Tsahi Tal

On April 23rd the FCC voted and approved allocation of the new 6GHz band for Wi-Fi. While it seemed like a blessing for the Wi-Fi users, in reality the industry encountered a problem: there are thousands of licensed microwave 6GHz links in the United States, mainly used by the cellular industry, various utility and safety services; furthermore, there are broadcasters (fixed and mobile) that are using part of this band for BAS (Broadcast Auxiliary Service, e.g. for sporting events, stadiums, etc). Naturally, now they fear that unlicensed 6GHz activity might cause signal disruptions. The mobile industry is taking steps of its own, applying to  the FCC to allocate a chunk of the 6GHz band for 5G operations.

The Wi-Fi industry in general is not interested in starting a war, so instead of fighting over 6GHz dominance, they’re actively searching for ways to share the spectrum, similar to the reality related to the existing bands that are shared successfully amongst different license exempt technologies. One solution is using Automatic Frequency Coordination, which could leave out unwanted interferences, but also requires Wi-Fi devices to be registered in databases and become ‘geo location aware’. The Dynamic Spectrum Alliance has already shared a detailed report on how AFC could automatically control any unlicensed band.

Encouraging the Regulators

In another instance, a group of tech giants appealed to the FCC for the approval of Very Low Power (VLP) Wi-Fi where portable devices that transmit below a certain power threshold (14 dBm EIRP) could traverse the 6 GHz spectrum without causing any interference even when used outdoors. This would be very beneficial when firing up AR/VR technology, games, in-vehicle entertainment, cloud services and IoT appliances that are so reliant on seamless connectivity.

A report to the FCC states that VLP gadgets wouldn’t interfere with existing point-to-point links even when used outdoors, while successfully delivering 2Gbps at a distance of 3 meters. It also goes on to say that short-range high-speed low-power connections are suitable for 5G mmWave backhaul, thus why VLP could also contribute to making 5G successful.

The “LPI Claim” (Low Power Indoor)

In August, another group presented new evidence on the usage of 6GHz. In a rare instance of solidarity companies such as Qualcomm and Broadcom have appealed to the FCC, presenting a fresh European study which shows that low-power indoor (LPI) Wi-Fi can share the 6GHz band without causing unwanted interference. Basically, the signal would be isolated, preferring network density over range. In their appeal to the FCC they also talk about provisions ensuring that indoor devices remain indoors. These include prohibiting removable antennas, weather-proof casing, battery-powered operations and labeling devices for indoor-only usage.

As a matter of fact, back in 2018 an American research paper also concluded that unlicensed radios don’t interfere with satellite, microwave or mobile, therefore they can coexist on the same spectrum.

The FCC Reaction

The FCC had taken a bold and clever move, aiming for a win-win: unleashing unlicensed innovation at the earliest in a new spectrum band, while reducing to minimum points of dispute and potential interference to incumbents;

The FCC vote on April 23rd (rule & order) enables immediate use for indoors use only, of low power devices across the entire 1200MHz band (5925-7125MHz), with the actual transmit power being proportional to the transmission bandwidth without the need for AFC. Saving the need for geo-locationing for the indoor devices keeps the devices low cost and simple to deploy as Wi-Fi is so favorable for today; while keeping the radiated spectral density (which is the proclaimed source of interference for the incumbent microwave links) the same no matter which channel bandwidth (20MHz to 320MHz) is being used by the Wi-Fi 6E device. Client devices would be limited to 6dBm lower tx power than that of the access point. As hinted above, the rule and order is actually forward looking towards the next generation of Wi-Fi standard (802.11be, a.k.a Wi-Fi 7) which aims at extended channel bandwidth of 320 MHz (802.11ax, Wi-Fi 6/6E are up to 160MHz channel bandwidth).

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The FCC vote on April 23rd further enabled indoor or outdoor use of standard power devices across 850MHz (UNii-5 and UNii-7) with the governing of AFC. It is expected to take a while before AFC (Automated Frequency Coordinator) server/service would be available (e.g. by Federated Wireless or others), which is why the indoor only low power profile described above is so important. Once available, AFC enabled APs would be able to transmit at higher power either indoor or outdoor:

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The Next FCC Steps

At the same time, the FCC opened a call for a second rule and order (towards a Final NPRM), proposing the following additions:

  • Increasing the power limits of indoor low power APs by 3dB
  • Enabling Very Low Power (VLP) devices indoor & outdoor

The FNPRM is open for comments until end of June ’20, and expected to be concluded in Q3 ’20.

How Are the Other Regulators Reacting??

In the meantime, other regulators worldwide are taking steps to follow the steps of the FCC:

  • In Europe, the EU is actively working for a while towards enabling this spectrum for use in the European Union countries. Under the EC, in CEPT/ECC, there are 2 main active groups (SE45 & FM57), working on the details of the regulation. One group works on the coexistence and the other on the regulatory rule making. They are expected to conclude their recommendations towards the end of 2020 enabling ECC voting and decision in Oct/Nov 2020.
  • In the UK, OFCOM have taken steps earlier this year, towards opening UNII-5 (similar to the EU target spectrum) for use and may possibly conclude the new rule even earlier than the EU.
  • Brazil, which traditionally follows FCC, has started active discussions following the steps taken by the FCC.
  • In Asia, South Korea, Japan and others are looking at releasing the 6GHz spectrum at a fast pace to make sure that they don’t fall behind the new services, devices, and innovation that would shortly be introduced to market.

Exciting times… with ~700MHz of spectrum in the 2.4 & 5GHz combined Wi-Fi is a major part of our life, work and industries, just imagine the meaning of additional 1200MHz of new spectrum, the unleashed innovation that is coming soon… WOW!

Stay tuned for updates and more exciting news very shortly.

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