🚀 go-pugleaf

On 5 May 2002 23:55:41 GMT, spp@cs.berkeley.edu wrote:

>Jeff Liebermann  <jeffl@comix.santa-cruz.ca.us> wrote:
>
>> The assumption with wireless is that the transmit and receive range of
>> each radio is similar.  If you increase the transmit power of the
>> access point, it would NOT impove the range unless the power of the
>> laptop PCMCIA card were increased the same amount.  The range is
>> limited by the access points ability to hear the laptop transmitter,
>> who's power is only about +15dBm.
>
>I think one could argue that, since one usually transfers more
>data in the downstream direction, that it is still useful to have 
>more AP power.  At a given range, 2 mbps upstream and 11 mbps downstream
>would require more transmit power in the AP than in the laptop.
>Steve

Good point and thanks for ruining my evening.  I've spent some time
reading through IEEE 802.11, and 802.11b trying to determine if
asymmetrical data rates are tolerated.  I couldn't find anything that
specifically proscribed such an arragement in the specs.  However, I
doubt that asymmetrical data rates has been implimented in the typical
firmware.  
  http://standards.ieee.org/getieee802/802.11.html
Reading 802.11 specs turns my brain to mush.

In 802.11, data rate is a negotiated parameter, where the negotiations
(and all management plus flow control packets) are at 1Mbit/sec.
That's why 802.11 has so much "overhead".  Once the rate is set, data
traffic continues at that rate.  Access point firmware allows
different data rates for each connection.  Client firmware allows only
one data rate.  

*If* asymmetrical data rates were possible, it should be possible (for
example) to set the AP to always xmit at 11Mbits/sec, and receive at
whatever rate the client radio finds useful.  Similarly, diagnostic
software should show data rate by direction.  Nope.  None of the
setup, config, or test software I have seen allows asymmetrical data
rates.  It's a good idea, worthy of consideration, but I don't think
it works that way in todays 802.11b MAC layer implimentations.




-- 
Jeff Liebermann  150 Felker St #D  Santa Cruz CA 95060
(831)421-6491 pgr (831)426-1240 fax (831)336-2558 home
http://www.LearnByDestroying.com   WB6SSY
jeffl@comix.santa-cruz.ca.us   jeffl@cruzio.com