Re: Atheros, hardware access layer, collisions

From: Sam Pierson (samuel.pierson_at_gmail.com)
Date: 07/26/05

  • Next message: Felix-KM: "RE: how to use the function copyout()" 
    Date: Mon, 25 Jul 2005 22:05:34 -0500
To: David Malone <dwmalone@maths.tcd.ie>

    > OK - you can probably achieve that by setting the retry limit to
    > be 1, setting CWmin to be very small. However, you'll need to make
    > sure that both machines transmissions are synchronised to better
    > than 20us (which is no mean feat), otherwise carrier sense will
    > foil your plan!

    I just had a lengthy discussion with a couple of guys about the 802.11
    protocol. One had said that the random delays inserted before
    transmission was one of the *IFS delays (can't remember which
    now), and that it was a standard 802.11 number, not a random
    delay. We all came to the same conclusion as this list, that we
    have to set the transmission attempts to 1 and that CWmin must
    be very small (like 1).

    The thing he said was that if carrier sensing "sensed" that the channel
    was busy, it would not decrement the CW, effectively NOT transmitting
    this packet until the channel is clear.

    Is the carrier sensing something done in the HAL, or is it embedded
    in the hardware itself?
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  • Next message: Felix-KM: "RE: how to use the function copyout()"

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