What might be 6G’s spectrum needs?

In a new report, ATIS’ NextG Alliance looks at anticipated 6G spectrum needs based on expected KPIs

With the telecom industry, and governments around the world, already looking ahead to future 6G systems and the spectrum that they might utilize, how should they be thinking about the amount of spectrum that will be needed for 6G? After all, the technology hasn’t yet been standardized, use cases are simply best-guesses at this point and “as much as we can get, especially in the midband range” leaves something to be desired as a basis for spectrum policy and planning.

The Alliance for Telecommunications Industry Solutions (ATIS)’s NextG Alliance, as part of its exploration of the roadmap to 6G, took a stab at assessing future 6G spectrum needs in a new white paper. The organization acknowledges that there are many unknowns at this point, but notes that in general, “The evolution of commercial mobile broadband over its generations is characterized by a continued increase in the efficiency in the use of spectrum
and in the amount of spectrum used to support novel and diverse wireless applications.” As in, the industry is using more and more spectrum with each G, but also doing so more efficiently, and both of those things are expected to continue in 6G.

“Spectrum is the lifeblood for all commercial mobile broadband,” said Andrew Thiessen of MITRE, who is the chair of the Next G Alliance Spectrum Working Group. “Absent available spectrum, the ability for countries to continue to move towards ubiquitous connectivity is stymied. This document offers a comprehensive first take at what spectrum will be needed as 6G development begins in earnest.”

The white paper focuses primarily on North American contexts and needs, and looks at potential spectrum needs for 6G in terms of key performance indicators and likely speed requirements for a variety of use cases, from very low-date-rate asset management uses and environmental sensors, to mid-speed use cases such as intelligent transportation and UAVs (remember, it’s assessing based on speed KPIs, not latency), to extremely demanding use cases like extended reality, autonomous systems and industrial robotics.

The paper looks at simulating demand, based on a broad range of speed categories anticipated to be needed for the various use cases, in candidate bands at 3.1-3.45 GHz, 7.125-8.5 GHz and 12.7-13.25 GHz—bands that are broadly considered midband and upper midband. Three cell sizes were simulated: 1,732 meters (or about a mile), 500 meters and 250 meters, with consideration of different urban and rural deployment scenarios including public macro cells, and public or private microcell deployments.

What did ATIS find? Broadly, that rural macro-cell deployments to support the broad expected span of 6G use cases will require the least amount of spectrum, and urban macro-cells will require the most, with urban micro-cell environments falling somewhere in the middle. While it warned that its numbers should not be taken as “practical needs of any 6G deployment” but instead reflect characteristics of KPIs for various applications, it did put some numbers out there as examples of spectrum needs per frequency band to achieve those KPIS: An estimated 1,070 megahertz in the lower 3 GHz band; slightly less, 1,019 megahertz at 7.125-8.5 GHz, and more than 2,100 megahertz to achieve the goal KPIs at 12.7-13.25 GHz. Read more on the methodology and assumptions in the actual white paper here.

“Proactively understanding next G spectrum needs and planning for them is essential to U.S. leadership in critical and emerging technologies,” said Next G Alliance Managing Director David Young. “Decisions about the use of spectrum depend on multiple aspects and require time to be implemented. This paper achieves an understanding of 6G spectrum needs so that these needs are considered in the development of data-driven policies, regulatory decisions, and technical solutions.”