Ability to scan multiple access point SSIDs at once (IDFGH-14831)

[bryghtlabs-richard]

Is your feature request related to a problem?

No response

Describe the solution you'd like.

I'd like the ability to specify multiple SSIDs in a wifi_scan_config_t.

Describe alternatives you've considered.

Currently to connect we do something like this pseudocode:

for each (SSID, Password) in CustomWifiManager's Credential List:
    if WiFiScan(SSID) is found:
        if Connect(SSID,Password) is okay:
            break

But, for SSIDs near the end of the list, we have to perform multiple scans first, which greatly lengthens the connection time.

Additional context.

We have a few product requirements to balance:

• Must support connecting to loudest AP in a mesh networks - for this we perform an all-channel scan before connecting to identify the best node to connect with. This is needed for pre-802.11kr access points.
• Must support multiple [SSID,password] pairs of credentials.
• Must support connecting to hidden SSIDs. To support meshes with hidden SSIDs, this currently requires a separate scan per SSID.
• Should support connecting to the loudest SSID if multiple are available.
• Should have fast connect time

[mhdong]

hi @bryghtlabs-richard
To scan for a specific SSID, we include the SSID field in the probe request. However, this field can only carry one SSID at a time, making it impossible to scan multiple AP SSIDs at once.
If hidden APs are not a concern, a full-channel scan can be performed first, followed by filtering the desired SSIDs. However, if hidden SSIDs need to be considered, each SSID must still be scanned individually.

[bryghtlabs-richard]

To scan for a specific SSID, we include the SSID field in the probe request. However, this field can only carry one SSID at a time, making it impossible to scan multiple AP SSIDs at once.

@mhdong, 802.11 has supported "SSID List" probe requests since at least 2012.

Please consider the following steps:

1. Allow sending multiple probe requests on a single channel during the scan so that wifi_scan_config_t.scan_time only applies per-channel instead of per-channel, per-SSID.
2. Allow coalescing multiple SSIDs into fewer SSID List probe request packets. If the SSID List is too long for a single probe request, a few may be required. The relevant section in 802.11-2012, "8.3.3.9 Probe Request frame format", "Table 8-26—Probe Request frame body", frame field/order 10. In 802.11ax-2021, it's "Table 9-38—Probe Request frame body"

[mhdong]

hi @bryghtlabs-richard
Thank you very much for your correction. We will discuss internally whether to add support for this feature and how to implement it.

[bryghtlabs-richard]

Thank you for your consideration @mhdong .