Is Cellular Handoff Nigh?

By Wi-Fi Planet Staff

February 09, 2004

The promise of the new 802.21 standard is handoff of signals between any and all wireless networks, but there are tremendous business and technical factors to face before it's a reality.

Call it fast roaming. Call it seamless handoffs. Call it the next evolution in wireless as we know it today. Either way, it's coming, and it will almost surely change the business of wireless access.

The new standard in question is being developed through the IEEE's 802.21 working group. The idea is to solve a problem that plagues wireless users today. "If you have a device which has multiple interfaces -- one that is capable of hooking up to more than one network time -- today if you disconnect from one network and switch to another, everything stops," explained Intel's David Johnston, interim chair of the IEEE 802.21 Working Group.

The 802.21 standard hopes to remedy this by making it possible to roam not just from one 802-based network to another, but also between 802-based networks and 3G cellular network.

With the coming of dual 3G/802.11 handsets there will likely be consumer demand for such a capability in the not too distant future. Other devices likewise will become available that will spur interest in seamless roaming. "There are compelling reasons from the point of view of the product manufacturers, who want to make their devices more useful to their customers," said Johnston.

At the same time, the steadily growing popularity of wireless LAN could further drive consumer interest. Finally, the idea of seamless handoffs could become vital as wireless networks become more readily enable to support real-time applications such as video transport, which are highly susceptible to session interruption

"We will definitely need to provide this handoff capability," predicted Luc Roy, senior director of product management at Chantry , a producer of wireless LAN hardware and software. "Look at the way you work and play. If I am working in the office and I go get coffee somewhere else, I want a way for my connectivity to be maintained as I go from one environment to another."

While most players do anticipate the demand, the business side of how 802.21 will be implemented in the marketplace is far less clear.

Consider first the economics of wireless connectivity as they stand today. The pay-per-use hotspot model has yet to catch fire. The coming together of cellular service and 802.11 remains shrouded in the mist (despite deals like Proxim's latest). In fact, viable financial models in virtually all aspects of public Wi-Fi have yet to take shape.

Combine that uncertainty with a seamless roaming capability, and things are apt to get a whole lot more confusing.

"Consumers will see it as a way to save money, so everybody is going to be compelled to do it because of competitive factors. But how will it be done?" said Roy. "If I am a carrier and I force you to use your cell phone, I am making money. So why would I want to give up that revenue by handing you off to another network?"

Could there be revenue-sharing between cell carriers and LAN providers? Possibly. Alternate rate structures for cell clients who want to roam and those who don't? That seems less likely.

For wireless Internet services providers, meanwhile, the seamless roaming protocol could be a boon. As people leave their offices and roam without a break into public space, the WISPs would be well-positioned to pick up that traffic. How will they charge for the service? It's another question mark on the screen.

Before these business aspects can shake themselves out, the engineers at work on 802.21 still have some technical hurdles to overcome. From the users' point of view, the most likely concern will be in regard to security.

"Right now 802.11 has all kinds of encryption and authentication," said Roy. "Obviously we will want a hand-off service that can maintain that level of security."

Originally published on .

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