Voice Standard on the Horizon?

Get ready to add another letter to the 802.11 alphabet soup.

A group that has been looking at some of the issues surrounding handoffs between wireless LAN access points will try to make the move from study Group to task Group at this week’s IEEE meeting in Vancouver, British Columbia. If it’s successful, the group would be charged with defining a new 802.11 standard — most likely 802.11o.

The Fast Roaming Study Group was spun out of the 802.11i Task Group, according to Ben Guderian, director of marketing at SpectraLink. In the interest of moving quickly on the security standard, the 802.11i group tabled discussions on some issues that specifically addressed real-time applications such as voice, he said.

One of those issues is handoffs. Guderian said the Fast Roaming group has tested about a half-dozen different implementations using the current Wi-Fi Protected Access (WPA) security protocol, and found that handoff times ranged from around 70 milliseconds to over one second. Those handoff times are simply too long for acceptable voice quality in an enterprise environment, he said. The goal is around 50 milliseconds.

“As you go above 50 milliseconds, you start to run into situations where you have to have larger buffers in order to compensate for the fact that there’s that variability in how long the handoff is going to take,” he explained. “What happens when you have larger buffers is that adds delay into the system. When you get above 50 to around 100 milliseconds, it’s a noticeable delay, kind of like what we used to deal with satellite telephone calls.”

While the testing was done on systems using WPA, Guderian said the group believes that 802.11i will yield similar results.

While there are some proprietary roaming mechanisms that fit the bill, Guderian noted that the group would prefer to see a standard adopted by the industry. He thinks a standard would come together relatively quickly, too.

“I know there’s a lot of skepticism and cynicism about how long these things take to happen, but … people already have a good idea of what the problem is that they’re trying to solve, and … we’re fairly optimistic that this is something that wouldn’t take years and years to resolve.”

Even if the voters do opt to bump Fast Roaming from study group to task group this week, the group may have to wait a couple of months before its new status is official, noted Brian Mathews, publicity chair for the 802.11 Working Group. Since this week’s meeting is an interim session, rather than a plenary, the vote may need to be reaffirmed at the next meeting, which is scheduled for the third week in March in Lake Buena Vista, Fla.

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