An asynchronous multirate decorrelator

This paper examines truncated window decorrelators for an asynchronous dire ct-sequence code-division multiple-access system supporting users transmitt ing at different bit rates. We decode a user by extending the observation w indow over a sufficient number of its bits. To characterize practical windo w sizes, simple upper and lower bounds for the asymptotic efficiency of bot h the truncated window and infinite window decorrelators are developed. Emp irical results show that as the length of the observation window increases, the bounds converge rapidly to the asymptotic efficiency of the infinite w indow decorrelator, The complexity of the receiver depends strongly on the ratio of the maximum to minimum bit rates.