On 7/26/05, David Malone <[EMAIL PROTECTED]> wrote:
> That's correct, but it probably takes a few microseconds for the
> carries sense to kick in (if there wasn't a delay there would
> be almost no need for the random backoff). That's why you'll
> also have to have your transmissions synchronised very closely.
> David.
Since my project is running in adhoc mode, I noticed that there is
a LOT of noise being generated by the two machines I want to use
in order to generate a collision. The noise is the adhoc beacon
being broadcast. Clearly they need to talk to each other, but I'd
really like to quiet down the channel so I can attempt this collision.
I found this in if_ath:
/* NB: the beacon interval is kept internally in TU's */
and this in /sys/contrib/dev/ath/ah_desc.h
HAL_TX_QUEUE_BEACON = 2, /* beacon xmit q */
HAL_TX_QUEUE_CAB = 3, /* "crap after beacon" xmit q */
and...
# cat ah.h | grep interval
* beacon interval (given in TU's) can also include flags
u_int32_t bs_intval; /* beacon interval+flags */
#define HAL_BEACON_PERIOD 0x0000ffff /* beacon interval period */
I think the carrier sensing is kicking in because the channel is not quiet
due to the beacons. Do the tx q things matter? seems like the
hal_beacon_period would be the most important line, but I don't see how
that flag (if it is one) can be used.
-Sam
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