Performance study of Internet traffic on high speed railways

Railway transportation uses specific technologies such as GSM-R for traffic signaling purposes, but commercial networks could also provide added value services to passengers and transport companies such as CCTV or telemetry. Furthermore mobile users increasingly want to be always connected even when they are traveling. Although current deployed technologies such as 3G provide wide coverage in general, when it comes to high mobility scenarios such as the railway, further analysis is required to ensure appropriate user experience. In this paper we propose a methodology to collect and to organize traffic information related to the behavior of Internet services over commercial mobile networks (UMTS and HSDPA). We apply our method to conduct an extensive study on a high speed train line in the south of Spain. The measurement campaigns comprised hundreds of VoIP sessions, comparing different network providers over more than 155 kilometers. We conclude that the characterization method is useful to provide information for railway operators (for instance, to migrate from GSM-R to LTE), telecom operators (to fit their network deployments) and for mobile software developers (to adapt their applications to the high speed environment).