Channel Capacity Improvement Of Indoor MIMO System

MIMO (Multiple-Input Multiple-Output) system attracts much attention and has been put into a practical use. It makes high-speed wireless communications possible by using plural antennas for each station without extending frequency bandwidth.As well know, the channel capacity is low using omni antennas as the base station antennas because of useless radiation. As to improve the channel capacity, this paper proposes that channel capacity of the indoor MIMO system can be improved using directional antennas rather than omni antennas. Using EEM-RTM software to simulate, Matlab software to calculate the channel capacity, and signal processing algorithms of terminal: MMSE(Minimum Mean Square Error) and MLD(Maximum Likelihood Detection) algorithms to process signal, the results prove that channel capacity of the indoor MIMO system can be improved using directional antennas rather than omni antennas. Moreover, the effects of directivity and beam direction of base station antennas on the system capacity are evaluated, it is proved that whenφ_B = 90°andφ_HP = 60°, we can achieve the maximum channel capacity. As to improve the performance of MIMO system and reduce the cost of system, this paper also discusses the way of selecting the terminal antennas with good characters. Selecting terminal antennas is according to the maximum channel capacity, it can be said that using two receivers with many terminal antennas is very effective.