The Next Generation Mobile Networks (NGMN) Alliance has established considerable clout in setting out roadmaps and use cases for cellular networks, based on requirements distilled from its many operator members.
Its influence reached a peak, perhaps, when it published the first major white paper about the definitions and commercial vision for 5G, in 2015. But with operators rolling out 5G at scale, it may feel its role is now diminished, so it is setting out its stall for the early 2020s, around three main topics – the route to disaggregation, sustainability and green networks, and (naturally) 6G.
It has streamlined its work program around these three big issues, though its CEO, Anita Doehler, insists that “we remain committed to further support 5G’s full implementation”. She said the Alliance is in “pole position” to address major operator and ecosystem issues in 5G and all three new areas because it is so MNO-driven.
For disaggregation, the Alliance will focus on creating blueprints, and providing guidance, for members to prepare operating models that rely on orchestrating the broad ecosystems of partners that are expected to deliver next generation, cloud-based networks. This work programme will aim to develop an end-to-end operating model that takes into account processes, technology, tools and skills needed to run a successful multivendor and flexible platform.
The green networks work programme will focus on techniques to run more energy efficient networks even as the numbers of users and level of usage rises; and will also address reducing wasted energy, and the eco-design of products and equipment. The aim is a consensus view among operators, and a collaboration with equipment vendors that could lead to “significant industry contribution in achieving UN and GSMA sustainability goals”.
Finally, the 6G work programme will focus on vision, built on socio-economic drivers, and also operational aspects. As with 5G, the work will result in the definition of key use cases and their end-to-end system requirements, which will help provide an operator-driven framework for standards bodies and other industry developments.
NGMN will liaise with stakeholders and “facilitate multilateral cooperation with the wider ecosystem at the right time” and plans to publish the first version of its 6G Vision & Drivers White Paper in 4-6 weeks’ time.
However, it is still focusing many efforts on driving blueprints for 5G, which help to reduce cost and time to market for operators and enable consensus. Its most recent paper argues for industry-wide support for Option 4 – one of the 3GPP-defined migration paths from 5G Non-Standalone (which uses the 4G core) to 5G Standalone, with the 5G core.
There are different ways to move from NSA to SA, some more abrupt than others, but Option 4 provides flexibility to retain dual connectivity for 4G and 5G base stations for as long as the operator’s business model requires that. The Alliance argues that there shouldn’t be intense pressure put on operators to refarm all their spectrum for 5G, and they should be able to keep some dedicated to LTE for a long period while also enjoying the benefits of the 5G core.
Option 4 supports dual connectivity for LTE and 5G NR, but whereas in NSA, the 4G core is retained, and LTE acts as the master, in SA Option 4, NR acts as the master. This means that baseline 5G NR radio performance can be enhanced by using LTE on top. 5G SA users can access both NR and LTE spectrum in the lower frequency bands, which helps the operator support wide coverage without having to build out 5G in every location, or refarm all its sub-GHz spectrum overnight.
Option 4 will allow the industry to “quickly and efficiently bring new 5G-based services to market”, says the paper, which is being published as the precursor to a trial of Option 4 to encourage development and uptake across the ecosystem.
“Development completion of Option 4 is urgently needed to enable all operators to invest in a new 5G core network without compromising user data rate performance,” said Arash Ashouriha, chair of the NGMN Alliance. “Advanced 5G users using 5G Standalone should be able to access LTE on top of NR for a seamless service experience.”
Without Option 4, the NGMA fears some users will experience lower performance with 5G SA than with LTE-Advanced, because the coverage will take some years to reach equivalence (this has already been seen in some early tests of T-Mobile USA’s SA network). Full 5G coverage will require lower band spectrum, but most bands below 3 GHz are occupied by LTE, and will not be freed up until operators can migrate most 4G users to the newer services (a long process). Some refarmed 2G and 3G spectrum, such as 2.1 GHz in Europe, will help but for many operators, the ability to use low-band 4G as a coverage layer even with SA will be economically important.
Raimund Walsdorf of Deutsche Telekom, the NGMN project lead, said: “Option 4 development will support many network operators planning an initial 5G Standalone service launch today or a more widespread launch in the future. This option benefits operators to more efficiently migrate spectrum from LTE to NR, while also relaxing the pressure on operators to refarm from LTE to NR as long as spectrum remains dedicated to LTE”.
The full White Paper entitled, Option 4 as a 5G SA complement can be found here.