IEICE Trans - Least Squares Based Timing Acquisition and Tracking for Closely Spaced Multipath in DS-CDMA

Least Squares Based Timing Acquisition and Tracking for Closely Spaced Multipath in DS-CDMA

Inwoo SONG
Jungwoo LEE

Publication
IEICE TRANSACTIONS on Communications Vol.E89-B No.3 pp.959-962
Publication Date: 2006/03/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.3.959
Print ISSN: 0916-8516
Type of Manuscript: LETTER
Category: Transmission Systems and Transmission Equipment for Communications
Keyword:
timing estimation, least squares, DS-CDMA,

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Summary:
In this paper, we present a time-delay estimation algorithm in a closely spaced multipath environment for a direct-sequence code division multiple access (DS-CDMA) systems. The proposed scheme first converts the observed signal to the frequency domain by Fast Fourier Transform (FFT). We then formulate a nonlinear estimation problem, and convert it into a large scale linear least squares problem. We apply conjugate gradients iterations on the resulting normal equations to obtain the solution. Unlike the methods which invoke the criterion of nonlinear least squares, the proposed scheme can achieve higher resolution. The delay estimation is combined with a tracking algorithm based on a FIR prefilter. Simulation results confirm the effectiveness of the proposed algorithm in both AWGN and Rayleigh fading channels.