Exploiting External Interference for Clock Synchronization Many wireless sensor network (WSN) applications require the synchronization of the networkxe2x80x99s independent node clocks. That synchronization is a challenging problem that often requires energyconstrained devices to exchange many messages.This paper introduces the Interferencebased Clock Synchronization (ICS) protocol, an approach suitable for dense WSNs located in urban environments. ICS uses external interference to synchronize the networkxe2x80x99s nodes to either a networklocal internal or global (e.g., UTC) external time. All of the networkxe2x80x99s nodes observe interference at roughly the same time, and the node possessing the common time transmits its observed pattern to the network. The network nodes then compare and align the received and locallyobserved patterns, and subsequently, they update their clocks to the common time.The protocol is evaluated using both a simulator and hardware. Using this approach, the number of transmitted messages scales linearly with the network size. In the simulator, ICSsynchronized clocks had a mean time difference of 0.3635 ms when compared with the common time. Using hardware, the difference was larger at 4.9388 ms, but much of that difference can likely be attributed to the experimental setup.

Time Synchronization Attack Scenarios and Analysis of Effective SelfDetection Parameters in a Distributed Industrial Wireless Sensor Network Time Synchronization is an essential communication component for Industrial Wireless Sensor Networks (IWSNs). An IWSN is composed of multiple distributed resourceconstrained sensor nodes, which require their local clocks to be synchronized with each other in order to exchange packets in real time precisely ordered schedule. Time synchronization strategies are not designed with security support. As a consequence, a new generation of attacks arose, specifically targeting the corresponding protocols. Recent research studies prove that some attacks are practical and severe. At the same time, the set of detection parameters proposed in emerging attack detection techniques are not sufficient to catch up on the attacks. In this paper, we analyze in depth some attack strategies and develop new useful detection parameters. The key concept behind our mechanism is to use the MAC layer protocol characteristics to figure out novel metrics as inputs for a selfdetection of time synchronization attacks.