Hello,
I am trying to understand the design in benchmark OFDM code in Gnuradio.
In the code, OFDM_RECEIVER use OFDM_SYNC_PN to do the timing and
frequency
offset synchronization, and then doing FFT_DEMOD to demodulate the
signal.
After that, SLICER and DEMAPPER in GR_OFDM_FRAME_SINK are used to output
it
in the message queue.
But the questions are:
Why there is PLL for carrier compensation in GR_OFDM_FRAME_SINK?
Should PLL be used before FFT_DEMOD ?
What is the difference between PLL here and timing and frequency
synchronization in OFDM_SYNC_PN?