Comparison of Outdoor to Indoor and Indoor to Outdoor MIMO Propagation Characteristics at 5.25 GHz

In this paper, the results of wideband outdoor to indoor and indoor to outdoor multiple-input multiple-output (MIMO) measurements at 5.25 GHz are presented. The results are compared in terms of large scale parameters in temporal and spatial domains to clarify the concept of reciprocity. Propsound CStrade, a state-of-the-art radio channel sounder, was applied to measure the channel with 100 MHz bandwidth. In outdoor to indoor scenario the transmitter (Tx), employing 16 dual polarized antenna (DPA) elements, was located at a height of 6 m outside the building where the receiver (Rx) with 9 DPA elements was moving. In indoor to outdoor case, the scenario was vice versa except that Tx was equipped with 25 DPA elements. The results show that the scenarios are not as reciprocal as one might assume even though the correlation of certain parameters is high.