Mobile communications such as associated with cell phones is frequently used by personnel located within an enterprise campus, typically using cellular carrier networks. However, many enterprise campuses are now blanketed with wireless packet infrastructures such as a wireless local area network (WLAN) implemented in accordance with the IEEE 802.11 standards. Rather than having personnel use a relatively expensive cellular network, it is desirable to employ mobile voice communications over the WLAN, so as to provide a “voice over WiFi” (VoWiFi) capability.
As with all mobile communications, it is desirable to maintain seamless, continuous service during roaming as mobile users move to different locations. However, WLANs typically have a “thin” configuration whereby multiple wireless access points (APs) perform essentially as transceivers and operate under the same controller which handles the actual processing functions.
Existing WiFi technologies do not enable mobile devices to roam among APs operating under different controllers due to lengthy authentication that can compromise the communications channel. In order to roam to APs under a different controller, an authentication process is performed to setup a secure channel between the mobile device and the different AP controller. This authentication can entail a time delay as long as one second. However, a latency of less than 50 milliseconds is necessary in order to maintain seamless voice communications. Excessive authentication delays can result in unexpected termination of the call or at least interruptions or annoying glitches in voice quality.