CESP: A Low-Power High-Accuracy Time Synchronization Protocol

Time synchronization is a fundamental problem in any distributed system. In particular, wireless sensor networks (WSNs) require scalable time synchronization for implementing distributed tasks on multiple sensor nodes. We propose an energy-efficient coefficient exchange synchronization protocol (CESP) based on a receiver-receiver synchronization scheme, which minimizes the impact of access-time delays. Most of the existing synchronization protocols focus on improving the synchronization accuracy by assuming the availability of packet-level timestamping and with little concern for power consumption. The proposed time-synchronization protocol achieves high synchronization accuracy similar to the classic reference broadcast synchronization (RBS) protocol without requiring packet-level timestamping but with a significant reduction on communication overhead to achieve low power consumption. CESP works in a fundamentally different way from RBS: In order to synchronize two receivers, RBS exchanges all beacon packets between two receivers, whereas CESP receivers first process a large number of received beacon packets and only then exchange a small amount of information between the two receivers: synchronization coefficients. The synchronization performance and power consumption are evaluated and compared with that of other well-known synchronization protocols through experimental results.