An autonomous discovery mechanism of surviving IoT devices for post-disaster coal mine cellular IoT

Coal mine Internet of Things (IoT) is a fundamental information infrastructure of realizing coal mine information perception, transmission and application.It has played a vital role in coal mine process monitoring, as well as disaster forecasting and early warning.In a post-disaster coal mine, the discovery of surviving IoT devices is the foundation and precondition of reconstructing the coal mine IoT.Aiming at the LTE-A based cellular IoT network for coal mine, an autonomous discovery mechanism for surviving IoT devices was proposed.After waking up from the disaster, each surviving IoT device attempts to randomly select a discovery resource unit from a post-disaster dedicated discovery resource period to send a beacon to the gateway of IoT network and broadcast the existence of itself.The surviving IoT devices with failed resource selection will select a random back-off interval to perform back-off.When the back-off time ends, they determine whether they have reached the maximum number of resource selection times in the upcoming dedicated discovery resource period.If yes, the surviving IoT devices will exit the current dedicated discovery resource period.If not, the surviving IoT devices will continue to perform resource reselection in the current dedicated discovery resource period.Once receiving a beacon, the gateway of IoT network decodes and analyzes it, and determines whether the signal to interference and noise ratio (SINR) of the received beacons is not less than the threshold of beacon decoding in gateway or not.The simulation results show that the proposed autonomous discovery mechanism of surviving IoT devices can significantly improve the ability of device discovery.With a large back-off interval, the number of conflicts during the dedicated discovery resource period can be further reduced, and finally increase the number of discovered devices in average.Under the certain random back-off intervals and dedicated discovery resources periods, a rational value of maximum resource selection times can improve the efficiency of discovering surviving IoTDs, so as to better meet the demand of Quality of Service (QoS) in the emergency rescue after a coal mine disaster.