for several years now, I've been running an ALIX-AP with a CM9 Atheros
5212 card.  The AP covers a whole house which has about 6 flats and the
average amount of active clients ranges from 10 to 15.

Recently I noticed high latency when pinging the AP itself which happens
when distant clients (who knows where around the house---could be inside
or outside) seem to cause "longs" (long on-chip tx retries) and/or
"xretries" (tx failed 'cuz too many retries).

The Rate, when talking to these distant clients, is usually below 11M
(sometimes as low as 1M) which is consistent with their low RSSI values
the AP is reporting.

With high latency I mean continuous bursts of 500-1000ms instead of
0.5ms so I wonder if this is normal.

The software is slightly out of date and athstats is not completely in
sync with the kernel i'm using (therefore its not reporting some values):

        # uname -a
        FreeBSD parrot.NGC004 8.1-RC2 FreeBSD 8.1-RC2 #2: Thu Aug 16 21:13:54 
CEST 2012

        # athstats -i ath0
        athstats: ath0: Invalid argument
        athstats: ath0: Invalid argument
        3181606  data frames transmit
        45659    tx frames with an alternate rate
        568149   long on-chip tx retries
        19091    tx failed 'cuz too many retries
        0M       current transmit rate
        25       tx stopped 'cuz no xmit buffer
        20922    tx frames with no ack marked
        3039151  tx frames with short preamble
        362335   rx failed 'cuz of bad CRC
        1181     rx failed 'cuz of PHY err
            315      OFDM restart
            866      CCK restart
        2        TDMA slot timing updates
        -0/+0    TDMA slot adjust (usecs, smoothed)
        26135    TDMA tx failed 'cuz ACK required
        -74      rx noise floor
        3070927  tx frames through raw api
        6299685  fast frames received
        1328215  fast frames flushed from staging q
        20835    ANI decrease noise immunity
        6593     ANI increased spur immunity
        121582   ANI decrease spur immunity
        160      ANI decreased first step level
        2        cumulative OFDM phy error count
        2        RTS without CTS
        1360093  beacons received
        Antenna profile:

Any ideas on how to avoid that?  Of course I could buy better antennas
but it seems that, generally speaking, this shouldn't happen.


                Petar Bogdanovic
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