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What is the Acceptable SNR for wireless deployments?

darylpotts
Level 1
Level 1

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.

Thanks

5 Replies 5

SHANNON WYATT
Level 1
Level 1

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
Hall of Fame
Hall of Fame

Anything better than -65 dBM is good enough. Higher than -75 dBM is not a good sign.

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
Level 1
Level 1

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
Level 4
Level 4

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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