UWB Derails But Wi-Fi Stays On Track

Colorado Springs, Colo. -- Two critical decisions at last week's IEEE 802 meeting in Waikoloa, Hawaii, underscore the different paths possible when implementation choices appear to be at loggerheads. Because the 802.15.3a effort to develop a common ultrawideband standard could find no common ground between the multiband-OFDM and direct-sequence groups, the project authorization request was officially abandoned.

But in 802.11, the groups working on a higher-speed .11n standard agreed unanimously to a compromise draft, even though many outside the Enhanced Wireless Consortium expressed frustration that the Intel-led EWC held up a draft for two months with little apparent reason. The draft now moves to a March vote in Denver, followed by letter ballots in the summer. Although participants emphasized last week that no vendor should yet claim to sample or ship silicon that is "802.11n-ready," Broadcom Corp. scheduled a press conference to claim immediate "draft 802.11n" silicon. It did not claim a final-standard guarantee, however.

Greg Raleigh, chief executive of Airgo Networks Inc., said all camps will benefit from the fact that the IEEE does not allow bloc voting, a mandate that he said the EWC tried to disrupt by suggesting that its coalition could replace the 802.11n work.

"Consider all proposals on their merits, but don't create a new vehicle to bypass the process," he said. "Airgo definitely felt that the EWC was not the way the standards process should work, and we were glad to see the Wi-Fi Alliance make clear that it would not participate in EWC efforts outside 802.11."

Raleigh said that "the politics of the last week seemed to be related to EWC members wanting to be able to say that their implementations are compatible with the first draft, but we think it is absolutely irresponsible for vendors from any camp to claim that their silicon is '802.11n-ready.' "Bill McFarland, chief technology officer at Atheros Communications Inc., a member of EWC, said it was impossible to say whether the consortium ultimately accelerated or delayed the draft. "In the early fall, before EWC was announced, the joint proposal committee had not gone very far toward a draft. It was only after the EWC announcement [in October] that acceleration happened," he said.

McFarland said he expects many vendors to announce 802.11n silicon that meets the draft specifications, which is a fair claim if customers understand what is meant by a draft. "Saying anything more about 802.11 readiness implies a guarantee of future compatibility, which could do damage to the standards process," he said.

Mike Rude, director of technical marketing at EWC member Metalink Corp., said one thing was abundantly clear to him when he got to Hawaii: There is a "wide world of letters of 802.11 that we've all but forgotten about in this single-minded focus on 802.11n. Everyone needs to get the 802.11n development back to a state of normality so that we can get on with other work in areas like E-911 services and intelligent network management."

The 802.11n draft is similar to the original joint proposal agreed upon by three standards coalitions--TGn Sync, WWiSE and Mitmo--last fall, before the advent of the EWC. The proposal is based on the use of multiple-input, multiple-output antenna systems to achieve 100-Mbit/second payload rates, in conjunction with optional beam-forming methods, and space-time block coding for antenna redundancy.

Rude said the compromise draft "amounts to a substantial reworking of both the physical and media-access control layers, leaving plenty of room to grow and add features at both layers. This is a very inclusive and expansive document." Atheros' McFarland said that the MAC layer's ability to handle low-latency voice-over-Internet Protocol or streaming-video traffic was a key advantage, along with speed, over earlier 802.11 MACs.Such compromise was not to be found in the ultrawideband camps, however, where more than two years of stalemate between direct-sequence and orthogonal frequency-division multiplex proponents led 94.7 percent of the working group to vote in favor of disbanding. The WiMedia Alliance now is taking the position that its horse--multiband-OFDM-based UWB--will be the only wireless personal-area network standard that matters. Many observers point out that rival Freescale Semiconductor Inc. must find more direct-sequence adherents within the UWB Forum who are willing to challenge the alliance's position.

Eric Broockman, chief executive of MB-OFDM proponent Alereon Inc., said the disbanding of the working group represented an effort to "quit wasting everyone's time" after two and a half years of trying to find common ground. He compared WiMedia development to Bluetooth, in that products would be developed independently with the support of multiple IC vendors and OEMs, relying on the market to determine winners.

Martin Rofheart, director of UWB operations at Freescale, said it's unfortunate that the IEEE could not consider dual DS and MB-OFDM solutions.

G. Smith Anderson, chief executive of UWB startup Uraxs Communications Inc., said the WiMedia Alliance may have the advantage of more backers, but that doesn't mean a direct-sequence implementation of UWB would be an inherently bad idea.

"There's no question that the WiMedia Alliance has the collective power of a small country and could very well close the gap of any lead the UWB Forum generates," Anderson said. "Yet it's hard to tell how far behind they will be when they officially get to the starting line. What if the market decides that it wants to go to both UWB parties?"IEEE's 802 networking group is no stranger to such turmoil. Ten years ago, a special 802.12 working group was formed for a demand-access priority local-area network, called VG-AnyLAN, that was promoted as a better prioritized-traffic alternative to Fast Ethernet. Hewlett-Packard Co.'s weight assured the formation of 802.12 amid sit-down protests and civil disobedience at a 1993 IEEE meeting in Denver, yet the 802.12 working group shut down by 1997 after no company outside HP implemented the LAN.