This paper introduces linear constellation precoding (LCP) for OFDM transmissions over frequency-selective fading channels. Exploiting the correlation structure of OFDM subchannels, and choosing system parameters properly, we first perform op

symbols, because covering all frequencies, could be effective against the selective frequency fading, but more sensitive for the impact of fast fading channel. Therefore, the block-type pilot is developed under the assumption of slow fading channel.