Measuring the Impact of Intrain Repeater Deployments in Real-Time

Abstract

Train commuters use smart devices that are continuously connected to the Internet via cellular networks. As such, end users' service perception depends on the interruption-free delivery that access networks can provide. Setting up a wireless reception inside the metal cabin of a train is a challenging task; more so when travelling in rural areas, where mobile coverage is limited, at high speeds. In the past decade, several technical advances, e.g., active repeaters in trains and along tracks, have been deployed to improve cellular coverage. The resulting overall performance of these active elements can be evaluated only through measurement. Thus, we present a methodology that can directly evaluate under different scenarios the performance gain that an in-train repeater solution delivers. The method delivers synchronous results for both cases of with and without in-train repeater. This then provides the means to drill down to specific cases at high spatial granularity, e.g., the impact of different cellular deployments. In this paper, we validate the methodology using extensive laboratory measurements, and then present the results of our real-world drive tests. Based on the results obtained from the real-world measurement, we can highlight the strengths and shortcomings of an in-train repeater system. Our results show that the static evaluation of the carriage can only partially reflect the scenarios observed in the dynamic measurement on the railroad track. The new method enables swift and resourceful measurement campaigns for the design, optimization, and maintenance of an in-train repeater system.