Cellular-to-WLAN Roaming Specification Published

Last week, a group of 14 companies announced the publication of the Unlicensed Mobile Access (UMA) specifications for extending mobile voice and data services over fixed wireless LANs. The companies involved include Alcatel, AT&T, BT, Cingular, Ericsson, , Motorola, Nokia, Nortel Networks, O2, Rogers Wireless, Siemens, Sony Ericsson, and T-Mobile USA.

Ken Kolderup is vice president of marketing at Kineto Wireless, a mobile solutions provider which participated in the development of the specifications. The aim of UMA, Kolderup says, is simple: to enable consumers to roam seamlessly between their cellular networks and the wireless LANs in their homes and offices. For carriers, that can be a very attractive proposition.

“They can allow their subscribers, using new dual mode mobile handsets, to roam seamlessly between the outdoor network when they’re out and about, and as they go into their home or office wireless LAN environment, to be able to leverage that to receive higher-performance mobile voice and data services at a significant cost savings,” Kolderup says.

For consumers, Kolderup says, the experience is truly seamless. “The normal mechanisms that are in the cellular network today for handing over calls between base stations as you drive down the freeway, it leverages those same mechanisms for handing the call off between the outdoor network and the wireless LAN,” he says. “So there’s no service interruption as they transition between different environments.”

Handset manufacturers, he adds, view UMA as an excellent selling point for Wi-Fi enabled mobile phones. “I think this is a service model that really makes a lot of sense for inclusion of Wi-Fi in mainstream mobile devices,” Kolderup says.

UMA Diagram
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At a basic level, Kolderup says, the technology simply delivers mobile services over a complementary network. “It allows [the carrier] to effectively create a parallel access network for delivery of all those services — voice services, mobile data services, music downloads, video, SMS and everything else — over a complementary access network that leverages broadband IP transport and unlicensed spectrum,” he says. To do that, two components are required. One is a controller box which is placed in the carrier’s core network, and the other is software in the handset itself.

“The controller box is responsible for extending and managing access to mobile services, and securing them, from all these wireless LAN endpoints,” Kolderup says.

The timing of this announcement, he suggests, is particularly fortunate. “For mobile operators, one of their largest opportunities for growth right now, now that subscriber penetration is so high in most developed countries, is trying to get more use of mobile services, and encouraging people to use a mobile device as their primary if not only device when at home and at the office,” he says.

Particularly in dealing with competition from services like voice over IP, Kolderup says, UMA can give carriers the perfect weapon. “UMA allows them to take advantage of voice over IP, Wi-Fi, and broadband, for them to also provide a very high quality, high performance service that subscribers are looking for, in exactly those locations where they can’t do it very well today,” he says.

The carrier can then charge for service however they like. “There is the ability to identify traffic and charge differently for it when you are in a wireless LAN environment, and my presumption is that most carriers will look to do that,” Kolderup says. To compete with VoIP services, he says, carriers might offer limited or unlimited WLAN access for, say, $5 to $20 a month on top of their usual mobile access fees.

Commercial deployments, Kolderup says, should start in the first half of 2005. “For a mobile operator, this is a way for them to encourage more use, and to give the subscribers what they’re saying they want,” he says. “It’s giving the subscriber more, and retaining them and their service.”

Jeff Goldman
Jeff Goldman has been a technology journalist for more than 20 years and a contributor to TechnologyAdvice websites since 1999. He's covered security, networking, storage, mobile technologies and more during his time with TechnologyAdvice.

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