I've read an article about some bluetooth devices. Bluetooth is a short-range radio
standard that IBM, ericson, nokia, intel, toshiba, and many other vendors of computer,
networking, and appliance industries are designing. Currently anyone can join
bluetooth (nearly 2000 companies right now) as long as they grant all other members a
royalty free license to use any bluetooth technology developed. Bluetooth devices
have small chips that talk to other bluetooth devices. The range standard is 10m.
For example, a practical application will be a headset and a walkman or phone. The
headset is wireless. The bluetooth chips use small transmitters that will transmit a
short distance. They (bluetooth committee) are planning on putting these chips in
everything: photocopiers, laptops, refridgerators, beer cans. The photocopier can
send out emails or other messages to repair men, etc. Refridgerators can order more
beer when you drink it all... An 'unwired' photocopier might 'ping' other bluetooth
devices nearby. Once it gets a signal, it can use them to route to other bluetooth
devices until it can find access to the internet.
The problem is that bluetooth chips use the unlicensed 2.4Ghz range. It's unlicensed
because 2.4Ghz is the resonant frequency of water, which microwaves operate on. (food
cooking microwaves that is). 802.11 and 802.11b also use this range. Some cordless
phones and other devices also use the same range. This means as more devices use this
range, there is more interference.
Bluetooth transmits by frequency hopping. It can use 79 channels, and will flip
through them, skipping any that have interference on them. It switches channels 79
times per second. So if another device that uses the 2.4 band is in the area, the
bluetooth device will loose one out of every 79 packets. But a device that hops
frequencies only 50 times per second, in use near bluetooth devices, will encounter
interferrence on every hop, and lose every packet. (this is out of the article I'm
reading, I don't think the math is completely accurate, but obviously the interference
is a problem). 802.11b transmits by sending data on several frequencies at the same
time, hoping it will get there. So it is theoretically a little better off, and more
resistant to bluetooth.
In a test by mobillian (.com), they tested 802.11b performance near some bluetooth
devices. The 802.11b performance was degraded unless the two 802.11 transceivers were
within 3 meters of eachother. (802.11b range standard is 100m).
In my opinion, after reading this article, it sounds like bluetooth has enough support
behind it, and enough attraction to consumers in front of it (how prevalent are
palmpilot and simlar devices?) to put it everywhere. MIT estimates each person will
personally own 5000 internet connected products by 2010. I think that as bluetooth
becomes more prevalent, it will force 802.11 and 802.11b in to retirement and require
wireless networking to change, either to a bluetooth compatible standard, or have it's
own licensed bandwidth. Bluetooth chips currently cost $30 to make. They are
working on getting this down to about $4. We all know this price will drop very fast,
making it very concievable to have them everywhere.
Source: 'Can Bluetooth Sink It's Teeth into Networking?' andy Dornan, Network Magazine
Nov 2000. www.networkmagazine.com
I believe the cards Bob was using were Lucents' Wavelans, which are the same cards UO
people can check out for one day (even repeatedly) from the EMU computer lab.
Happy thanksgiving!
Cory
On Thu, Nov 23, 2000 at 11:27:36AM -0800, Kent Loobey wrote:
> Bob, thanks for the talk. I enjoyed it a lot.
>
> Could you repeat the names of the wireless lan cards you were using. Also
> who do you think will be the dominate wireless lan in two years.
>
> Thanks.
>
> Kent
>
> At 09:53 PM 11/22/00 -0800, you wrote:
> >jakob wrote:
> >
> >> On an on-topic note...i believe it was kbob giving the linux on
> >> laptops schpeel last weekend. In it, he demonstrated putting his
> >> laptop to sleep while in X. Just to clarify, I have been unable to
> >> do so and not have XFree lock up. Are you using XFree, bob? In
> >> addition, the XFree docs seem to suggest this isnt possible (smoke
> >> and mirrors?)
> >
> >Yes, I'm using XFree86 3.3.6.
> >
> >If it doesn't work for you, it seems like a bug in the video driver.
> >My Sony and Anne's Dell each have a NeoMagic NM256-something-or-other.
> >They use the XF86_SVGA server binary.
> >
> >Or it could be you have a different input device driver. Although
> >we have Alps GlidePoint compatible touchpads, we tell the X
> >configuration that it's a PS/2 compatible 2 button mouse.
> >
> >Sorry I can't tell you exactly what's wrong with your config...
> >
> >--
> > K<bob>
> >[EMAIL PROTECTED], http://www.jogger-egg.com/
> >
