VoWLAN: The Return of 802.11a?

By Ed Sutherland

June 18, 2004

The combo 'Enterprise Phone' planned by partners Avaya, Motorola, and Proxim could push the need for 802.11a -- and analysts concur that it should be used instead of 11g/b.

As promised last year, Avaya , Motorola , and Proxim plan to offer a dual-mode "enterprise phone" allowing employees to make calls using either wide-area cell phone connections or corporate WLANs. The trio expect to ship the handset and accompanying infrastructure this September.

The rub is, the proposed phone will require companies to install 802.11a networks. They say the more-prevalent 802.11g/b standard cannot provide the level of service needed by voice-over-IP (VoIP).

802.11g/b, with only three channels that do not overlap, is able to support between six and eight calls at a time. In comparison, 802.11a boasts 21 non-overlapping channels able to handle 25 voice-over-IP calls from a single WLAN access point.

The goal of the enterprise phone the companies propose is to provide employees a mobile phone experience with the familiar functionality of wired digital handsets connected to the corporate PBX. People will be able to manage up to three simultaneous calls while putting a fourth caller on hold.

Motorola intends the "enterprise phone" be built upon the Schaumberg, Ill., company's i.250 series.

Motorola says the phone will have a battery life similar to cell phones with talk time between 10 and 12 hours. Standby time will be close to double that -- between 20 to 24 hours, claims Motorola. Although it refuses to be specific on how they managed the battery savings, Motorola will use Texas Instruments' (TI) Wi-Fi chipset in the phone. TI, along with chipmakers Atheros and Broadcom, has previously announced plans of lowering the power demands placed on devices by Wi-Fi.

"The cellular and WLAN markets are on a convergence path to provide users with phones that can handle voice and data traffic in both wireless networks," said Marc Cetto, general manager of TI's Wireless Business Unit in a statement.

Motorola will begin testing the phone this summer.

"Motorola believes that tying together wireless LANs, IP telephony, and cellular technologies in a single handset will extend the mobility of the cellular networks inside the enterprise, and provide the best available access to the user," said Dan Coombes, Motorola's senior vice president and general manager for Motorola's Network Systems Group.

The dual-mode phone will work with either GSM or CDMA cell networks, according to Motorola.

Companies interested in testing the "enterprise phone" will need to invest in network infrastructure equipment from Avaya and Proxim, Motorola's partners on the enterprise phone. A gateway controls access points and a communications manager shuttles incoming calls from local and long-distance networks to the WLAN. The management software also converts circuit-switched phone calls into IP-based packets.

These three companies may have helped set the current trend toward embracing voice over wireless LANs. Wireless switch vendors like Aruba Networks, which originally hawked their solutions "as ways to centralize management of wireless LAN," says ABI Research analyst Phil Solis, "have reinvented themselves as purveyors of VoWi-Fi platforms."

In May, Solis also gave the nod to 802.11a over 11b or 11g for voice applications in the wireless enterprises.

"For converged networks, voice should be deployed over 802.11a while data is deployed over 802.11g."

Calling 802.11a "the future," Craig Mathias, principal analyst with the Ashland, Mass.-based Farpoint Group, declares there is no other option for voice over Wi-Fi.

"11a will have to be used," Mathias says.



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