**5.1.1 Functional requirements**

484 Wireless Communications and Networks – Recent Advances

makes a communication request to the platform. Then the system make a decision about what priority requests can be served concurrently by the system taking into account active

On the train side, the OCM must be able to prioritize communication requests made by the on board applications. So, the OCM queues train applications' requests in base of established prioritization criteria. Then taking into account communication active link bandwidth properties, the OCM notifies to TCM about the on board most priority requests that could be served concurrently by the system respecting these requests QoS requirements. TCM will ultimately decide and notify the OCM which communications can be addressed at every moment, considering the rest of the terrestrial applications'

Therefore, on the ground side the TCM will manage terrestrial applications' requests as OCM do in the train. Besides, TCM will have a queue for each train on the system containing that train's requests (notified by its OCM) and terrestrial requests in order to make decisions about what applications' requests can communicate at every moment.

Now we will explore the benefits of having a train-to-earth wireless communication technology like the one presented before. These benefits will be justified by mean of the new valued added railway services which will be able to be developed using this communication architecture. In this section we will show the functionality of two specific services as well as the way in which they interoperate with the train-to-earth wireless communication channel. The first one is a Backup Traffic Management Service (BTMS) which uses the slight communication infrastructure and the second one is a Remote Application Management Service (RAMS) which uses the heavy communication model and integrates with the

Security in railway industry is a critical issue. Intelligent Transportation Systems are becoming a very valuable way to fulfill these critical security requirements. In fact, today, rail traffic management is performed automatically using Centralized Traffic Control systems (CTC) (Ambegoda et al., 2008). These systems are based on sensors and different elements fixed on the tracks. They allow real-time traffic management: (a) location of trains, (b) states of the signals, (c) status of level crossings and (d) orientation of the needles. Most of the infrastructure management entities have a CTC that handles centralized all these issues. The applications and systems that handle these tasks are very robust and have a performance index near 100%. Problems occur when these systems fail. In those situations, traffic management has to be performed manually and through voice communications

In this section web described a support system to assist traffic operators in emergency situations in which CTC systems fail. The main objective of this system is to reduce human

error caused by the situations in which priority systems do not work properly.

**5. Developing railways services over train-to-earth communications** 

link bandwidth limitations and requests QoS requirements.

request.

broadband communication manager.

**5.1 Backup Traffic Management Service (BTMS)** 

between traffic operators and railway drivers (Sciutto et al., 2007).

CTC traditional systems are centralized and rely on wired communications. When CTC system or communications fail, no one knows the location of trains, thus increasing the chances of an accident. In these situations, the railway companies put into operation its security procedures that transfer the responsibility of traffic management to traffic operators, who are people that monitor traffic in the terrestrial control centres. These people should manage the traffic manually communicating through analogical radio systems to the drivers of the trains. As people get nervous in emergency situations and that leads to mistakes, the new service aims to reduce these errors by creating a new tool to help traffic operators in emergency situations. This new tool must be based on different technologies to those used by traditional CTC systems so that failure in the former does not cause failure in the latter.

Taking into account these motivations and requirements, a Backup Traffic Management Service (henceforth BTMS) has been developed (Carballedo et al., 2010b). This service will assist traffic operators when the primary system fails. The main functions of this new system are:


Fig. 6. Traffic situation representation.

The BTMS provides a traffic assistance application that works independently of the main CTC system. Thus, the new service is based on an application that informs about the position of the trains on track and permits to make tasks related to traffic management and control in an easier way. Moreover, this system permits a new way of communication between the traffic operators and trains drivers: exchanging control messages.
