Low-Complexity Delay-Doppler Channel Estimation in Discrete Zak Transform Based OTFS
Vineetha Yogesh, Sandesh Rao Mattu, A. Chockalingam
Abstract
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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$i$ </tex-math></inline-formula> ) decoupling the estimation of channel gains, delays, and Dopplers using a decoupled representation of the channel matrix that leads to low complexity, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ii$ </tex-math></inline-formula> ) use of the knowledge of the adjacent bin levels in the matched filter response of the transmit-receive pulses for delay estimation, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$iii$ </tex-math></inline-formula> ) 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.