An algorithm to synchronize the time of a computer to universal time
IEEE/ACM Transactions on Networking (TON)
Proof of a fundamental result in self-similar traffic modeling
ACM SIGCOMM Computer Communication Review
Measurements and analysis of end-to-end Internet dynamics
Measurements and analysis of end-to-end Internet dynamics
Improving TCP Congestion Control over Internets with Heterogeneous Transmission Media
ICNP '99 Proceedings of the Seventh Annual International Conference on Network Protocols
Adaptive stream resource management using Kalman Filters
SIGMOD '04 Proceedings of the 2004 ACM SIGMOD international conference on Management of data
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Time information is critical for a variety of applications in distributed environments that facilitate pervasive computing and communication. This work describes and evaluates a novel Kalman filtering algorithm for end-to-end time synchronization between a client computer and a server of "true" time (e.g. a GPS source) using messages transmitted over packet switched networks, such as the Internet. The messages exchanged have the NTP format and the algorithm evaluated, is performed only at the client side. The Kalman filtering algorithm is compared to two other techniques widely used, based on linear programming and statistical averaging and the experiments involve independent consecutive measurements (gaussian case) or measurements exhibiting long-range dependence (self-similar case). Performance is evaluated according to the estimation error of frequency offset and time offset between clientand server clock, the standard deviation of the estimates and the number of packets used for a specific estimation. The algorithms can exploit existing NTP infrastructure and a specific example is presented.