Special Feature: Keeping flexibility in key frequencies

This Special Feature appeared in the March 2023 edition (Issue 8) of the Wi-Fi Alliance^® Wi-Fi 6E Insights newsletter. To subscribe to the newsletter, please sign up here.

A change in the status of the upper 6 GHz band could see this vital spectrum squandered

For governments pondering the future of the upper 6 GHz frequency band (6425-7125 MHz), decision time looms. Should they support an IMT identification at the ITU World Radiocommunication Conference 2023 (WRC-23) later this year or should they advocate a “no change” position that will keep the band technology neutral and keep their options open?

The “no change” option is appealing for many reasons. The incumbent services in the band – fixed links and fixed satellite services – will be able to continue to use the spectrum – and potentially expand – without fear of harmful interference from IMT services. At the same time, the upper 6 GHz band can be harnessed by license-exempt low power technologies, such as Wi-Fi 6E and Bluetooth, enabling citizens to take advantage of the expanding ecosystems supplying compatible equipment^[1]. Furthermore, the current “Mobile” allocation doesn’t prevent the spectrum from being used by IMT technologies, if required, now or at some point in the future.

By contrast, an IMT identification would signal that the band is reserved for IMT applications, likely prompting a very expensive migration process out of the band for all incumbent services. An IMT identification would also prevent a global harmonization and curb the economies of scale available to providers of Wi-Fi and Bluetooth equipment.

After carefully weighing up the arguments on both sides, UK regulator Ofcom is advocating a “no change” position^[2], noting that that would give it the flexibility to respond to market and industry developments.

In many countries in Region 1, there is an urgent need for more mid-band spectrum for Wi-Fi, which carries the vast majority of internet traffic. By contrast, the mid-bands allocated to 5G and other IMT technologies are far from congested.

In Saudi Arabia, the Communications, Space & Information Technology Commission (CST) has said that the 3 GHz band “will be sufficient to cover the mid-band spectrum needs of IMT for the foreseeable future. The existing mid-bands for exclusive IMT use have robust ecosystems already as well as superior propagation characteristics.”

Mr. Abdulhadi Alharthi, General Manager Spectrum Monitoring at CST, commented: “Saudi Arabia is keen on supporting the fast-growing development in wireless technologies, including mobile broadband, IoT, and other innovative applications. We are among the world’s leading countries in IMT spectrum allocation, and we believe that the current IMT identifications between (1-6) GHz provide sufficient spectrum for these services for the short and long terms. Therefore, IMT identification in the upper 6 GHz in WRC-23 would hinder the capabilities for mobile broadband deployment and risk the continuity of satellites’ crucial operations under the fixed satellite services (FSS) in the band as well as the fixed services (FS) due to potential harmful interference. Thus, maintaining a no change position is vital to safeguard these services and ensure flexibility for all administrations to make informed decisions in future WRCs.”

Crucially, low power Wi-Fi and other license-exempt technologies can coexist comfortably with the incumbent satellite and fixed link services in the 6 GHz band, whereas high power IMT services cannot.

IMT services are not designed to share spectrum

The Global Satellite Operators Association (GSOA) has warned^[3] that wide area IMT systems will interfere with the space receivers employed by incumbent fixed and mobile satellite services. It notes that a geostationary satellite can “see” around one third of the earth surface and hence would receive interference from potentially millions of mobile base stations and terminals. “Experience in some other frequency bands used by satellite uplinks, such as the 2.5 GHz band, has shown that IMT systems can cause interference to satellites that effectively prevent all satellite operations,” says GSOA.

One of the satellite services in the band – the Inmarsat network – provides critical communications to citizens, businesses, and government users and is vital to maritime operations in Europe and the rest of the world, according to the GSOA.

The sharing studies conducted to-date suggest that IMT services in Europe, for example, could only cover up to 0.15% of the landmass before they would begin to interfere with satellite systems. As GSOA points out, this constraint would severely limit the benefits arising from the use of the upper 6 GHz band for IMT. There is also no clear benefit that would come from IMT use of the 6 GHz band that cannot be achieved by use of the other bands already identified for IMT. Instead, as GSOA suggests, the upper 6 GHz band could be shared by satellites and WAS/RLAN systems, which includes Wi-Fi, if deployed with adequate power limitations.

Fixed service (FS) operations are also spread throughout most of the 6 GHz band. These point-to-point microwave links support a variety of important services, such as public safety systems, management of electricity grids, and backhaul for IMT. The first set of studies focused on IMT sharing with FS has shown that separation distances of up to 68km would be necessary in the FS main lobe. Given that constraint, it may be necessary to clear the band of FS usage to allow for the deployment of commercial IMT services.

In short, the cumulative restrictions required for IMT to coexist comfortably with incumbent services would make the business case for IMT deployment commercially unviable.

More broadly, an IMT identification would incur major opportunity costs. Reserving a portion of the 6 GHz band for a later decision on whether to allow IMT (or not) would forego the immediate economic gains that would have accrued from opening the full 6 GHz band to license-exempt operations.

UK regulator Ofcom and other experts have noted that IMT services in the upper 6 GHz band would not be deployed until later this decade. During the intervening period, the global economy could forego trillions of euros of economic value that could be generated by Wi-Fi 6E.

Ofcom has forecast that Wi-Fi demand in residential environments could grow between six and ten times between 2020 and 2030, driven by increased video quality and the adoption of virtual reality devices. In public venues, such as arenas or concert halls, demand could increase up to 15 times over the same period. With Wi-Fi traffic doubling every three years, Wi-Fi will need all 1200 MHz available in the 6 GHz band in both the consumer and enterprise markets.

It is not surprising then that countries representing more than 40% of the global gross domestic product (GDP) have opened, or have proposed opening, the full 6 GHz band for license-exempt use. As a result, these frequencies will not be harmonized for licensed 5G. In fact, an identification of the upper 6 GHz band for IMT could disrupt global harmonization efforts for license-exempt use and potentially cause major economic damage.

Ultimately, governments’ decision on an IMT identification versus no change should be taken on a risk/opportunity basis. Given the momentum behind Wi-Fi 6E, making the entire 6 GHz band license-exempt would maximize the opportunities to meet the growing demand for high quality connectivity, while minimizing the risks associated with fragmentation.