Identification of time-varying linear systems, which introduce both time-shifts (delays) and frequencyshifts (Doppler-shifts) to the input signal, is one of the central tasks in many engineering applications. This paper studies the problem of identification of underspread linear systems, defined as time-varying linear systems whose responses lie within a unit-area region in the delay
Waheed U. Bajwa, Kfir Gedalyahu, Yonina C. Eldar