Incorrect addition of noise in the example: ('lte/NPDSCHBlockErrorRateExample')

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Karine 2025-12-17，16:58

Hello,

I noticed an incorrect addition of noise in the matlab example ('lte/NPDSCHBlockErrorRateExample').

In line 385 and 388, there is:

N0 = 1/(sqrt(2.0*enb.NBRefP*double(ofdmInfo.Nfft))*SNR)

noise = N0*complex(randn(size(rxWaveform)), ...

randn(size(rxWaveform)));

If we separately compute the noise power : Pnoise = mean(abs(noise).^2);

and then the signal power: PrxWaveform = mean(abs(rxWaveform).^2);

The SNR obtained : SNR_result = 10*log10(PrxWaveform/Pnoise) is very different than the SNR value defined in the code.

I think some division by sqrt(12/128) is missing when generating the noise as it represents the power factor at the end of the OFDM modulation.

Could you please clarify and let me know if there is indeed something wrong in the example?

Thanks

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Incorrect addition of noise in the example: ('lte/NPDS​CHBlockErr​orRateExam​ple')