Facilitating Digital Transformation of Railways with FRMCS

Railway development has undergone three eras and two transformations: the steam engine railway, the electrified railway, and now the information railway. To embrace digital economy and promote high-quality railway development, the railway industry is actively exploring new ways of digital development, marking its third transformation, namely, digitalization. Since the 18th CPC National Congress, China has issued a series of policy documents to systematically promote the digital transformation of all industries. In February 2023, China rolled out a plan for the overall layout of the country's digital development, which provides direction and a basis for digital transformation and high-quality development of the railway industry. In September 2023, China State Railway Group (China Railway for short) released the “Digital Railway Plan”, which serves as an important basis and action guide for digital railway construction. The plan emphasizes the need to strengthen the construction of private 5G networks and broadband wireless access capabilities at stations and yards, and to make every effort to promote the construction of the future railway mobile communication system (FRMCS).

On September 26, 2023, the Ministry of Industry and Information Technology approved the test frequency for China Railway’s FRMCS system. This approval is a powerful driver for the digital transformation and high-quality development of the railway industry and is of great significance for promoting the upgrade and sustainable development of China's railway mobile communications technologies. Following the approval of the FRMCS test frequency, the railway mobile communication system will be fully tested, verified, and applied on high-speed railways, plateau railways, alpine railways, and heavy-load railways. Through large-scale experiments and tests, world-leading comprehensive supporting systems and network equipment will be built.

By promoting the construction and application of the FRMCS system, railway communications are facing both new opportunities and various challenges. In terms of FRMCS system construction, China Railway proposes the overall development concepts of “Four Intelligences” and “Six Abilities”.  The “Four Intelligences” refer to the development directions of intelligent network operation, intelligent resource management, intelligent system maintenance, and intelligent service applications. The “Six Abilities” refer to the development goals of an intelligent railway communication network that is visualizable, manageable, controllable, testable, reliable, and credible (see Fig. 1).

Among the development goals of the FRMCS system, being visualizable is the basis. Being manageable, controllable, and testable are the pathways, while being reliable and credible are the cores.

FRMCS Visualization

FRMCS visualization aims to establish a railway visualization platform, advancing from graph visualization to 3D, virtual reality, and digital twin visualization. Digital twin visualization is implemented by using technologies such as the Internet of things (IoT), full HD video, and virtual reality (VR)/augmented reality (AR). Network state visualization is achieved by using technologies such as artificial intelligence (AI) and big data, employing AR for remote decision making.

The FRMCS system provides visibility into network resources, network status, maintenance management, network performance, and network security. This visibility spans the entire lifecycle of FRMCS planning, construction, maintenance, optimization, and operation. The goal of FRMCS visualization is to make network construction more accurate, network operation more transparent, network maintenance more intelligent, network security better guaranteed, improving the overall FRMCS network experience and management level.

FRMCS Manageability

FRMCS manageability reconstructs the O&M management processes and modes for the railway communication network, enhancing the safety management and control capabilities across the entire process and network, thereby achieving automation, intelligence, and integration of management methods and modes.

As a new generation of railway mobile communication system, FRMCS develops its network management system architecture towards large capacity, centralization, intelligence, and openness, while still meeting traditional management capabilities. The FRMCS "manageable” application system architecture is shown in Fig. 2, comprising four layers: manageable applications, manageable capabilities, manageable technologies, and manageable objects.

A “manageable” application is a specific application platform or NF management system. A FRMCS network’s manageable application includes both the existing internal part of the system and the extended or incremental part. The internal manageability of the system includes resource manageability, operation manageability, quality manageability, and security manageability. The extended part mainly refers to the manageability of system services.

FRMCS Controllability

FRMCS controllability mainly includes independent control over core technologies, the supply chain, security, and the network. It aims to achieve independent control over software, hardware, instruments, meters, and chips, integrating advantages to build an independent and controllable industry chain while overcoming technical barriers.

Core technologies that are independently controllable include chip design, embedded software R&D, cloud platform R&D, equipment redundancy solutions, and reliability solutions.

Supply chain controllability refers to ensuring the security of downstream industry ecosystems related to production materials and suppliers. It involves avoiding risks associated with single suppliers, implementing security management for material products, and ensuring manufacturing security management by vendors. Key core components should have domestic options.

Security controllability involves the security of infrastructure, access, transmission, data, and O&M for the FRMCS network. Controllable technical requirements should be considered in end-to-end product design.

Network controllability includes coverage control, capacity control, and network service quality control. Coverage control involves using the wireless network planning technology, coverage enhancement technology, and multi-antenna technology to achieve full coverage of the targets along the railway line while avoiding issues such as overshooting and weak coverage. Capacity control means utilizing interference detection and coordination technology to improve the anti-interference capability of the equipment and avoid the interference within the FRMCS system, as well as between the FRMCS and other systems such as the ITU-T system and the Tiantong 1 satellite system. This improves the system capacity and ensures that capacity planning meets the requirements of railway users. QoS control means applying FRMCS 5QI technology to formulate QoS policies tailored to specific railway service requirements in terms of bandwidth, delay, and packet loss rates.

FRMCS Testability

FRMCS testability targets different network construction phases with various objectives, including software functions, hardware RF indicators, dynamic inspection and detection, and daily operation and maintenance. Sub-systems are tested using terminals, base stations, and core networks as test objects, while field tests involve coverage, electromagnetic environment, interference, and drive tests as test objects. In addition, product security testing and independent security assessments are indispensable parts of testability.

• Software function tests: Perform both laboratory and field tests according to the functional requirements specified in the “Interim Technical Specifications for FRMCS  System Base Station Equipment” to evaluate the extent to which railway equipment meets user requirements.
• Hardware RF tests: Analyze the baseband spectrum, receiving spectrum, passive intermodulation, VSWR position measurement, and carrier frequency spectrum of the base station to test whether the base station hardware meets the protocol consistency requirements.
• Dynamic acceptance tests: Conduct tests to determine whether network optimization meets expectations and whether the current network meets the application requirements by setting different speed levels during dynamic vehicle inspection.
• Routine O&M tests: Periodically test devices and networks in accordance with the O&M specifications of the communication center to evaluate their health.

FRMCS Reliability

The FRMCS reliability technology, which integrates FRMCS redundancy network architecture and software algorithms, improves the overall performance and reliability of the FRMCS system. Redundancy networking technologies include access control-level, device-level, RF module-level, and baseband board-level redundancy. Software algorithms include Doppler frequency offset compensation, super cell technology, and uplink joint reception technology.

FRMCS Credibility

FRMCS credibility involves using key technologies such as secure storage, secure boot, and secure version to build a trustworthy environment for wireless devices, and implements system hardening, transmission hardening, and account hardening to achieve product trustworthiness. Additionally, the need to pass 5G product security certification further enhances the product's trustworthiness level.

ZTE is a global leader in 5G networks and has been researching next-generation railway mobile communication systems for more than 10 years. As a major global supplier of GSM-R, ZTE strives to achieve the “Six Abilities” of the FRMCS railway system through managing and controlling the entire process of product design, planning, R&D, and production. In the era of digital transformation and intelligent railway communication network construction, ZTE has always been the most powerful partner for railway users.