Cancellation techniques of Co-channel interference in asynchronous spread spectrum multiple access systems

A linear algebraic method for the cancellation of cochannel interference (CI) in asynchronous spread spectrum multiple access systems is described. Equations for the ratio of desirable-to-undesirable components for both pre- and post-cancellation are derived, and it is shown that the proposed cancellation method provides a significant improvement in this ratio. The method considers the CI as components that can be reproduced at each receiver; if the correlations among the PN sequences of all the active channels become known, the CI can be cancelled using the linear algebraic approach. As a result, a larger number of channels can share the same frequency band more efficiently; and the distant-dependent problem can be alleviated if initial synchronization is implemented.