Wi-Fi Vendors Talk the Talk

While voice traffic is already traversing Wi-Fi networks to a certain extent today, the Interop show this week in Las Vegas provides further evidence that VoIP is expected to be a growing traffic type on these wireless networks.

A handful of Wi-Fi equipment vendors exhibiting at the show are discussing how they’re addressing the requirements of voice with new solutions that deliver more widespread coverage, include various QoS mechanisms, provide fast AP-to-AP handoffs to significantly lessen latency, or some combination of the above.

For example, Meru Networks unveiled a new group of Radio Switches – which can offer 1.2gbps of capacity in a single access point – for high-density data and VoIP mobility applications.

Joel Vincent, Meru’s director of product marketing, explains that the new switches allow enterprise customers to expand their wireless networks to create “blankets of coverage” without adding a large number of APs, thereby eliminating co-channel interference problems that result from multiple APs; this also provides providing increased coverage and an otherwise better environment for voice traffic, he says.

Creating a high-density network traditionally requires the addition of many APs, says Vincent, but handoff (and related reauthentication) between APs adds delay – typically between 300 milliseconds and a full second -- that voice traffic simply cannot tolerate.

Vincent adds that the Meru Radio Switch, which is an indoor solution, offers 12 times the capacity in terms of the number of clients supported and total throughput of the average AP, so fewer APs are required. That capacity is achieved with Meru’s patent-pending Wideband RF Combination/Omni-Directional (WRC/OD) antenna technology, which combines wideband RF signals from multiple channels into a single omni-directional antenna. “With our system, one box does 12 channels,” Vincent says. “When you add a nearby AP, that’s coordinated with our controller, so it doesn’t interfere with other APs’ channels.” When deployed with a Meru Controller, multiple Radio Switches coordinate with each other to create up to 12 channels (or “virtual cells,” as Meru calls them), which are continuous footprints of total throughput per Radio Switch coverage area from up to 648mbps with 802.11 a/b/g radios, and up to 1.2gbps with future 802.11n radios.

The Meru Radio Switch products include the four-radio RS-4000, the eight-radio RS-8000, the 12-radio RS-12000 and a patent-pending, built-in omni-directional antenna. The Meru RS-4000, RS-8000 and RS-12000 will be available in July 2005. Pricing for the four-radio RS-4000 starts at $1,595, and the eight-radio RS-8000 starts at $2,995 U.S. list. Pricing for the RS-12000 will be announced at a later date.

Another Interop exhibitor and Wi-Fi equipment vendor, Colubris Networks Inc., in April publicly released its blueprint to help customers integrate Wi-Fi networks with wireline LANs and add more applications on their pipes.

The first piece of the two-pronged strategy includes the introduction of a MultiService Controller in May to work in a distributed switched architecture offering centralized management, scalability up to hundreds of APs per controller and the ability to support multiple services. This platform will be an open system and provide interfaces to third-party applications, which can include VoIP and location-based applications to track assets. “We are focused on providing hooks into VoIP PBXs,” said Carl Blume, director of product marketing, in an interview at Interop.

The function of the MultiService Controller is to do automatic discovery of new APs; handle authorization for those APs; push software upgrades, service configuration and policy information to the APs; and connect the WLAN with the wired LAN switch. The controller also is designed to coordinate AP-to-AP roaming with very fast handoff times sufficient to handle voice QoS; do RF policy and management; and perform real-time monitoring of QoS available on the network on an ongoing basis.

In the second phase of the plan, Colubris expects to introduce a Unified Edge Switch, which, along with its MultiService Controller, will allow the vendor to deliver what it calls its Unified WLAN Architecture. This architecture was designed to allow for seamless access to voice, video and data with a single policy engine and enforcement of QoS over both wireless and wireline LANs. The Unified Edge Switch is slated for release in the first half of 2006.

On the network infrastructure side, several Wi-Fi vendors offer QoS today based on a traffic prioritization method called WMM, or Wi-Fi MultiMedia, that came out of the Wi-Fi Alliance last fall. WMM is a subset of the IEEE’s 802.11e initiative, which is expected to be expanded later this year with an ATM-like scheduling-based approach to QoS, says Frank Hanzlik, managing director of the Wi-Fi Alliance. He adds that 802.11e is expected to be ratified by the IEEE later this summer, and that the alliance will follow that up by offering equipment certification testing relating to the standard.

Another effort within the IEEE called 802.11r aims to provide a standard way to do fast handoffs between APs, says Hanzlik, who adds that 802.11r should be ratified by the IEEE by the second half of 2006.

The IEEE also is working on a standard called 802.11n, which is expected to be ratified in the first quarter of 2007, which will deliver 100mbps-plus bandwidth and leverages MIMO technology for greater coverage indoors or outdoors.

While voice already is running over Wi-Fi networks, says Hanzlik – noting that Cisco Systems Inc. has outfitted Dartmouth College with a campuswide Wi-Fi network that carries voice; and that UTStarcom at the Consumer Electronics Show this January came out with a Wi-Fi cordless phone – creating standard ways to deliver voice services over Wi-Fi is expected to bring equipment prices down and allow for multivendor interoperability, both of which will help voice over Wi-Fi move toward the mainstream.

In fact, the Wi-Fi Alliance has a Voice over Wi-Fi committee that is focused on considering what IEEE standards can be leveraged to support voice over Wi-Fi. The group in the first quarter of 2006 plans to introduce a certification program for standards-based voice over Wi-Fi equipment, says Hanzlik, adding that will likely be followed by a handful of plugfests.

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