Characterization of an Outdoor-to-Indoor wireless link in metro environments at 2.6 GHz

An Outdoor-to-Indoor (O2I) wireless link allows obtaining information from devices located outside a train. This is the case for devices installed on the roof that need to be monitored wirelessly by data-collecting devices located inside the train. In these situations, the electromagnetic signal is diffracted around the structure of the train and reflects on the environment or goes into the car through the windows. This creates a non-line-of-sight channel which is strongly dependent on the physical structure of the train, its materials, and the surrounding environment. In this work, the O2I channel of a metro car is characterized at 2.6 GHz. Narrowband channel measurements are carried out in station, tunnel and open field environments, and obtained results are modeled and discussed.