LMDS, millimeter wave & 5G: Spectrum bands play on, just with a different tune

Walking down memory lane, it occurs to me that when it comes to millimeter wave spectrum, it seems as though what's old is new again. It's not quite the same as how the old spectrum "garbage bands" were repurposed for Wi-Fi, but it's making use of some spectrum that was originally intended for something else.

I say this after a recent conversation with Brian Goemmer, president of Allnet Insights & Analytics, who used to work at Western Wireless and later Clearwire, that triggered a lot of flashbacks to earlier wireless days, including when local multipoint distribution service (LMDS) licenses were first awarded. In 1997, the FCC developed a band plan making 1,300 megahertz of LMDS spectrum available in each basic trading area across the U.S. It allocated two LMDS licenses per BTA, an "A Block" and a "B Block" in each. The A Block license was comprised of 1,150 megahertz of total bandwidth, and the B Block license was comprised of 150 megahertz of total bandwidth.

One of the license holders back then was Teligent. I still remember getting a tour of Teligent's facilities in Denver and being awed by the shiny fixed wireless, point-to-multipoint technology that could send high-speed broadband from rooftops to surrounding small- and medium-sized businesses. It sure sounded cool at the time. It was renegade and kind of like the Wild West. New entrants trying to take on the entrenched bullies – how novel!

Alas, their dreams did not come to fruition despite attempts by Teligent and others like Winstar and NextLink and backing by some big names like Craig McCaw and Microsoft. I don't recall everything that happened in between – seems to me there were bankruptcy hearings and a lot of court wrangling over assets. In the end, a lot of the LMDS licenses fell back into the hands of the FCC, and now wireless operators are eyeing that and related spectrum for 5G trials and services.

Challenges remain. "This spectrum does not propagate very far," Goemmer notes. "These frequencies are going to be very short range." By way of perspective, at 2.4 GHz, Wi-Fi can cover most of a house that's under 3,000 square feet, but at 5 GHz, it probably would cover maybe 60 percent of a two-story house because it just doesn't travel as far at the higher range.

Fortunately, engineers have developed techniques to make better use of this LMDS and other higher-band spectrum, and thanks to researchers at forward-thinking institutions like NYU Wireless, there's a lot more confidence in millimeter wave technology. By way of its purchase of XO Communications' assets – which was NextLink at one time – Verizon is also in the LMDS game. Its deal with XO allows Verizon to lease LMDS spectrum in the 28 and 39 GHz bands with an option to acquire it before the end of 2018.

Another smaller player in the space, Straight Path, holds 828 spectrum licenses in the 39 GHz band, making it the largest single holder of 39 GHz licensed spectrum in the United States. It also holds 16 LMDS A licenses and 117 B licenses in the 28 GHz band. It ended up with the spectrum licenses that originally were under Winstar's management. IDT spun off its spectrum holdings that it acquired from bankrupt Winstar into Straight Path in 2013.

Not everybody is convinced that Straight Path's spectrum is valued properly, and not everyone is convinced in the mobile viability of the higher band spectrum in general. But the rapid speed at which big and small companies today are moving to 5G and "pre-5G" technologies, it's hard not to be impressed.

Teligent's spectrum is now under the management of FiberTower Spectrum Holdings, which recently paid a visit to the FCC to discuss the Spectrum Frontiers proceeding, pointing out the propagation characteristics of the millimeter wave bands and noting that advancements in chipsets and their increased processing power have made it possible to reassemble signals traveling through foliage and other materials or being refracted or reflected off materials, further increasing the reach of services delivered in the millimeter bands.

All of this is encouraging for the future of these bands. But as Goemmer points out, there's the Apple test. No matter how much the carriers – Verizon, AT&T, Sprint, T-Mobile US and others – invest in their networks and new technologies, getting Apple's support is key. Granted, ecosystems change and the balance of power can move in other directions when it comes to devices and device makers. But Apple represents such a significant and sizable customer base today and in the near-term that it's essential it will support these bands.

In the meantime, it's encouraging to see these bands get a second life again -- and this time, for keeps.--Monica

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