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: Research Article Efficient Delay Tracking Methods with Sidelobes Cancellation for BOC-Modulated Signals | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2007 Article ID 72626 20 pages doi 2007 72626 Research Article Efficient Delay Tracking Methods with Sidelobes Cancellation for BOC-Modulated Signals Adina Burian Elena Simona Lohan and Markku Kalevi Renfors Institute of Communications Engineering Tampere University of Technology . Box 553 33101 Tampere Finland Received 26 September 2006 Accepted 2 July 2007 Recommended by Anton Donner In positioning applications where the line of sight LOS is needed with high accuracy the accurate delay estimation is an important task. The new satellite-based positioning systems such as Galileo and modernized GPS will use a new modulation type that is the binary offset carrier BOC modulation. This type of modulation creates multiple peaks ambiguities in the envelope of the correlation function and thus triggers new challenges in the delay-frequency acquisition and tracking stages. Moreover the properties of BOC-modulated signals are yet not well studied in the context of fading multipath channels. In this paper sidelobe cancellation techniques are applied with various tracking structures in order to remove or diminish the side peaks while keeping a sharp and narrow main lobe thus allowing a better tracking. Five sidelobe cancellation methods SCM are proposed and studied SCM with interference cancellation IC SCM with narrow correlator SCM with high-resolution correlator HRC SCM with differential correlation DC and SCM with threshold. Compared to other delay tracking methods the proposed SCM approaches have the advantage that they can be applied to any sine or cosine BOC-modulated signal. We analyze the performances of various tracking techniques in the presence of fading multipath channels and we compare them with other methods existing in the literature. The SCM approaches bring improvement also in scenarios with closely-spaced paths which are the most problematic from the .
