Empirical Analysis of Broadband 2×2 MIMO Channels in Outdoor-Indoor Scenarios

This paper presents the experimental characterization of a wideband 2×2 MIMO channel in typical indoor-outdoor scenarios in the 3.5 GHz band. The transmitter array emulates a base station positioned on the terrace of a building, and the receiver array, situated inside a nearby building, represents the end-user terminal. In a previous work, the authors analyzed the advantages attainable with a 2×2 MIMO channel compared to a SISO channel for the case of narrowband wireless systems in these types of environments without line-of-sight (NLOS). The new results for the wideband channel show that as in the narrowband case, the capacity degradation due to penetration losses can be practically compensated for by the gain of a 2×2 MIMO channel. Furthermore, the frequency diversity attainable in the case of wideband systems appears as a new contribution, reinforcing the conclusion obtained for the narrowband case. This paper also presents a stochastic 2×2 MIMO wideband channel-modeling method that represents a novel simplification with respect to other wideband MIMO models. The resulting models are accurate, but also easy to implement and computationally efficient, Using this method, outdoor-indoor channel models are obtained from a measurements campaign on real MIMO channels in different environments. The empirical data and the models presented in the paper will be very useful in the deployment of future and present broadband fixed wireless-access systems (BFWAS).