Inverse filtering criteria for CDMA systems

Abstract

Linear blind CDMA receivers are derived using inverse filtering criteria. The receiver parameters are directly obtained without explicit estimation of the system/channel. Both synchronous and asynchronous cases are addressed, and multipath distortions are explicitly considered and compensated for. The approach is based on minimizing the receiver's output energy subject to appropriate constraints. Similar approaches have been used before in multiuser systems but without considering multipath distortions. Batch and adaptive blind algorithms are derived that are near-far resistant and do not require knowledge of the interfering users' codes. Global convergence is shown, optimality and performance issues are discussed, and some illustrative simulations are presented.