**7. Conclusion**

In the railway industry, communications were born almost exclusively for the purpose of managing and regulating traffic flow, requiring by the mobile nature of this sector two modes of communication: those that occur between fixed elements of the rail infrastructure, which are based mainly in wired systems; and those which participate in the fixed and mobile elements (communications known as "train-to-earth"), which require a wireless communication channel and traditionally have materialized on the use of analogical communication systems such as traditional phone or radio.

Today, despite the maturity of the railroad industry and the advances in wireless communications technologies, the rail industry continues to base the operation of its priority services in analogical and wired communication technologies, which in fact belong to the past but still are efficient and robust.

New generation of wireless communications technologies, such as those based on conventional mobile technology (GSM, GPRS or UMTS), or broadband solutions (such as WiFi or WiMax), opens countless possibilities of use in the railway industry. As the cost of their deployment is very low, they perfectly complement traditional communication systems, and they have wide bandwidth and wide coverage that enable the deployment of new generation services in this area, some of them directly related to the end user, in order to provide a high quality transport service. On the other hand, the rise of high-speed trains is facilitating EXPANSION GSM-R as a basis for communication between signaling and regulation systems for the railway traffic.

This is precisely the topic on which this chapter is focused. It described a specific architecture of next-generation wireless communications for the rail industry to establish a train-to-earth bidirectional communication channel. This architecture is a single channel of communication between all train applications and those in the control centres. The aim of this communication channel is to standardize the way the data is transmitted between them. Thus, this channel is a resource shared by all the applications that simplifies the complex details related to communications and provides advanced services oriented to communication; services such as the selective treatment of the transmissions based on the nature and volume of the information, the location of the messages destination, the management of priorities and arbitration of communication shifts, attempts management, and so on. Moreover, we illustrate the challenges of bandwidth management in railway wireless broadband communications, and how we have faced to them. We have designed a new system that distributes communication shifts between terrestrial applications and train systems, which require the exchange of large amounts of information.

This chapter summarized the results of the research in train-to-earth wireless communications done during the last five years in collaboration with train manufacturers, railway technology providers and railway operators. Our wireless communications architecture has been incorporated into the manufacturing process of a new series of trains, which is a European-wide revolution since it enables wireless and transparent communication between terrestrial applications and those which are deployed on the trains. Furthermore, this architecture is being the basis for new digital services currently under development which will be in the market in a short time. They have different nature and purpose: from services that control the status of the train, to services for the end-user, and support systems for the train drivers.
