The effect of antenna deployment in outdoor to indoor MIMO measurements at 5.25 GHz

In this paper the results of outdoor to indoor multiple-input multiple-output (MIMO) measurement study at 5.25 GHz with 100 MHz bandwidth are presented. The effect of the antenna deployment to the measured radio channel characteristics is investigated. Especially a conventional nontilted microcell case versus a tilted microcell case sets an interesting study scenario. It is obvious that the actual antenna deployment has a strong impact on indoor coverage from an outdoor base station. Thus it is a very interesting topic in the development of future wireless networks. Comparative measurements with different antenna deployments are needed to identify potentially the best antenna constellation, e.g. in terms of the best possible link performance. Important characteristics such as path loss are studied to compare different antenna schemes. In the MIMO measurements, 32x18 radio channels were recorded for each channel sample using the Propsound (TM) Channel Sounder. The transmitter was located outside at the height of 16 meters (tilted microcell) and 6 meters (nontilted microcell) while the receiver was moving indoors with the antenna height of 1.50 meters. Dualpolarized antennas were employed at both ends. The results show no remarkable differences in the delay spread but the angular properties in the base station were quite different when changing the antenna deployment and e.g. the fractal for 50% for the azimuth spread of the base station was double for the nontilted case than it was for the tilted case.