Abstract
The authors study the statistical properties of the outputs of some basic multirate filtering operations when the input is a wide-sense-stationary (WSS) or a cyclo-WSS (CWSS) process. They give necessary and sufficient conditions under which the output remains WSS or CWSS. For some multirate filters, the output response to a WS input is CWSS. Expressions for the periods of cyclostationarity for such cases are given. As an application of the theory, the optimal (Wiener) solution for a new efficient multirate adaptive filtering method suitable for identification of bandlimited channels is derived. It is shown that the optimal (Wiener) filter is a linear periodically time-varying (LPTV) filter. Simulations are included which verify that an LPTV adaptive filtering structure gives better performance than a transversal adaptive filtering structure.