Dave Stephenson is at the center of one of the most important efforts in mobile networking, the move to shepherd smartphones and other devices among Wi-Fi hotspots safely and automatically.
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Stephenson has been a key player in the development of Hotspot 2.0, a set of specifications for how users can move among Wi-Fi networks operated by different service providers without having to look up network names and enter passwords. He remains chairman of the Wi-Fi Alliance Hotspot 2.0 Technical Task Group even though he just changed day jobs: After almost 14 years at Cisco Systems, Stephenson has joined Ruckus Wireless as a senior principal engineer.
Ruckus is something of a Wi-Fi upstart, a fraction of the size of Cisco, the dominant player. Stephenson heard the company's name come up frequently with carriers, talked to its top executives and was impressed with the leadership team, he said. He'll help Ruckus form a system architecture group to make sure all of the company's products work together as an overall architecture. But with its focus on wireless LANs for service providers, Stephenson said, Ruckus was also a good place to keep up his work on Hotspot 2.0.
"I do like to finish what I start, so that was a really good opportunity for me," Stephenson said.
What the Hotspot 2.0 group started working on in mid-2010 was nothing less than a way for users to roam from one Wi-Fi hotspot to the next just as easily as they can from one carrier's mobile network to another's. "We wanted it to be as automatic and secure as cellular," Stephenson said.
Mobile users can already move automatically onto Wi-Fi networks operated by their own carriers, but getting onto the many hotspots run by other service providers is usually harder. Beyond just the technical issues, carriers want Wi-Fi roaming agreements to work like cellular roaming deals, meaning that they get paid when another service provider's customers use their networks. Hotspot 2.0 is one of several initiatives aimed at making practical Wi-Fi roaming work.
Today, Hotspot 2.0 is in trials in labs and on carrier networks, and Stephenson expects to see commercial deployments with it in the second half of this year. A service provider group called the Wireless Broadband Alliance (WBA) and the GSM Association also are working to make it easier for service providers to set up commercial Wi-Fi roaming agreements.
Stephenson is optimistic about the future of Wi-Fi roaming, which should help carriers offload the growing volumes of data from their cellular networks and keep offering the roaming capability that subscribers are used to. He knows how much work has been required to make that possible, having been involved in several parts of the effort.
The Hotspot 2.0 group built on IEEE 802.11u, a mechanism for automatic handoffs under the 802.11 Wi-Fi standard that was developed starting in 2005, another project Stephenson was involved in. The 802.11u specification gives Wi-Fi network operators a standard way to automatically tell mobile devices about their roaming relationships, Stephenson said. With that information, a device can join the network using whatever credentials it may have for one of those networks.
Hotspot 2.0 combined that capability with other components including security, defining a way to protect all sessions on a hotspot using standard Wi-Fi encryption. Last June, the Wi-Fi Alliance used the complete Hotspot 2.0 standard to set up its Passpoint certification program, in which it tests and certifies Wi-Fi devices for interoperability under the standard.
Meanwhile, the WBA has been working on the back end to help make Wi-Fi networks capable of offering roaming. Under a program called Next-Generation Hotspot (NGH), the WBA has been overseeing trials for about 18 months in which devices roam among networks, said Shrikant Shenwai, CEO of the WBA.
In December, the WBA announced its Interoperability Compliancy Program, which set out a common set of requirements and procedures for Wi-Fi roaming. It includes guidelines for security, device authentication, network selection, and charging and billing. There is also a program for carriers to assess their compliance with the guidelines. If would-be roaming partners both comply, it should be easier for them to set up a roaming relationship, Shenwai said.
The WBA is also working with the GSMA to harmonize roaming systems for Wi-Fi and cellular, respectively. That ongoing effort should help carriers incorporate Wi-Fi into their regular accounting and billing systems, making it easier to set up roaming relationships with many service providers.
As an engineer, Stephenson said Hotspot 2.0 has faced only "routine" technical challenges, with the bigger issues coming from the differences between the cellular and Wi-Fi worlds. Education both ways has been needed, he said.
In the deployment phase of Wi-Fi roaming, the carriers themselves face the biggest challenges, Stephenson said. "They are big, have a lot of momentum to overcome, have to make sure via testing and trials that the Hotspot 2.0 technology is ready and that their networks are ready."