[MLB-WIRELESS] Single slow link can bog network: New Scientist

[rick]

sounds just like a add for 802.11g

----- Original Message ----- 
From: "Clae" <clae at tpg.com.au>
To: <melbwireless at wireless.org.au>
Sent: Saturday, August 09, 2003 3:44 AM
Subject: [MLB-WIRELESS] Single slow link can bog network: New Scientist


> http://www.newscientist.com/news/news.jsp?id=ns99994018
>
> Single slow user can throttle wi-fi network
> 18:27 04 August 03
> NewScientist.com news service
>
> A single user with a slow connection to a wireless network can
> significantly degrade the overall service to everyone using that
> wi-fi access station, new research shows.
>
> Researchers from the Institut d'Informatique et Mathématiques
> Appliquées de Grenoble, part of France's CNRS, studied the
> performance of networks using the popular wi-fi standard 802.11b.
>
> They found that if a single user's connection is slowed, perhaps
> because they are far from the access station, every user can suffer
> reduced data transfer speeds. "That computer may degrade the nominal
> bit rate," Duda told New Scientist.
>
> This is because of the way bandwidth is allocated to each user by the
> wi-fi standard's access protocol, called Carrier Sense Multiple
> Access/Collision Avoidance  (CSMA/CA).
>
> If just one person is unable to connect at the optimal speed, the
> CSMA/CA protocol throttles back the maximum connection speed for all.
> This guarantees that any user, no matter what their access speed, can
> get stable access to the network.
>
> If the faster users were not limited and the network approached its
> maximum bandwidth, the slower user's service would be the first to
> degrade to the point of uselessness. However, the speed limit could
> mean that the best connected users see their transfer speeds cut from
> 11 Mb per second to about 1 Mb/s.
>
> Duda says users may not notice a network snarl-up unless they are
> using a lot of bandwidth by, for example, downloading large files.
> And he adds that some manufacturers have already begun to address the
> issue with their latest wireless networking hardware.
>
> But it is particularly important, he says, that devices using the
> newer and higher-bandwidth networking standards such as 802.11g do
> not suffer from the same problem.
>
> "In general, designers should be aware of this problem," says Mingyan
> Liu, a wireless networking expert at the University of Michigan in
> the US. He says it is a question of balancing the stability of the
> network for all with the quality of service delivered to the majority
> of users.
>
> "But it would be worthwhile for researchers and engineers to come up
> with mitigating methods," Lui told New Scientist.
>
> Will Knight
>
> -- 
> ---
> "People that are really very weird can get into sensitive positions and
> have a tremendous impact on history. - Dan Quayle
>
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