Peter Judge

Wireless LAN (WLAN) networks were originally developed as standalone “hotspots” for data applications, which is precisely how they are still used in homes and coffee shops. But when IT people started to use access points (APs) to cover whole offices, they ran into problems.

Multiple APs on one site have to be set to different frequencies to avoid interference, and each has to be configured separately. Around 2002, Symbol challenged this architectural model, which relied on intelligent or “thick” APs, by linking “dumb” or “thin” APs to one central switch that handles issues like roaming, coverage and security.

In 2005, Cisco, the last big opponent to thin APs, finally caved in and bought thin-AP vendor Airespace – end of story. Or so we thought. Some IT managers are still resisting WLANs, so vendors have come up with a new “killer” application – voice. Give corporate users a phone that calls using voice on IP (VoIP) over the WLAN and they can make calls away from their desks, without running up a big mobile bill.

But are the WLANs up to it? Voice does not tolerate tiny breaks in service, and that is just what you get when you walk round the office while making a voice over WLAN call, roaming from one AP to another.

Thin AP pioneer Trapeze has opted to put some intelligence back into the APs to better handle fast 802.11n devices, and lots of simultaneous voice calls. Rival Aruba has promised fast latency-free handover and upgrades to call quality on its centralised switch.

If I were an IT manager, I’d play with voice over WLAN, but try to obtain a discount from my friendly Vodafone agent.

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