In ofdm the transmission of each frame is independent because of the use of CP. But in OFDM/OQAM we don't use CP, hence the transmission is continuous, not frame by frame as in ofdm. So my doubt is how the addition of CFO in OFDM/OQAM is different from OFDM? or it is same.
Hi,
first, note that the transmission can be done frame by frame, the specificity of OFDM/OQAM is that two consecutive frames overlap. Therefore, it is exactly the same in OFDM and OFDM/OQAM.
Behind your question, I suppose that you wonder "how does it work in simulation"? Once again, the addition of the CFO is almost the same in OFDM/OQAM as in OFDM, it is a multiplication of the signal in time domain by a time-varying complex exponential function. Just note that if you want to process frame by frame, you have to store in a memory matrix the overlap from the consecutive frame.
Vincent
Dear Prem,
The answer of Vincent is okay. I want to stress some principles which may lead to better understanding of the multifrequency orthogonal frequency modulation. It is so that every carrier is modulated with digital signal such that the information is embedded in its amplitude and phase. here is no difference between he 4 QAM and the the OQAM except that the diagonal transitions in the constellation diagram is restricted by inserting a delay element with half symbol time in either the I or the Q branches.
So, the ofdm symbol formed will contain a cyclic prefix like the that of the normal QAM.
In order to shift the carrier frequency you must multiply the OFDM symbol S(t) in time domain by exp j delta w t , where delta w i the frequency shift and t is the time.
Which is the same for any modulation symbol S(t).
Best wishes
Dear Prem
Actually offset in I and Q doesn't change anything in CFO and it is exactly the same as OFDM/QAM.
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