Wireless LAN vendors will be out in force at the NetWorld+Interop show in Las Vegas next week with new or improved products.

Israeli WLAN start-up Extricom will use the show to launch thin access points and a central switch that boast patent-pending technology that detects and in effect sidesteps radio interference. As a result, executives say, access points can be packed much closer together than they can with conventional WLANs, boosting overall throughput and network reliability.

Extricom achieves this in part by using an approach similar to that adopted by ill-fated start-up AirFlow : by moving all media access control (MAC) functions from the access point to the central switch. The access point has no software, acting simply as a conduit passing wireless packets to the central switch.

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The next step is to avoid radio interference. Extricom does this with an algorithm in programmable silicon in the central switch. The key change Extricom does in hardware is what rivals have tried to do in software, according to CEO Gideon Rottem. Via the algorithms, the switch can "see" the entire radio environment in real time - all the access points and wireless clients, and every packet moving between them. If a transmission from one access point is interrupted or degraded, the switch can have another Extricom access point handle communication with that client on a packet-by-packet basis.

"If Access Point 1 and Access Point 2 transmit at the same time, you'll have interference," Rottem says. "So the switch doesn't let them. By knowing at all times the complete radio map of the network, we can assess when and where to transmit, and through which access point."

Compared with conventional WLANs, Extricom lets more users be closer to a larger number of access points, and therefore lets them connect at the maximum possible throughput rates of 5M to 7M bit/sec for 802.11b and 20M to 25M bit/sec for 802.11g and 802.11a, Rottem says.

Sangikyo, a network engineering firm in Yokohama, Japan, has been beta testing the Extricom switch, initially for wireless VoIP covering the four floors of its headquarters. Sangikyo set up the switch and eight access points, testing up to 10 WLAN phones over 802.11b and 802.11a connections. "We've been able to support up to 10 simultaneous calls on one" access point, says Matthew Drechsler, a test engineer with Sangikyo's business development division.