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6G needs substantially more spectrum, but its commercial viability will depend on finding frequencies that deliver wider channels without forcing operators to abandon the economics of the existing macro network
Standards will define what 6G can do, but spectrum will determine where, and economically, whether it can meet the definition. The capacity requirements alone are significant. The GSMA estimates that mobile networks in dense urban areas will require an average of 2–2.5 gigahertz of mid-band spectrum between 2035 and 2040, rising to 2.4–3.3 gigahertz in higher-demand countries. With roughly 1 gigahertz of mid-band spectrum identified for mobile in many markets today, that leaves an additional requirement on the order of 1–2 gigahertz.
That demand is pushing 6G into higher frequencies, but not necessarily the extreme bands that dominated some early visions of the technology. Instead, a broad industry consensus is forming around the upper mid-band or centimeter-wave spectrum as a new wide-area capacity layer.
The World Radiocommunication Conference in 2027 will consider several ranges for potential IMT identification, including 4.4–4.8 GHz, 7.125–8.4 GHz and 14.8–15.35 GHz. The upper 6 GHz band is also increasingly important. The GSMA argues that 200–400 megahertz channels will be necessary for 6G and says 6.425–7.125 gigahertzz already has a harmonized mobile footprint covering more than 80% of the global population.
Setting aside varying regulatory machinations, this is fairly straightforward. Existing low- and mid-band frequencies have favorable propagation characteristics but relatively little unused contiguous bandwidth. Millimeter-wave and eventually (maybe) sub-terahertz frequencies offer enormous bandwidth, but their propagation characteristics make them difficult and expensive to use for ubiquitous wide-area coverage.
Spectrum roughly between 6 GHz and 15 GHz offers a potential middle ground with enough contiguous bandwidth to create very wide carriers, but frequencies low enough that advanced antenna systems could compensate for much of the additional propagation loss. That last point is critical to the business case.
Qualcomm is developing what it calls Giga-MIMO for the 6–8 GHz range. Because wavelengths become shorter as frequency increases, more antenna elements can be packed into an array of similar physical dimensions. Denser arrays enable narrower beams, greater effective radiated power and more spatial multiplexing. Qualcomm’s system-level evaluations indicate an upper-mid-band Giga-MIMO layer could support approximately five times greater network load and three times higher average user throughput while providing coverage comparable to lower mid-band. Those are vendor research results rather than commercial-network measurements, but the intended outcome is to add capacity without adding another layer of cell sites.
Nokia is pursuing the same fundamental objective with extreme massive MIMO, and explicitly identifies 7–15 GHz spectrum as important to cost-effective 6G coverage and capacity. Ericsson likewise expects centimeter-wave spectrum, particularly the lower portion of 7–15 GHz, to support wide-area deployments when combined with massive MIMO and beamforming. That said, the spectrum challenge is not limited to finding new bands. 6G will also have to coexist with 5G for years.
Ericsson is working on multi-RAT spectrum sharing, or MRSS, to allow 5G and 6G to dynamically use the same spectrum across both FDD and TDD bands. The company expects long device lifecycles and limited spectrum below 7 GHz to require efficient 5G/6G sharing for at least a decade. The emerging 6G radio design is being shaped in part around that requirement.
In the U.S., another form of sharing and coexistence hinges on gaining access to spectrum occupied by federal systems. NTIA is examining portions of 2.69–2.9 GHz, 4.4–4.94 GHz and 7.125–7.4 GHz for potential commercial 6G use. Qualcomm argues that at least 600 megahertz of full-power mid-band spectrum should be ready by 2029, emphasizing “full power” because heavily constrained access can diminish the coverage and deployment economics that make mid-band valuable in the first place. That makes spectrum-sharing technology, incumbent relocation and coexistence mechanisms part of the 6G architecture—not peripheral regulatory questions.
Although millimeter wave and potentially sub-terahertz frequencies have a role to play, the defining 6G spectrum question is how much contiguous bandwidth operators can obtain while preserving enough coverage, transmit power and infrastructure reuse to make deployment economically rational. To reiterate: 6G will absolutely require new spectrum, but successful deployment means it cannot require a new network grid.
For a deep dive into 6G, register for the upcoming 6G Forum virtual event.
