Real-time DSP and FPGA Implementation of Wiener LMS Based Multipath Channel Estimation in 3G CDMA Systems

Abstract

This paper investigates real-time DSP and FPGA implementations of a low complexity technique for asynchronous multiuser delay acquisition and time varying channel tracking for multipath channels in WCDMA and cdma2000 systems. A multiuser-LMS-like structure along with smoothing/prediction filters to improve tracking quality is reviewed. We investigate an efficient implementation based on FFT/IFFT technique, under fixed-point data representation and computation constraint. The measured BER reveals that fixed-point implementation is feasible at possibly no performance degradation. Based on real time execution made on a fixed-point high performance DSP, the maximum number of users is 15 and 17 for the proposed method and correlator, respectively. Due to the inherent parallelism and regular data flow FPGA implementation is suggested wherein a maximum number of users more than 80 can be afforded in Xilinx Virtex? II Pro device.