James Ketrenos wrote:
Larry Finger wrote:
The initial rate for STA's using rc80211_simple is set to the last
rate in the rate table. This is too fast for the bcm43xx-mac80211
driver.
To correct this situation without affecting any other driver,
an initial_rate parameter is added to the rc80211_simple module. This
parameter is set to 10 times the desired initial rate. If the parameter
is zero or not set, the original behavior is kept. If the parameter
does not match a valid rate, the first rate in the table will be set.
Initial rate selection should be based on the RSSI of the last frame(s)
received from the target network. One way to do that would be for the
driver to map a minimum RSSI value to each rate. If the RSSI for the
target network is greater than the value listed, that rate could be used
for initial selection. The ieee80211_rate with the highest 'rate',
which is in the supported rates mask and with a min_rssi <= the AP's
reported RSSI, is selected.
The mechanism by which the magic values for min_rssi are determined for
each rate is more observational than scientific--and is vendor
specific. You can pick a set of values, but different hardware and
environments will yield different levels of success / failure. Some
hardware can be very lenient if it has automatic hardware retry. Other
hardware will need to be very conservative (since, as you point out, the
first few frames Tx/Rx'd are important)
I didn't state it above -- doing what is described requires adding one unsigned char (min_rssi) to ieee80211_rate in mac80211.h and then modifying rc80211_simple to take advantage of that information (so if you're grepping for min_rssi and can't find it, that's why...)
James
James
Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
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