Low-complexity Iterative Doppler Spread and Channel Estimation over Rayleigh Fading Channels

This paper proposes a new approach to joint Doppler spread and channel estimation over Rayleigh fading channels through an iterative process between a Doppler spread estimator and a channel estimator. Our proposed Doppler spread estimator is based on the autocorrelation function (ACF) of the estimated channel coefficients, where we devise an ACF lag selection mechanism to maximize the performance of the Doppler spread estimation. We use a Forney-style factor graph to represent the fading channel with a first order autoregressive (AR(1)) model and implement a Gaussian message passing based channel estimator for Doppler spread estimation, where the AR(1) model coefficients are optimized. Compared to the existing joint Doppler spread and channel estimation approaches, the proposed approach achieves similar or better performance with lower complexity.