Channel Estimation for Doubly-Spread Channels

This paper presents a novel method for low-complexity estimation of doubly spread channels, specifically channels with path-dependent Doppler scaling. A time selectivity phenomenon, specifically appearing on doubly spread channels, and impairing methods based on autocorrelation, is described. To devise a low complexity method, we propose employing a composite preamble made of hyperbolic chirps, and a greedy path-matching algorithm at the receiver. The performance of the method is evaluated through simulations, and we show its effectiveness in shallow water scenarios. The advantage in computational complexity with respect to state-of-the-art methods like orthogonal matching pursuit is discussed.