Extending the transfer function calculus of time-varying linear systems: a generalized underspread theory

We extend the approximate transfer function calculus of “undersnreadll linear time-varvine fLTV1 svstems introduced by W. Kozek. Our extensiog is‘ based o”n a new, generalized definition of underspread LTV svstems that does not assume finite support of the systems”’ spreading function. We establish explicit bounds on various error quantities associated with the transfer function approximation. Our results yield a simple and convenient transfer function calculus for a significantly wider and practically more relevant class of LTV systems than that previously considered.