Why are OFDM Subcarriers Sinc Functions?
Explains the relationship between the time domain OFDM transmitted signal, and the orthogonal subcarriers in the frequency domain.
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Пікірлер: 8
thank you very much,
@iain_explains
9 күн бұрын
You are welcome!
The vector C_n represents just integer values of the base function f1 - ist that right? Or can use other step sizes e.g. f2 = 1.5*f1; f3 = 3*f1.....
@iain_explains
Ай бұрын
They need to be integer, in order to maintain the orthogonality between the subcarriers. Hopefully this video explains it: "OFDM Waveforms" kzread.info/dash/bejne/eGp2lq2ympXYfNo.html
2:04 If only the first element is nonzero, the output of IDFT has to be the DC value, not the sinusoid of fundamental frequency. The subcarriers range from C_0 to C_{N-1}. C_0 will correspond to the DC value at the output and C_1 will give the fundamental sinusoid of period = N. Please respond if I am wrong.
@iain_explains
Ай бұрын
Yes, you're right. I simplified the diagram, only showing the elements of the vector that relate to the data-carrying sub channels.
@028gnanadathareddy4
Ай бұрын
@@iain_explains I did not understood how output of IDFT is sinusoidal with .output of IDFT will be all of same elements for given example right.
@iain_explains
Ай бұрын
Try running these lines of code in Matlab: X=zeros(1,40); % Frequency domain vector X(2)=1; % Put data into the first subcarrier (only) ... note that X(1) corresponds to f=0 x=ifft(X); % Use IFFT to generate time domain signal stem(real(x)) % plot the time domain signal