煤矿蜂窝物联网灾后残存物联网设备自主发现机制

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

煤矿物联网是实现煤矿信息感知、传输和应用的信息基础架构,在煤矿生产监测和灾害预测预警中发挥了重要的作用。残存物联网设备的发现是实现煤矿物联网灾后重构的基础和前提。针对基于LTE-A的煤矿蜂窝物联网,提出了1种灾后残存物联网设备自主发现机制。首先,煤矿发生灾害事故后不断苏醒的残存物联网设备从灾后专用发现资源周期中随机选择一个发现资源单元向物联网网关发送信标广播自己的存在。然后,资源选择失败的残存物联网设备选择一个随机退避间隔进行退避。当退避时间结束时,判断本身在即将到来的专用发现资源周期中是否已经达到了资源最大选择次数。如果是,则残存物联网设备退出当前专用发现资源周期;如果否,则残存物联网设备在当前专用发现资源周期中继续进行资源重选。物联网网关对接收到的信标的信干噪比值进行解码分析,判断残存物联网设备信标的信干噪比值是否大于等于物联网网关的信标解码阈值。仿真结果表明,采用所提出的基于LTE-A的煤矿蜂窝物联网灾后残存物联网设备自主发现机制,可显著提高残存物联网设备的平均发现性能。随着退避间隔的增大,可进一步降低灾后专用发现资源周期中残存物联网设备之间的资源选择冲突,增加残存物联网设备的平均发现数。在一定的随机退避间隔和专用发现资源周期下,残存物联网设备的资源最大选择次数取值合理可在较短的时间内发现尽可能多的残存物联网设备,更好地满足煤矿蜂窝物联网灾后应急救援的QoS需求。

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.