An FFT-Based Approach for Fast Acquisition in Spread Spectrum Communication Systems

  • Authors:

  • Sascha M. Spangenberg;Iain Scott;Stephen Mclaughlin;Gordon J. R. Povey;David G. M. Cruickshank;Peter M. Grant

  • Affiliations:

  • Signals and Systems Group, Department of Electronics and Electrical Engineering, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JL, U.K. E-mail: ssp@ee.ed.ac.uk;Signals and Systems Group, Department of Electronics and Electrical Engineering, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JL, U.K. E-mail: ssp@ee.ed.ac.uk;Signals and Systems Group, Department of Electronics and Electrical Engineering, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JL, U.K. E-mail: ssp@ee.ed.ac.uk;Signals and Systems Group, Department of Electronics and Electrical Engineering, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JL, U.K. E-mail: ssp@ee.ed.ac.uk;Signals and Systems Group, Department of Electronics and Electrical Engineering, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JL, U.K. E-mail: ssp@ee.ed.ac.uk;Signals and Systems Group, Department of Electronics and Electrical Engineering, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JL, U.K. E-mail: ssp@ee.ed.ac.uk

  • Venue:
  • Wireless Personal Communications: An International Journal
  • Year:
  • 2000

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Abstract

This paper describes a non-coherent technique forfast acquisition of direct sequence spread spectrum(DS/SS) signals in low earth orbit (LEO) satellitecommunication scenarios. Large Doppler offsets areinherent to such environments and are likely to causemajor problems during the code acquisition phase dueto the introduced frequency ambiguity. In the presentpaper we discuss the use of a set of partialcorrelators for code phase acquisition, combined witha fast Fourier transform (FFT) for the purpose of simultaneous Doppler estimation. We will show that theuse of this architecture largely accelerates thesynchronisation process compared to conventionaltechniques over a wide range of Doppler offsets.Furthermore we discuss the implementation of azero-padded FFT that increases the frequencyresolution to such an extent, that acquisition timesidentical to scenarios without existing Doppler offsetcan be achieved.