APPROFONDIMENTO

The road to 5G

 

5G will be a key enabler in transforming our economy and society by providing connectivity in three broad areas: Extreme mobile broadband, Massive machine communication (IoT), Critical machine communication and Ultra-reliable low latency communication.
5G core will need to run in heterogeneous environments, interacting with multiple types of access network and serving a wide ecosystem of applications and players. This is a radical change compared the existing 3G/LTE networks which has been designed to carry on mainly voice and mobile broadband data traffic.
The current existing model of “one big pipe network“ does not fit all the variety of uses cases that the 5G eco-system will make possible.
End-to-end network slicing will be a key enabler for efficiently manage the diversity of the uses cases in the operator network and it should be a relevant factor to be taken into account when designing the 5G core network. Indeed the overall network architecture should be designed with the right capabilities to able to deliver the right level of scalability, flexibility and TCO efficiency.
A cloud native core network which is modular and programmable is key pillar of the 5G core network. Moreover, software techniques like micro services, digital delivery, Open API can be leveraged to give the expected level of business agility.  All these aspects should be on top of the agenda for 5G core network design.
Core networks of the 5G era will be subject to major architectural transformations to enable new business models (e.g. for vertical markets) as well as the need for extreme operational agility and automation.
While the normative phase of the 3GPP Release 15 is ongoing, Nokia envisaged the following architectural characteristics for Next Generation Core (5G core):

  • A layered architecture with User Plane/Control Plan/Data Layer;
  • The UP/CP split enables independent scaling, possibility to geographically allocate UP function based on the use case requirements (e.g. latency, reliability) and develop the functionalities in separated entities;
  • A data layer introduction to store subscription, session data, policy data enhances the resiliency model, facilitate the VNF introduction, reduce operational costs and it improves analytics and automation capabilities;
  • Control plan functional decomposition to enable more agile delivery models with smaller modules of orthogonal functions each covering a specific domain, e.g. session management, access mobility management, policy, charging, …;
  • Core control plane functions should provide their functionality via service interfaces, realized as APIs and defined in a service reference architecture. Any function can use the services of any other function if that results in a useful feature and is allowed by the operator defined API usage policy;
  • Network slicing;
  • Interface to MEC.

Though there are several other features which has to be considered in the core network design (flow base QoS, connection less services, UP relocation with service continuity, mobility/session on demand, PDU session types, new mobility management framework , …)  the above listed key architectural principles combined with cloud native core, micro services, Open API characteristics should be considered as key pillars of the next generation 5G core.
Today’s mobile core networks will need to evolve in key areas to deliver on the promise of an innovation engine for business and society transformation in the 5G eco-system. Some of these changes have already started to be implemented in today’s networks as we move beyond 4G (e.g. SDN, Telco Cloud).
A 5G core will make use of and improve these new capabilities, driving them to the next level.
As presented in this paper, solutions to make core networks more flexible, more efficient and more open exist, and are being developed as 5G standards firm up. They will transform the way the core networks are designed and managed, and the way operators, application providers, enterprises, public sector and subscribers work together. The journey toward 5G has already begun.

 

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