A year after its acquisition of AT&T Wireless, Cingular Wireless has emerged from integration mode and has launched its two most ambitious network projects since the company originally formed from the cellular networks of BellSouth and SBC Communications.

Last week, it turned on the world's first three live high-speed downlink packet access (HSDPA) markets, positioning Cingular's network to become what is presumably the fastest 3G network in the world. Also, the company announced plans for implementing an IP multimedia subsystem (IMS) architecture in its core, creating a separate control plane and applications layer that will allow it to build and launch new converged 3G services.

Despite the aggressive network moves, Cingular is still taking a fairly conservative approach to services. Unlike other carriers, it hasn't announced a flagship service, such as push-to-talk or video, to run over its new next-generation architecture (though Cingular officials said several services are now in the planning stages). It hasn't yet announced IMS-based fixed/mobile convergence (FMC) service with its RBOC parents BellSouth and SBC, though SBC also last week announced it would launch IMS with Lucent Technologies, the same vendor Cingular is using.

Even its HSDPA network, now carrying voice and data in three of the UMTS markets acquired from AT&T Wireless, isn't utilizing HSDPA's expanded bandwidth capabilities. Cingular isn't launching any HSDPA handsets or data cards until after its main rollout of 3G services later this year. And even then, Cingular will build up gradually to the full-capacity of the network, adopting what Cingular Chief Technology Officer Kris Rinne described as a “good, better, best” approach that migrates its customers through different phases of HSDPA as better technology and handsets become available.

Kelly Williams, executive director of technology strategy for Cingular, said Cingular is just trying to be realistic with its next-generation approach to avoid past industry pitfalls of making unrealistic 3G promises.

“Carriers have to be careful how much they're banking on IMS,” Williams said. “In that sense, we're being conservative.”

As for future services, Cingular has many ideas it's exploring, but for now, it's deploying the basic control plane elements that make up the heart of the IMS network: Lucent's Unified Subscriber Data Server, which serves the role of the home subscriber server for the architecture, and Lucent's Session Manager, the call session control function that acts as the “traffic cop” for the entire network. Although those two elements will be critical to managing any IMS service, in Cingular launches they don't contain or run services themselves. Williams said Cingular hasn't picked vendors for applications or features servers, media gateways or gateway controllers or individual applications developers. Nor is Cingular opting to go with an overall systems integrator like Ericsson or IBM to help implement the architecture and applications — an approach adopted by Sprint and other carriers.

“We don't view putting these control plane elements into the network as something we need help with,” Williams said. “It isn't rocket science.”

Cingular hasn't settled on specific applications, but Williams said his team is investigating point-to-point video services such as phone-to-phone video conferencing. The beauty of such an application is that it wouldn't be tied to a particular service. Since video would be an another application connected to the control plane through session initiation protocol (SIP) signaling, Cingular could attach a point-to-point video feature to virtually any application — mobile messaging service, customized voice mail, even push-to-talk. It's just a question of how and when to deploy it, Williams said.

Cingular is also considering an unlicensed mobile access (UMA) service to allow offload of voice traffic onto a public Wi-Fi network. Such a service could evolve into a FMC service with its corporate parents BellSouth and SBC, using IMS as the common link between the cellular network and a SIP-based client accessing the public Internet. But the standards for that kind of SIP-based service are not yet complete.

Just as Cingular is deploying an IMS network in anticipation of future services, the carrier is turning on an HSDPA network, the full potential of which it doesn't expect to reach for years. Rinne said that the first HSDPA devices will be PC data cards, which will be available at the launch of Lucent-, Ericsson- and Siemens-built networks in 15 to 20 markets by the end of the year. The initial UMTS handsets won't take advantage of HSDPA's added capacity. But in 2006, Cingular will offer HSDPA phones supporting 400 kb/s to 700 kb/s.

From there, Cingular will focus on increasing the overall network capacity, rather than on data-speeds available to individual users, Rinne said. HSDPA is a phased technology, with several releases allowing increasing capacity over an individual carrier. Starting with category 1 and a theoretical ceiling of 1.8 Mb/s, HSDPA advances through 11 more releases, eventually supporting theoretical speeds as high as 14.4 Mb/s. Cingular is starting with handsets embedded with lower-category chips, capable of 1.8 Mb/s. The higher-category handsets will be introduced as they are available, Rinne said, but the development time between releases is fairly quick. Qualcomm earlier this month announced it has begun sampling HSDPA silicon supporting theoretical speeds of 7.2 Mb/s. With chipset technology maturing so quickly, Cingular will be able to upgrade the capacity of the network equally as quickly, Rinne said.

“The infrastructure we're deploying now supports the entire range of HSDPA up to 14.4 Mb/s,” Rinne said. “We just have to launch the handsets as they become ready.”

Cingular anticipates adding enough capacity to the network through handset upgrades that data capacity over the 10 MHz of spectrum allocated for UMTS in its 3G markets should hold out until well into 2008 or 2009. In fact, Rinne said Cingular would probably expand the UMTS network for its voice capabilities before it hits its capacity ceiling. Unlike the current generation of CDMA 1X EV-DO, UMTS supports voice. As Cingular achieves higher penetration levels of UMTS handsets, it can grow its voice capacity with the UMTS network, switching frequency bands once allocated for GSM to UMTS.

“Over time, that's exactly how we plan to build out our [voice] networks, adding voice and data capacity simultaneously,” Rinne said. That expansion could occur as early as 2007.

Cingular is also planning ahead for its first trials of HSDPA's sister technology, high-speed uplink packet access (HSUPA), culminating in a launch following a dual network and handset upgrade path. HSUPA trials could come by the end of next year, Rinne said, and Cingular's vendors are already preparing.

“That timing would work very well with our HSUPA product development,” said Toby Seay, the Ericsson vice president responsible for the Cingular account. “We'll certainly be supporting trials in HSUPA in that time frame.”

The big question, however, is how Cingular will integrate its new technology into its parent companies' networks, if at all. While both BellSouth and SBC will deploy IMS (see story on page 32), so far they are proposing converged services only over their own networks, without wireline/wireless bridging.

SBC last week also selected Lucent as its IMS provider, which would make integrating with Cingular's IMS architecture that much easier. Both SBC and Cingular said their decisions to select Lucent were made entirely independently of one another. SBC's IMS rollout is part of Project Lightspeed, its fiber-to-the-home initiative, allowing the carrier to integrate its voice, video and data offerings into services like on-TV-screen caller ID and find-me/follow-me voice services, an SBC spokesman said. But just because there are no announced plans with Cingular for a converged offering doesn't mean there aren't discussions. “We obviously work very closely with Cingular,” the spokesman said.