# Signal Power in OFDM

**URL:** <https://www.ruby-forum.com/t/signal-power-in-ofdm/240523>\
**Category:** GNU Radio\
**Created:** [April 18, 2014, 4:10am UTC](https://www.ruby-forum.com/t/signal-power-in-ofdm/240523 "2014-04-18T04:10:40Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [April 18, 2014, 4:10am UTC](https://www.ruby-forum.com/t/signal-power-in-ofdm/240523/1 "2014-04-18T04:10:40Z")

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Hello

I have written a OFDM transmission reception chain in MATLAB.  
I would like to calculate the signal power and compare it with the  
MOS(Minimal operational Sensitivity). I am using the following equation:  
P = 10_log10((abs(S).^2)/R_1000)  
S is the FFT result after the channel  
R = 50 ohms

This calculated power is getting bigger with the noise power.  
Do I need to subtract the power with the channel attenuation in order to  
compare with the MOS ?

When I compare with the MOS, should I take the mean power or the maximum  
power or something else ?

Thank you in advance