Wireless: client switchover time when AP fails

Hello,

I have a customer demanding very short downtime on clients connected to an AP that fails/disconnects. When an AP fails, the clients connected should switch to another AP in less than 1 second. Is this even possible?

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From what I understand, the reconnecting process goes like this:

1. Client has to become aware that he lost connection to the AP (I don't exactly know how but I know it takes some time)

2. Client scans (with probe requests) all channels (some clients allow setting the channels, and smaller amount of channels results in lower scanning time, but I don't think this can be done in every environment)

3. Client receives probe response from an AP and has to go through the process of authentication and reassociation

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Can the process above be sped up in any way? In my testing, clients lose about 3-4s of pings, and Webex/Whatsapp calls take 6-9s to reconnect, but apparently this is not enough, even though the chanse is very small that an AP disconnects, let alone that the client is connected to that exact AP and sending data at that exact time.

I know 802.11k/r helps with roaming, but could it maybe also help with this?

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Thanks in advance!