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Matthew Gast has posted audio files showing the quality of VoWLAN in testing at Interop: Gast, who works for enterprise switch maker Trapeze Networks, is part of the Interop Labs testing crew, which this year put together systems to test handsets and Quality of Service (QoS) using the 802.11e Wi-Fi Multimedia (WMM) prioritization scheme. WMM should allow voice packets to move unimpeded in the queue ahead of other data, thus making a VoWLAN call sound like a POTS (plain old telephone service) call.
Gast’s first audio recording explains the parameters of their testing and notes a lot of the particulars that make VoWLAN so difficult to implement correctly. Two following audio files show a call without WMM and with WMM. The difference is very noticeable. Gast made the calls in the challenging RF environment of Interop in which he could stop 40 to 70 APs from the booth in which he was working.
In months past, Gast has estimated the practical number of VoWLAN calls possible in 802.11b, g, and a networks. I’ll be looking forward to his analysis of 802.11n, which has vastly higher throughput and range; it can also preserve higher speeds at greater distances. One of the stumbling blocks in moving 802.11n through the IEEE process was a concern about certain elements that might make 802.11n’s use in handsets impractical. Those concerns have apparently been addressed.
Matthew Gast reports on pre-Interop festivities in configuring VoWLAN devices: Gast worked with Interop Labs to set up the VoIP over WLAN systems that will be demonstrated and tested at the enormous conference in Las Vegas next week. They spent quite a bit of time pre-flighting to make sure that what they want to work will work before they’re on site at the show.
Gast says that they’re testing VoIP’s interaction with security features this year, along with examining the year-over-year improvement in 802.11 phones.
Strix Systems deployed a Wi-Fi network to support voice and data at the Voice on the Net (VON) show: Strix says that one IT manager deployed 25 nodes in a day. All but two were fully wireless so the network operated on a mesh architecture. Strix reports that as many as 450 users were on the network at one time, with 25 percent of them using voice devices. The network separated voice and data traffic, giving priority to voice traffic.
It would be nice to get more of a third party evaluation of the network, only because Strix and Pulver have a vested interest in the success of this network. Still, it sounds like it was a fairly simple network to deploy and it supported a high volume of voice and data users.