E-SATS: An Efficient and Simple Time Synchronization Protocol for Cluster- Based Wireless Sensor Networks

Using Bluetooth Low Energy Technology to Perform ToF-Based Positioning

“…In particular, ToF measurements require accurate time synchronization between all the involved nodes and a reference time source node, ensuring a common time scale. Over the past few years, various time-synchronization techniques for WSN that have been investigated apply packet synchronization techniques to trigger the network or to synchronize the clocks' nodes [37][38][39][40][41][42][43][44][45][46]. Among the different available time-synchronization schemes, the one-way message exchange, the two-way message exchange, and the receiver-receiver synchronization appear to be the most widely used [39,46].…”

“…Finally, the nodes exchange the obtained reference time of arrival with each other to estimate the offset and skew. Moreover, the timing-sync protocol for sensor networks (TPSN) is based on the use of a classical approach that synchronizes two nodes instead of a set of Over the past few years, various time-synchronization techniques for WSN that have been investigated apply packet synchronization techniques to trigger the network or to synchronize the clocks' nodes [37][38][39][40][41][42][43][44][45][46]. Among the different available time-synchronization schemes, the one-way message exchange, the two-way message exchange, and the receiverreceiver synchronization appear to be the most widely used [39,46].…”

“…Moreover, the indoor propagation of RF signals can be affected by different factors, such as multipath phenomena, fast fading, strong human body absorption, non-lineof-sight (NLOS) propagation conditions, and clock frequency skew swinging; thus, the synchronization error will increase severely [37][38][39][40][41][42][43][44][45][46]. In addition, WSNs are typically characterized by size and cost constraints that limit resources such as power, memory space computational power and communications bandwidth.…”

“…This may reduce the average distance between the mobile node and the anchors and enable use of sensor fusion techniques that achieve increased accuracy and range by combining the information acquired by several noisy measurements. Thus, in recent research activities, different approaches to synchronizing the time in low-power wireless sensor networks have been studied [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51]. It is worth noting that BLE systems are low-power, but most of the available BLE positioning solutions are based on RSS measurements.…”

A Design of a Time Synchronization Protocol Based on Dynamic Route and Forwarding Certification

“…For example, the dynamic route list based timing-sync protocol (DRL-TSP) [ 14 ] is a strategy that chooses a parent node in the last hop as the synchronization reference for each node, which provides the minimal hops from the root node by dividing the network into a hierarchical structure. Efficient and simple algorithm for time synchronization (E-SATS) [ 15 ] is proposed for reducing computations and energy consumption. However, for the WSN with a limited energy, a fixed hierarchical structure or a settled clustered structure results in a strong dependency on topology, which will consume extra energy in the process of building and fixing the established structure.…”