Hello,
I'm working on OFDMA performances, i'm a little bit confused between SNR & Eb/N0 because of the presence of many definitions in the Internet,in some books,and in Matlab help!
In my simulation,i generate an OFDMA signal X,i use the Matlab function awgn to add AWGN noise to my signal X:
awgn(X,snr,'measured');
SNR: [0:1:20] [dB]
Then i demodulate my OFDMA signal & calculate BER vs SNR.
My next task was to try to get BER vs Eb/N0. I searched how is it calculated,i found many definitions.I found that:
1) In AWGN channels,Eb/N0 is part of the calculation of the variance (sigma^2) of the additional noise n.Linear equation:
sigma = sqrt(2)*sqrt(1./(2*Rm*Rc*EbN0));
Rm = log2M: Modulation rate
Rc: Code rate
2) I found then SNR[dB] is calculated from Eb/N0[dB]! found many equations in dB format:
a) From Matlab help:
snr = EbNo + 10*log10(Rc) + 10*log10(Rm); [in dB]
b) From Matlab help:
snr = Eb/N0 + 10*log10(Rc) + 10*log10(Rm) - 10*log10(Tsymb/Tsampl);
I'm really confused.My questions is:
1) What's difference between Eb/N0 & SNR? Which is important on performances basis?
2) Do i have to program my own awgn function to simulate Eb/N0 or is it possible to use awgn Matlab function knowing it requires snr in entry not eb/b0?
3) Equation 2)a) & 2)b) are different knowing it's both on matlab help,wich one is adequate? and how using them?
I will really appreciate your answers.Thanks.
Regards,
