T-Mobile has changed tack on its support for multi-operator core network (MOCN) neutral-host 4G and 5G enterprise systems in CBRS spectrum in the US. Without withdrawing support completely, it has directed its neutral-host vendor partners – notably, Celona, InfiniG, and IONX – to “prioritize” its licensed mid-band spectrum, mostly at 2.5 GHz, plus at 1.9 GHz, for new shared infrastructure projects. Otherwise, it will continue to offer some selective support for CBRS deployments, it seems.
It reiterated the line about the superiority of carrier-licensed spectrum, versus shared frequency bands like CBRS, on the grounds of better network performance. It suggested rising 5G traffic makes it the best way to deliver reliable and performant cellular connectivity. “We continue to support CBRS-based MOCN and neutral host networks, however, we are encouraging our vendors and partners to prioritize licensed mid-band FDD/TDD spectrum over CBRS,” it told RCR Wireless.
CBRS should be considered only as a “supplemental tool”, it said. T-Mobile stated: “The reason is straightforward: licensed spectrum delivers the certainty, performance, and scale required for 5G, while CBRS – because of its unlicensed nature, uncertain availability, and limited support in the 5G roadmap – is better suited as a supplemental tool. As mobile traffic continues to accelerate on 5G, our focus is on ensuring T-Mobile customers get the most consistent, high-quality experience.”
It added: “In that context, licensed spectrum is the foundation, and CBRS can play a role in select, complementary scenarios.” Lots of questions remain, clearly. T-Mobile’s neutral-host vendor partners in the US have been in discussion with the firm since last week about contingency plans of some kind. It is understood existing customers, already running MOCN neutral-host 5G systems in CBRS spectrum, will retain support from T-Mobile – on the proviso performance KPIs are met.
But new venues will be required, as a rule, to connect customers on shared RAN infrastructure on T-Mobile spectrum – whether it is leased for shared usage in MOCN deployments via its vendor partners (or via roaming deals with carrier peers); or else in more-expensive multiple-operator RAN (MORAN) setups, where licensed carrier spectrum and core networks are kept separate. Whatever; the move brings T-Mobile in line with Verizon, and leaves AT&T out on its own.
Verizon has stood apart among the big three US mobile operators, until now, by consistently advocating such a position. It said in a statement: “Verizon’s neutral-host networks leverage Verizon’s licensed spectrum, sometimes paired with an active or dormant private 5G core that can run a private network in parallel or be turned on at a later date. Either element – neutral host or private wireless – can run on either Verizon’s licensed spectrum or CBRS.”
But its position has always been that both neutral-host and private 5G components should run on its licensed c-band spectrum, between 3.7 GHz and 3.98 GHz. It makes tactical usage of shared CBRS frequencies, depending on the use-case setup for both, but it has always controlled the sale, whether direct or via select channel partners. For instance, it works with Celona (plus Ericsson and Nokia), but has never certified the Celona system for third-party CBRS deployments.
T-Mobile and AT&T both have. AT&T’s position has not changed, as yet. Cameron Dunn, associate vice president for network project management, said: “We’re always looking into new ways to provide affordable and reliable in-building coverage. That includes exploring options like CBRS and neutral-host or MOCN solutions. For any option to work, it has to offer flexible, high-quality connectivity that keeps up with what our customers need as their demands evolve.”
Clearly, T-Mobile’s move throws the whole neutral-host CBRS market into some confusion – on the grounds a neutral-host proposition with support for only a single carrier host is not a neutral-host proposition. RCR Wireless will bring reaction, as available, from the primary vendors in the space, including about how their products might change following T-Mobile’s partial-withdrawal. But AT&T’s note about “high-quality connectivity” is the talking point with CBRS for all the carriers.
Sources suggested that carrier-grade quality controls have proved hard to meet for third-party vendors and integrators, hawking CBRS-based MOCN systems as cheap replacements for multi-carrier distributed antenna system (DAS) infrastructure in venues in the US. T-Mobile has grown frustrated, it seems, as the market has grown busy, and part-time operators have struggled to manage indoor 4G/5G performance for its customers in the CBRS band.
There are compliance issues with public voice telephony services in shared CBRS spectrum, too, which have split the market – insofar as 911 emergency services and lawful intercept (CALEA) capabilities must meet the same standards imposed on public carriers, including accurate location, proper call routing, and legal comms access. Which introduces major technical and regulatory complexity, especially in shared spectrum – and makes carriers (and enterprises) twitchy.
It might be noted, usage of CBRS spectrum for private 4G and 5G networks is not fraught with the same tensions as they are effectively optimised for IoT-style machine connectivity, with private IP-based voice communications thrown as a sweetener, or a bonus, without the same strict regulatory requirements as public voice telephony. But again, the same technical logic (confused by lobbying noise about new spectrum for new 6G capacity) holds around why public operators are pushing their own licensed spectrum for such cases.
