LTE MIMO performance measurements on trains

Providing passenger internet on board trains with continuous connectivity at high speeds and over large rural distances is a challenging issue. A frequently used solution to the problem is to use an on board WiFi network connected to the 3G or 4G networks deployed outside the train. In order to be able to provide the capacity and the data rates that tomorrow´s business travelers are expecting it has been suggested to use a combination of MIMO and carrier aggregation in the LTE-Advance standard. In this study, we practically investigate the plausibility of using MIMO functionality in an 900 LTE system when the receive antennas are mounted at a train roof about 4m above ground and the base stations antennas are on average placed 2.3km away from the track in towers with an average height of 45m and, hence, most of the time in line of site. It is found that along our test route MIMO is in practice supported by the radio channel at around 70% of the time when the train is travelling with an average speed of 185km/h and the MIMO antennas are mounted 10.5m apart.