Light appears at end of wireless LAN tunnel

The standard for 802.11n may be about to be ratified after a breakthrough proposal is accepted

An industry group seeking common ground on the emerging IEEE 802.11n high-speed wireless LAN specification has agreed on a compromise proposal that may form the basis of a final standard.

The joint proposal group, which includes backers of all the major factions in the fight over how to boost the speed and range of wireless LANs, approved a proposal by a unanimous online vote with two abstentions, according to Bill McFarland, chief technology officer at Atheros Communications, a semiconductor vendor that belongs to the group. The group will finalise the plan in a face-to-face forum in Kona, Hawaii. Barring any unforeseen problems, it will present the proposal to the IEEE 802.11n Working Group at its regularly scheduled meeting this week in the same location.

The 802.11n standard is intended to be the next step up in wireless LANs, offering real throughput of more than 100MBit/s and support for multiple VoIP and video streams. But the road to a standard has been long and rocky. The joint proposal group was formed in the middle of last year after none of the plans that had yet been proposed could garner enough votes for approval. The Enhanced Wireless Consortium (EWC) was created in October, with the backing of heavyweights including Intel, Cisco Systems and Atheros, and proposed its own plan.

The joint proposal group adopted the EWC's approach along with some elements from its own work, McFarland says. With this backing, the plan is likely to be approved by the official Institute of Electrical and Electronics Engineers (IEEE) task group when it votes, McFarland says.

Even Airgo Networks, which last year slammed the creation of the EWC and said it would slow down the standards process, voted for the proposal. The Palo Alto, California, company has been selling multiple-antenna technology for two years and counts among its customers Netgear, Buffalo Technology and Cisco's Linksys division.

"Airgo believes this is an extremely positive development for the industry because it marks the return to an open forum process where broad-based industry discussions will lead to a ratified IEEE 802.11n standard," Airgo says in a statement. Airgo President and Chief Executive Officer Greg Raleigh says over the past few months the EWC had gradually modified its own proposal to line up with that of the joint proposal group.

In addition to speed of more than 100MBit/s, which users probably will get all around a typical home, the technology includes features for improved quality of service, he says. Consumers should be able to transmit multiple streams of high-definition TV. With speeds in excess of Fast Ethernet, the technology now used most often for desktop LAN connections, small and medium-sized businesses will be able to go entirely wireless without paying a bandwidth penalty, McFarland says. In addition, new features in the standard proposal will allow for simultaneous calls on 50 or more VoIP phones, he says.

Under the proposal, 802.11n gear would use multiple antennas in both clients and access points to increase bandwidth and improve range by about 50%, McFarland says. Along with the antenna technology, it uses a coding method called space-time block codes that will make networks more reliable and lead to improved performance even if only the access point has multiple antennas, he says.

The proposal also includes features that speed up the way a LAN ensures packets have reached their destinations correctly, called packet aggregation and block acknowledgement. Instead of the network having to acknowledge each packet that comes through, it groups packets together and checks many at once, eliminating back-and-forth network signaling that could slow down the network, McFarland says.

The one major technology from the joint proposal group that was included is an error correction mechanism called low-density parity check mode, which should make networks more reliable and give them a longer range, McFarland says.

Even if the new proposal gets the required 75% approval vote at the IEEE 802.11n task group, the standard probably would not get formally sign-off for about a year, McFarland says. But partly because the standards process has taken so long and vendors have gained experience with the new technology, there will probably be pre-standard products on the market in the middle of this year that are mostly interoperable and can be upgraded to the final standard via software or firmware upgrade, he says.

The Wi-fi Alliance, which certifies interoperability of 802.11 products, does not give products wi-fi certification until after each IEEE standard is formally adopted.

The new technology will make wireless LANs far more useful to enterprises, which eventually are likely to go entirely wireless within buildings, says Craig Mathias, principal at advisory and systems integration company Farpoint Group, in Ashland, Massachusetts. This breakthrough will help bring a new standard by year's end, even though there are probably more debates ahead about details, he says.

"If that had not happened, we would probably not have had an 11n standard this year," Mathias says.

"We have more than enough spectrum now, but we can make better use of it with 11n, so we'll have more than enough capacity to meet the needs of any enterprise going forward," he says.

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