Performance Evaluation of MIMO Base Station Antenna Designs

Cellular standards like the third generation partnership program (3GPP) long term evolution (LTE), ultra-mobile broadband (UMB), high speed downlink packet access (HSDPA) and IEEE 802.16e (WiMAX) support multiple-input multiple-output (MIMO) wireless communication technology. MIMO uses multiple antennas at the transmitter and receiver along with advanced digital signal processing to improve link quality and capacity. Existing base station use antenna arrays to provide transmit and receive diversity; it is not clear if shifting to MIMO will require a change in the base station antenna designs. In this article, we describe some features of an effective MIMO base station antenna. We evaluate the performance of two popular existing base station antenna designs a vertically polarized planar array and a pair of two dual polarized base station antennas to determine if they will work well as MIMO base station antennas. We show that the dual pol array is more effective as a MIMO base station antenna. We optimize the array with two dual pols for space, cross-pol pattern isolation and port-to-port isolation to obtain the best tradeoff of data rate versus design specifications.