IEEE 802.11n spec set for first draft vote

[David Farber <dave () farber net>]

Begin forwarded message:

From: Dewayne Hendricks <dewayne () warpspeed com>
Date: January 22, 2006 4:40:37 AM EST
To: Dewayne-Net Technology List <dewayne-net () warpspeed com>
Subject: [Dewayne-Net] IEEE 802.11n spec set for first draft vote
Reply-To: dewayne () warpspeed com

IEEE 802.11n spec set for first draft vote
Wi-Fi products at 100Mbps throughput should be shipping by midyear
By Ephraim Schwartz

January 18, 2006
<http://www.infoworld.com/article/06/01/18/74302_HN80211n_1.html? 
source=NLC-WIR2006-01-19>
After much wrangling between opposing interests among the members of  
the IEEE, a first draft for the Wi-Fi IEEE 802.11n specification will  
be voted on by the membership later this week.

The compromise draft, which represents the work of a joint sub- 
committee, is expected to pass, according to Bill McFarland, a member  
of the IEEE and CTO at Atheros.

Although it is now water under the bridge, the original debate  
divided the group between those who believed that ratification of the  
specification was taking too much time, represented by Enhanced  
Wireless Consortium (EWC) -- made up of many of the mainstream Wi-Fi  
players such as Atheros, Cisco, Intel, Symbol, and Toshiba -- and  
those that wanted more in the way of power management for handsets  
and VoIP devices, including Motorola, Nokia, and Samsung.

From first draft to final approval will take about a year. However,  
802.11n products are expected to ship by mid-year, said McFarland.

"Long before final ratification the draft becomes stable and once the  
core is extremely consistent, it makes people feel comfortable to  
design products," said McFarland.

The benefits of 802.11n are quite dramatic, with performance at the  
physical layer expected to reach, in initial products, 300Mbps using  
two antennas, and over time scaling to 600Mbps using four antennas.

Actual throughput at the application level is expected to be 100Mbps,  
equivalent to 100/10Base T wired Ethernet networks.

The range of 802.11n is also expected to improve by as much as 50  
percent, according to McFarland, by using Beam Forming technology  
that focuses energy in a particular direction on both send and receive.

Another technology called Space Time Block Coding (STBC) will reduce  
signal dropout by using multiple antennas for redundancy.

This technology in particular is key to enhancing the VoIP user  
experience.

Finally, packet aggregation and block acknowledgement protocols will  
reduce power consumption and data collisions in a congested  
environment by building a so-called super-frame to send multiple  
packets simultaneously.

The protocol allows designers to create a beacon that tells other  
devices to be quiet and tells all devices using the same access point  
when their timeslot is and when they can transmit. This prevents  
collision. It also allows devices to stay asleep saving power until  
it is their time to send or receive.

One of the first benefits will be for those providers looking to  
offer what is called in the industry "triple play service provision"  
-- voice, video, and data.

While it may not immediately replace wired Ethernet for the  
enterprise, for smaller companies using 100/10Base T, IEEE 802.11n  
may prove to be a less expensive alternative.

Weblog at: <http://weblog.warpspeed.com>



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