Blind periodically time-varying MMOE channel shortening for OFDM systems

In this paper, the problem of synthesizing a blind channel shortening algorithm for orthogonal frequency-division multiplexing (OFDM) systems is addressed. In particular, a commonly adopted assumption in the channel shortening framework is discussed, showing that, when it is violated, the data statistics usually needed for the synthesis of the shortening algorithms turn out to be periodically time varying (PTV) rather than time-invariant. Elaborating on this point, and considering in particular the recently proposed minimum-mean output-energy (MMOE) blind channel shortening algorithm, it is shown how its synthesis must be modified in order to account for the PTV nature of the data statistics. Numerical results assessing the performance of the proposed blind PTV-MMOE channel shortening algorithm are reported.