the skinny on broadband wireless

A CENTRAL PURPOSE OF BROADBAND WIRELESS TECHNOLOGY IS TO CREATE BIG PIPES for bandwidth-loving applications like Internet access and video. But voice also is a very central part of the WiMAX and overall broadband wireless picture.

That’s why Airspan Networks Inc. in April acquired Israeli softswitch company Arelnet, says David Reeder, Airspan’s vice president of sales for the USA. Airspan will offer the Arelnet softswitch as an optional part of its WiMAX solution, says Reeder, adding that Airspan already has done interoperability tests at customer request with voice switch vendors including CopperCom, General Bandwidth and Tekelec. Over time, Airspan may even introduce a WiMAX base station with an integrated softswitch, he says.

“IOCs, which we serve, want infrastructure that can support VoIP, and the only way to do that is with QoS,” Reeder adds. The Airspan equipment, he says, uses tags to prioritize traffic over the air.

Aperto Networks, meanwhile, has what it calls an intelligent classifier to read headers and prioritize traffic, says Reza Ahy, CEO of Aperto Networks. That’s a key capability to differentiate traffic such as voice and video from data on broadband networks, he says.

Greg Caltabiano, COO of broadband wireless equipment vendor Soma Networks, says voice is an important application because it allows service providers to generate more revenue, offer a bundle of services to reduce churn, and gives carriers the ability to cross-subsidize services. If carriers offer broadband, some people will use it for VoIP anyway, he adds, but broadband wireless that isn’t set up for voice can support only one or two Vonage-type VoIP customers a sector because of latency, he says, explaining Vonage uses a big channel.

Soma sells a little CPE device it calls a home/business gateway that normal phones plug into. It includes a SIP client and compresses headers for more bandwidth efficiency. Soma’s solution also breaks up data bits (which are big) so they don’t overpower the smaller VoIP bits in the network, Caltabiano says.

Of course, voice traffic over WiMAX needn’t be IP-based. Zarlink Semiconductor and Wavesat proved that point this spring in announcing what they call the industry’s first successful testing of circuit-switched traffic over a WiMAX connection. These tests demonstrated carrying E1 and T1 services across a WiMAX broadband wireless access network, using CESoP technology.