I have been studying carrier frequency offset estimation techniques in OFDM systems. I have understood several of them. when using Pilot tones, as stated in paper (1), the process involves two methods namely: acquisition and tracking modes. a large range CFO is estimated in the acquisition mode while in the tracking mode, only fine CFO is estimated. I have confusion, What are the nature of those Pilot tones? how are they being generated? the authors of the paper wrote equation (18) without any derivation? can I get the system model for this technique? the questions may sound easy, but I really need it. Thanks in advance.
Reference: (1) Praween Kumar Nishad, P. Singh, "Carrier Frequency Offset Estimation in OFDM Systems", National Institute of technology http://dspace.nitrkl.ac.in/dspace/bitstream/2080/1928/1/ID-451_praween.pdf