Channel estimation by set partitioning for OFDM with cyclic delay diversity

For OFDM based systems using cyclic delay diversity (CDD), a multiple input channel is transformed to a single input channel with increased frequency selectivity. While CDD provides additional frequency diversity which can he utilized by the outer channel decoder, a conventional channel estimator may have difficulties tracking the increased dynamics of the received signal. However, the knowledge about the cyclic delays can be utilized by the channel estimator. We show that for maximum cyclic delays, adjacent subcarriers become uncorrelated. By partitioning uncorrelated subcarriers into sets, and performing channel estimation for each set separately, a simple and yet very efficient channel estimation scheme can be derived.