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Darsys
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Location: Illinois, USA

Good signal poor quality (ccq)

Mon Feb 12, 2007 5:33 pm

I have a ptp link using sr5's and 3' solid parabolics. I have good signal strengths and good los (clear fresnal). The link has very adequate signal for its purpose but I am having lots of quality issues with the link. There are some sources of external interferance I know. One is an alvarion 5.8vl ap colocated. I turned down its power and did not affect this issue. The other is another ptp located on a tower a couple of blocks away. It belongs to another isp but I know it is a freq hopper and is close to my los. It is pointed about 90 degress from my los. This looks like interferance to me but I am unfimiliar with interferance as most locations I am alone in microwave bands. I have moved freq all over both 5.2 and 5.8 spectrum with no significant change in ccq. Using the frequency usage in mt show only blips of the freq hoppers and another colocated link. Anyone have any idea what could cause this. I am going to try swapping antennas and radios today I think in an act of desperation. The link does work but obviously throughput is a problem when demand comes up. I am posting configs. The wireless is configured a little weird for me just to move it around a litte. Any help appreciated.

At client end info on registration
signal:61 tx signal:66
ccq tx:90-100 rx:11-30

At ap end via status
signal tx:61 rx:66
ccq tx:11-30 rx:90-100

signal fluctuate some but generally no more than +-1db
sometimes the ccq will jump up to nearly 50 but does not stay there long.

_____One end_____
1 R name="wlan2" mtu=1500 mac-address=blah arp=enabled disable-running-check=no
interface-type=Atheros AR5213 radio-name="blah" mode=ap-bridge ssid="blah" area=""
frequency-mode=manual-txpower country=no_country_set antenna-gain=0 frequency=5800 band=5ghz-turbo
scan-list=default rate-set=default
supported-rates-a/g=6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,36Mbps,48Mbps,54Mbps basic-rates-a/g=6Mbps
max-station-count=2007 ack-timeout=dynamic tx-power-mode=default noise-floor-threshold=default
periodic-calibration=default periodic-calibration-interval=60 burst-time=disabled dfs-mode=none
antenna-mode=ant-b wds-mode=dynamic wds-default-bridge=bridge1 wds-default-cost=100 wds-cost-range=50-150
wds-ignore-ssid=no update-stats-interval=disabled default-authentication=yes default-forwarding=yes
default-ap-tx-limit=0 default-client-tx-limit=0 hide-ssid=no security-profile=default
disconnect-timeout=3s on-fail-retry-time=100ms preamble-mode=both compression=no allow-sharedkey=no

_____Other End________
0 R name="wlan1" mtu=1500 mac-address=blah arp=enabled
disable-running-check=no interface-type=Atheros AR5213
radio-name="blah" mode=station-wds ssid="blah"
area="" frequency-mode=manual-txpower country=no_country_set
antenna-gain=0 frequency=5800 band=5ghz-turbo scan-list=default
rate-set=default supported-rates-a/g=6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,
36Mbps,48Mbps,54Mbps
basic-rates-a/g=6Mbps max-station-count=2007 ack-timeout=dynamic
tx-power-mode=default noise-floor-threshold=default
periodic-calibration=default burst-time=disabled dfs-mode=none
antenna-mode=ant-b wds-mode=dynamic wds-default-bridge=none
wds-ignore-ssid=no update-stats-interval=disabled
default-authentication=yes default-forwarding=yes default-ap-tx-limit=0
default-client-tx-limit=0 hide-ssid=no security-profile=default
disconnect-timeout=3s on-fail-retry-time=100ms preamble-mode=both
compression=no allow-sharedkey=no
 
Darsys
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Location: Illinois, USA

Mon Feb 12, 2007 5:35 pm

fyi one end is a 500 mhz pc and the other is a mt532
 
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ivaring
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Thu Feb 15, 2007 9:18 am

Hi there.
I think you could have a lot of power, that is also my problem right now.
I'm trying test with smaller power.
Give a look to your SNR.

Regards.
 
Darsys
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Tue Feb 20, 2007 6:56 pm

I have reduces power at both end showing a linear change at the other. Quality does not change significantly.

I replaced radio on one end which made problem worse (dont really see that at significant) but so was the signal. Swapping antennas at least at one end today.

Could the fact this is a pc be relavant? (sr5 on pci card)

SNR is 34-38
 
Darsys
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Location: Illinois, USA

Thu Feb 22, 2007 3:59 am

No real change with antenna. Please ANY input would be appreciated!
 
Dave_W
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Location: Limerick, Ireland

Thu Feb 22, 2007 12:02 pm

have you tried Nstream?

It sounds like the backoff protocol of wifi is killing your ccq with the frequency hopping link nearby. I imagine something like this is happening, your node goes to tx, checks frequency, sees its clear, and sends a packet...next packet comes along, frequency hopping node is using your frequency...your node says ok I'll wait until its free again, it keeps polling the channel until the frequency hopping node has gone on to another frequency, then it transmits.

As far as i know the frequency hopping protocol doesnt comply with wifi CSMA (http://www.zytrax.com/tech/wireless/802_mac.htm). I would try changing to Nstream, maybe one of the guys here who is more familiar with Nstream than me, might tell us if it uses CSMA.

I hope this helps,

Dave_W
 
Darsys
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Location: Illinois, USA

Thu Feb 22, 2007 3:59 pm

Nstreme is enabled on the link.. best fit

I turned off one of the hoppers last night and did not affect the problem. Swapping ALL equipment on the other end today.

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