tailieunhanh - Báo cáo hóa học: " Research Article Distributed Time Synchronization in Wireless Sensor Networks with Coupled Discrete-Time Oscillators"

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 Distributed Time Synchronization in Wireless Sensor Networks with Coupled Discrete-Time Oscillators | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2007 Article ID 57054 13 pages doi 2007 57054 Research Article Distributed Time Synchronization in Wireless Sensor Networks with Coupled Discrete-Time Oscillators O. Simeone1 and U. Spagnolini2 1 Center for Wireless Communications and Signal Processing Research New Jersey Institute of Technology University Heights Newark NJ 07102-1982 USA 2 Dipartimento di Elettronica e Informazione Politecnico di Milano Piazza Leonardo da Vinci 32 20133 Milano Italy Received 25 September 2006 Accepted 30 March 2007 Recommended by Mischa Dohler In wireless sensor networks distributed timing synchronization based on pulse-coupled oscillators at the physical layer is currently being investigated as an interesting alternative to packet synchronization. In this paper the convergence properties of such a system are studied through algebraic graph theory by modeling the nodes as discrete-time clocks. A general scenario where clocks may have different free-oscillation frequencies is considered and both time-invariant and time-variant network topologies or fading channels are discussed. Furthermore it is shown that the system of oscillators can be studied as a set of coupled discrete-time PLLs. Based on this observation a generalized system design is discussed and it is proved that known results in the context of conventional PLLs for carrier acquisition have a counterpart in distributed systems. Finally practical details of the implementation of the distributed synchronization algorithm over a bandlimited noisy channel are covered. Copyright 2007 O. Simeone and U. Spagnolini. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. 1. INTRODUCTION Distributed timing synchronization refers to a decentralized procedure that ensures the .