IEEE 802.11n working group approves draft 2.0

Next draft of IEEE specification will go out as version 2.0 by the end of the month

After much debate and a lot of contention among the overall IEEE membership, the all-important IEEE 802.11n working group has given its stamp of approval to the next draft version of the specification.

Temporarily dubbed draft version 1.10, it will go out as version 2.0 when it is released to the full IEEE 802.11n committee, about 400 strong, by the end of the month.

According to Bill McFarland, a member of the working group just back from the London meeting where version 1.10 was approved, all of the contending parties who caused the original delays appear to be satisfied.

This includes the handset and handheld manufacturers who wanted more consideration given to low power consumption and VOIP capabilities, consumer electronics manufacturers who wanted the standard to accommodate more than access points, and the major hardware network and chip manufacturers who wanted to put the 802.11n spec on a fast track to approval.

Manufacturers like Atheros, Intel, and Apple and their customers will be happy to hear that version 1.10 is compatible with the pre-802.11n products they have already created.

"It will only require a minor firmware upgrade for complete compatibility," said McFarland.

The major change was around the implementation of the 40MHz channel. It has been adjusted to accommodate older 2.4GHz band devices, which may be confused by the wider channel bandwidth.

The new spec calls for the use of two 20MHz bands. Under version 2.0, the system will scan the environment looking for legacy devices that might not understand the wider bandwidth, in which case the 802.11n device will back off and send data over only a single 20GHz band. While this would slow down overall data throughput to a single 20MHz channel, 802.11n's MIMO (Multimedia In Multimedia Out) technology will still give 802.11n faster performance.

A second change will allow an 802.11n device to check to make sure both channels are clear before sending data. A third change allows devices, such as Bluetooth-enabled devices, to send a signal saying it does not want to receive data in the 40MHz mode.

In order for a Bluetooth device to send this alert, it must also include wireless LAN, which, for example, the Apple iPhone includes.

Wireless LAN IEEE 802.11a devices in the 5GHz band will be able to use the full 40MHz channel.

While the spec is now much closer to completion, there are still a number of steps that must be taken before final approval.

The 2.0 draft spec is expected to be mailed to the membership for comments and voting by the end of January. Voting is expected to be completed on version 2.0 by the end of March with a new draft, version 3.0, ready by the end of May.

At that time, draft 3.0 would be created, and if 75 percent of the members approve, the spec will go into recirculation balloting.

"At this point, the documents are considered stable," said McFarland.

Assuming 3.0 is approved, it will go out for "sponsor" balloting by January 2008.

"The sponsor ballot process and completion takes time," said McFarland.

Final approval, called the publication date, is expected by October 2008.

Benefits of 802.11n include higher throughput (about 120Mbps real world) than the current standard and a range that's 50 percent longer. Also, because of its multiple antennas that can stitch together a fractured signal, it eliminates many indoor spots where the signal would normally be dropped.