An Approach to Designing Critical Railway Voice Communication

Abstract

The digitalization of railways allows for improvements in service reliability, safety, security, and predictability. It relies on stable connections and innovative services. This paper presents an approach to designing critical railway voice communication applications, which follows the principles of a service-oriented architecture. Security-related functions, such as user data management and policy management that can be reused by different railway applications, are identified and designed as services. Common features, such as role management and presence, location, invite-a-user messaging, assured voice communications, and multiuser talker control, are also designed as services. The resources relevant to each service are defined and their unique identifiers are organized in tree structures. Moreover, the supported methods are described. Use cases illustrate the use of the services’ Application Programming Interfaces (APIs) in critical voice communication applications. The common application logic is modeled using call-state models, which present the application and network views. The models are formally described and it is proven mathematically that they exhibit equivalent behavior. The service API’s performance is studied through emulation to evaluate the injected latency.