This month's cover story, "IP Mobility Ensures Seamless Roaming," tackles a subject that is near and dear to my heart, and which will soon be near and dear to your heart too if you plan to stay in wireless. About three years ago, when the fruits of the IEEE 802.11 Wireless LAN Working Group's labor were about to drop on all of us, I postulated among a group of peers that it would be no time at all until we "connect the dots" and have seamless connectivity between localized, WLAN hot spots and wireless wide-area networks (WWANs). They doubted it.
Months later, I chaired a panel at Comdex/Spring and asked that panel, which included Nokia and Ericsson, if they had any plans to introduce a dual-mode (WLAN, WWAN) phone. They scoffed at the idea. Of course, in hindsight it was kind of silly to ask top carrier business managers whether they would support a technology (WLANs) that was about to eat their pie. Anyway, the arguments against such a phone were fairly convincing. Words like cost, power consumption, size, billing management and security all fell trippingly from the skeptics' tongues. Some even ventured to ask, "Who would want to roam between the two networks?"
Fast forward three years, and, my, how the landscape has changed. WWAN carrier Voicestream has picked up the assets of defunct WLAN hot shot Mobilestar and turned it into T-Mobile in your local Starbucks; Ericsson has partnered with Proxim and Agere; AT&T, IBM and Intel have partnered to realize a nationwide network of WLANs; and now Motorola, Avaya and Proxim have partnered with the goal of eventually allowing seamless call roaming between an enterprise voice-over-Internet Protocol (VoIP) WLAN network and a circuit-switched WWAN.
Most of those announcements are interesting because they show that carriers have finally come—kicking and screaming—to the WLAN table. I find the last one, however (Motorola, Avaya and Proxim), particularly interesting as it's the first WLAN/WWAN partnership (of the year so far) to explicitly say that it intends to allow seamless voice calls between the two heterogeneous networks. To that end, Motorola will partner with a low-power WLAN IC manufacturer (yet to be named) to realize a dual-mode phone that can do so.
So now we have the partnerships and the technology intent in place that should see us roaming between WWAN/WLAN networks by next year, if Motorola is to be believed. But what does all this have to do with IP roaming? After all, it's a long way from VoIP in the corporate WLAN to full VoIP roaming from local- to wide-area networks.
What Basavaraj Patil describes in his IP Mobility piece is the next step for data; seamless transglobal, transnetwork IP roaming with fast handoffs. Now that companies like Spectralink, Symbol and soon Proxim have the VoIP latency and management problem almost licked for WLANs, it's natural to strive to resolve it for the wide-area network and achieve the ultimate dot connection of true voice/data IP roaming. It's a lot harder than the enterprise, but the potential gains make it inevitable.
Patrick Mannion
pmannion@cmp.com
