Signal Strenth, Signal Quality and SNR

[wildker]

Signal Strenth is defined as signal power at anthenna mesured since syncronization till the end of the PLCP header.

Signal Quality is a correlation quality mesured during the same period of time.

SNR can be counted using Signal Strength(in dBm) and Noise Ratio(dBm).

So, my question is how can I find Noise Ratio if I know only Signal Strength and Signal Quality mesured in % ?

It seems, Cisco Aironet 350 can mesure SS, SQ, NR and SNR. But how can they be converted to each other.

[sbilgi]

The signal strength depends on the SNR (Signal to noise ratio). The lower the noise the better the signal strength. Signal quality is dependent on the interference.

[wildker]

you' wrong! Signal to noise ratio is a function of a signal strength. signal strength does'n depend on noise level, so it cant be "the lower the noise the better the signal strength". of cause Signal quality depends on the interference, but I asked how noise level could be converted to signal quality.

[scottmac]

Random noise/interference doesn't really play into the SQ: that's why redundant bits are sent.

SQ is more likely to be affected by multipath. You can have a 100% signal STRENGTH, but still have a bad Signal QUALITY because of extreme multipath or other devices on overlapping frequencies.

SNR and SQ seem like they should be tied together (i.e., good SNR, good SQ) ... but I'm not sure if multipath falls into the category of what would normally be called "Noise." It's more like "self-interference."

Given only the parameters mentioned, I don't think it would be possible to provide a definitive scale.

FWIW

Scott

[per-johan-skansen-loe]

Bip, bip!

If you go into Aironet Client Utility PREFERENCE and marke for dbm in stead of percent, than you get at the display just what you are looking for.

[melisei]

Here is a link from Cisco explaining the RF Power Values. I hope it helps.

ME

http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a00800e90fe.shtml