OFDM signal

[marko]

Hi,

I have problem concerning generating OFDM signal. For example if I have such bins:
(1) (0) (0) (1+j) (1) (-j) (0) (0) (0). Then if I use IFFT I will have complex time domain signal.
In many textbooks it is written that OFDM signal is real part of IFFT, so why after IFFT block is
IQ modulator? I presume IQ modulator is used for upconversion, but isn't it change real part of IFFT?
If IQ modulator change real part of IFFT, would it has influence on properties of waveform OFDM signal
and OFDM signal spectrum?


Martin

[gpi]

The ifft over constellation symbols produces real and imaginary parts. In a simulator, you have a fft at the receiver which resembles symbols of a constellation, with Im and Re parts.

maybe also this tutorial could clarify
zone.ni.com/devzone/cda/tut/p/id/4805

Hope this helps
gian paolo

[flong]

You may also consider looking at the following tutorial;

www.digitalradiotech.co.uk/cofdm.htm

[rrrahul4u]

Hi Everyone ,

Plz tell me difference between wideband transmission and narrowband transmission and when and why are they used?

[aya2002]

Hi friends

I will repeat the quistion of marko. Please Please Please i need more cleared answer

I have problem concerning generating OFDM signal. For example if I have such bins:
(1) (0) (0) (1+j) (1) (-j) (0) (0) (0). Then if I use IFFT I will have complex time domain signal.
In many textbooks it is written that OFDM signal is real part of IFFT, so why after IFFT block is
IQ modulator? I presume IQ modulator is used for upconversion, but isn't it change real part of IFFT?
If IQ modulator change real part of IFFT, would it has influence on properties of waveform OFDM signal
and OFDM signal spectrum?

thank you in advance