[MLB-WIRELESS] 802.11 and 802.11b

Tony Langdon tlangdon at atctraining.com.au
Thu Nov 15 08:16:34 EST 2001

> I see from some 11Mbit cards specs that they will do 802.11b 
> (11Mbit) and 
> 802.11 (2Mbit).  I know not everyone has the $250-$300+ to 
> play with 11Mbit 
> cards.  What scope is there for use of the far cheaper 2Mbit 
> cards ($80 
> odd) with the Melb Wireless network?  Do 802.11b cards need 
> to be forced to 
> do 802.11 or will they autodetect 802.11 and seamlessly 
> switch between that 
> and 802.11b?

Be careful here.  802.11 isn't a single standard, but effectively has 2 sub
standards - FH and DS.  AFAIK, 2Mbps DS (direct sequence) can communicate
with 802.11b cards (which are DS AFAIK), at the 1 and 2 Mbps bit rates.

However, 802.11 can also be used on FH (frequency hopping) hardware.  This
is _NOT_ compatible with the higher speed cards (again, AFAIK, YMMV).

> Or, should 2Mbit be confined to west Melb and east Melb kept 
> 11Mbit?  ;) 
> <Flame retardant clothing on>

Given where I am, the lower speeds are the more practical anyway (see
> Mind you, 802.11 should get better range than 802.11b (due to 
> the higher 
> process gain.)

Indeed, there is a law called Shannon's Law that determines how much data
can be pumped down a given channel - and lower bitrates can always survive a
noisier channel (i.e. better range).

Well, if 2Mbps gear is available for $80....  tempting to have a play.  I
don't have a need for a super huge pipe out (that's what sloptus cable is
for ;) ), and my interests in WLANS are more experimental than anything.
Yes, I think this old stuff has a place. :)

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