Wi-Fi AP Handover and Real Time Services

Earlier this year when I was on vacation in the Austrian alps, I noticed an interesting Wi-Fi behavior that I thought I should note down here for future reference: The impact of a handover from one Wi-Fi access point to another in a distributed system.

It was very very early in the morning when I attended a global conference call. Instead of attending the call in the hotel apartment, I chose to go to a comfortable sitting room inside the hotel, in which I unfortunately didn’t have good cellular cover. So despite usually not relying on hotel Wi-Fi, I didn’t have a choice there. The connection was throttled to 10 Mbps in both directions, but for a conference call, that’s good enough. The sitting room, however, was located between two Wi-Fi access points of a distributed Aruba installation and both had a downlink signal strength of around -70 dBm. In the cellular world, such a signal level is stellar, in the Wi-Fi world, however, it’s rather medium. So every few minutes, the distributed Wi-Fi system decided it would be a good idea to hand me over between two access points. Unfortunately, this was noticeable in the conference call as the speech path was interrupted each time for around a second. So I started to investigate and saw that each time the voice path interruption occurred, the MAC address of the access point changed. And as I could hear the speech path interruption, it obviously took too long for a smooth real time service experience. An interesting learning!