Subject: [NEXTEL-1] Final 802.11g draft standard throttles data rates down

From: [email-masked]
Date: Fri, 23 May 2003 11:10:20 -0400

Final 802.11g draft standard throttles data rates down

By Bob Brewin
MAY 22, 20003

The Institute of Electrical and Electronics Engineers Inc. (IEEE) has
approved a new and final draft standard for 802.11g wireless LANs that
will have a true throughput for Internet-type connections of between 10M
and 20Mbit/sec., far lower than 54Mbit/sec. raw data rate initially
billed for the standard.

The standard was approved by the IEEE on May 15 but won't be made
publicly available until members of the IEEE 802.11 working group ratify
it next month, according to Sheung Li, a product line manager at Atheros
Communications Inc., a Sunnyvale, Calif-based WLAN chip manufacture.

Li said the lower actual vs. raw data rates for 802.11g arose from the
need to assure backward compatibility with millions of existing 802.11b
Wi-Fi client devices and access points that operate in the same 2.4-GHz
frequency band. The 802.11g standard includes built-in protection
mechanisms to ensure that the devices don't interfere with older 802.11b
devices. That means the 11g systems will need to transmit an electronic
warning to 11b devices that a 11g device is operating, a warning that is
enough to cause a cutback in actual throughput, Li said.

Li estimated that that in mixed 802.11b and 802.11g networks running
standard TCP/IP Internet protocols, this will reduce actual throughput
to 10Mbit/sec. -- while pure 802.11g networks will have actual data
rates of around 20Mbit/sec. Li pointed out that even at these data rates
the 802.11g devices still outperform 802.11b devices, which have a raw
data rate of 11Mbit/sec. but an actual throughput of about half that
speed.

Randy Conklin, director of operations for Broadband Central, a wireless
Internet service provider based in Draper, Utah, that serves seven
western states with a network built around wireless LAN gear, said
the10Mbit/sec. data rate for 802.11g isn't good enough for advanced
applications such as voice over IP or video. To support those
applications, Broadband Central would need at least 20Mbit/sec. data
rates, he said. As a result, the service provider will look to deploy
pure 802.11g service offering the faster data rates.

Pat Hurley, an analyst at TeleChoice in Boston, said companies looking
for higher speeds from their WLANs should consider using hardware based
on the 802.11a standard, which provides a real data rate of about
24Mbit/sec. in the 5-GHz band. Hurley said companies starting from
scratch could consider a combined 802.11a/g network, which would offer
two options for high data rates in a campus environment as well as the
ability to access 802.11b hot spots while on the road -- since 802.11g
clients can operate with 802.11b access points.

However, 802.11a devices operate in a different frequency band than the
11b and 11g devices, meaning they aren't compatible with them.

Atheros has already shipped prestandard 802.11g chip sets to WLAN
manufactures, such as D-Link Corp. in Taipei, Taiwan. Li said end users
would only need to download a software driver to update their 802.11g
cars with the new standard.
Jeff Abramowitz, director of wireless LAN marketing at Broadcom Corp. in
Irvine, Calf., which supplies WLAN chip sets for PC cards used by Dell
Computer Corp., said end users of prestandard Broadcom 802.11g chips
will also need to download new drivers to make their older gear
compatible with the final IEEE standard.

Another computer maker, Apple Computer Inc., has also released devices
using the 802.11g standard -- and has promised that its customers will
also be able to upgrade to the final standard once it's in place.

Bill Carney, director of wireless LAN marketing at Texas Instruments
Inc. in Dallas, said his company has decided to wait until the IEEE
ratifies the 802.11g standard and expects to start shipping
standard-compliant chip sets in July.
Brian Grimm, spokesman for the Wi-Fi Alliance in Mountain View, Calif.,
said the alliance expects to start testing and certifying 802.11g
products in June.
Source: Computerworld

http://www.computerworld.com/mobiletopics/mobile/story/0,10801,81450,00.html?nas=PM-81450

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