Wireless networking [was Re: [NCLUG] Re: Sean's Social Hacking]

[John L. Bass]

> On Sun, 21 Jan 2001 at 12:54:34 -0700, Quent <quent at pobox.com> wrote:
> The ones I've found seem to go for between $600 and the price of
> a good used car, except for the $299 Apple Airport, which requires a
> MacOS machine to configure it.  The Apple card is only $99 but it's
> only compatible with their systems, AFAIK.

Low end consumer stuff:

	Linksys has one of the better low end units, with important
	features like diversity antennas on the AP. The units are
	PRISM-II chipset, based on the reference design.

	http://www.us.buy.com/retail/product.asp?sku=10259366&loc=101
		Linksys WAP11 (802.11b 11mbps) Access Point   $226.95
		Linksys WPC11 PCMCIA card                     $116.95
		Linksys WDT11 PCI CARD ADAPTER FOR DESKTOPS   $ 46.09

	   (Linksys AP's are backordered everywhere - high demand)
	   a few $$'s more at Egghead (also BO'd)

	It has been reported that the Samsung Linux drivers/firmware work
	with these cards in Ad-Hoc mode which could save the cost of
	an AP (which are hard to find right now):

	http://www.sem.samsung.com/eng/product/rf/wlan/download_linux.htm

	This also has a good chance of working with other PRISM-II cards
	that are based on the reference design.

Commercial 802.11b stuff:

	CISCO/Aironet 4800/4800B/340 cards are available on Ebay, quite
	often under $100. Aironet implements the ENTIRE 802.11B protocol
	stack on the card firmware ... which makes drivers very small
	and fast (especially on older slower notebooks) - with minimum
	interrupts. With the Linux stock drivers (>= pcmcia-cs-3.1.19)
	in current Linux release (RH7.0/KRUD) these cards just work and
	configure almost like a normal ethernet nic, either in Ad-Hoc
	mode or infrastructure mode (w/AP).

	There are several Private Labeled OEM versions of the Aironet
	card - IE Dell. The firmware on these cards was reported to be
	crippled (subset of Aironet product) - do some research first.

	Lucent WaveLan 802.11b cards are also available on Ebay at well
	under $100. These work well under Linux too, either in Ad-Hoc
	mode or infrastructure mode (w/AP) using Lucent drivers. I got
	my Silver card for $79.00+4.50 shipping off Ebay. Beware that
	some of the Apple Lucent cards are not PCMCIA, although they
	have the same form factor and connector.
	
Apple Airport ... follow the Airport links reported earlier, my understanding
is that they can be configured without a MacOS machine around.

> On Sun, Jan 21, 2001 at 02:18:46AM -0700, Sean Reifschneider wrote:
> > Yeah, unfortunately WebGear isn't really pushing them any more.  Not
> > suprising when you consider how poor those cards are at handling
> > multiple streams of traffic.  Don't get me wrong, they're cool,
> > but it doesn't take much load on the air to make other sessions
> > nearly or completely unusable.

802.11b DSSS radios have a modulation data rate of 11mbps, 802.11 FHSS
radios like the WebGear have a modulation data rate of 1-2 mbps. Effective
data rates depend on packet size mixes, but are around 2-5mbps for
802.11b DSSS radios and FHSS 1-2 mbps radios have effective data rates
well under 700kbps (basically floppy speed). With either technology,
collisions are costly, and significantly impair performance - the slower
the data rate, the higher the probability of collisions and the higher
the cost of a collision, as the number of stations increases.

It's no wonder FHSS systems like WebGear don't scale well under load.

John Bass