The K-dual Bessel generators for unitary groups of Hilbert spaces

Structured frames have interested many mathematicians and engineers due to their potential applications. This paper addresses the theory of K-frames associated with unitary groups. Let U be a unitary group for a separable Hilbert space 94. Given a K-frame generator U for U, we present an explicit expression of all K-dual Bessel generators of eta for U under two cases, and simultaneously, prove that its canonical K-dual Bessel generator corresponds to the most economic presentation of the element from the range of K. (C)2019 Elsevier Inc. All rights reserved.