Ofcom Proposes Wi-Fi And Cellphones Share Upper 6GHz Band

Brit telecoms regulator Ofcom has kicked off a consultation over proposals that would see both mobile networks and Wi-Fi users have access to frequencies in the upper 6GHz band, if appropriate mechanisms can be agreed to make it work.

According to Ofcom, the upper 6GHz band, covering frequencies in the 6425-7125MHz range, is currently “a focus for industry interest” in the lead up to the World Radiocommunication Conference (WRC) held by the International Telecommunications Union (ITU) later this year.

Much of the activity centers on approaches that would see the frequencies given over to exclusive use either by high-power licensed mobile users, or low-power licence-exempt uses such as Wi-Fi, says Ofcom.

However, the UK regulator reckons that with the growing demand for spectrum from a range of new and existing services, it is becoming harder to justify awarding bands for the exclusive use by a single application. It believes an alternative approach is possible which would allow both mobile and Wi-Fi to use the upper 6GHz band, even when in relatively close proximity to each other.

Ofcom is proposing that hybrid sharing approaches could be adopted to enable more than one application to use these frequency bands, and if successful, the same could be extended to other frequency bands now being considered for future applications, such as the 7-24GHz and THz ranges being floated for 6G networks.

One way of doing this could be to take advantage of the different usage characteristics of mobile and Wi-Fi, Ofcom says in its consultation document. For example, Wi-Fi access points tend to be deployed indoors, whereas mobile base stations are located outdoors, so it may be possible to support the indoor use of Wi-Fi in the upper 6GHz band while also allowing licensed mobile use of it outdoors.

Alternatively, a geographical sharing model could be adopted, whereby mobile network use of the upper 6GHz band could be licensed for specific high-traffic locations whilst allowing Wi-Fi use elsewhere.

But hybrid sharing will require the use of mechanisms to manage coexistence between the different technologies, which in this instance means Wi-Fi and mobile networks. Ofcom sets out several of these in its consultation document, including the use of managed databases to specify where and when access is allowed, and modifications to channel sensing mechanisms.

In the latter case, Wi-Fi already uses channel sensing to detect if other nodes are transmitting, but has not been designed to detect mobile signals. An enhancement of current protocols may allow for coexistence between Wi-Fi and mobile, Ofcom claims.

The UK regulator also notes that the upper 6GHz band is already being used for other services, such as fixed wireless links, and there will likely be coexistence challenges with these that would have to be addressed in order to support any hybrid sharing scheme.

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Ofcom recognizes that such mechanisms will also need to be supported in more territories than just the UK, saying in its document that “international harmonization is important to create economies of scale” in a way that would be unlikely for UK-specific requirements.

Earlier this year, mobile industry body the GSMA published its own report outlining how important the 6GHz band is for the future of mobile communications. It said at the time that governments around the world need to “consider carefully” what the most efficient use of 6GHz spectrum will be, and even claimed that deployment of 5G in the upper 6GHz band would be crucial for countries that want to “maximize the socio-economic benefits” delivered by mobile communications.

However, that ship may have already sailed, since the Federal Communications Commission (FCC) in the US opened up the entire 6GHz band from 5.925 to 7.125GHz for unlicensed use back in 2020, largely driven by demands to make more bandwidth available for Wi-Fi. Ofcom followed its lead by opening up the lower 500MHz of the 6GHz band.

The FCC gives low-power Wi-Fi for indoor use the unrestricted freedom of the entire 6GHz band, while standard power applications that operate outdoors must do so under the control of an automated frequency coordination (AFC) system that manages spectrum access to ensure they do not interfere with legacy services that still operate in the 6GHz band.

Ofcom is seeking feedback from “interested stakeholders” on both the principle of hybrid sharing and on the practicalities of its implementation, and a form is available from the regulator’s website to submit responses, which must be delivered by 15 September.

The regulator said it intends to follow up with a further consultation in 2024 on specific proposals for the implementation of hybrid sharing in the upper 6GHz band. This will take the responses to this consultation into consideration, as well as ongoing harmonization work with other relevant international bodies. ®