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28 March 2019

US MNOs try to grab some of the 6 GHz band back for licensed use

The FCC’s rising enthusiasm for shared and unlicensed spectrum options, to boost competition and the range of services available to US users, is placing the MNOs on the defensive. From T-Mobile’s point of view, it is wanting to spend large sums on acquiring Sprint, largely in order to boost its spectrum capacity for 5G, while at the same time, growing amounts of shared spectrum for 4G and 5G could enable challengers, such as cablecos and webscalers, for free.

The established operators lost the fight, on balance, in CBRS. They did score some points on the rules for the licences in the PAL (Priority Access Licensed) tier of the 3.5 GHz band, but were defeated in their wish to have very large licence sizes (similar to those for other 5G spectrum) and 10-year durations. Those rules would have made it hard for smaller players and industrial specialists to win spectrum. The final rules do not allow for such short-term, small-sized licences as disruptors like Google and GE had wanted, but they should still be within the reach of new entrants such as cablecos.

But the real MNO anger with CBRS focuses on the 150 MHz that was set aside for unlicensed GAA usage (and unlicensed devices can also access any spectrum that is not being used by federal incumbents or PAL owners). That lowers the barriers to entry for many kinds of service provider, especially those which have localized businesses – regional WISPS or industrial providers, for instance. It promises to introduce some of the competition and open ecosystem that defines WiFi to the cellular world – some of the heat has gone out of the rows over LTE-Unlicensed in 5 GHz in the USA since the cellular community has seen the prospect of its ‘own’ shared band (WiFi-like technologies could be developed for 3.5 GHz, but that has not seen much momentum as yet).

Of course, MNOs can make use of GAA to supplement their own reserves of spectrum capacity at low cost, but they complain that they will be stuck with LTE for some years if they do this, because 5G standards for shared airwaves will not find their way into commercial equipment for a couple of years or more (see previous item).

Now, the battle is shifting to 6 GHz, a band which the FCC wants to be opened up for unlicensed usage as an extension to the current 5 GHz spectrum. Last October, the FCC voted to make up to 1.2 GHz of additional spectrum in the 5.925-7.125 GHz range available for WiFi and other shared technologies.

This could see a revival of the territorial fights between the WiFi and cellular ecosystems, as previously seen in 5 GHz. This has been regarded as WiFi’s natural home, with 6 GHz as a logical extension to it – and so, just as the MNOs are angry at sharing being introduced to one of ‘their bands’ in 3.5 GHz, so the WiFi community will fight against any attempt to make LTE or 5G a mainstream option in the new 6 GHz band.

The MNOs are trying to go a step further and not just push their preferred technology into 6 GHz, but seize a portion of it for licensed 5G usage. The CTIA, which represents US MNOs, is ranged on one side of a debate which is likely to be echoed round the world, as the cellular industry defends its established power against the need – if 5G really is to fulfil its promise as a network for every industry and every type of service – for a far wider base of service providers.

The cablecos and the IT industry – Cisco, Microsoft, Apple, Google and others – have been major supporters of expanding shared spectrum, from TV white spaces to CBRS to 6 GHz, and they will not let the CTIA’s members claw back some of the airwaves without a fight.

The CTIA, Ericsson and the MNOs are arguing that the upper portion of the 6 GHz band, at least, should be set aside for licensed use, partly because some companies, such as  AT&T and US Cellular, use this band for wireless backhaul. According to LightReading, US Cellular uses this spectrum for backhaul in 3,500 locations across 2,000 licences, either in 5.925-6.425 GHz or 6.425-7.125 GHz. Other incumbents include some cities, such as Los Angeles, which use parts of 6 GHz for public safety communications.

The proponents of opening up the 6 GHz band argue that, if we have learned anything from the TV white spaces and the CBRS system, it is how licensed/unlicensed usage is no longer an either/or, because different levels of priority access can be set by Spectrum Access Systems (SAS) to protect incumbents. Those lobbying for unlicensed operations in 6 GHz – which include cellular giant Qualcomm alongside Apple, Broadcom, Cisco, Facebook, Google, Microsoft and others – argue that many use cases are localized and so the FCC could focus on areas that would not cause interference to incumbents like AT&T, CenturyLink or US Cellular.

The need for more access spectrum is just too high to leave valuable airwaves dedicated to applications that may not fully use the capacity, argue the WiFi supporters.

“There is no disagreement that more spectrum capacity is needed to meet the rapidly growing demand for WiFi,” wrote the WiFi Alliance in a submission to the FCC. “Increased capacity requirements are unsurprising based on the central role that WiFi plays in the telecommunications infrastructure, a role that is only expected to intensify as more and new use cases for WiFi and other unlicensed technologies develop.”

But the cellular sector tries to counter-argue that WiFi has plenty of spectrum now, and 5G needs more – there would be more sense, they say, in letting 5G occupy part of 6 GHz, because it could be more easily coordinated with cellular backhaul, and it is in more urgent need of mid-band spectrum.

In its own filing, the CTIA adopted a resentful tone at the perceived bias towards unlicensed spectrum in recent FCC decisions, which it now feels must be redressed in the favor of 5G.

“In the Spectrum Frontiers proceeding, the Commission designated a full 7 GHz of millimeter wave (mmWave) or high-band, spectrum – the 64-71 GHz band – for unlicensed operations, on top of the 7 GHz that it had already made available for unlicensed at 57-64 GHz,” wrote the CTIA. “In contrast, the Commission has dedicated only 5.5 GHz of high-band spectrum for licensed use.”

It even managed to draw in the recent FCC decision to explore potential future use of bands above 95 GHz, adding: “And beyond the 14 GHz of mmWave unlicensed spectrum, the Commission recently adopted an order in the Spectrum Horizons proceeding designating an additional 21.2 GHz of spectrum for unlicensed in the above-95 GHz bands.”

These points, of course, focus on mmWave, which has very different characteristics to mid-band spectrum, and different economics. The CTIA’s points about shortage of mid-band spectrum for 5G carry more weight, given that 3.5 GHz – the key 5G band in most countries – is supporting unlicensed usage in the USA, and smaller licensed tracts than might be suited to a national 5G wide area roll-out.

On this topic, the group wrote: “The Commission has made significant progress in repurposing low- and high-band spectrum available for exclusive use, flexible rights licensing in recent auctions, but access to licensed mid-band spectrum for 5G remains extremely limited. By 2020, Canada, China, France, Germany, Japan, Russia, Singapore, South Korea and the UK will have available, on average, nearly 300 MHz of mid-band spectrum for 5G. For example, China assigned 460 MHz of mid-band spectrum to three of its national carriers last year.”

CTIA and Ericsson have proposed that the FCC make the upper portion of the 6 GHz band (6.425-7.125 GHz) into licensed spectrum, to help address the shortage of mid-band options (though this would be yet another example of the USA having 5G spectrum that is out of kilter with global allocations). They suggest that the proceeds from auctioning the 6 GHz airwaves could then be used to relocate the 6 GHz incumbents into the 7 GHz band.

In separate filings, Verizon, AT&T, T-Mobile and US Cellular all supported this proposal.

“The 6 GHz band offers the Commission a unique opportunity to promote both licensed and unlicensed use of this valuable mid-band spectrum,” Verizon wrote, calling for exclusive licensing in the upper portion, with sharing systems in the lower portion, and protection for incumbents.

Against the motion were IT companies like Cisco as well as several cablecos. Charter wrote in its own riposte that the Ericsson proposal would “significantly limit the amount of spectrum potentially available to unlicensed users in the 6 GHz band; under Ericsson’s proposal, four of the seven 160 MHz channels in the 6 GHz band would be designated for licensed use. Such an approach would hinder the ability of providers like Charter to offer Gigabit WiFi speeds using WiFi 6 and other advanced WiFi technologies, and deprive consumers from utilizing high bandwidth, high speed services and applications, including augmented and virtual reality, at lower costs.”

Cisco said the idea was “conceptual … not supported with any detail, remains wholly undeveloped, and should not be given any further consideration.” The accusation of lack of detail was echoed in a joint submission by Apple, Google and Facebook, which wrote: “How will their proposed relocation occur? They do not offer any insights. What frequencies will displaced government systems use? There is no roadmap. How long will this process take? Clarity on this delay is conspicuously absent. Because they have not even tried to address these basic questions, CTIA and Ericsson have not provided the Commission with any way to reasonably evaluate their proposal. For this reason alone, the Commission should not pursue it.”

The WiFi contingent were no more sympathetic to a different proposal, from Qualcomm, which wants the FCC to set aside some of the 6 GHz band for the forthcoming standards for 5G-Unlicensed (which have been spearheaded in 3GPP by the chip provider). Qualcomm said the UNII-7 portion of the 6 GHz band should be reserved for “unlicensed services that require coordination”, which would apply to standalone 5G NR-Unlicensed, but not WiFi.

“While Qualcomm claims this proposal is technology-neutral, it is not,” Charter wrote. “Qualcomm’s proposal would favor synchronized operations over asynchronized operations in this band. By requiring synchronized mode of operation, any technologies that currently do not employ synchronization would either be prohibited from or be provided second class treatment when operating in this band.”