I am trying to understand the Time Reversal OFDM where ,According to my opinion, the channel is reversed in time domain at receiver side and then equalized.
what I found online is something similar to the below diagram:
but, What's about if the channel can not be known at the transmitter end? I mean it need to be estimated at the receiver end, how can we perform the time reversal in that case ? Is there any reference documents I can read about that topic, that will be really appreciated.