Technical challenges of railroad communications using long term evolution

As a next generation railroad communication technology, 3GPP has been considered to provide railroad communication using LTE, known as LTE-R, including railroad control, passenger services, wireless surveillance video, etc. International Union of Railways (UIC) has commenced to generate LTE-R requirements. There are some technical challenges for LTE to be used for today's railroad communications because of the mobility of train up to 430km/h. Since railroad communication is related to public safety, very tight reliability requirement also needs to be met. In this paper, some technical considerations of LTE-R in terms of the possible frequency bands are provided. Upper limit of frequency band for high-speed train up to 500km/h is suggested by investigating the Doppler spread of wireless channel and physical channel structure of LTE.