly, we study the conventional antenna selection algorithms in MIMO system and compare their performance in distributed MIMO system. Lastly, a novel fast antenna selection algorithm is proposed for the downlink transmit antenna selection in distributed MIMO systems. The performance of the proposed algorithm is compared with other algorithms. Simulation results indicate that the proposed algorithm decreases the computational complexity and selective time a lot with just a little system capacity lost. |
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