A group of wireless vendors, led by customer Verizon Wireless, are proposing a "next-generation network architecture" for mobile networks that attempts to fill in gaps in an evolving industry specification for converging IP-based wireline and wireless services.
Cisco, Lucent, Motorola, Nortel and Qualcomm have been quietly working with Verizon Wireless over the past year to develop a framework to extend the 3GPP's IP Multimedia Subsystem (IMS) specification. Among other enhancements, the framework -- called Advances to IMS, or A-IMS -- is intended to facilitate improved support for non-SIP devices, applications and services, end-to-end security, and wireless VOIP QoS.
"Once we identified these issues that we wanted to address, we decided the best way to be a catalyst here was to work with a group of vendors that we had a good relationship with," says Bill Stone, executive director of network strategy for Verizon Wireless, who adds that Verizon Wireless assembled the "best and brightest" engineers and strategists for the effort.
"In no way is this intended to be a closed solution," Stone asserts. "Our intent is to bring it forward, to make it public and to ask others to take a look at what we've done and think of ways to improve upon it...and standardize it."
The effort, however, presents yet another activity to define an architecture for next-generation, converged fixed/mobile IP networks and services. These multiple developments could fragment the industry, further delaying delivery of these advanced services to businesses and consumers, observers note.
Conceived by the 3rd Generation Partnership Project (3GPP), IMS is an architecture that essentially takes the place of the control infrastructure in the traditional circuit-switched telephone network, separating services from the underlying networks that carry them. It uses the Session Initiation Protocol (SIP) as its signaling method for setting up calls and handling data sessions, and enables services such as text messaging, voice mail and file sharing to reside on application servers anywhere and be delivered by multiple wired and wireless service providers.
IMS is generally accepted by the industry as a core component of virtually all next-generation, IP-based communications networks for SIP-based applications. It is designed to assure standardization of multimedia services across all interconnected wireless and wireline networks.
But it is still evolving.
"The architecture is still generic," says Doug Wolff, vice president and general manager for Nortel's CDMA operations.
Verizon Wireless -- which is not a member of the GSM-focused 3GPP but of the CDMA-focused 3GPP2 -- noted shortcomings in the IMS architecture two years ago, Stone says, most notably in legacy non-SIP elements, security and wireless VOIP.
"In our opinion, the IMS standard really left security to be addressed on a link-by link basis or layer-by-layer basis," Stone says. "There's no end-to-end security solution baked into existing IMS standards."
The task force has completed a 300-page concept and architecture document that it plans to share with the 3GPP and other industry standard consortia. Stone says A-IMS is also intended to simplify the complex IMS standard.
The elements of A-IMS include:
Bearer Manager (BM): Allocates resources and manages bearer traffic to meet customer's service quality requirements. The primary functions include policy enforcement, mobility management, security, accounting, and access control.
Policy Manager (PM): A primary policy decision point for network policies, deciding the ways that the underlying network supports applications on behalf of subscribers and visitors to the network.
Application Manager (AM): The SIP services platform in the network that authorizes access to SIP services, provides SIP registration and authentication functions, and is responsible for the invocation and management of SIP-based features.
Security Manager (SM): Responsible for monitoring the network for security threats and responding to them in real time, making decisions on what devices are allowed access to the network based on their posture -- a measure of the safety of the device based on the freshness of its software patches and security features.
Services Data Manager (SDM): The main repository of subscriber and network control data and collects and stores charging data for the network.
Yet the A-IMS work is in addition to several efforts underway to arrive at the next-generation converged fixed/mobile infrastructure. The European Telecommunications Standards Institute (ETSI), for example, is developing its TISPAN specification for such an environment, which also includes support for non-SIP network elements and applications.
Also, A-IMS lacks the participation of Verizon Wireless rivals Cingular Wireless and Sprint Nextel, and partner Vodafone. Cingular has tapped Lucent as the IMS supplier for its 3G network, which is based on UMTS/HSDPA, a competing technology to Verizon Wireless' EV-DO.
Vodafone, based in Great Britain, is involved in the recently formed Next Generation Mobile Network Forum, which also includes T-Mobile, Orange, KPN, NTT DoCoMo and China Mobile. Cisco is also involved in this forum, says Jonathan Hindle, senior manager in Cisco's Worldwide Mobile Marketing Organization.
Stone says Vodafone is aware of the A-IMS work and that the technical merits of it "resonates with them." While not specifically mentioning the A-IMS task force, Stone said he expects Vodafone to continue to participate in the overall industry standards process.
Stone also says A-IMS is "technology agnostic," and not a CDMA EV-DO version of IMS to face-off against a GSM/UMTS version of the architecture.
Stone and Hindle downplayed the potential for further industry fragmentation of IMS.
"We're bringing forward solutions that we hope will be considered based on technical merit, not where they originated from," Stone says.
Adds Hindle: "There's still a negative reaction from other people who feel they've not been included. I think there's also a level of pragmatism that's enabled the cellular industry to cooperate where it makes business sense."
Yet Cisco, on more than one occasion, has referred to IMS as a "walled garden" that locks customers in with particular service providers. Hindle says walled gardens will still exist but that A-IMS will provide more flexibility in allowing service providers to offer a wider array of options through partnerships.
"A-IMS will allow them to not be limited by having to own all of the services," he says. "It gives them a lot of flexibility to create whatever the right business model is going forward."
Lucent says A-IMS is in "lockstep" to where the industry is headed.
"I'd be very surprised" if A-IMS is received coolly by Verizon Wireless' competitors and others in the industry, says John Marinho, vice president of corporate strategic marketing for Lucent. "It's built upon work already done, there's nothing that supplants (work already completed). It's intent is to be inclusive."