Research And Application On Optimization Of Mine Wireless Ad Hoc Network Protocol

The wireless ad hoc network does not need to rely on fixed infrastructure.All network nodes have dual functions of routing transfer and terminal reception,and the nodes can be moved,which is convenient for network expansion.At the same time,it also has strong antidestruction ability,which can achieve dual-purpose disaster relief and is suitable for application in mine environment.After researching and analyzing the relevant theories,the wireless ad hoc network protocol is improved and optimized in combination with the mine environment.Aiming at the problem of unreasonable setting of contention window reset rules in IEEE 802.11 MAC layer protocol backoff algorithm,a dynamic contention window initial value adjustment mechanism is designed to evaluate the channel state of the previous round of data frame transmission process,and predict the channel congestion degree of the next round of data frame transmission process from the evaluation results.The corresponding initial value adjustment strategy of the contention window is designed according to the different congestion degree.The simulation results show that the network throughput is improved after the algorithm is improved.Aiming at the problem that AODV routing protocol simply relies on the shortest hops as the basis of routing selection judgment in practical application,which will lead to the problem that the routing is not robust enough,the judgment basis for routing selection is improved.Combined with the underground tunnel environment and the limited battery energy of wireless nodes,the received signal strength of the node and residual energy virtual hops are designed respectively.The difference ratio between the received signal strength of the node and the set threshold and the proportion of residual energy are divided into levels.Different virtual hops are set at different levels.The virtual hops and real hops are added to obtain the comprehensive hops.Finally,the path with the shortest comprehensive hops is selected as the route.The simulation results show that the main performance indicators of the network,such as packet receive ratio,end-to-end average delay and normalized routing overhead,are better than those before the improvement of the protocol.Based on the improvement of the protocol,this thesis completes transplantation of network protocol before and after the improvement on the i.MX6ULL terminator development board,and uses multiple embedded development boards to build a multi-hop wireless ad hoc network in the mine modeling tunnel.The network performance before and after the improvement of the protocol is tested through many experiments.The experimental results show that in the actual application scenario,the average round-trip delay and packet loss rate of the network are better than those before the improvement of the protocol.Simulation and experimental results verify the effectiveness of the improved network protocol,which is more suitable for mine wireless ad hoc network.