Hi
Looking at the ofdm receiver at ofdm_rx grc, I see that schmidl and cox synchronisation algorithm uses sync1 and sync2 which are two ofdm training symbols that help in frequency offset correction and also timing estimate to detect the start of the packet.
Then there is channel estimator block in grc that again uses preamble ofdm symbol to detect coarse frequency offset. In the entire implementation I haven't seen the use of pilot symbols in each ofdm symbol for either channel estimation or synchronisation. So does that mean that if you are using a packet structure with a preamble there is no need of pilots for any receiver processing.
I get this doubt because benchmark_rx.py which uses ofdm gives you a terminal option saying occupied tones which can be set by user at terminal. So if you can set or increase occupied tones to any number less than fft length, then that means you can be flexible with increasing or decreasing pilot symbols to a value that you want. Am I right?
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Regards
Karan Talasila