Subspace-based maximum Doppler spread estimation for LOFDM systems with reduced time averaging

The subspace-based maximum Doppler spread estimation algorithm with reduced time averaging (RTA) for Lattice Orthogonal Frequency Division Multiplexing (LOFDM) systems in doubly-dispersive channels is proposed. The proposed algorithm applies basis expansion model (BEM) to achieve the LOFDM block transmission strategy and estimate the averaging channel auto-correlation matrixes in time domain. Based on the frequency correlation among adjacent LOFDM pilots, the correlation matrix´s dimension was reduced through superposition average processing. Consequently, the number of time samples required by the accurate estimation is reduced.