At present, traditional networks are due for an upgrade and are no longer suitable for large-scale investments. Industry-leading operators are actively promoting the commercialization of virtualization. The deployment of 5GC can speed up virtualization, and it often uses the following concepts :
●Centralized deployment of control plane: Centralized deployment of 5GC control plane helps unify services across the whole network, develop slice-based services, and achieve centralized and intelligent O&M to reduce Opex.
●Layered and phased deployment of user plane: The user plane can be deployed in centralized mode for early-stage 5G deployments. A layered approach will be adopted at the middle and later stages with the user-plane functions deployed close to the access network as needed to reduce latency and improve customer experience. User plane virtualization allows resources to be shared across layers, solving the holiday tidal effect.
●Phased construction of 5GC NF: At the early stage of 5G, basic NFs can be deployed, and optional and unimportant NFs deployed later as needed. At the early stage, 3GPP-compliant 4G/5G convergent NFs can be deployed for interoperability, and more NFs deployed later to achieve full convergence of 4G/5G NFs.
●Phased opening of interoperability interfaces: At its early stage, the 5GC needs to open interfaces for subscription, RAN, UE, 4G/5G interoperation, network management and billing to reduce testing and deployment time. More interfaces should be gradually opened to achieve features like international roaming.
To build a 5GC, it is necessary to deploy convergent UDM+HSS for unified, centralized management of 2G/3G/4G/5G user subscription data. At the early stage, data migration can be carried out for users who have upgraded from 4G to 5G. At the middle and later stages, the existing 4G users will be gradually migrated to the new convergent UDM+HSS, depending on the aging degree of legacy HLR/HSS. The flexible number routing (FNR) scheme is used to solve the call routing problem of users with discrete number sections at the initial stage.
To support 4G/5G interoperability, the 5G SMF and 4G PGW-C will be converged. At the early stage of 5G, 4G billing interfaces, which are supported by the convergent SMF+PGW-C, can still be used. This avoids large transformation work and delay of commercial 5GC use that might be caused by the introduction of 5G billing system.
Simplified Service Deployment
At the early stage of 5G with limited industrial applications, it is preferred to perform sub-slice management first in the core network, and then gradually carry out slice trials and verifications based on the 5GC. The initial focus is on eMBB slice services such as HD video, AR/VR and HD game, and with the 5GC user plane moved to the edge, the demands of some ultra-low latency services will be met. At this stage, the ability of slices to fulfill the differentiated SLAs can be verified, so as to set up exemplary industrial applications. With the maturity of 5G slice standard, transmission/wireless sub-slices will be gradually introduced. Based on the orchestration and management system constructed in the previous stage, the 5GC will add the functions of slice design, assurance analysis, and policy management, and provide the life-cycle management of E2E slices. It is necessary to consider network slice operation, including slice delivery, pricing, billing, and opening of capabilities, accumulating operational experience and related technologies for slicing commercialization.
The 5G voice standard defined by 3GPP R15 has been mature, and commercial 5G terminals will reach the market in 2019. Mainstream operators have deployed IMS networks to support VoLTE. At the early stage of 5G with only hotspot coverage, to reduce the voice handover between 5G and 4G, it is preferred to upgrade the software for IMS and perform 5GC EPS fallback for VoLTE. Along with the expansion of 5G coverage, VoNR can be used to provide 5G voice services.
E2E 5GC Products
5GC is the key technology for 5G network construction and service bearing. ZTE’s core network products address the urgent needs of the world’s leading operators to construct a 5GC with advanced architecture and innovative technologies. Based on previous simplified solutions, ZTE provides the following products to meet different deployment demands.
CloudStudio (O&M system): It is the ZTE 5G oriented O&M system that will continuously optimize user experience and networks with its self-evolution capabilities (design – deployment – operation – analysis – redesign). In the future, it will introduce AI and machine learning to achieve intelligent policy prediction, a more intelligent system, and zero-touch operations.
Common Core (5G convergent core network): It is the ZTE fully convergent 5GC product, which is based on SBA and supports mobile access (2G/3G/4G/5G) and fixed access (trusted and un-trusted non-3GPP access).
Tulip Elastic Cloud System (TECS): It is the ZTE cloud platform product that provides 5G-ready VIM and NFVI functionalities and creates a robust and reliable infrastructure for operators.
Considered the brain of 5G network, 5GC directly impacts the realization of operators’ network innovation strategy. ZTE’s simplified 5GC solutions and products speed the way to 5G deployment and help operators step into the 5G/IoE era.