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Research on Time Synchronization of High Latency Networks

Author: WangTing
Tutor: ZhouJun
School: Shanghai Jiaotong University
Course: Electronics and Communication Engineering
Keywords: Long latency network Time Synchronization Resource-constrained networks Algorithm simulation
CLC: TN915.01
Type: Master's thesis
Year: 2011
Downloads: 17
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Abstract

Long latency network is a communication network, such as water acoustic communication network of information propagation time between nodes is much larger than the transmission time, and deep-space communications network. The former is due to the propagation rate of the water due to the lower, the latter is due to the very long propagation distance and result in the propagation delay increases. Longer propagation delay, the long delay network time synchronization process, will produce large clock skew and propagation delay between each node in the network is also inconsistent, so the traditional network time synchronization technology NA long latency networks, it is necessary to study the long delay network time synchronization technology proposed for long delay network time synchronization program. The long delay network is a resource-constrained network, so the goal of the long delay network time synchronization technology is a high-precision, low-cost. Firstly, a Tri-Message protocol-based smoothing time synchronization algorithm to further reduce the consumption of resources while ensuring synchronization accuracy. The algorithm is performed using the Tri-Message single synchronization of multiple synchronization calculating clock frequency offset calculated weighted smoothing and Tri-Message transmission frequency W times lower, in the synchronization of the calculation process by using the clock frequency offset and the time offset of the variation in the absence of the synchronization signal is carried out periodically active time offset compensation. This article smoothing time synchronization protocol used in the OMNET network simulation platform, and evaluate its performance. Simulation results show that the W = 3, the smoothing time synchronization protocol data consumption rate Tri-Message 50%. Second, due to the existing applicable to the long delay network time synchronization technology for stable propagation delay or short-term stability, the paper proposes a applied to the long latency network between the mobile node dynamically tracking time synchronization algorithm, constant rate of change of the propagation delay was long delay network time synchronization. The algorithm makes use of a number of information exchange between nodes to calculate the propagation delay variation rate, and then estimate the delay variation to offset the compensation for time in order to achieve time synchronization. The simulation results show that the algorithm is able to reach the 10-microsecond synchronization accuracy rate of change of the long latency of 10ms / s network propagation delay. Finally, the long delay network time synchronization mode and multi-node synchronization program analysis and research, a slow sync clock offset compensation mode to prevent nodes moment backwards. A central node-based interactive synchronization scheme for multi-node network, the program can be made from the relative clock frequency offset between nodes synchronized time information.

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