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Should the 6GHz band be completely or partly unlicensed or licensed? The US and South Korea went the unlicensed way, China chose a licensed approach. Many countries are debating which way to go; some have defined a lower band for unlicensed use and an upper band for licensed use. While the allocations are technologically neutral, the expectation is that unlicensed spectrum will be predominantly for Wi-Fi access, and licensed for IMT/3GPP cellular technologies (i.e., 5G). The most recent proposal comes from Ofcom, which proposes a hybrid use of the upper 6GHz band, which would allow shared use of the band by licensed entities (most likely mobile operators) and unlicensed users (most commonly enterprise and residential Wi-Fi users).
This is a high-stakes debate with an eagerly awaited recommendation expected at WRC-23 this fall because 6GHz is a highly valuable band. Even though power levels are limited to enable coexistence with incumbent users, 6GHz has lots of spectrum (1.2 GHz) with desirable propagation characteristics (better than mmWave, for instance).
Mobile operators want licensed access to 6GHz: Should they?
The positions in this debate are predictable. Wi-Fi users and vendors want as much unlicensed spectrum as possible. Mobile operators and vendors want as much licensed spectrum as possible. There are many models and papers to present support for both approaches. I have written about this too, but here I would like to step back and question the assumption that mobile operators stand to benefit from licensed access in the 6GHz band.
Can we all agree that 6GHz will be valuable to our society and economy regardless of whether it is licensed or unlicensed? I hope so. Let’s leave aside whether this value is higher if the band is licensed or unlicensed, and just look at the bottom line of mobile operators. Are they better off if the band is all or partly licensed? I am not sure it is so.
Looking backward: 2.4GHz and 5GHz
Initially, mobile operators were not supportive of Wi-Fi, but then they relented and embraced it. Some built their Wi-Fi networks, but in most cases, they use the existing Wi-Fi infrastructure quite liberally. According to Ofcom, most traffic through their subscribers’ Android handsets (73%) goes through Wi-Fi. It is as close as you can get to a free lunch – a fair one that everybody loves and benefits from: Wi-Fi provides a traffic offload from their macro networks that mobile operators do not pay for.
Clearly, this is not a realistic option, but ask yourself as a thought experiment: would mobile operators want 2.4GHz and 5GHz as licensed bands? They are extremely valuable, aren’t they? If the spectrum were licensed, they would have control over it, but they would also have to pay to get licenses and deploy the infrastructure to give their subscribers access to it. Would they be able to recoup the investment? I doubt it. My gut feeling is that mobile operators would prefer to leave these bands as unlicensed and keep spending their money on the 5G bands they have.
Could the situation be similar for 6GHz?
Is a licensed upper 6GHz band good for mobile operators?
Regardless of the regulatory regime, most of the demand for 6GHz access comes from indoor and high-density environments. These are two environments where unlicensed technologies (Wi-Fi, but also LAA or 5G-NRU) do well. Mobile operators cannot afford to build the capillary indoor coverage that Wi-Fi has achieved. Small cells are great for indoor coverage, especially in enterprise or public areas, but are not likely to carry the same amount of traffic as Wi-Fi. In high-density environments, much traffic comes from indoor locations, so Wi-Fi offload is an effective way to reduce macro traffic as well as the macro infrastructure cost for mobile operators.
More generally, spectrum reuse is much higher in unlicensed bands than in licensed bands for the simple reason that everybody can use it. There is no reason to expect this to change with 6GHz (or 5G), and traffic forecasts typically assume the Wi-Fi/cellular traffic ratio to stay the same.
In this context, what does an operator gain from having to pay for a 6GHz license and deploy the infrastructure? It is doubtful they could use the additional capacity to get additional revenues from their subscribers (this did not work with 4G or 5G). The licenses may come with coverage requirements that may increase the financial burden of deploying the 6GHz infrastructure, which they will only need in a small fraction of their footprint.
Instead, if the 6GHz band is unlicensed, residential and enterprise users will pay to deploy and operate the infrastructure and provide free offload for mobile networks. Because the 6GHz ecosystem is already in place with Wi-Fi 6E with smartphones and access points, congestion relief may come soon and be driven by demand: the upgrade to Wi-Fi 6E will most likely happen where there is a need for additional capacity.
With licensed 6GHz, would mobile operators pay for something they could otherwise get for free?
A licensed/unlicensed regime in the 6GHz that benefits all?
The social and economic value of wireless connectivity comes from the combination of Wi-Fi and cellular. Each technology on its own would not have been good enough to make smartphones the quintessential connectivity device that we can no longer live without. So, when we look at 6GHz, we must ask ourselves what combination of licensed and unlicensed access best serves our connectivity needs. And we may find out that the answer to this question is the same regardless of whether we are on the Wi-Fi or cellular side of the wireless ecosystem.
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