Mobile network evolution: getting ready for the takeoff of 5G

Telecoms.com periodically invites expert third parties to share their views on the industry’s most pressing issues. In this piece Jon Baldry, Metro Marketing Director at Infinera, reflects on the current state of 5G networks.

As we close out 2021 and move into 2022, it’s interesting to look back at the last year and the progress made in 5G networks. Mobile operators globally have continued to roll out new 5G networks and expand 5G footprint within existing networks, and handset manufacturers have continued to bring new 5G-capable devices to market. At a quick glance, end-users of 5G and potential new end-users considering upgrades to 5G might think that overall, this is nothing new – just more of the same from 2020. There are no new services yet, just faster 4G in a few more places via a wider range of devices. Many of us within the telecoms industry have an obvious advantage over other 5G end-users in that we can “lift the hood” and peer into the inner workings of 5G networks. We would see that a lot has happened in 2021 within these networks to help prepare them for the next phase of 5G, when we expand beyond those initial enhanced mobile broadband (eMBB) “fast 4G” services to the newer service offerings that 5G promises.

The Move to Standalone 5G Core

The most obvious change in 2021 has been the start of the migration to the standalone (SA) 5G core from the initial non-standalone (NSA) implementation that reused the older 4G core. Initially this doesn’t change much for the end-user, but it is an important first step toward new advanced 5G services beyond eMBB. Initial upgrades for 5G SA became available in mid-2020, and after the usual period of certification testing and type approval, the first few operators started migration to 5G SA right at the end of 2020. In 2021, this trickle turned into a flood as operator after operator made the move. With a new 5G radio access network (RAN) and a new 5G SA core, many operators then turned their attention to the underlying transport network connecting the two.

Upgrading transport networks typically isn’t a quick job, and many operators have been preparing for transport network upgrades for some time. In 2021 we, and I’m sure many others who provide optical transport solutions, saw a significant increase in 5G-related projects because of this.

Transport Network Upgrades in 2021

5G obviously drives a need for significantly higher capacity within the mobile transport network to support more bandwidth per user, more users, and more connected devices overall. However, this creates various challenges depending on where in the optical network you look. Over existing multi-service transport networks, it is driving capacity upgrades and even 100 Gb/s capacity services from wholesale operators to support planned growth. Closer to the cell tower, it is pushing 10G/25G DWDM, and even coherent 100G DWDM, deeper into access networks. This drives specific requirements to harden DWDM platforms, as many of the locations that DWDM is being pushed to are non-telco environments like street cabinets.

Additionally, 5G is driving tighter requirements into the transport network. The significant reduction in overall network latency to support new low-latency services is an often-discussed example of this. The optical network has a role to play here by ensuring the minimum possible latency is added by the network. Most of the latency added by the transport network comes from optical fibers, and to address this, network operators are starting to the move to multi-access edge compute (MEC) architectures that bring compute and storage capabilities closer to the user. A further network performance aspect that isn’t discussed so widely is network timing and synchronization. 5G drives significantly tighter requirements into the transport network, and in 2021 we’ve seen a significant uptick in the focus on synchronization requirements and performance from network operators. This is a complex topic and one that should not be overlooked in mobile transport network evolution. There are significant challenges in this domain, although these can be overcome with the right approach to the problem.

Looking to the Future

I mentioned MEC just now and the impact this can have on helping network operators meet the millisecond-level latency aspirations for 5G. We are not at the stage where low-latency services are available to mobile users, so MEC capabilities are a preparatory step toward these. MEC does, however, have another role to play in supporting the virtualization of 5G radio functions, specifically the distributed unit (DU) and centralized unit (CU) devices that together with the radio unit (RU) at the cell site manage the radio network. Industry organizations such as the O-RAN Alliance are working toward an open environment where operators will be able to mix RU, DU, CU and core products from multiple vendors to break lock-in and speed network innovation. Parallel to this, the industry is moving toward virtualizing these functions and running them on cloud-native environments. MEC locations will ultimately overlap with DU and CU locations and virtualized vDU and/or vCU software could be an initial use case of MEC.

Some network operators are now planning for this future transport network environment with MEC, vDU/vCU nodes, and an overall cloud-native environment using existing facilities wherever possible. One new optical networking initiative that is being evaluated in this environment, especially space- and power-constrained locations, is point-to-multipoint XR optics. This approach delivers the high bandwidth needed in this 5G environment and adds numerous new capabilities that will enhance the transport layer. The Open XR Forum is driving industry adoption of point-to-multipoint optics for a range of use cases, including 5G.

Wrapping Up

2021 has been a very busy year for 5G transport networks and 5G networks overall. The vast majority of this will be unseen by end-users. Perhaps a good analogy here is the one of the swan smoothly moving across a lake. Unseen by onlookers, its legs are paddling away like mad under the surface. The networking industry has been paddling away very fast in 2021 and will continue to do so in 2022 as we get ready for the moment that the 5G swan really takes off!

As Infinera’s Metro Marketing Director, Jon has responsibility for strategic and technical marketing for the company’s metro access and aggregation portfolio in applications such as 5G in mobile networks and DAA in cable networks. Jon has spent over 25 years working in the telecoms industry and joined Infinera through the acquisition of Transmode in 2015, having joined Transmode in 2004. Prior to Transmode/Infinera Jon worked for Lucent Technologies and Sycamore Networks in a variety of engineering, sales and marketing roles. Jon is a Chartered Engineer and holds a Bachelor of Engineering Degree in Electrical Engineering and Electronics from the University of Manchester Institute of Science and Technology (UMIST).