A note on the invertibility of the Gabor frame operator on certain modulation spaces

Kurzfassung/Abstract

We consider Gabor frames generated by a general lattice and a window function that belongs to one of the following spaces: the Sobolev space V1=H1(Rd), the weighted L2-space V2=L21+|x|(Rd), and the space V3=H1(Rd)=V1∩V2 consisting of all functions with finite uncertainty product; all these spaces can be described as modulation spaces with respect to suitable weighted L2 spaces. In all cases, we prove that the space of Bessel vectors in Vj is mapped bijectively onto itself by the Gabor frame operator. As a consequence, if the window function belongs to one of the three spaces, then the canonical dual window also belongs to the same space. In fact, the result not only applies to frames, but also to frame sequences.