ler224
Newbie level 3
fft in ofdma
1- what type of signal does the input to a IFFT take (ofdma)?
my understanding is that before the IFFT stage that each parallel digital binary stream is modulated (QAM etc...) and that it turns the signal into a vector. I understand that the IFFT takes in a real & imaginary part. Is it taking a digital binary input of 1 0 (real) & 1 1 (imaginary) and know that this is a 16-QAM input? I know sometimes mathematically it is referenced as Ae-(jwt2pi), but this must be represented as a digital signal. The FFT block must know what type of modulation there is.
2- IFFT take an input of parallel streams (individual users/sub carriers), and FFT produce an output parallel streams, but are these streams TDM to the FPGA etc?
I don't believe there are real/imaginary inputs & outputs for each data stream. For example if there are 600 sub carriers
3 - what is the difference between a frequency bin & subcarrier?
the number of bins has to be larger than subcarriers?
1- what type of signal does the input to a IFFT take (ofdma)?
my understanding is that before the IFFT stage that each parallel digital binary stream is modulated (QAM etc...) and that it turns the signal into a vector. I understand that the IFFT takes in a real & imaginary part. Is it taking a digital binary input of 1 0 (real) & 1 1 (imaginary) and know that this is a 16-QAM input? I know sometimes mathematically it is referenced as Ae-(jwt2pi), but this must be represented as a digital signal. The FFT block must know what type of modulation there is.
2- IFFT take an input of parallel streams (individual users/sub carriers), and FFT produce an output parallel streams, but are these streams TDM to the FPGA etc?
I don't believe there are real/imaginary inputs & outputs for each data stream. For example if there are 600 sub carriers
3 - what is the difference between a frequency bin & subcarrier?
the number of bins has to be larger than subcarriers?