What is the Acceptable SNR for wireless deployments?

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Oct 13th, 2009
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Is there a link or document explaining and laying out the acceptable range of SNR? I have seen one forum that stated +35 was a good number but would like to have some documentation to back our findings of a Spectrum Analyer report to a client.


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Overall Rating: 3.6 (5 ratings)
SHANNON WYATT Mon, 11/09/2009 - 17:35
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35 would be good. You would almost close enough to touch it at 35.

Depends what you are trying to do. I know that the old deployment guide for the 7920's stated no less than 20. I've been using that with good results.

Leo Laohoo Mon, 11/09/2009 - 18:48
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Anything better than -65 dBM is good enough. Higher than -75 dBM is not a good sign.

RTHRESHIER_2 Tue, 03/21/2017 - 10:31
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I know this is old but to clarify, i think Leo was confusing SNR to Signal strength.  -65dBm is a good standard for signal strength with the higher numbers being bad.  i.e. -65dBm is better than -67dBM.

SNR is the difference between noise, Interference vs actual signal strength which is being discussed in this thread.

mbayramo Mon, 11/09/2009 - 21:23
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40 dB Excellent signal strength

25-40 dB Very good signal s

15-25 dB Low signal

10-15 dB Very low signal

5-10 dB No signal strength

For the Voice you need a minimum -25 dB

Johannes Luther Mon, 11/09/2009 - 22:58
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The answer to your question is: "It depends" :-))

Correct me if I'm wrong, but the SNR directly affects the chosen data-rate.

Each wireless device has a table, which describes, what data-rate should be used against the SNR.

The table can be reviewed in an IOS AP. Issue the command "show controller dot11radio[0|1]". Sowhere in this output, you'll find a listing stating data-rate vs. SNR.

To get back to your question: The target SNR of your survey depends on the requirements. If you want a target data-rate of 54 MBit/s the SNR must be much higher than with 11 MBit/s.

Sorry, I don't have any reference on my theory. At least I couldn't find any reference on CCO - but the "show output" at the IOS AP is quite revealing


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