A case against routing-integrated time synchronization

To achieve more accurate global time synchronization, this paper argues for decoupling the clock distribution network from the routing tree in a multihop wireless network. We find that both flooding and routing-integrated time synchronization rapidly propagate node-level errors (typically due to temperature fluctuations) across the network. Therefore, we propose that a node chooses synchronization neighbors that offer the greatest frequency stability. We propose two methods to estimate a neighbor's stability. The first approach selects the neighbor whose Frequency Error Variance, or simply FEV, is smallest with respect to the local clock. The second approach selects the neighbor that reports the lowest FEV relative to its synchronization parent. We also propose the node-level time-variance FEV as an additive metric for selecting more stable clock trees than either na

• Type: Journal
• Year: 2010
• Where: SENSYS
• Authors: Thomas Schmid, Zainul Charbiwala, Zafeiria Anagnostopoulou, Mani B. Srivastava, Prabal Dutta
• Keywords: Clock, Global Time Synchronization, Sensor Networks, SENSYS 2010, Time Synchronization