Wi-Fi 6E Access Point Discovery

The Wi-Fi 6E revolution is here. An abundance of spectrum is available to use and see the full potential of Wi-Fi.

But how do we validate Wi-Fi 6E devices operation and access point discovery? With the massive amount of spectrum provided with Wi-Fi 6E, it will take capable devices over 5 seconds to scan all the channels.

5 seconds is a long time in the Wi-Fi world. It’s enough time to impact roaming performance. It’s enough time to delay a warehouse of handheld scanners.

Deploying Wi-Fi 6E today requires specific configuration. A 6 GHz-only network is not recommended. Your network will need to be operable on both 5 GHz and 6 GHz. There are a few features of Wi-Fi 6E that will help devices perform access point discovery efficient for devices.

Reduced Neighbor Reports

A Reduced Neighbor Report (RNR) is a method in which an access point informs a device of neighboring access points. The RNR contains channel and other information about these neighboring access points. This list will help a device find an access point much more faster than scanning the whole Wi-Fi 6E bands. The device can then probe for those neighboring access points using information such as the BSSID and reachability information.

Preferred Scanning Channels

Wi-Fi 6E devices can actively probe for access points in 6 GHz but must do so using Preferred Scanning Channels (PSC). These are set channels, every fourth 20 MHz channel, a device will send probes on. There are many 6 GHz channels that would take up a considerable amount of time for a device. Wi-Fi channel planning becomes important as we need to ensure access points are configured for PSC as well.

Fast Initial Link Setup

Where PSC is an active scan for 6 GHz access points, on the opposite end is a passive method called Fast Initial Link Setup (FILS). Using the FILS method, access points broadcast action frames every 20 ms over the air. The FILS Discovery frame contains a short SSID which maps to the full SSID name. The goal of FILS is to help 6 GHz devices find a 6 GHz SSID. But not every vendor supports FILS → something to look out for.

Summary

There are three methods Wi-Fi 6E devices use to discovery Wi-Fi 6E access points using Reduced Neighbor Reports, Preferred Scanning Channels, and Fast Initial Link Setup. In our testing with a Samsung S22+, it did not initially probe for any Wi-Fi 6E access points. It needed a Reduced Neighbor Report to learn about those access points and then perform a probe. Vendors may implement these features differently as we found that FILS is not used widely.