Pseudodifferential operators on time-frequency invariant Banach spaces and applications to Gabor Frames

Starting from the study of pseudodifferential operators with completely periodic symbols, we obtain results of continuity and invertibility of a class of Gabor operators on time-frequency invariant Banach spaces. As an applications we find sufficient conditions for the existence of Gabor frames on the space of square integrable functions, associated to a general lattice.