Blind channel estimation for OFDM systems based on non-redundant linear recording

In this paper we consider a novel approach that can be applied on a single transmit/receive antenna OFDM system, to increase multipath diversity, and at the same time, enable blind channel estimation at the receiver. A non-redundant linear precoder is applied on each pair of blocks before they enter the OFDM system. It is composed of unitary sub-matrices, which spread each symbol onto multiple sub-carriers, thus enabling robustness to subcarrier nulls. Due to the introduced structure, the channel can be estimated at the receiver based on cross-correlation operations, without increasing transmission power.