| This study focuses on the Multiple Input Multiple Output (MIMO) systems, the new technology which has recently received a great deal of attention because of its possible applications in Digital Television (DTV), Wireless Local Area Networks (WLANs), Metropolitan Area Networks (MANs), and mobile communications.; MIMO system is a technology for wireless communications in which multiple antennas are combined at both transmitter and receiver sides to minimize errors and optimize data speed. The success of MIMO systems is due to the fact that they exploit the spatial dimension of the available radio spectrum more than previous systems.; In conventional wireless systems, a single antenna is used at both transmitter and receiver sides which in some cases, this can cause problems with multipath effects. In fact, in digital communications systems such as wireless Internet, it can cause a reduction in speed of data and an increase in the number of errors. The use of two or more antennas, eliminates the troubles caused by multipath wave propagation, and can even take advantage of this effect.; In this study, it is shown that for some applications the MIMO performance may be further improved by using multi-beams rather than multi-antenna elements. This type of MIMO system utilizes angle diversity instead of space diversity. In this type of MIMO, beams can efficiently be pointed towards the best directions to give the highest capacity in the desired directions while do not create interference for other directions. Therefore, it can be very attractive for environments where interference should be minimized such as hospitals where the radio frequency interference can cause problems through interfering with medical monitoring equipment. Therefore, multi-beam MIMO can be a new and efficient solution which improves wireless communications in critical environments. |
