To the casual observer, it would appear that the proponents of mobile, Wi-Fi and WiMAX standards have been traveling down their own private paths for some time. Over the last five years, more often than not, the backers of these technologies have painted one another as competitive to their own causes.

They also have each moved at their own pace, with mobile public network standards often taking years to play out at the 3GPP and 3GPP2 standards organizations. Wi-Fi standards moved more quickly, with several often being juggled at once by the IEEE's 802.11 working group. The WiMAX standardization effort is still only just beginning.

Recent market and usage trends, such as the rapid user migration from wireline to wireless and the emergence of hybrid cellular/Wi-Fi devices and wireless voice over IP, prompted standards bodies to re-think what were once seemingly competitive and single-minded philosophies for standards development and see them as being on evolutionary paths that will not only make them complementary but also unified.

“In all of wireless, we're all using the same physics book,” said Eshwar Pittampalli, senior technical member of Bell Laboratories. “They cannot do anything much different than we can do. We all calculate value in the same way.”

One way to see that gradually converging evolution at work is to look at the technical standards issues being tackled in each wireless industry segment, both imminently and during the next few years.

“When the 3G standards effort started, everyone wanted one technology so that everyone could roam,” said Fran O'Brien, director of wireless standards development at Lucent Technologies. “But then, reality set in.”

The reality was that CDMA proponents favored a more incremental 3G evolution grounded in improvements to CDMA, while GSM backers wanted a quicker path to UMTS (also called wideband CDMA). Though the CDMA and GSM camps both have been able to successfully pursue their own 3G paths — and standards groups will continue to do the same in the short term — their efforts will gradually, but eventually, converge toward that one-network vision.

On the CDMA side, while an increasing number of wireless operators have already begun to adopt CDMA 1X EV-DO technology commercially, O'Brien said the standards process currently is still focusing on additions to that standard. “We're now looking at a Revision B, which would increase the reverse link bandwidth,” he said.

EV-DO Rev. B would result in roughly 3.1 Mb/s downstream and 1.8 Mb/s upstream, which would improve the technology's ability to support voice-over-IP (VoIP) services on its data-only channels as well as symmetrical video phone service.

In addition to the reverse link improvements, another item in Rev. B deals with adding multiple carriers to improve bandwidth — similar to a capability in the standard for GSM-based high-speed downlink pack access (HSDPA). “That will give the flexibility for bandwidth-on-demand kinds of services,” said Pittampalli. Rev. B of the standard probably will be finished by the third quarter of 2006.

Though the EV-DO Rev. B standard is probably not the end of further additions to the EV-DO standard, CDMA2000 standards developers also will focus over the next few years on the EV-DV standard, which is likely to be finished in 2006 or 2007.

In the GSM world, standards developers are progressing down a similar path to increase bandwidth and improve the capabilities of UMTS networks to support symmetrical high-bandwidth services. In the forum of 3GPP, the content contribution phase recently closed for UMTS Release 6, which includes high-speed uplink packet access (HSUPA), the upstream sibling of HSDPA that is designed to produce similar bandwidth results.

3GPP next will begin work on UMTS Rel. 7, which is expected to have further bandwidth improvement. The group also is holding several standards evolution workshops this year to get some ideas about what they should do next.

“People bring in various ideas for how to evolve the standard, and if it's a really wild idea, that's fine, but then we need to decide if there are business requirements that support it,” said O'Brien. With what O'Brien described as a friendly working relationship between the 3GPP groups and other wireless standards bodies, some of the ideas for future mobile standards revision are being borrowed from other sectors. For example, O'Brien said 3GPP eventually will look at multiple input multiple output (MIMO) technology, a concept derived from the Wi-Fi community that promises an efficient way to introduce greater bandwidth for Wi-Fi.

Eventually, both the CDMA and GSM technology camps will move toward their own unified vision, but ultimately, that vision might not have much to do with air interface standards. As carriers increasingly adopt IP multimedia subsystem (IMS) in the network cores, these architectures will support a variety of protocols, and it won't really matter whether the air interface is CDMA or GSM, O'Brien said.

“IMS will be common to all standards,” he said. “That's where the real convergence of technologies will happen.”

Just when you might have thought the alphabet soup of Wi-Fi standards couldn't get any chunkier, there are several new 802.11 specifications currently in the works. Frank Hanzlik, chairman of the Wi-Fi Alliance, outlined several standards in the works and their various stages of development, including the upcoming 802.11e standard, which supports quality of service for multimedia applications, including voice over Wi-Fi. 802.11e should be ratified next quarter, though several products with 802.11e capabilities already are available, having graduated from the Wi-Fi Alliance's Wireless Multi-Media (WMM) interoperability certification program.

Certifying products using information from the working standard will enable 802.11e to hit the ground running in the market, something especially important to Wi-Fi's reputation as a voice carriage method, Hanzlik said.

Next up for Wi-Fi will be the 802.11n standard. Two technology proposals vying for 802.11n standardization caused a split among IEEE member companies for most of last year, but Hanzlik said the standard is back on track and expected to be completed by November 2006. The 802.11n standard advances Wi-Fi throughput beyond 100 Mb/s, and through the employment of MIMO technology, also broadens its range.

There are no less than four other standards coming to fruition out of the 802.11 working group in the next three years (see table page on 20) — efforts that started within the last year at IEEE to come up with a mesh networking standard, a fast roaming standard and others. “We have a robust road map for the next several years,” Hanzlik said.

Aside from directly leveraging IEEE work, the Wi-Fi Alliance also is putting some of its own working groups in place based on emerging market trends and seeking to improve upon some of the basic standards. It launched a Wi-Fi Cellular Convergence (WCC) task group last fall. “It will be a streamlined certification program for all of the new converged devices coming out,” Hanzlik said. Independent of the world of standards development, semiconductor companies actually are doing most of the heavy-lifting, with their increasing ability to put multiple standards on a single chipset.

Hanzlik added that people working on Wi-Fi standards are ready to retire the old line of thinking that Wi-Fi and cellular are competitive enemies. “You never will have Wi-Fi everywhere you have cellular, but you will never have cellular that is as fast as Wi-Fi,” Hanzlik said. “It's like peanut butter and jelly — you want both on the sandwich.”

The 802.16 standardization effort is the relatively young cousin of cellular and Wi-Fi standards projects. The most recent version of the standard, 802.16 Rev. D, moved quickly through the IEEE, and though interoperability certification by the WiMAX Forum is happening a little more slowly than first expected, certification plugfests should happen this summer.

“The last 10% of the fight is always the hardest,” said Mo Shakouri, chairman of the forum's marketing working group.

With 802.16 Rev. D virtually certified and ready to be commercialized by early next year, the WiMAX Forum has turned its attention to the IEEE's 802.16e standard, which probably will be approved in May or June of this year.

802.16e lends mobile roaming capabilities to the metropolitan area networking standard and is being viewed by the 802.16 community as the evolutionary step that will allow the technology to mature and gain commercial viability and utility. “All of our energy right now is being spent on 802.16e,” said Shakouri.

Jeff Orr, senior product manager at Proxim, also said 802.16e will mark a point at which 802.16 technologies and standards begin to overlap with Wi-Fi and mobile. “When it gets ratified, there are going to be some really vast capabilities and potential markets waiting for it, but it also won't be operating in a vacuum,” he said. “Other technologies will continue to evolve.”

Like Hanzlik, Orr said the emergence of multi-standard devices will improve the ability of each technology to succeed on its own merits, but in a complementary way to the others. “Multi-mode devices will give users a choice,” he said. “They need to be removed from what's happening in the network and just be able to trust they have a reliable service, whatever the conditions might be.”

After 802.16e is commercialized, the next standards awaiting IEEE and the WiMAX Forum will be 802.16f and 802.16g, both of which will deliver new network and service management capabilities to the standard.

“Those standards are about three to five years out,” said Shakouri.

You would expect some level of healthy competitive feeling to persist between the wireless industry's various standards bodies, but more than ever, they seem comfortable working with each other and sharing information about where they stand on certain technical issues. “They're all connected organizations in a somewhat loose fashion,” Lucent's O'Brien said. “You see a lot of the same faces at different meetings.”

Seeing the same people and sharing documents has become especially common since each group has begun considering how to address intra-wireless convergence. What the wireless industry still might lack is a single common forum in which experts from each part of the industry can gather to debate these issues.

The closest approximation to that is the relatively new 802.21 working group, which began at the IEEE about 10 months ago. The group's work in progress has been called the Media-Independent Hand-over Specification.

“As you move from a Wi-Fi to 3G environment, you will need hand-off controls, and that's what this group is looking at,” O'Brien said. “With cellular, Wi-Fi and WiMAX, there is liable to be overlap between any one of the two from a network perspective. The catch is how it will be perceived. Each service provider will be able to choose the technology most appropriate for their audience.”

While convergence of different kinds of wireless networks seems daunting, the creation of multi-mode devices at the user end and the development of integrated systems like IMS at the core leave the network hand-off as the primary concern standards groups must tackle. It appears this challenge also can be solved by simply ensuring that the various wireless standards groups don't pursue single-minded evolutions in the next few years, something they already seem determined not to let happen.

Perhaps the addition of yet another standards forum — a convergence standards forum — would help, but it seems unlikely such an effort will be needed. Nor would it be a terribly popular idea.

O'Brien said, “Will all these groups come together in one massive organization? I hope not because that is a group that would move really slowly, which is sometimes the problem with standards groups. Right now, you have some smaller groups out there that are demonstrating how you can accomplish something if you set your mind to it.”

MORE WI-FI STANDARDS ON THE WAY

802.11i — Improved security, ratified in August 2004

802.11e — Voice and multimedia service quality, expected approval Q2 2005

802.11j — Special standard addressing market implications in Japan, expected approval late 2005

802.11n — 100 Mb/s-plus bandwidth and improved range, expected approval late 2006

802.11s — Wi-Fi mesh networking standard, under development

802.11k — Radio resource management protocols, under development

802.11r — Fast roaming for voice applications, under development

802.21 — Roaming between disparate wireless and fixed networks, under development