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WLANs for dummies?

Sep 22, 20032 mins
Cellular NetworksNetwork SecurityWi-Fi

* AirFlow aims to obliterate RF hassles

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New solutions to radio frequency-related wireless LAN problems seem to be hitting the streets every week.

This time around, start-up AirFlow Networks (who we last heard from officially in January) says it’s now shipping 802.11b products that completely eliminate co-channel interference caused by neighboring access points (AP). That’s because in an AirFlow network, neighboring APs don’t exist.

AirFlow purports to remove the radio frequency complexity from WLAN deployments by creating one big “virtual AP” in a centralized wireless controller, enabling users all over an organization to associate to a single AP configured to operate on one channel. Because mobile users technically associate with just one centralized wired box (instead of with multiple, distributed APs running on different frequencies), the need to configure and carefully tune ceiling-mounted APs to avoid interference should disappear.

As reported here early this year, the AirFlow architecture separates the 802.11 MAC and PHY radio components. The MAC that all users associate with resides in either a $7,500 data-center wireless AP controller called the AirServer, which plugs directly into your wired backbone network, or in an $8,750 AirSwitch, a wiring-closet device that’s a combination wireless AP controller and 10/100/1000 wired Ethernet switch.

The PHY component of the radio (digital spread spectrum sequence, or DSSS, technology in the case of 802.11b) resides in distributed “packet antennas,” brand-named AirHubs. These devices physically resemble traditional distributed APs. But they function like unmanaged mini Ethernet hubs that require no configuration or special placement, because contention for the transmission medium happens in the central controller, not in the air.

The AirHubs ship in packages of four for $1,000, and a single AirServer or AirSwitch can support about 30 of them.

Analysts point out that AirFlow doesn’t yet address outside sources of interference in 802.11b’s 2.4 GHz band, such as cordless phones and Bluetooth devices.

A couple other issues: The products support 802.11b only today; an 802.11a/b/g product set is due in the first half of next year. Also, at press time, the product supported access control lists and 802.11 Wired Equivalent Privacy for security; company officials say Wi-Fi Protected Access and IPSec support will be available in one month.