BT’s new network vision

BT leans into a converged core, with diverse access.

BT CEO Marc Allera has announced what he called “the most ambitious and complete network vision the UK telecoms industry has ever seen.”

Allera said BT would achieve 5G coverage anywhere in the UK by 2028, and that it would have a “fully converged network” by the mid 2020s.

To achieve its 5G coverage plans, the operator will exploit 700MHz spectrum, but also a range of new technologies, including High Altitude Platforms, Drone and Satellite connectivity to give the capability to provide “5G on demand” to even the most remote areas. Allera said that this would provide “a diversified network that will go beyond our existing and future mast infrastructure.”

The company has recently announced an MoU with OneWeb to explore using the satellite provider’s services for backhaul to FWA and other units, and it is open to exploring other tie-ups, it said.

BT will also explore solutions for in-building and indoor locations, and will provide connectivity on a neutral host basis to other operators, CEO Allera said. The operator also said it would continue to partner in the Government’s Shared Rural Network as it expanded rural coverage.

It will also be switching off 3G by 2023, whilst keeping 2G alive for longer to meet M2M requirements.

Underpinning the carrier’s 5G, Fixed Wireless Access and mobile plans, CTIO Howard Watson also announced BT would “bring together its mobile, WiFi and fixed businesses towards a converged and virtual network to deliver the next level of reliability and performance.”

That will provide a “truly responsive” network with lower latencies and an improved experience for data-heavy services, Watson said.

Watson outlined a Smart Network vision that integrates the company’s fixed and mobile cores in a modular architecture – built on its converged network cloud infrastructure. It will start moving customers over to its 5G core from 2022 and the 5G core will be fully live by 2023. The company will also start demonstrating 5G SA capabilities for certain use cases.

The company is now ready to accelerate its Huawei swap-out, and will take the opportunity to upgrade 4G capability at those sites as it deploys equipment from its partners Nokia and Ericsson. Watson said that OpenRAN solutions would not be a part of the RAN mix at scale until the end of the decade, although the company would look at some potential small cell and rural uses.

Open RAN must meet the additional needs of its Emergency Service Network, Watson said, and the company is contributing to efforts within TIP to accelerate the maturity of the technology.


As you can see from the above schematic, BT is looking to leverage its distributed telco cloud capability to enhance its network capabilities, with an interesting approach in the access layer, although it’s cautious on Open RAN.

Although it is committing to explore new access technologies as part of its drive to be able to offer “5G on demand”, the question for BT is if its core and RAN strategy will give it the flexibility to take quick advantage of new software innovation in those areas. One advantage of the Service Based Architecture of a 5G Core is that it can take advantage of cloud native microservices on a best of breed or use case specific basis, if an operator wants to go down that route.

BT’s network cloud is built along with several key partners, for example with Ericsson providing the cloud 4G and 5G core. Watson added that the company would also “expect to have cloud solutions from other providers co-existing with the BT Cloud”.

That means there may well be a role for public cloud partners to meet certain edge or private network use cases, for example. Watson told TMN in an interview published in June that the operator sees Private Networks as a potential introduction point for distributed 5G Standalone Core network deployments.

BT mentioned the Network Data Analytics Function (NDAF) as a key part of its 5G Core capability, using Machine Learning to predict and resolve network issues. It will be interesting to see what more BT says about the strategy to adopt Machine Learning and AI capabilities to underpin capabilities such as network slicing and  enhanced, SLA-backed, service offers.

On Open RAN, BT is prioritising software-defined single RAN rollouts from Nokia and Ericsson. It clearly believes that gives it the speed of rollout, as well as the features and capabilities, it needs. Watson said that although the company would indeed be later than some competitors to Open RAN – for example Vodafone has a commitment to replace 2.5k rural sites with Open RAN technology – he didn’t think that the company would suffer from any lack of access to innovation as a result.

One proposed benefit of Open RAN is that by opening up the control function (RIC), as well as the base station software itself, operators can take advantage of new, more focussed, RAN software such as algorithms for Massive MIMO optimisation or SON. But BT clearly feels that it will get the smarts it needs from its vendor partners, and also that it must be extremely conscious of reliability and security, as its network also underpins the UK’s Emergency Services Network. It should also be noted that Nokia, one key partner, is fully committed to supporting Open Fronthaul interfaces and the O-RAN near real time RIC, and Ericsson is involved in the non real time RIC contributions as well. So it’s not as if BT is entering a closed RAN world entirely.

A final point was how BT would expose its network as a partner within the Shared Rural Network. In January, the UK’s three other operators announced that they would be building 72 new sites each, and sharing them amongst themselves, in rural areas. Many of these areas already had BT towers in them, but the other operators preferred instead to use their own masts. Watson said that BT would be “fully leaning in” to the SRN to use its 800MHz band to close any partial not-spots (an area where a user cannot receive service from all four operators) and to come together and share infrastructure on total not-spots (an area where no operator provides coverage).