Each year Interop sees new wireless LAN products aiming to be in the next generation of unwired offices. This year is no different, with a clutch of companies showing technology they claim will ultimately take the wires out of the office.

Last year, the big news was "single channel WLANs" offered by Meru and Extricom. This year, the new idea seems to be wireless backbones - systems in which wireless links push the wires one step further back toward the wiring closet.

Once again, it's Meru making the biggest noise about it, with a system that bonds channels to make a 100 Mbit/s backhaul from access points to distribution switches.

Xirrus also launched a bonded backhaul for enterprise WLANs, in the form of a software upgrade, Release 2.0 of its Integrated Access Point, that bonds three radios together for links which it claims are up to 162 Mbit/s. The software will be available at the end of May.

Other companies added mesh networking to their systems, to allow businesses to scrap some of their wires in hard-to-reach places. These included Symbol which announced it would add mesh ability to its wireless LAN system.

New systems support bonding
The Meru and Xirrus announcements are of particular interest, because they both offer a bonded channel, with greater capacity than a normal Wi-Fi link, and both offer features on it above and beyond what you might expect in a regular mesh.

Meru's system offers a full-duplex link, with quality of service, which Meru director of product management at Meru says is different from a mesh.

Xirrus' system appears to be faster on the face of it, but the 162 Mbit/s claim is almost certainly based on simply multiplying the theoretical 54 Mbit/s rate of three 802.11g channels by three - and therefore is probably around twice the actual throughput that can be expected.

Like Meru, Xirrus promises reliability above and beyond a normal mesh: "All security and WLAN policies are enforced across the backhaul links and radio bonding provides load balancing and fail-over capabilities allowing for a uniform and fault-tolerant deployment across an entire enterprise campus," the release says.

Both architectures, - in different ways - derive from the novel wireless architectures the two companies use.

Meru uses a "blanket" architecture, in which the access points all use the same wireless LAN channel(s). So far, Meru has sold this on the fact that there is no need for client devices to hand off between access points, which is good for real-time applications such as voice. The bonded backchannel makes use of the fact that, with all the access points using specific channels, other channels are free for backhaul.

Xirrus, meanwhile uses a sectorised architecture (reviewed here), in which one access point contains up to sixteen radios, that use directional antennas to reach a wedge of the building.

In Xirrus' case, the sectorisation makes it possible to bond channels together without danger of their interfering with radios which are beaming out in a different direction.

Other systems use one Wi-Fi radio for backhaul, or else backhaul duties share time with client access, says Xirrus.

MIMO and 802.11n on the way
To some extent, these systems are place-holders. There are a limited number of indoor settings, where it is currently too expensive or difficult to run wires; for those where wiring is at all possible, Gigabit Ethernet is so cheap, it makes very little sense to use a wireless LAN connection, even if it approaches the 100 Mbit/s of Fast Ethernet.

Those situations where it is worth taking a performance hit, and paying the cost of a wireless LAN system with extra extensions for backhaul, are a niche market. It's a worthy niche, and one where Xirrus and Meru are going to get useful experience.

But in future, when 802.11n arrives, wireless LANs will evolve that have access to all the available channels in the 2.4GHz band and the 5GHz band, as well as the multiple paths provided by MIMO technology. They should also be more reliable, as MIMO extends the range and throughput of Wi-Fi. Wireless LAN management systems should also get more automatic, and involve less of the hours of RF tweaking which can demolish the cost-of-ownership of a wireless LAN.

Wireless LANs might then be able to deliver parity with wired networks, for real - or close enough to parity for the savings on installation costs to make it worth using them instead of wired LANs.

802.11n is still a long way from the enterprise, which won't adopt it till the standard is more solid. But there are already signs of the benefits that it will bring to the office. Bluesocket has announced the first enterprise access point that uses MIMO.

The company - which missed the first bloom of the thin AP WLAN switch market, and addresses smaller companies that are prepared to take more risks - has not launched a mesh system, but it has produced an AP that uses non-standard MIMO, to give better range and throughput. It promises to upgrade it to 802.11n when the standard appears, with a hardware swap.

The individual steps are partial and incomplete, but the people that want to unwire your office are showing signs of getting their act together.