matlab-add-awgn

To add AWGN correctly in MATLAB, call the awgn function using explicit signal power rather than the 'measured' option. This avoids scaling anti-patterns and ensures the noise level matches your intended SNR definition for both unit-power and non-normalized signals.

OFDM simulation noise levels are often incorrect due to wideband SNR and per-subcarrier SNR mix-ups. Use the convertSNR function for all SNR conversions, applying the two-step OFDM workflow to accurately translate between definitions before adding noise.

To pass correct noise variance to a soft-decision demodulator, capture the output nVar from the awgn function and pass it directly into the demodulation function using the NoiseVariance parameter for accurate LLR computation.

Converting Eb/No to SNR for coded systems in MATLAB requires providing BitsPerSymbol, CodingRate, and SamplesPerSymbol to the convertSNR function. This ensures the conversion accounts for modulation and coding overhead accurately.

You can add AWGN after a Rayleigh fading channel by providing the explicit signal power to the awgn function. This maintains correct noise scaling for computing soft-decision BER and LLRs without mismatched SNR definitions.