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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Feedforward Delay Estimators in Adverse Multipath Propagation for Galileo and Modernized GPS Signals | Hindawi Publishing Corporation EURASIP Journal on Applied Signal Processing Volume 2006 Article 1D50971 Pages 1-19 DOI 10.1155 ASP 2006 50971 Feedforward Delay Estimators in Adverse Multipath Propagation for Galileo and Modernized GPS Signals Elena Simona Lohan Abdelmonaem Lakhzouri and Markku Renfors Institute of Communications Engineering Tampere University of Technology P. O. Box 553 Tampere 33101 Finland Received 31 May 2005 Revised 8 March 2006 Accepted 29 March 2006 The estimation with high accuracy of the line-of-sight delay is a prerequisite for all global navigation satellite systems. The delay locked loops and their enhanced variants are the structures of choice for the commercial GNSS receivers but their performance in severe multipath scenarios is still rather limited. The new satellite positioning system proposals specify higher code-epoch lengths compared to the traditional GPS signal and the use of a new modulation the binary offset carrier BOC modulation which triggers new challenges in the delay tracking stage. We propose and analyze here the use of feedforward delay estimation techniques in order to improve the accuracy of the delay estimation in severe multipath scenarios. First we give an extensive review of feedforward delay estimation techniques for CDMA signals in fading channels by taking into account the impact of BOC modulation. Second we extend the techniques previously proposed by the authors in the context of wideband CDMA delay estimation e.g. Teager-Kaiser and the projection onto convex sets to the BOC-modulated signals. These techniques are presented as possible alternatives to the feedback tracking loops. A particular attention is on the scenarios with closely spaced paths. We also discuss how these feedforward techniques can be implemented via DSPs. Copyright 2006 Elena Simona Lohan et al. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and .
