[Voyage-linux] Difficulty associating at good signal strengths

[Edwin Whitelaw]

I'm running Voyage 0.2 on a WRAP with one CM9 as the 5GHz backhaul and 
an Engenius 2611 as the wlan0 AP for customers. 

The nine clients are mostly Engenius CB3s (one SmartBridge outdoor) at 
1.5-3.0 miles using a variety of antennas (typically PacWireless 16db 
Yagis or 15/19db grid) as required by the client site.  All of them have 
excellent signal strengths (as reported by the CB3 web interface and 
also as compared to other AP/clients elsewhere in my system).

In general, the CB3s will associate and work well at reported "Quality" 
values of anything in the high 40s% and up but on this particular AP, 
they take an inordinately long time to associate (if at all) at quality 
values below about 70% and sometimes may take hours before finally 
linking.  Once associated, the link works well with data rates pushing 4 
mbs download.  I'm using a PacWireless 13db horizontal omni connected to 
the AP radio with about 6' of LMR400.  The cable has been replaced once 
with no noticeable improvement.

hh1:/usr/local/bin# iwlist wlan0 scan
wlan0     Scan completed :
          Cell 01 - Address: 00:02:6F:41:FC:8C
                    Mode:Managed
                    Quality=34/70  Signal level=-66 dBm  Noise level=-90 dBm
          Cell 02 - Address: 00:02:6F:41:FB:88
                    Mode:Managed
                    Quality=34/70  Signal level=-65 dBm  Noise level=-89 dBm
          Cell 03 - Address: 00:02:6F:41:FB:89
                    Mode:Managed
                    Quality=37/70  Signal level=-64 dBm  Noise level=-90 dBm
          Cell 04 - Address: 00:30:1A:02:12:BC
                    Mode:Managed
                    Quality=33/70  Signal level=-66 dBm  Noise level=-89 dBm
          Cell 05 - Address: 00:02:6F:37:BA:9F
                    Mode:Managed
                    Quality=34/70  Signal level=-65 dBm  Noise level=-89 dBm
          Cell 06 - Address: 00:02:6F:45:82:88
                    Mode:Managed
                    Quality=35/70  Signal level=-64 dBm  Noise level=-89 dBm
          Cell 07 - Address: 00:02:6F:41:FC:A6
                    Mode:Managed
                    Quality=37/70  Signal level=-64 dBm  Noise level=-90 dBm
          Cell 08 - Address: 00:02:6F:43:0A:84
                    Mode:Managed
                    Quality=37/70  Signal level=-63 dBm  Noise level=-89 dBm
          Cell 09 - Address: 00:02:6F:41:FE:1D
                    Mode:Managed
                    Quality=40/70  Signal level=-61 dBm  Noise level=-89 dBm

wlan0     IEEE 802.11b  ESSID:"nrvu-hh1"
          Mode:Master  Frequency:2.447 GHz  Access Point: 00:02:6F:42:BC:AA
          Bit Rate:11 Mb/s   Tx-Power=23 dBm   Sensitivity=1/3
          Retry min limit:8   RTS thr:off   Fragment thr:off
          Encryption key:XXXXXXXXXXXXXXXXXXXXXX   Security mode:restricted
          Power Management:off
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:396511  Rx invalid frag:0
          Tx excessive retries:860573  Invalid misc:58515241   Missed 
beacon:0

I've got potential customers in locations that should connect easily but 
site survey tests have been disappointing.  Any suggestions on what may 
be happening here are greatly appreciated.

Note that this site is almost identical to many others where signal 
strengths are sometimes significantly lower (many in the mid to upper 
-70db range as reported at the AP by iwlist wlanX scan) than those above 
and yet the clients associate at those sites immediately and work well.

Thanks,

Edwin



-- 
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Edwin Whitelaw, P.E.
New River Valley Unwired, LLC
2200 Lonesome Dove Dr
Christiansburg, VA 24073
540-239-0318