Network Innovations Call for a New Core
5G will enable a diverse array of services and meet varying connectivity need. The three major application scenarios defined by ITU for 5G include eMBB, uRLLC and mMTC. To meet the needs of these scenarios, 3GPP has defined a new 5G core network (5GC), featuring service-based architecture, network slicing, CUPS and stateless function, as well as two architectural options (5GC and EPC) to adapt to different wireless deployment scenarios.
●5GC: Depending on wireless deployment mode, a 5G new radio (NR) base station and a 4G eNodeB are independent from each other or mutually dependent. The 5G NR directly connects to the 5GC or serves as a secondary RAT to access the 4G eNodeB; the UE is in single connection or dual connections with the 5G or 4G RAN.
●EPC: This is a non-standalone deployment based on the existing 4G core. The 4G eNodeB serves as the anchor RAT and the 5G NR as the secondary RAT; the UE simultaneously connects to the 5G NR and 4G eNodeB; and the 4G/5G interoperability is achieved through RAN.
Operators can select different core network architectures according to their commercial 5G deployment plans, available spectrum resources, the maturity of terminals and industry chains, and TCO.
5G is targeted at coping with the OTT challenge, exploiting the vertical industry, and increasing revenue streams for operators. It should be capable of rapid customization, slice-based network operation, and highly-automated, intelligent O&M. The 4G EPC based on the traditional architecture cannot meet those requirements. The cloud- and SBA-based 5GC is the target 5G network architecture. Its advanced network architecture can help operators avoid overlapping investments, frequent network transformations and achieve a leading market position. The 5GC with SBA is a one-step-to-reach approach to architecture, and makes centralized construction and intensive O&M easy. With the support for FMC, it also facilitates the introduction of big data and AI to improve the level of network intelligence. By leveraging the 5GC, operators will be able to expand cooperation with industry verticals and quickly roll out new services. Therefore, adopting a 5GC architecture is aligned with world-leading operators’ goal for strategic innovations and the needs of 5G commercialization.
Challenges on the Way to Innovation
As a brand-new core network, 5GC adopts new technologies and is naturally accompanied by various challenges and speculations. Only by facing challenges and finding solutions can an operator stand out from the market competition. Considering the needs of commercial 5G deployments, building a new 5GC has three major challenges: network deployment, network function, and new service development.
Virtualization is central to 5G. All the new 5GC-enabling technologies are based on virtualization. The virtualized 5GC built around the COTS severs maximizes resource sharing, and operators can enjoy the benefits of Moore’s Law (i.e. performance improved by 30% at least every 18 months). 5GC is based on the VM or container technology, and the brand-new SBA and interfaces. It uses a lot of horizontal and vertical interfaces. When operators test new network functions, they have to complete the interoperability tests between horizontal and vertical interfaces. Therefore, how to fast deploy a commercial 5GC based on virtualization and SBA is a big challenge.
A 5G network provides many service functions, mostly related to key functions such as user data and billing. For user data, full convergence is the goal of network construction. Operators have to consider how to implement the network migration from 4G to 5G so that users don’t have to change their SIM cards or phone numbers. With respect to billing, there is a big difference between the target converged online/offline charging system based on the SBA and the existing architecture with online/offline separation based on traditional equipment. The challenge is to how to rapidly put the convergent billing system into commercial use while achieving compatibility with the existing billing system.
New Service Deployment
Network slicing is a critical service for 5G. It is a key technology for operators to adapt to different service needs and scenarios and build new profit models. For the differentiated requirements from vertical industries, government and enterprise customers, and low-latency ISPs, how to flexibly divide a network into slices is the key challenge for network slicing deployment. Voice and SMS services will continue to be essential in the 5G network, for which, several solutions have been defined by 3GPP. It is important to find out which solution allows speedy deployment of 5G voice and SMS services while having the least impact on the existing network, and how to ensure service continuity and quality.
Simplified 5GC Solution
ZTE proposes a simplified 5GC solution (Fig. 1) to help operators gain a lead in 5G network construction and benefit from 5GC’s new technologies.