Re: Re: SBC routinely installing 2Wire 400 mW AP/FW

On Apr 22, 2004, at 7:20 PM, Jim Thompson wrote:
> If its FCCID: PGR2WHPLHW, (which is, btw, an older certification), 
> then they claim (and tested) 26.02dBm of tx power into a 2dBi antenna, 
> for 633.9mW EIRP.  This is the 400mW unit.

I forgot to add that this unit shows a real lack of understanding of 
RF.  Its senseless to have this much downlink power when the client's 
will have (much) less.   Even a 100mW Cisco card will be 6dB down, with 
Agere and other cards perhaps 10dB down.

So the AP sends a packet at 11Mbps, it gets through, and the client 
ACKs (likely at 2Mbps, but lets not get into that just now.)

The the client (STA) wants to send a packet,  It 'knows' that the AP 
got through at 11Mbps, so it attempts at 11Mbps, doesn't get an ACK, 
retries N times, then starts to fall-back.  In the worst-case scenerio, 
it succeeds at 1Mbps, and receives an ACK for its trouble.

Then, sometime a short while later, the AP downlinks again 
(successfully) at 11Mpbs, and the whole thing starts over, since, for 
all the STA knows, the situation that caused the massive fall-back has 
become (much) better.

(Fortunately, most of the traffic in a home is *from* the Internet, not 
*to* it.)

Jim

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