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matlabtelecommunicationmodulationsoftware-defined-radio

BER result for QAM modulation Matlab

I'm trying to put a binary vector through a 16-QAM modulator, AWGN channel, demodulator and measure the BER in the end. for some reason it keeps giving me BER=0, even after if I change the length of the vector. (I'm supposed to do it with a Rayleigh channel later, but I'm not even there yet).
when I do the same but without a modulator I get BER!=0 which is fine.
what am i missing here?
here's my code:

Sig = randi([0 1],1,1E5);
SigMod=qammod(Sig,16);
y=awgn(SigMod,50);
SigDemod=qamdemod(y,16);
z=SigDemod>0;
BER = biterr(Sig,z)
Solution

  • The second input to awgn is SNR in dB. In your example you have a SNR of 50 dB, which gives a very small BER.

    Try reducing the SNR, for example to 5 dB, and you will observe some bit errors.