Channel estimation in time-varying flat-fading channel using superimposed pilots with interference avoidance

Superimposed (SI) pilots have been proposed as an alternative pilot insertion method against conventional time-division multiplexed pilots. Due to the negative effect of non-orthogonal multiplexing of SI pilots, various algorithms have been developed in order to enhance the channel estimation accuracy. Probably the most promising approaches include an additional feedback from pre-detected data symbols. This, however, increases the computational complexity of the receiver. Inspired by some recent studies related to block-transmission scenarios, we propose a novel channel estimation method applicable to narrowband systems. The method is based on preprocessing the signal waveform already in the transmitter. Furthermore, no additional feedback loop is required in the receiver. It is shown by analytic derivations and computer simulations that the proposed approach has considerable benefits over other available methods in the literature.