Channel Access Control for Collisions Caused by Hidden Nodes and Phase Synchronization among Periodic Data Flows

With the rapid increase in IoT (Internet of Things) applications, more sensor devices, generating periodic data flows whose packets are transmitted at regular intervals, are being incorporated into WSNs (Wireless Sensor Networks). However, packet collision caused by the hidden node problem becomes serious particularly in large-scale multi-hop WSNs. Moreover, focusing on periodic data flows, continuous packet collisions among periodic data flows are caused once periodic packet transmission phases are synchronized. In this paper, we tackle the compounded negative effect of the hidden node problem and the continuous collision problem among periodic data flows. To realize this objective, we propose a new MAC layer mechanism. The proposed method predicts risky durations during which collision can be caused by hidden nodes by taking into account periodic characteristics of data packet generation. In the risky duration, each sensor node stops the transmission of packets in order to avoid collisions. To the best of our knowledge, this is the first paper that considers the compounded effect of hidden nodes and continuous collisions among periodic data flows. Other advantages of the proposed method include that any new control packets are not required and it can be implemented in widelydiffused IEEE 802.11 and IEEE 802.15.4 devices.