Signal Quality

[rx33328]

We have Cisco 340 and 350 AP's installed in our plant. We aren't having any complaints, but while doing a site survey I noticed that the signal strenght is high but the signal quality is low. Is there something to be concerned about and if so what can we do to correct this?

[blue.modal]

The first and easiest step in troubleshooting this is to run the Carrier Test from each AP (which drops all users, so do it early or late).

That will tell you how much signal each AP sees in each channel. You may have more bleed over from cell to cell than you think.

You can do this by telnet or browser - just watch each one for 3-5 minutes and write down the average results.

Then, map out your channelization plan on paper or a whiteboard - in 3 dimensions. If you decide to make changes, write down why so this process is a little quicker next time.

Matthew Wheeler

[jhelm]

Good response from Mathew you should adhere to this. If you are still experiencing issues with quality after designing the system with proper channels and hopefully good cellular isolation then you may have issues with the environment itself. This is not an uncommon issue with WLAN especially in the manufacturing type of environment where high levels of metallic surfaces are common and perhaps general building construction with corrugated steel walls that are also a reflective surface, I've seen many instances of only 20 feet of connectivity in an 80,000 square feet open facility due to the elevated noise levels of the environment and high level of multipath mitigation. Ways to combat this include various power settings, antenna types and mounting methods; all of which can be found during the course of your site survey. Antenna characteristics can easily preclude good propagation in any given environment if not installed correctly, there is a reason so many antennas are on the market...that is because there are so many diverse environments that we have to adapt the WLAN designs to so we need the diversity out there and full understanding of their characteristics such as E and H planes and gain. There are of course other things to consider such as your client device characteristics and other sources of RFI or EMI. Hope this was helpful.