Summary Bullets:
- The UK government has proposed limits in how much Huawei 5G RAN gear mobile operators deploy.
- Exactly how operators will implement those limits is unclear, raising several questions.
The National Cyber Security Centre (NCSC), the UK’s technical authority on cybersecurity, made big headlines this week by issuing recommendations for UK operators regarding how to honor national security concerns in selecting 5G network suppliers. But, beyond the headlines – primarily regarded as a win for Huawei, since the NCSC allowed a role for Huawei in UK 5G networks despite pressure from the U.S. – the NCSC’s actions raise plenty of questions about how UK operators will source, plan, and deploy their 5G radio access networks (RANs).
The NCSC recommended UK operators: (a) exclude 5G network gear from Huawei and any other ‘high-risk vendor’ (HRV) from sensitive areas such as the network core; and (b) limit the amount of 5G RAN gear from HSVs including Huawei. Some media reported the recommendations as a 35% market share cap on Huawei RAN gear. That’s not quite accurate. The caps are specific to each operator, not the market in aggregate. That matters because, if it were a market share cap, one operator choosing to use less Huawei gear would allow another operator to use more. The caps being set per operator instead make it harder for Huawei’s overall market share to approach 35%.
Although the caps apply to equipment from HRVs – a group that includes, but is not technically limited to Huawei – Huawei is the only such vendor the NCSC called out by name. In addition, the NCSC recommends never using more than one HRV; for the UK’s major mobile operators – EE, Vodafone, O2, and 3, all four of which have already deployed Huawei 5G networking gear – that one supplier, in the RAN, will be Huawei. ZTE, the second-biggest China-based RAN supplier behind Huawei, is excluded from UK 5G networks entirely following the NCSC’s 2018 warning that ZTE represents a “national security risk.”
The NCSC described two kinds of limits on high-risk vendors’ RAN gear: “For 5G access networks, at most 35% of expected network traffic volume on any particular network passes through HRV equipment and at most 35% of base station sites nationally on any particular network should be served by equipment from an HRV.”
For UK operators, planning their networks to accommodate these two restrictions could be complicated. Here’s why:
How Is Traffic Volume Measured?
Network traffic volume tends to shift around dynamically from site to site. A base station that carries 40% of network traffic today might carry 20% tomorrow. One that carries 20% in the morning might carry 40% in the evening. Will 35% of network traffic volume be over the course of a month? A year? We don’t yet know.
At first glance, there seems to be some wiggle room in the fact that the recommendation refers to “expected” network traffic volume. But, that just prompts more questions: Whose expectations does this refer to – the operators themselves? What happens if those expectations are wrong?
Things get even more complicated when you consider infrastructure that is shared by multiple operators, as some versions of Huawei’s LampSite enterprise RAN solution are designed to do.
How Are Base Stations Counted?
The NCSC’s recommended cap on 35% of base stations doesn’t seem to make a distinction between macrocells and small cells (the NCSC defines a 5G base station as “any base station supporting or routing functionality added in 3GPP Release 15 or later”). That distinction matters, because small cells are deployed in much higher unit volumes and are likely to be important in both (a) achieving 5G network densification imperatives and (b) serving indoor enterprise and Internet of Things use cases.
In a blog post, the NCSC said, “It’s important to make sure [the caps] can’t be easily gamed – for example by using an HRV’s base stations in all the cities and a non-HRV’s products in the countryside.” Yet, because small cells are primarily used for dense urban areas, failing to make a distinction between macrocells and small cells could create similar kinds of country-versus-city quandaries.
Also, it’s not clear how open RAN base stations figure into all of this. A key aim of the NCSC’s actions is to promote diversity in the supplier ecosystem. The open RAN movement is aimed at achieving that diversity, which makes it directly relevant to the NSCS’s imperatives. But open RAN base stations don’t come from a single vendor. If a UK operator deploys a base station comprised of one vendor’s baseband (or baseband software) and another vendor’s radio unit and still another vendor’s antenna, whose base station is it for the purposes of counting toward the 35% cap?
Ultimately, the details of the NCSC’s recommendations will be refined. The guidance released this week is expected to be implemented in legislation. If that legislation doesn’t fill in the details of how operators will abide by these guidelines, regulators will presumably finish the job. In the meantime, UK operators will be in for some complicated planning sessions as they strategize their 5G network rollouts (and estimate the costs of following the NSCS advice). And in some respects, complexity and uncertainty come with their own risks.