System architecture milestone of 5G Phase 1 is achieved


Yet 5G is more than a new generation of technologies, says GSMA

The first edition of the new 5G standard was been defined by the 3GPP on 21 December 2017, providing an initial outline of what the new standard will look like. The 3GPP Release 15 of the 5G system architecture provides the set of features and functionality needed for deploying a commercially operational 5G system.

SA2, the 3GPP architecture working group, has now specified the overall 5G system architecture; detailing features, functionality and services including dynamic behaviour defined by information flows.

5G is the next major evolution of mobile networks, commented Steve Plunkett, chief technology officer, at Red Bee Media, formally known as the broadcast and media services division of Ericsson. He goes on:  “It introduces significant improvements in performance and capacity over 4G LTE networks, through a combination of more efficient radio transmission, access to greatly more radio spectrum and changes to the core networks that connect radio base stations. This translates into much more bandwidth for mobile devices, less transmission delay (latency) to better serve real time video and augmented reality (AR) and virtual reality (VR), along with more certainty and performance guarantees for different categories of user and applications. In short, it’s faster and better than the best on offer today and it will change how we work and play.”

However, 5G is more than a new generation of technologies; it denotes a new era in which connectivity will become increasingly fluid and flexible. According to Michele Zarri, technical director, GSMA, 5G, “will be a catalyst for innovation and enable richer, smarter and more convenient living and working”. GSMA Intelligence expects 5G to cover 74% of the EU population by 2025 with over 170 million connections.

The 5G stage 2 level specifications include the overall architecture model and principles, eMBB data services, subscriber authentication and service usage authorisation, application support in general, but also specifically for applications closer to the radio as with edge computing. Its support for IMS includes also emergency and regulatory services specifics.

Further, the 5G system architecture model uniformly enables user services with different access systems, like fixed network access or WLAN, from the onset. The system architecture provides interworking with and migration from 4G, network capability exposure and numerous other functionalities.

According to Frank Mademann, 3GPP SA2 chairman, “compared to previous generations the 3GPP 5G system architecture is service based. That means wherever suitable the architecture elements are defined as network functions that offer their services via interfaces of a common framework to any network functions that are permitted to make use of these provided services. Network repository functions (NRF) allow every network function to discover the services offered by other network functions. This architecture model, which further adopts principles like modularity, reusability and self-containment of network functions, is chosen to enable deployments to take advantage of the latest virtualisation and software technologies”.

A distinct key feature of the 5G system architecture is network slicing. The previous generation supported certain aspects of this with the functionality for dedicated Core Networks. Compared to this 5G network slicing is a more powerful concept and includes the whole PLMN. Within the scope of the 3GPP 5G system architecture a network slice refers to the set of 3GPP defined features and functionalities that together form a complete PLMN for providing services to UEs. Network slicing allows for controlled composition of a PLMN from the specified network functions with their specifics and provided services that are required for a specific usage scenario.

Earlier system architectures enabled what was typically a single deployment of a PLMN to provide all features, capabilities and services required for all wanted usage scenarios. Much of the capabilities and features provided by the single, common deployment was in fact required for only a subset of the PLMN’s users/UEs. Network slicing enables the network operator to deploy multiple, independent PLMNs where each is customized by instantiating only the features, capabilities and services required to satisfy the subset of the served users/UEs or a related business customer needs.

The service based architecture together with softwarisation and virtualisation provides the agility enabling an operator to respond to customer needs quickly. Dedicated and customised network slices can be deployed with the functions, features, availability and capacity as needed. Typically, such deployments will be based on a service level agreement. Further, an operator may benefit by applying virtualisation, platforms and management infrastructure commonly for 3GPP-specific and for other network capabilities not defined by 3GPP, but that a network operator may need or want to deploy in his network or administrative domain. This allows for a flexible assignment of the same resources as needs and priorities change over time.


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