Efficient, Single Hop Time Synchronization Protocol for Randomly Connected WSNs

Abstract

Abstract-This paper develops a fast, accurate and energy-efficient time synchronization protocol in wireless sensor networks that operate in harsh environments. The suggested protocol concept is based on an electrical physical metaphor. The protocol treats the nodes times as the states of an unconditionally stable discrete dynamical system that uses only single hop communication. The system can terminate at a low number of message exchanges while still in the transient phase. Making all the WSN nodes agree on a common time which is most likely that of a gateway node is one of the activities (e.g. routing, topology/geometry reconstruction, etc.) the network has to perform in order to function. While the literature abounds with techniques on synchronization [3]- [5], most of these methods do not suit operation in harsh environments. They assume that the WSN has a specific stationary connectivity, node labeling or multi-hop communication, among other assumptions.

Optimal operation mode selection for energy-efficient light-weight multi-hop time synchronization in linear wireless sensor networks

“…where α 12 and β 12 are the relative offset and drift, respectively, and t 1 and t 2 are local time of two nodes. A two-way handshaking mechanism to pass timestamps can be used to estimate relative offset and drift at a node [11].…”

“…In fact, the complex nature of the problem to be solved and demanding system requirements lead to the development of numerous synchronization algorithms. In this context, several accurate time synchronization methods have been proposed for WSNs [10][11][12][13], in general, and for LWSNs [14,15], in particular. A dual-time or two-time sources per node were introduced in [14] to decrease the time fluctuations with increasing hops but requires maintenance of those clocks thus adds complexity to the system model.…”

Optimal Message Bundling with Delay and Synchronization Constraints in Wireless Sensor Networks

“…To fulfill the desired requirements of energy efficiency and synchronization accuracy, many schemes have been proposed such as [1,20,21,22,23,24,25,26]. Among those, EE-ASCFR proposed in [1] particularly suits the E2E delay calculation since computing the E2E delay at the head is completely in conformity with the preferential asymmetric scenario of EE-ASCFR.…”

“…For instance, in human activity and gesture recognition based on the novel device-free wireless sensing [18,19], the sensed data must be ordered accurately and processed timely, which requires high-precision time synchronization for the former while demands certain latency—i.e., E2E delay—for the latter. Among many research works on WSN time synchronization aiming at improving time synchronization accuracy while lowering energy consumption [1,20,21,22,23,24,25,26], the energy-efficient time synchronization scheme we proposed in [1], which we call it EE-ASCFR—i.e., short for E nergy- E fficient time synchronization scheme based on A synchronous S ource C lock F requency R ecovery—throughout the paper—leverages data bundling to further reduce the energy consumption in terms of the number of synchronization message transmissions; thanks to the reverse two-way message exchange scheme adopted in EE-ASCFR, the time synchronization is done at the head node and the corresponding synchronization data are bundled together with measurements into a bundled message at a sensor node. Consequently, the time synchronization accuracy is tied to the interval of the bundled message transmissions from the sensor node to the head node, i.e., the synchronization interval (SI).…”

An Energy Efficient Synchronization Protocol for Target Tracking in Wireless Sensor Array Networks

“…In many cases, WSNs are large-scale and decentralized with thousands of nodes [12]. Time synchronization, which builds a common understanding of time among all nodes, is one of the most important techniques in WSNs [13,14,15] and other wireless scenarios [16,17,18]. However, due to the low quality of crystal oscillations, the limited computation capabilities, the uncertainty in wireless communication, and the limited power supply, time synchronization in WSNs is still a challenging problem.…”