Multi-Channel Magic?

As larger and more diverse enterprise and public wireless LAN networks are deployed, some vendors are resorting to channel tricks to beef up performance. Specifically, they're looking to divide and prioritize different traffic types, therefore adding capacity to their networks.

The idea is that by separating voice, video, and data on a network, the most crucial packets can be delivered first. Of course, such tactics can't avoid the fact that 802.11 wireless LAN is a shared medium and performance will suffer if there is too much traffic for the radios to handle. But if a network has enough capacity in place, then these channel tricks are said to improve delivery of voice calls and other multimedia over WiFi.

Public and enterprise wireless LAN startup Colubris Networks Inc. was one of the first to start talking up using "virtual" channels for stranding out services on enterprise networks. The firm's "virtual AP" technology works by spoofing the network into believing that there are up to 16 service set identifiers (SSIDs) being broadcast by a single device. SSIDs are the network names that identify separate wireless LANs. So, using VLAN tagging, network administrators can deliver different services to users on the same access points (see Colubris's Enterprise Ambitions).

The firm bulked out the concept with the introduction of its Unified Services Network (USN) architecture earlier this year. USN is a distributed WLAN/LAN switching architecture with centralized management and control that supports multiple services -- such as voice, video, and data -- over a single wired and wireless network (see Colubris: Fat Is Back).

Startup Meru Networks Inc. has always made a big play of its ability to determine traffic types and apply different levels of QOS to the data. In March, it took the idea one step further by introducing a massive "Radio Switch" that aims to offer blanket corporate coverage in one box using multiple radios (see Interop Unwired).

Newcomer Xirrus Inc. has taken a similar approach with its own massive multi-radio switch, jokingly described as a "smoke detector on steroids." (See Reinventing the WLAN Wheel?)

"I do believe that this is the way the industry is moving," says Meru's VP of marketing, Ben Gibson. "First, this multi-channel approach... overcomes the performance and predictability challenges of a shared medium in 802.11. It elevates WLANs to the level of assurance normally associated with 10/100-Ethernet connectivity. The nice thing about our approach is that it is modular and can be upgraded with 11n radios in the future."

Some in the industry question the viability of using these massive radio boxes rather than a standard network of access points to provide coverage. Certainly, a similar approach has been tried in the past by startups like Vivato Inc. and was found to be wanting for enterprise applications.

But there's also no question that a couple of factors are causing the industry to look for more sophisticated traffic management and wireless capacity.

Voice-over-WLAN and upcoming devices that can handle VOIP and cellular communications are one big aspect of this. "We've seen a big increase in WiFi-enabled handsets/PDAs hit the market this year," says Gibson (see Meru Talks Up Japan).

This will become especially relevant -- and not just to enterprise vendors -- if operators manage to get fixed/mobile convergence services off the ground (see BT Unveils FMC Service). And, as network deployments grow larger, scaleability becomes an issue, as hundreds rather than tens of users could log onto the network at a particular point. "Conventional WLAN systems without this integrated multichannel approach simply break under such high-density usage," claims Meru's Gibson.

Some vendors are betting that multi-channel magic will be the solution.

— Dan Jones, Site Editor, Unstrung

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