Method and apparatus for coherent detection in a telecommunications system

摘要

A method of channel estimation in a Code Division Multiple Access (CDMA) transmission system that incorporates Pilot Symbol Assisted Modulation (PSAM) using an iterative coherent detection method to estimate the phase and frequency of the received pilot symbols. Arctangent calculations are used to estimate phase and frequency. An iterative least squares linearization identifies and corrects values of the arctangent associated with an incorrect 2pi alias, which arise due to the multiple-valued nature of the arctangent function. An alternative non-iterative least squares linearization also corrects the arctangent values, based on a calculation involving stored values of the pilot symbols.