Low-Complexity Delay-Doppler Channel Estimation in Discrete Zak Transform Based OTFS

In this letter, we propose a novel low-complexity delay Doppler (DD) channel estimation scheme suited for discrete Zak transform based orthogonal time frequency space (DZT-OTFS) systems with embedded pilot frame and fractional delays and Dopplers. Key novelties in the proposed scheme include
$i$
) decoupling the estimation of channel gains, delays, and Dopplers using a decoupled representation of the channel matrix that leads to low complexity,
$ii$
) use of the knowledge of the adjacent bin levels in the matched filter response of the transmit-receive pulses for delay estimation, and
$iii$
) de-rotating the phase introduced by channel delays/Dopplers to estimate channel gains. Simulation results show that the proposed estimation scheme achieves better normalized mean squared error and bit error performance at a lesser complexity compared to sparse Bayesian learning based estimation scheme in the literature.