New standard could give Wi-Fi a voice

A standards effort was launched early this year, which should allow office Wi-Fi networks to handle voice calls. A group of vendors, including Airespace and Spectralink, has requested permission to create a Fast Roaming study group, working on handover between access points, within the IEEE standards body. The IEEE already has a quality of service standard, 802.11e in progress, that can prioritise voice packets over data, but the new proposal is needed for the separate issue of handling phone calls when users move between access points within a wireless network. The original 802.11 Wi-Fi standard specified that users should be able to move to a different access point, but this "roaming" creates a brief interruption in the data stream.

The break has been made worse by security features implemented on Wi-Fi networks, ironically. When a user moves from one access point to another while making a voice call, an encrypted tunnel must be broken down through one access point and re-formed through the new one; if this process takes more than 50ms, the user will hear a break in the voice conversation. Vendors have reported hand-over times of more than 70ms.

"With the new security of 802.11i, there is a feeling that roaming has been slowed down and needs to receive a kick in the pants," says Bob O'Hara, director of systems engineering at Airespace, a wireless switch vendor which majors on voice over Wi-Fi, and a member of the study group.

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