Track apps

Rail communications on the expressway: extended networks for digital rail

For today’s and tomorrow’s digital rail, we need signal-based coordination, which enables strong optimization and densification of rail traffic, as well as increased automation of rail transport. This critical application depends on ubiquitous and consistent connectivity wherever the train travels. The railway’s communication network is therefore an essential tool for the real-time control and monitoring of trains and for maintaining safe and efficient operations.

Railways have been allocated dedicated spectrum for safety-critical operations, but Railway Infrastructure Managers (IMs) may be challenged to meet all their needs with only this spectrum available. Although they can deploy a dedicated, stand-alone network using their allocated spectrum; additional spectrum will be required to serve all intended applications and provide radio redundancy. One potential solution is for railways to work with communications service providers (CSPs) whose existing infrastructure can be reused. Railways and communication service providers have a common interest in extending coverage along railway lines. By sharing infrastructure primarily used for passenger connectivity, they both benefit from reduced investment.

Diversified rail services

Depending on their criticality and purpose, communication services for digital rail operations can be grouped into three categories: critical communication, performance communication and business communication. [source: UIC URS].

Critical communication, as defined in UIC URS, is needed for “applications essential to the movement and safety of trains or a legal obligation” such as emergency voice calls or automatic train protection (ATP) which manages the safe movement of the train along along his journey. If the critical communication services fail, the respective trains have to stop, causing major delays in the train schedule. This is why the high availability and resilience of these systems are of utmost importance.

Performance communication is required for “applications that help improve the performance of railway operations”. The aim is to optimize and support railway operations – for example, by enabling live video monitoring for better situational awareness or telemetry data to proactively anticipate and manage potential infrastructure failures and trains.

Business communication is required for “applications that support general railroading”. Business communication includes internet access to train and platform passengers, for social media, video streaming, checking train schedules and other infotainment use cases.

The right type of spectrum for the right application

To provide network connectivity support for all of these types of applications, railways must provide 5G NR coverage in both dedicated railway spectrum and shared public spectrum owned by CSPs. Although dedicated spectrum is primarily required for mission-critical applications, it can also carry traffic for performance applications as long as sufficient capacity is available. In cases where only 5G NR can provide the bandwidth required for both performance and commercial applications, shared public spectrum should be used. Finally, unlicensed spectrum can provide additional capacity for commercial applications that may be needed in crowded areas such as train stations.

Performance and critical applications should further make extensive use of 3GPP-specified Mission Critical Services (MCS) for voice, video and data communication, providing the functionality required for session establishment, authorization, location services, etc.¹ All critical applications require very high availability of MC Services, the Core Network and the Radio Access Network. Some applications also require ultra-reliable, low-latency communications. Therefore, mission-critical applications have higher requirements for underlying services and infrastructure than business applications, a factor to consider when considering different deployment options.

Cost-effective network deployment and operation

While a rail IM may deploy and operate a network with dedicated spectrum, shared public spectrum is generally managed by the network of the respective CSP that owns the spectrum. The reuse of CSPs’ existing mobile network infrastructure, combined with a collaborative approach to building new infrastructure, provides a fundamental cost advantage. European countries have significant differences in terms of size, population density, mobile network infrastructure, railway communications infrastructure, economy and regulation, which leads to differences in the collaborative approach. Despite their differences, countries can achieve the same cost advantage by investing in new mobile network infrastructure with both dedicated and public spectrum. There are also different ways for rail IMs and CSPs to collaborate for a flexible and cost effective network deployment.

The CSP-only approach

A simple approach is for the CSP to deploy and operate the complete communication system on behalf of the rail IM. The CSP has full flexibility when it comes to network configuration and optimization, and the IM can leverage the CSP’s experience and expertise in network operations, while only hosting the applications.
Hybrid approaches

In more hybrid approaches, the IM can have its own network and integrate with a CSP’s network at different levels (e.g. national roaming, MOCN multi-operator core network or MC services integrated into the CSP’s core network at the same time). network exposure function /NEF). In this approach, the railway IM has full flexibility in configuring and optimizing the network for dedicated spectrum, and varying degrees of control for shared public spectrum, depending on the integration model. IM expects proper isolation for passengers, performance, and critical communications traffic in the CSP network using network slicing.

Mixed approaches

Finally, mixed approaches are also possible where, in some regions, the IM operates its own RAN while relying on the RAN deployed by CSP in other regions. In addition, third parties can play an important role. A CSP specializing in private networks may operate a dedicated network on behalf of the IM, or a neutral host may operate a dedicated RAN along the railroad tracks for the IM and one or more CSPs.

Collaborating for 5G-powered rail operations across Europe

When deploying a wide area network for digital rail, a railway needs dedicated 5G spectrum or a dedicated network slice using CSP spectrum to ensure performance and service availability for railway applications. reviews. Performance applications and some enterprise applications require 5G coverage of additional CSP-owned spectrum due to their need for high capacity. Unlicensed spectrum can supplement other frequencies at stations and depots to meet demand for large capacity and high traffic. There are several deployment options, with varying degrees of control and responsibility on the side of rail IMs and CSPs. It is also possible that other parties will fully exploit the potential to reduce network deployment and operating costs.

Ericsson is ready to ride with you

Ericsson’s comprehensive portfolio and experience enables us to support all deployment options for railways, from fully dedicated networks to hybrid networks. As a provider of RAN, core network and critical network components and services, we offer a portfolio that enables tailored deployment and integration of high availability subsystems. By taking into account the country-specific environment in rail networks, we are paving the way for fully 5G-supported rail operations across Europe.

Further reading:

Page: Reinforcing rail with critical 4G and 5G – Ericsson

¹Line-of-business applications can also use MCS when useful.