Xirrus Array Debuts

By Eric Griffith

March 28, 2005

A new vendor brings a new architecture— the WLAN Array—to market today, with hopes of taking on the experienced wireless switch startups as well as the big boys.

Your typical wireless LAN switch is comparable to a wired switch— it's a central controller, but it runs multiple wireless access points that are not much different from a standalone AP. That means you need quite a few APs to get full coverage in a big building. Xirrus, a startup in Westlake Village, Calif., came out of stealth mode today with what it says is a new architecture that combines the usual elements of a WLAN switch and APs into a single long-range device.

Xirrus' new Wireless LAN Arrays come in various configurations, all meant for enterprise customers. For example, the XS-3900 unit is the shape of a small tire (18 inches in diameter), but is nevertheless made to fit into a corporate space—it resembles an oversized smoke detector, to be mounted on a ceiling. Inside is a 16-port array controller with a multi-channel MAC running 16 integrated access points (in this unit's case, 12 for 802.11a and 4 for 11b/g).

Unlike the high-range Vivato panels—which Vivato tried to call WLAN switches early on, before dropping that nomenclature—Xirrus arrays don't use any smart antennas with beamforming to control the signal. Each AP has only a single directional 7 dBi gain antenna, but in the 3900 hardware that means a total of 16 antennas, one for each AP. The antenna angles have minor overlap to provide full coverage without gaps, but use different channels to avoid interference. This multi-sector antenna coverage with the extended range means one Wireless LAN Array can cover the same physical space as four standard access points, according to Xirrus.

The arrays come in various configurations. In addition to the 3900, the XS-3700 holds eight APs; the XS-3500 has only four. They scale down in size as they carry fewer APs, with the smaller sizes suitable for smaller locations or branch offices.

Xirrus says part of its value proposition to customers (beyond ease of installation and extended coverage) is capacity. Their materials claim a single XS-3900 has 864Mbps of aggregate radio frequency (RF) bandwidth by using the non-overlapping channels available in both 11a (which has 23) and 11b/g (which has three—one of the 11b/g radios can be dedicated to monitoring the airwaves).

The Array hardware connect via 2Gbps switching fabric to the Ethernet network -- and with it back to the optional rack-mounted centralized management controllers, which can sit anywhere on the network. There are three models of controllers, one for up to 10 arrays, one for 50 arrays, and a one for up to 500 arrays.

The units don't use Power over Ethernet (PoE), which Xirrus said would defeat the purpose since more cable would have to be pulled, but can be powered by either regular AC power or remote DC (using an optional power station).

Future wireless standards can be built into the array hardware, though the units' field upgradeability would require trained technicians.

Xirrus will start shipping its product line in volume sometime in May through VARs and system integrators. Prices for the arrays will start at $4,000, going up to $12,000.

Originally published on .

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