PREFACE page XI
1 INTRODUCTION page
1.1 Wireless Sensor Networks
1.2 Time Synchronization
1.3 Importance of Time Synchronization
1.4 History of Clock Synchronization
1.5 Outline
2 SIGNAL MODELS FOR TIME SYNCHRONIZATION page lO
2.1 Definition of Clock lo
2.2 Design Considerations
2.3 Delay Components in Timing Message Delivery
3 TIME SYNCHRONIZATION PROTOCOLS page
3.1 Pairwise Synchronization -
3.1.1 Timing-Sync Protocol for Sensor Networks(TPSN)
3.1.2 Tiny-Sync and Mini-Sync
3.1.3 Reference Broadcast Synchronization(RBS)
3.1.4 Flooding Time Synchronization Protocol(FTSP)
3.2 Network-Wide Synchronization
3.2.1 Extension of TPSN
3.2.2 Lightweight Time Synchronization(LTS)
3.2.3 Extension of RBS
3.2.4 Extension of FTSP
3.2.5 Pairwise Broadcast Synchronization(PBS)
3.2.6 Time Diffusion Protocol (TDP)
3.2.7 Synchronous and Asynchronous DiffusionAlgorithms
3.2.8 Protocols Based on Pulse Transmissions-
3.3 Adaptive Time Synchronization
3.3.1 Rate-Adaptive Time Synchronization(RATS)
3.3.2 RBS-based Adaptive ClockSynchronization
3.3.3 Adaptive Multi-Hop TimeSynchronization (AMTS)
4 FUNDAMENTAL APPROACHES TO TIME SYNCHRONIZATION page
4.1 Sender-Receiver Synchronization (SRS)
4.2 Receiver-Only Synchronization (ROS)
4.3 Receiver-Receiver Synchronization(RRS)
4.4 COmparisons
5 MINIMUM VARIANCE UNBIASED ESTIMATION (MVUE)OF CLOCK OFFSET page
5.1 The System Architecture -
5.2 Best Linear Unbiased Estimation Using OrderStatistics(BLUE-OS)
5.2.1 Symmetric Link Delays
5.2.2 Asymmetric Link Delays -
5.3 Minimum Variance Unbiased Estimation (MVUE)
5.3.1 Asymmetric Link Delays
5.3.2 Symmetric Link Delays
5.4 Explanatory Remarks
6 CLOCK OFFSET AND SKEW ESTIMATION page
6.1 Gaussian Delay Model
6.1.1 Maximum Likelihood (ML) Clock OffsetEstimation -
6.1.2 Cramer-Rao Lower Bound (CRLB) for ClockOffset
6.1.3 Joint Maximum Likelihood Estimation (JMLE)of Clock Offset and Skew
6.1.4 Cramer-Rao Lower Bound (CRLB) for ClockOffset and Skew
6.2 Exponential Delay Model.
6.2.1 Cramer-Rao Lower Bound (CRLB) for ClockOffset -
6.2.2 Joint Maximum Likelihood Estimation (JMLE)of Clock Offsetand Skew
7 COMPUTATIONALLY SIMPLIFIED ScHEMEs FOR ESTIMATION OF CLOCK OFFSETAND SKEW page
7.1 Using the First and the Last DataSample
7.1.1 Gaussian Delay Model
7.1.2 Exponential Delay Model
7.1.3 Combination of Clock Offset and SkewEstimation
7.1.4 Simulation Results
7.2 Fitting the Line Between Two Points at Minimum DistanceApart
7.2.I Simulation Results lol
7.2.2 Computational Complexity Comparison lo
8 PAIRWISE BROADCAST SYNCHRONIZATION (PBS) - page lo
8.1 Synchronization for Single-Cluster Networks lo
8.2 Comparisons and Analysis lo
8.3 Synchronization for Multi-Cluster Networks - lo
8.3.1 Network-Wide Pair SelectionAlgorithm (NPA) lO
8.3.2 Group-Wise Pair Selection Algorithm(GPA) - 1io
8.4 Comparisons and Analysis
9 ENERGY-EFFICIENT ESTIMATION OF CLOCK OFFSET FOR INACTIVENODES page
9.1 Problem Formulation
9.2 Maximum Likelihood Estimation (MLE)
9.3 Cramer-Rao Lower Bound (CRLB)
9.3.1 CRLB for the Clock Offset of Inactive Nodeq
9.3.2 CRLB for the Clock Offset of Active Nodet'
9.4 Simulation Results
10 SOME IMPROVED AND GENERALIZED ESTIMATION SCHEMES FOR CLOCKSYNCHRONIZATION OF INACTIVE NODES page
10.1 Asymmetric Exponential Link Delays
10.1.1 Best Linear Unbiased EstimationUsing Order Statistics (BLUE-OS)
10.1.2 Minimum Variance Unbiased Estimation(MVUE)
10.1.3 Minimum Mean Square Error (MMSE)Estimation
10.2 Symmetric Exponential Link Delays -
10.2.1 Best Linear Unbiased EstimationUsing Order Statistics(BLUE-OS)
10.2.2 Minimum Variance UnbiasedEstimation (MVUE)
10.2.3 Minimum Mean Square Error (MMSE)Estimation
11 ADAPTIVE MULTI=HOP TIME SYNCHRONIZATION (AMTS) pageI
11.1 Main Ideas -
11.2 Level Discovery Phase
11.3 Synchronization Phase
11.4 Network Evaluation Phase 16o
11.4.1 Synchronization Mode Selection 16o
11.4.2 Determination of SynchronizationPeriod
11.4.3 Determination of the Number ofBeacons
11.4.4 Sequential Multi-HopSynchronization Algorithm (SMA)
11.5 Simulation Results -
12 CLOCK DRIFT ESTIMATION FOR ACHIEVING LONG-TERM SYNCHRONIZATION -page
12.1 Problem Formulation 17o
12.2 The Estimation Procedure
13 JOINT SYNCHRONIZATION OF CLOCK OFFSET AND SKEW IN aRECEIVER-REcEIVER PROTOCOL page
13.1 Modeling Assumptions
13.2 Joint Maximum Likelihood Estimation (JMLE)of the Offsetand Skew
13.3 Application of the Gibbs Sampler
13.4 Performance Bounds and Simulations
14 ROBUST ESTIMATION OF CLOCK OFFSET page
14.1 Problem Modeling and Objectives -
14.2 Gaussian Mixture Kalman Particle Filter(GMKPF)
14.3 Testing the Performance of GMKPF -
14.4 Composite Particle Filtering (CPF) with BootstrapSampling (BS)
14.5 Testing the Performance of CPF and CPF withBS
15 CONCLUSIONS AND FUTURE DIRECTIONS page
ACRONYMS page
REFERENCES page
INDEX page