T-Mobile and Charter propose 5G spectrum sharing in 42GHz band

This June, we noted that the FCC was exploring shared use of the 42 GHz band using in 500 megahertz of spectrum. Recently, T-Mobile and Charter voiced support for some kind of spectrum sharing scenario.

“While wireless carriers continue to require additional spectrum that is licensed on an exclusive-use basis, T-Mobile agrees that the technical characteristics of the 42GHz band, along with its separation from other millimeter wave spectrum that has already been licensed, means that the commission may wish to consider a different approach here,” T-Mobile wrote in an August 30th FCC filing.

“The commission, however, should avoid applying untested, novel sharing approaches to the 42GHz band. Instead, it should implement the nationwide non-exclusive licensing framework currently used in the 70/80/90GHz bands, with a few modifications to ensure that the spectrum will be used efficiently and may be deployed for [a] variety of advanced communications services.”

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Charter has long eyed the 37GHz band as a way to bolster mobile operations in its planned 3.5GHz CBRS network. The MSO/cableco has said it could offer speeds up to 1 Gbit/s via concurrent operations in the CBRS and 37GHz bands.

Charter’s FCC filing is similar to T-Mobile’s, as it supports a “unified nationwide, non-exclusive simple shared licensing regime.” The company urged the FCC to implement the same spectrum sharing design across both the lower 37GHz band and the 42GHz band.

“Allocating the lower 37GHz band for non-exclusive use would offer 600 megahertz for innovative new wireless connectivity in the United States,” Charter noted. “The allocation of the 42GHz band alongside the lower 37GHz band would of course increase the total spectrum available for innovative new deployments by 500 megahertz.”

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Backgrounder:

The 42GHz band resides in what is known as millimeter wave (mmWave) spectrum. 5G transmissions in those bands are at very high speeds, but they typically travel just a few thousand feet, and generally cannot pass through obstructions like walls, trees, glass or concrete, i.e. they require line of sight communications.

WRC 19 identified mmWave frequencies for 5G, but ITU-R WP 5D did not complete and agree on the frequency arrangements for same (revision 6 of ITU-R M.1036) until very recently. WRC 19 identified the frequency bands: 24.25-27.5 GHz, 37-43.5 GHz, 45.5-47 GHz, 47.2-48.2 and 66-71 GHz for the deployment of 5G networks and the frequency arrangements for them is in draft recommendation ITU-R M.1036 which is expected to be approved this November. Note that 42GHz is not included!

Some analysts are quite positive on mmWave communications. For example, “mmWave 5G offers a way to improve on the current situation because the bands have extremely high capacity that are able to support very large amounts of data traffic and users, although in a small area,” wrote OpenSignal analyst Ian Fogg in a post on the network-monitoring firm’s website.

Qualcomm is also an advocate of spectrum sharing in mmWave bands since at least July 2022.

Image Credit: Qualcomm

Qualcomm’s filings to open the Lower 37 GHz band to shared licensed access ask the FCC to adopt a Notice of Proposed Rulemaking (NPRM) to allocate six 100-MHz-wide priority licenses in the Lower 37 GHz band and allow each priority operator—which may be a federal government or a commercial operator—to use the rest of the band on a secondary basis. To enable these secondary operations on an interference-free basis, each priority operator would implement a technology-neutral, equipment-based rule to provide coordinated, periodic listening of the channel, referred to as long term sensing (LTS), to determine whether its secondary operations on spectrum outside its priority licensed spectrum may cause harmful interference to the priority license holder of that swath of spectrum.

Secondary operations are only allowed for communications links that sensing determines will not cause interference to the priority licensee. The coordinated sensing procedure allows each priority license holder to access all other channels (i.e., the other 500 MHz) on a secondary – and interference-free – basis, increasing overall spectrum utilization while not degrading the QoS for the priority licensee.

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