In this work we analyse the performance of a joint coding-precoding scheme for OFDM systems over fading channels. The design of the precoder is based on the information redistribution of the input modulated symbols amongst all the output precoded symbols. The proposed precoder decreases the variance of the instantaneous noise power at the receiver produced by the channel variability. In this sense, the noise at the output of the receiver deprecoding block can be considered as gaussian causing an improvement in the performance of the channel coding scheme employed in the system. The proposed system is evaluated under realistic radio channels which present multipath frequency-selective fadings and are affected by Doppler spread.