Close-loop decision-directed pre-equalization for OFDM systems

The paper proposes a close-looped decision-directed pre-equalization scheme for OFDM systems, which can be divided into two stages: i) initialization stage; ii) calibrating and tracking stage. At the first stage, the transmitter set the pre-load information to all ones, and the receiver estimates the real channel information and returns it to the transmitter; after that the receiver would view an almost-flat fading channel and directly decode the constellations, and when no error found, it remap the data to constellation to create a local pilot to obtain a better estimation of apparent channel for the transmitter to repeatedly adjust its pre-load information. Simulation results show that the performance of iterative pre-equalization is better than that of conventional pre-equalization and post-equalization in the receiver and will be much better at high SNR.