The UK telecoms regulator, Ofcom, has published some of the responses they’ve received from fixed broadband ISPs and mobile operators to their consultation on enhancing network resilience in order to “reduce the risk of network outages“ (here). Suffice to say that many operators are balking at the costs of deploying national battery backup.
At present Communications Providers (CSPs) already have a legal obligation to identify, prepare for and reduce the risk of anything that compromises the availability, performance or functionality of their network or service. But network outages still occur and Ofcom has previously warned that the consequences of these are “likely to become more severe as society becomes increasingly dependent on them to function.”
NOTE: The new Electronic Communications (Security Measures) Regulations 2022 (
summary) also impose new obligations on network operators, which is partly why Ofcom are seeking to update their guidance on network resilience.
One of the most interesting and contentious aspects of this has been the regulator’s pursuit of greater battery backup for both fixed line and mobile networks. For example, their consultation asks questions about the feasibility of mobile operators installing a minimum 1 hour of battery backup on Radio Access Network (RAN) sites.
Currently, the amount of battery backup across the mobile RAN varies by operator (EE, O2, Vodafone and Three UK), in terms of both the proportion of cell sites that are backed up and for how long. But the impact of recent winter storms and the migration away from traditional landline phones helps to underline that consumers are placing greater importance upon the dependability of their mobile phones, such as for emergency calls.
In addition, Ofcom suggests that having a 4-hour power backup in active cabinets on fixed line broadband networks would be an “appropriate level” because this is currently said to be a “typical practice when installing new active cabinets to support technologies such as Fibre-to-the-Premises” (FTTP). Some network operators do indeed do this, but others do not or deploy a lower level of battery backup.
However, the biggest obstacle here is likely to be cost, particularly for mobile operators. Ofcom’s illustrative example suggests that to install a minimum 1 hour of battery power backup on RAN sites, where power backup is likely to be feasible, could cost in the region of £0.9 – £1.8bn (this would end up being passed on to consumers as higher prices). Due to this the regulator doesn’t consider it “proportionate” to include such a measure in their future guidance “at this stage“, but they do seem to be moving in that direction.
Suffice to say that the publication of the first official responses to this consultation have helped to set out the different viewpoints. Naturally we’ve summarised a few of those below, which mostly focuses upon the issue of battery backup as the wider aspects of network resilience are trickier to reflect without a much longer and more laborious article.
BT highlights how it is “difficult to understand what benefit to citizens or consumers would derive from 1hr battery back-up in urban locations given the majority of these outages cover a single sites, there is cell site overlap resilience alongside Distribution Network Owners (DNO’s) resilience, which means a security compromise is unlikely to occur.”
The provider naturally agrees with Ofcom that the “cost of ubiquitous battery back-up would be ‘disproportionate’ for operators to bear alone“, but they remain “concerned, however, that the suggestion of widespread deployment of non-mains power back-up across the entire mobile estate will go well beyond the intent of section 105A of the Communications Act.” BT also sets out some of the measures they’ve adopted to help with resilience.
The key measures deployed by BT’s mobile RAN include:
• Overlapping cell site coverage;
• Deployment of targeted non-mains power back-up to appropriate [“high risk”] sites;
• Use of ‘roving’ engineering teams and equipment to provide power back-up where needed;
• Development of new tools and processes to enhance coordination with energy companies;
• Availability of limited national roaming to allow continued emergency access where coverage allows.
Cellnex, which is perhaps more focused on the infrastructure delivery than service side, took a more optimistic view and highlighted how battery backup is a solution already used in mobile networks and improvements in battery technology “makes this solution more compelling for wider deployment“. The company noted that batteries are “relatively easy to install“, can be recharged directly from the mains and have lower maintenance than diesel generators.
Cellnex also pointed out that one way to partially off-set the costs of deploying greater battery backup would be to help cut energy costs. “Batteries could be charged at night when power demand is low and per kWh pricing is lower and then utilised during peak power demand to reduce consumption costs,” said the company. “Another optimisation could be to deploy solar panels alongside the batteries” to help reduce peak power load and bring down costs. But that’s not always viable with the limited space available at mobile sites.
Cellnex example
For example an MNO site consuming 6 kW of power could save c.£870 per annum if 2 hours of peak power consumption per day can be supplied with batteries recharged at night when power costs are lower. Over a 15 year term the NPV of this saving would be c.£10,000 which would offset part of the cost of installing a battery back-up solution. The economics of the savings versus cost to deploy requires further investigation and more detailed financial modelling.
However, they also warned that a “significant challenge in cellular networks is battery theft, especially from remote cell sites“, which they said meant there would be “additional costs to provide adequate security and insurance to protect these assets.” Various other operators raised the same concern and we’d agree that this could be a big issue, especially with the size of units likely to be needed for such a task.
The mobile trade association noted how the UK’s power networks “are generally very reliable”, before highlighting a report from Ofgem, which noted that the average ‘customer minutes lost’ (CML) across the UK was 32 minutes in 2022 (down from 39 minutes in 2015) – a tiny fraction of overall usage. “It follows that operators’ scarce capital resources would be very much better targeted on customer known priorities such as reducing congestion (including investing in 5G), extending coverage and improving security,” said Mobile UK.
Naturally, Three UK felt as if mobile operators “should not be required” to utilise battery backup at the RAN Cell Site level in order to mitigate against short term power-related incidents because:
(i) Distribution Network Operators (DNOs) are already providing high levels of availability.
(ii) The cost to deliver and maintain battery backup at RAN Cell Sites is prohibitive.
(iii) Short-term power outages are de-minimis in comparison to the overall network availability and any other outages due to planned activity.
Meanwhile, in areas of high customer density, where the impact of short-term power loss is most felt, they echoed BT by saying that “there is overlapping coverage from adjacent sites” and “thus a loss of power at one cell site does not necessarily imply a total loss of service.” Three UK suggested that it would be better to improve resilience by focusing any power backup on critical “Hub Sites” and at “pre-Aggregation nodes” (Exchanges).
VMO2 actually submitted two responses to different parts of the consultation, albeit with a fair bit of cross-over. For example, Virgin Media said they “do not believe that introducing a blanket requirement for a minimum of 4-hour battery backup for all active street cabinets is appropriate or proportionate.”
VMO2 added that they felt battery backup at the access layer (fixed and mobile) ought to be considered holistically as part of a wider cross sector consultation on power resilience before implementing any minimum requirement for active cabinets. The operator also highlighted a problem with the hard suggestion of a 4-hour backup.
VMO2 Statement
Best practice for new fibre networks is to build with battery backup at the OLT. However, as currently worded, even new full fibre networks may have to replace batteries recently installed, as they have generally been architected to meet 3-4 hours in typical use as published by the supplier.
Requiring newly built networks to replace batteries which have approximately 3-4 hours battery backup because they do not have a minimum of 4 hours battery backup would not in our view be appropriate or proportionate given the cost of this exercise compared with the minimal additional benefit to customers.
The operator also added that battery life is affected by temperature, use and will deteriorate over time. At some point batteries will need to be replaced. By specifying a minimum battery backup in the Guidance, “the implication is that CSPs would be expected to replace batteries as soon as they offered less than 4-hour minimum backup. We are not clear how we would be able to determine this, and even if we could, replacement at this point would be costly, environmentally wasteful and, we believe, disproportionate.”
Finally, O2 suggested that Ofcom still seemed “minded to require a minimum of 1-hour battery backup for all cell sites” (i.e. whether now or in the future), and they “do not agree that this measure is appropriate or proportionate.”
Vodafone said that the primary responsibility for ensuring the reliability of the electricity grid rests with licensed Distribution Network Operators (DNOs), which they felt meant that the “single most effective step” to improve the reliability of the UK’s mobile and fixed line networks is to “better assure the power grid, making it more robust and better able to withstand weather events, while simultaneously improving processes to prioritise mobile sites for restoration should power be lost.”
The operator added that it would be particularly difficult (maybe even impractical) to add battery backup to sites that exist in “exposed, elevated locations” (i.e. many remote rural areas), which are much more “vulnerable to the impact of bad weather“. Vodafone suggested that “at a practical level, this restricts the ability of mobile networks to act as a network of last resort, with the fixed network often better placed to perform this role.” The latter argument is of course debatable.
Vodafone also noted, correctly, that there needed to be some “recognition that longer outages, such as those experience with storm Arwen, are unlikely to benefit from MNO battery investment“, which is because such outages are often much more protracted (lasting days or even weeks) and, in these situations, tactical emergency generator deployment can be used (although we do see examples where this doesn’t happen or is slow to occur).
Vodafone Statement
It may not be possible nor sensible to power all sites for 1 hour due to the costs involved. The expenditure required might not be justified, particularly when improvements in the reliability of the energy grid, the use of priority restoration processes, more extensive use of fixed network BBUs, the introduction of direct to device satellite technology in the medium term and environmental considerations around large-scale battery deployment are all fully taken into account.
Ofcom’s July 2023 impact assessment guidelines require all these issues to be fully quantified and considered before any decisions are taken. The question of funding must also be addressed upfront to ensure no unfunded obligations are placed on the UK mobile sector. Without this, investment in 5G, coverage and capacity are all at risk.
Finally, INCA, which represents alternative broadband networks (often of the fixed line variety), warned that “mandating four hours of back-up” (active cabinets) for smaller operators “is considered excessive and would result in not just the installation of larger batteries but wholesale change of cabinets as many are not large enough to accommodate batteries of that size. Individual INCA members have quoted costs between several £100ks and several £1ms.”
INCA Statement
This level of incremental cost, being imposed after networks have been built and investment cases signed off based on a different level of battery back-up in cabinets, is not feasible for a number of Altnets and is potentially fatal to their ongoing viability. This would have the adverse effect of slowing down full-fibre deployment and reducing competition and consumer choice.
In addition to the initial expenditure, the costs of ongoing maintenance of such infrastructure must be taken into account, including the replacement of battery packs. A battery pack would typically last for a few years, but batteries start to degrade towards the end of their lifespan. Monitoring of remaining battery capacity would become a reoccurring expense which is again not in the network operator budgets.
The full range of responses from different network operators and interested parties can be seen below, although it’s clear that there would be many issues of cost, security and maintenance / durability / replacement to consider in some of the battery related questions that Ofcom are currently exploring.
On the other hand, it doesn’t look as if the regulator will be taking a hard line on things this time around (i.e. not imposing a national requirement for all sites) and some organisations, such as Cellnex UK, have highlighted how harnessing battery backup as a way of reducing peak-time energy costs / usage could potentially offset some of the economic challenges. But Ofcom might well propose something more targeted, at least to start with.
Responses to Ofcom’s Consultation on Resilience Guidance
https://www.ofcom.org.uk/internet-based-services/network-security/resilience-guidance/
