Research On Opportunistic Network Routing Algorithm And Buffer Management Policy In Mine

The working environment of coal mines is harsh,and the deployment of an efficient safety monitoring system plays an irreplaceable role in ensuring the safe production of mines.With the dynamic advancement of coal mining face,the wired communication line in traditional mine safety monitoring system is difficult to lay in time,and it is extremely vulnerable to wear and fracture and loss of communication function.Underground wireless sensor networks may be affected due to resource constraints,geological activities,and human factors,which will inevitably lead to regional connectivity or disconnection of communication links,and normal information transmission cannot be performed.Therefore,the opportunistic network based on the "carry-store-forward" mechanism is applied to mine safety monitoring to solve the problems of "energy hole",multipath effect and link interruption in mine communication.In order to verify the effectiveness of the opportunistic network in the mine safety monitoring system,this paper takes Shanxi Horsinghe Coal Mine as the background to study the routing algorithm of the mobile opportunistic network in the coal mine tunnel environment.The main innovations are:(1)For the coal mine safety monitoring system,an IPR-NU routing algorithm using the comprehensive effect of nodes is proposed.The algorithm first analyzes the environmental characteristics of coal mines and the requirements of the underground safety monitoring system to build a mine opportunity network system model.The encounter connection time duty cycle is used as an important factor of historical encounter information to improve PRoPHET to avoid blind forwarding and copying of message copies by nodes.Then,based on the improved probabilistic routing,the global context information such as the average delivery distance and average delivery time of the node is obtained,and different conditions for selecting the relay node are applied according to the hop index of the message,thereby further improving the message delivery rate and reducing network overhead.The IPR-NU is simulated by the ONE emulator and compared with Epidemic,PRoPHET and RPC.The results show that the IPR-NU has a significantly improved message delivery rate and the lowest transmission delay when the cache size and number of mobile nodes change.(2)Aiming at the overrun warning information in the coal mine safety monitoring system and the buffer overflow problem in the opportunity routing,a MWBMP cache management strategy based on message weights is proposed.The algorithm first guarantees the priority transmission of the warning information,and at the same time fully considers multiple message attributes such as the number of copies of the message,TTL,size and number of nodes encountered to calculate the weight of the message.The queue is divided according to the weight,and the delivery rate and delay utility are comprehensively considered to determine a reasonable message replacement strategy to alleviate network congestion and reduce transmission delay.The simulation results show that the MWBMP strategy performs better than the three cache management strategies of Drop-Largest,Drop-Oldest and Drop-Youngest when the cache size and simulation time change.The thesis has 36 figures,4 tables,and 101 references.