Fixed-to-Mobile Substitution: UMA Now, IMS Later

By Mae Kowalke

TMCnet Associate Editor

 

In a recent article, TMCnet presented one perspective on the UMA vs. IMS debate, namely that the first technology has limited functionality and carriers who adopt it may find themselves locked into a bad situation as IMS deployments become more widespread.

 

For another look at this topic, we followed up by speaking with Steve Shaw, Director of Marketing at Kineto Wireless, who expressed a different view: that UMA is the only fully developed technology available today for carriers who need to roll out fixed-mobile substitution (aka convergence) solutions.

 

 

Shaw described UMA, or Unlicensed Mobile Access, as “a mobile operator specification.” Ratified during 2005 by 3GPP, the specification has seen an overwhelming amount of interest in the operator community.

 

That interest is driven by business realities: the telecom industry has become even more competitive since the advent of Voice over IP, or VoIP, and many operators now need to find new ways to differentiate themselves.

 

One way to do that is to offer a fixed-to-mobile substitution (FMS) system, sometimes also referred to as fixed-mobile convergence. This type of service lets mobile phone users roam seamlessly between two service networks: VoIP delivered by WiFi (News - Alert) inside the house, and voice delivered on a traditional cellular network outdoors.

 

Probably the biggest advantage of such a system is price: inside the home, voice signal is routed over the public Internet, so the cost to operators is essentially nil—and those savings are passed on to consumers.

 

UMA enables operators to send mobile voice signal over the Internet by fooling the network into thinking that a WiFi router is another cell tower, Shaw explained. Compatible handsets recognize the WiFi access point, resulting in seamless handover of service that does not affect the way users interact with their phones.

 

IMS is described in more detail below, but for now here is a basic explanation of how an IMS-based FMS system works: service is handed off to the IP network, and is picked up by a SIP client (interface) running on the handset. Depending on how it is designed, that client may look and behave differently than the interface used for outdoor service.

 

 

Of course, FMS solutions can also be developed using IMS, or IP Multimedia Subsystem (News - Alert), a group of mobile network specifications also developed by 3GPP.

 

Shaw explained that carriers first started building IMS in order to standardize the process for wirelessly delivering the types of data services that IP enables—including push-to-talk, videoconferencing, and mapping.

 

As development of IMS got underway, Shaw told TMCnet, carriers realized that it could have applications for traditional voice services as well, and the specifications grew to become a potential enabler of FMS.

 

Today, IMS is generally viewed as the way in which all networks—both fixed and mobile—will evolve to become completely IP-based.

 

The problem is that, although IMS has lots of promise for many applications (including FMS), it is not yet fully developed and the number of specifications involved is still growing.

 

“IMS isn’t a specification, it’s a journey,” Shaw said

 

He added that IMS eventually will solidify and deliver on its promise, but that probably will take another decade or more.

 

Although beginning the transition to IMS-based systems now may theoretically be a good long-term investment, for many carriers the cost simply cannot yet be justified. That leaves them looking for a non-IMS way to cost-effectively deliver FMS now.

 

 

As a fully-developed specification capable of delivering low-cost FMS service today, UMA is the no-brainer choice for most operators, Shaw told TMCnet.

 

“UMA is unbelievably inexpensive and low-impact. There is really nothing else that has the same approach,” he said.

 

UMA isn’t perfect, of course, and cannot provide all the functionality that IMS promises to someday deliver.

 

Shaw noted that some companies who build IMS-based applications have positioned UMA as being a temporary solution, and one that operators will regret investing in because new specifications will come along and render UMA obsolete.

 

That could end up being true, but operators still need a way to cost-effectively deliver FMS now, and for the time being UMA is the only specification available to do that.

 

Shaw added that 3GPP has started work on a second-generation version of UMA—dubbed eUMA—that will add more functionality including the ability to natively connect into high-speed data portions of 3G networks.

 

 

The debate between UMA and IMS is really misplaced, Shaw told TMCnet. That’s because IMS is a set of many specifications, while UMA is a single specification. He emphasized that comparing one specification out of thousands to the evolution of all networks toward IP is not a productive exercise.

 

Shaw said that Internet Protocol, or IP, has had a huge impact on the telecom industry—it has helped lower costs, improve performance, and encourage innovation. Today those benefits touch not just wireline service, but wireless as well.

 

“UMA is a huge step toward bringing IP to the mobile network,” he said.

 

 

It takes more than just UMA’s fully-developed status to make FMS commercially viable for carriers, Shaw pointed out. Adoption of the new technology also requires the production of competitively priced controller units (needed to set up UMA-based FMS systems) and compatible handsets.

 

The critical mass now seems to have been reached for both those market segments.

 

Shaw said that UMA controllers are now being manufactured by Nokia, Motorola, Ericsson, and Alcatel. Plus, compatible handsets are coming out from Samsung, LG, Nokia (News - Alert), and Motorola (News - Alert).

 

Because there still is not a solid definition of how IMS-based FMS systems will work (e.g. form and function of the SIP-based interface), equipment manufacturers do not yet have the information they need to competitively produce IMS-compatible phones.

 

 

There does seem to be some confusion in the telecom industry regarding how UMA, IMS, and SIP inter-relate, Shaw said.

 

First, to once again define UMA, Shaw explained that it is an access-layer specification, similar to DSL or GSM.

 

“It really does not care what applications are running on it,” he said. That includes SIP (Session Initiation Protocol (News - Alert)), the signaling protocol around which IMS specifications are wrapped.

 

Because UMA is unaware and uncaring of the applications run over it, operators can—if they want—provide SIP-based applications that roam between the in-home WiFi access point and the outdoor cell network.

 

IMS, as a group of specifications, represents a different network layer than UMA. The two inter-relate because “IMS is agnostic of access technologies,” Shaw explained.

 

Given all the facts, Shaw said that UMA and SIP are complementary rather than competitive.

 

 

Shaw sees a bright future for UMA, which he said is the best tool available right now for deploying FMS services.

 

He said that Telecom Italia is planning to launch UMA-based services in July, and Orange will do the same in the fourth quarter of 2006. Additionally, T-Mobile has been very vocal about possibly adopting UMA.

 

“When a company like Orange starts saying UMA is how they're going to deliver services indoors, it makes everyone sit up and take notice,” Shaw told TMCnet.

 

Equipment vendors and handset makers are also taking note, as mentioned earlier.

 

The industry’s first conference specifically about UMA—hosted by Informa—is scheduled for this summer (June 27-29 in Barcelona).

 

“UMA must be real if there's a conference about it,” Shaw quipped.

 

 

UMA may be the best tool for FMS today, Shaw said, but that doesn’t mean IMS is without promise.

 

“There's definitely a place for IMS in fixed-mobile convergence,” he emphasized.

 

Even though IMS started out as a set of mobile specifications, Shaw told TMCnet, right now it is mostly being championed by fixed-line operators.

 

He said that’s because IMS-based services are viewed as one way to fight back against the competition of mobile operators’ FMS offerings.

 

 

Shaw’s company, Kineto Wireless, was founded in 2001 by a group of engineers who specialized in mobile technologies. Kineto’s focus today is on improving coverage and lowering costs for wireless services.

 

Even more specifically, Kineto’s UMA-compliant Cellular/Wi-FI Convergence Solution provides a low-cost way for operators to offer FMS service.

 

Shaw noted that the growth of VoIP has helped drive the merging of fixed and mobile lines. FMS is appealing because it lets operators offer some minutes (those used in the home on a cheap IP network) at a lower rate, a great way to gain and retain customers.

 

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Editorial Note: For more information about UMA, IMS and fixed-to-mobile substitution, see Kineto’s whitepaper How UMA Enables Broadband IMS, and Steve Shaw’s recent IMS Magazine article, UMA and IMS: In Network Evolution.