Artificial intelligence: a modern approach
Artificial intelligence: a modern approach
A 2-Approximation Algorithm for the Undirected Feedback Vertex Set Problem
SIAM Journal on Discrete Mathematics
Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
Probabilistic Clock Synchronization in Distributed Systems
IEEE Transactions on Parallel and Distributed Systems
Model-based clock synchronization in networks with drifting clocks
PRDC '00 Proceedings of the 2000 Pacific Rim International Symposium on Dependable Computing
Fine-grained network time synchronization using reference broadcasts
ACM SIGOPS Operating Systems Review - OSDI '02: Proceedings of the 5th symposium on Operating systems design and implementation
Estimation and Removal of Clock Skew from Network Delay Measurements
Estimation and Removal of Clock Skew from Network Delay Measurements
Lightweight time synchronization for sensor networks
WSNA '03 Proceedings of the 2nd ACM international conference on Wireless sensor networks and applications
Timing-sync protocol for sensor networks
Proceedings of the 1st international conference on Embedded networked sensor systems
The flooding time synchronization protocol
SenSys '04 Proceedings of the 2nd international conference on Embedded networked sensor systems
Secure time synchronization service for sensor networks
Proceedings of the 4th ACM workshop on Wireless security
Generating all vertices of a polyhedron is hard
SODA '06 Proceedings of the seventeenth annual ACM-SIAM symposium on Discrete algorithm
TinySeRSync: secure and resilient time synchronization in wireless sensor networks
Proceedings of the 13th ACM conference on Computer and communications security
On extracting consistent graphs in wireless sensor networks
International Journal of Sensor Networks
Computational Complexity: A Conceptual Perspective
Computational Complexity: A Conceptual Perspective
Secure Time Synchronization in Sensor Networks
ACM Transactions on Information and System Security (TISSEC)
A secure time synchronization protocol for sensor network
PAKDD'07 Proceedings of the 2007 international conference on Emerging technologies in knowledge discovery and data mining
Exact computation of maximum induced forest
SWAT'06 Proceedings of the 10th Scandinavian conference on Algorithm Theory
Finding a minimum feedback vertex set in time O(1.7548n)
IWPEC'06 Proceedings of the Second international conference on Parameterized and Exact Computation
Secure neighborhood discovery: a fundamental element for mobile ad hoc networking
IEEE Communications Magazine
A novel approach to multi-sensor data synchronization using mobile phones
Proceedings of the Fifth International Conference on Body Area Networks
Proceedings of the 7th International Conference on Body Area Networks
A novel approach to multi-sensor data synchronisation using mobile phones
International Journal of Autonomous and Adaptive Communications Systems
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Time synchronization in highly distributed wireless systems like sensor and ad hoc networks is extremely important in order to maintain a consistent notion of time throughout the network and to support the various timing-based applications. But, cheating behavior by the participating nodes in the network can severely jeopardize the accuracy of the associated time synchronization process. Despite recent advances in this direction, a key fundamental question still remains unanswered: Is it theoretically feasible to secure distributed time synchronization protocols, given complete (or global) time and time difference information in the network? In this paper, we attempt to answer this question with the help of sound mathematical modeling and analysis. We first formulate the problem of distributed time synchronization as a Constraint Satisfaction Problem (CSP) in a graph-based model of the network. Then, we prove that efficiently eliminating cheating behavior in distributed time synchronization protocols is combinatorially hard (NP-hard), i.e., it is highly unlikely that there exists an algorithm that solves, or even approximates, this problem in polynomial (in terms of total number of nodes) time. Due to this negative result for the general case, we focus on studying the problem for a special case of the graph-based model of the network, namely completely connected graphs. We derive an upper bound on the best possible solution quality for this problem, propose two polynomial-time approximation strategies, and present an empirical evaluation of their performance.