Hello Mike,

Certainly the SNR is better than LEDs, but not as important or useful as a
RSSI reading.  As others here have pointed out it is very possible the SNR
could improve by misaligning the link.  A misaligned link will only cause
you more trouble down the road.  I'm hoping Patrick follows through and
pushes the Alvarion engineers to provide it.

During one of the many calls into Alvarion Support we did look into the
modulation counters and we settled on forcing the AU and SU to 6.  The AU
counters look like this:

Modulation Level:|     1     2     3     4     5     6     7     8 | 
SUCCESS         :|     1     1     1     1     1 2760796     0     0 | 
FAILED          :|     0     0     0     0     0     0     0     0 | 

The SU looks like this:

Modulation Level:|     1     2     3     4     5     6     7     8 | 
SUCCESS         :|    25     1     1   110  3604 2139679     0     0 | 
FAILED          :|     0     0     0     7    27    85     0     0 | 

Average Modulation Level                    : 6

The SU counters were reset last night and as such do not reflect usage
during business hours.  I'm sure the interference increases during the day
as neighboring radios at the AU side become more active.  Are these
acceptable results?

Alvarion never suggested trying a 10MHz channel and at this point we are
willing to try anything before we are forced to remove the VL gear all
together.

I appreciate your input.

Best,


Brad


-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Mike Cowan
Sent: Wednesday, October 11, 2006 6:11 AM
To: WISPA General List
Subject: Re: [WISPA] Are these good or bad Alvarion VL statistics...

Hi Brad,

A lot of what Dave has said is good info and my reply is a bit 
redundant.  The lights on the bottom of the radio should really only 
be used for a rough indication of signal level.  This is true for 
most radio products that offer lights for RSL.  Once you have 
achieved association via lights on the bottom it is best to Telnet as 
Dave suggested and then tune for highest SNR.  The lights can help 
here, but only roughly.  If you are looking at continuous link 
quality display that will give you the fine indications to help you 
aim and achieve the best connection possible.  You may also see the 
effects of heavy multipath while watcing this in the form of bouncing 
SNR.  This can also be seen in the lights as little light 
movement.  OFDM does a much better job with multipath than a 
traditional radio, but it does not eliminate MP type problems.

Best SNR is only part of the equation.  The counters also need to be 
reviewed and I find the Breezeconfig site survey page the easiest to 
read.  You need to look at retrans vs total as a percentage and also 
look at drops which are frames rxtx that never successfully made 
it.  You also need to look at the per rate counters, particularly if 
the area is noisy.  The radio will auto modulate from level 8 to 
level 1 based on noise.  The automodulation scheme is pretty decent 
in the radio but I klike to hard set the max mod rate when noise is 
present. The radio will always try to mod at the highest level and 
sometime that level might be close to the SNR threshold and 
performance may be acceptable to the algorithm but not acceptable to 
you.  If I see the radio counters showing many fails at mod8, fewer 
at mod 7, and clean at mod 6 I would lock the radio to 6.  No sense 
in allowing it to try to do better than 6 if conditions mostly won't allow
it.

Channel size (10 or 20Mhz) is another tool available to help find 
open spectrum to run on.

Hope this helps,

Mike






Mike Cowan
Wireless Connections
A Division of ACC
166 Milan Ave
Norwalk, OH  44857
419-660-6100
[EMAIL PROTECTED]
www.wirelessconnections.net

-- 
WISPA Wireless List: wireless@wispa.org

Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless

Archives: http://lists.wispa.org/pipermail/wireless/

-- 
WISPA Wireless List: wireless@wispa.org

Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless

Archives: http://lists.wispa.org/pipermail/wireless/

Reply via email to