FPGA implementation of correlation and ML channel estimation for long code CDMA systems

The estimation of channel delays along with their respective complex channel coefficients of different users constitutes the first stage in the detection process at the receiving base station in a CDMA communication system. This stage forms the bottleneck for the detection of users´ bit streams; both in terms of accuracy as well as execution time. In this paper, we address the problem of channel estimation in the complex scenario involving multiple users, multiple paths, and fading channels in CDMA systems. We will highlight a simple pipelined architecture for recursive channel estimators and describe the implementation issues related to the dominant type of operations, data flows, structure regularities, FPGA implementation and further figures to discuss the WCDMA real-time requirements in terms of processing capabilities..