ZTE 5G-R Core Network Drives High-Quality Development of Digital Railways

Since China officially launched commercial 5G services in 2019, 5G has penetrated all sectors of the economy and society, becoming a key infrastructure that supports their digital, network-based, and intelligent transformation. As a critical transportation infrastructure of the country, the railway has very stringent requirements on communications technologies. 5G for railway (5G-R) is a new-generation railway mobile communication system based on 5G technology. It features ultra-large bandwidth, ultra-low latency, and massive connections, promising to bring revolutionary changes to railway communication networks.

As the backbone of the 5G-R system, the 5G-R core network supports a variety of key services, including wireless scheduling communication, train operation control, train operation command, and operation and maintenance (O&M) information transmission. Focusing on the future intelligent railway communication and with the development goals of being "visible, manageable, controllable, measurable, reliable, and credible", building an autonomous and controllable high-quality 5G-R core network is crucial for the evolution of the new-generation railway mobile communication system.

5G-R Core Network Architecture

The 5G-R core network is divided into a two-level architecture: railway bureau equipment and shared equipment. The railway bureau core network equipment includes 5G core (5GC) equipment, mission critical (MC) equipment, DNS, RADIUS, and location service equipment (optional). The shared core network equipment includes 5G equipment identity register (5G-EIR), level-1 NRF, level-1 service communication proxy (SCP), level-1 DNS, and short message service center (SMSC). The dual data center (DC) disaster recovery and backup network architecture is used for both railway bureau devices and shared devices to ensure network reliability. For railway application services requiring large bandwidth or low latency, edge computing nodes can be deployed close to the service side.

The 5GC equipment complies with the 3GPP standards and uses the service based architecture (SBA), which includes network functions such as AMF, SMF/I-SMF, PCF, NRF, UDM, AUSF, NSSF, SMSF, UPF/I-UPF, CHF, and SCP.

ZTE 5G-R Core Network Products and Solutions

The ZTE 5G-R core network products align with the overall development objectives of intelligent railways and fully comply with the overall technical requirements of the 5G-R system in terms of architecture, function, and performance, as well as the interim technical conditions of 5GC equipment released by China State Railway Group. The ZTE 5G-R core network supports a two-level architecture for railway bureaus and bureau-shared equipment, inter-site dual-DC disaster recovery, on-demand distributed deployment of edge computing nodes, exposure of intelligent O&M capabilities, and offers intrinsic security capabilities. It delivers 5G network support for data, voice, and video services of the new digital railways.

The ZTE 5G-R core network products introduce brand-new designs and innovative solutions in four areas: cloudified architecture, reliable disaster recovery, security and control, and intelligent O&M, providing new infrastructure for the future railway services and facilitating the upgrade and evolution of the railway wireless private network to a new-generation mobile communication system as shown in Fig. 1.

• Cloudified Architecture

The ZTE 5G-R core network product adopts a mature NFV architecture and microservice-based component design, runs on a carrier-class dual-core cloud platform, and is deployed in a unified cloud resource pool. This setup provides an elastic and scalable virtualized network for the new-generation railway-dedicated communication system.

ZTE’s virtualized NFs comply with the 3GPP Release 16 standards. Control plane NFs and user plane NFs can be deployed either separately or together. Control plane NFs related to signaling processing are deployed at railway bureaus in a centralized manner, providing high concurrent processing capability and continuous capacity expansion. User plane NFs related to railway applications can be deployed centrally at railway bureaus or at nearby railway edge data centers as needed, and they can provide high-bandwidth and low-latency network services for new railway applications through innovative software and hardware traffic acceleration technologies.

• Reliable Disaster Recovery

Railways impose extremely high reliability and disaster recovery requirements on wireless private networks. The ZTE 5G-R core network equipment provides multi-level and multi-dimensional high-reliability technology innovations, ranging from hardware to software and from components to NFs, meeting long-term stable operation and disaster recovery requirements of railways.

——High-reliability cloud resource pool: The resource redundancy mechanism prevents services from being affected by software and hardware faults. The dual-network and dual-plane mechanism ensures reliable networking, while distributed storage provides multi-copy data security.

——NF-level disaster recovery protection: NF-level or device-level remote disaster recovery is implemented through the NF Pool or AMF sets. The signaling storm suppression function can withstand over 64 times the network signaling impact, and the NF bypass function provides service degradation and availability in extreme fault scenarios.

——For major changes in the core network, such as disaster recovery switchover and device version updates in the data center, automation pipelines and operation dashboards are introduced. This enables the automatic execution of operational steps in a navigational manner and monitoring of network operation via an easy-to-use large screen, reducing engineering operation risks and improving operation efficiency.

• Secure and Controllable

To ensure the security of the railway communication system’s supply chain, the ZTE 5G-R core network supports diversified and high-performance servers, and achieves independent control over key software and hardware, ensuring the long-term sustainable supply and maintenance of private network products.

ZTE is committed to providing a multi-layered and three-dimensional endogenous security protection solution. It provides differentiated security capabilities that can be extended and orchestrated at the infrastructure layer, network function layer, service data layer, and O&M management layer, thereby building a 5G-R core network with a high security level.

• Intelligent O&M

The O&M  of cloud resource pools is a critical and challenging aspect of cloud core network devices. ZTE provides powerful network orchestration and management functions to intelligently and uniformly monitor, configure, and scale  core network resources, significantly reducing the O&M difficulty after the NFV is introduced and effectively improving O&M efficiency.

In fault scenarios, ZTE’s core network equipment provides multi-dimensional intelligent O&M capabilities. By utilizing multi-layer fault detection and prediction methods (such as key performance indicators, alarms, and O&M kits), fault root cause analysis, and cross-layer fault linkage solutions, it assists railway O&M personnel in accurately locating and rapidly resolving faults.

Relying on the experience gained from large-scale commercial deployment of public 5G core network for Chinese operators, the ZTE 5G-R core network provides a one-stop commercial delivery process including network design, hardware installation, NF deployment, data configuration, security hardening and service testing. With the help of mature end-to-end delivery tools, the ZTE 5G-R core network achieves "zero potential risks and quality self-control" before the core network is provisioned, providing a full-process guarantee for the delivery of high-quality commercial networks to China State Railway Group.

Conclusion

As the world’s leading provider of integrated communications and information solutions, ZTE provides core network products to more than 100 operators and over 500 industry customers worldwide, acquiring extensive and leading experience in large-scale commercial use of 5G networks. In the 5G-R market, ZTE actively participates in the formulation of 5G-R technical specifications and laboratory tests. Leveraging its profound technical accumulation and rich practical experience, ZTE accelerates the maturity of 5G-R technologies and continuously fosters the high-quality development of digital railways.