在多傳送多接收天線通訊系統中,系統的傳送速率或是通信容量在不同的信號雜訊比均隨著天線的秩數(Rank)成正比。本論文將針對環境因素對於MIMO rank的影響做了一些量測,從天線的數目、樓層的差異,轉角的有無,以及隔板的有無等,使用ZigBee來做訊號強度的量測,並且以RSSI的訊號強度來判定有效rank數。 In the multi-input multi-output (MIMO) communication system, the system transmission rate or the system communication capacity at every signal to noise ratio is propotional to the rank of the transmitter and receiver antennas. In this paper we perform some trial measurements and study the effects of various communication environments on the system MIMO rank; it utilizes the ZigBee-built system to measure the receiver signal strength and trough the resulting RSSI levels to estimate the effective system MIMO rank. The various communication environments studied are formed by intergrating the following system parameters such as the physical mumber of MIMO antennas, the number of floors the transmission path flows, whether the transmission path is clear or blocked and are there an isolations set up between transmitting antennas and how the isolations are arranged etc.