Sampling-related frames in finite U-invariant subspaces

Abstract

Recently, a sampling theory for infinite dimensional U-invariant subspaces of a separable Hilbert space H where U denotes a unitary operator on H has been obtained. Thus, uniform average sampling for shift-invariant subspaces of L-2(R) becomes a particular example. As in the general case it is possible to have finite dimensional U-invariant subspaces, the main aim of this paper is to derive a sampling theory for finite dimensional U-invariant subspaces of a separable Hilbert space H. Since the used samples are frame coefficients in a suitable euclidean space C-N, the problem reduces to obtain dual frames with a U-invariance property.