Research Of Adaptive Scheduling Mechanism On WSN Based On Quorum

The WSN is a wireless network composed of a large number of sensor nodes deployed in the monitoring area which have the function of data acquisition, data processing and communication. Because of its flexibility building a network, good dynamic topology, low costs and without the support of fixed infrastructures, the WSN has been widely applied to all kinds of monitoring systems. But, the sensor nodes are often equipped with the button batteries and dry batteries, and often working in the harsh environment where people hardly reach. Therefore, saving the energy consumption of sensor nodes and extending the life cycle of the network have been becoming the urgent issues facing us. The quorum system is a new collection system based on the redundant design and the study results show that applying the quorum system to WSN can reduce the nodes’ energy consumption and improve the performances of WSN. The WSN adaptive scheduling mechanism is being used by nodes to adaptively adjust their working states based on the existing network strategies. With the superior dynamic nature and flexibility, the adaptive scheduling mechanism has been widely applied to WSN. According to the features of WSN, the dissertation researched the adaptive scheduling mechanism in WSN based on the quorum system. This dissertation mainly carried on the following creative work:(1) A new energy-efficient uneven clustering algorithm was designed to alleviate the energy consumption unbalance in WSN. The new algorithm adopts cluster head election strategy based on the residual energy of nodes, and always chooses the node with high residual energy as a cluster head at every round. Calculating the radius of the cluster, the cluster head take the residual energy of itself and the distance to the base station over. When building the inter-cluster forwarding link, the adjacent cluster heads’ residual energy, the number of cluster members, the relative distance to itself and the relative distance to base station should been taken into consideration by cluster heads. Finally, the dissertation uses the OMNeT++ simulation software to verify the superiority of EUCA.(2) In order to address the issue of neighbor discovery caused by periodic sleep of sensor nodes, an asynchronous adaptive asymmetric scheduling mechanism was proposed based on the quorum system. The core idea of this mechanism is that the node chooses the cycle length of the prime grid adaptively according to the congestion status of networks and the node’s communication demand. Then, the node selects the slots in which the node turns on its radio to receive and transmit packets from the prime grid using a quorum, and informs the node’s neighboring nodes. Accordingly, each pair of neighbor nodes must complete the neighbor discovery within limited time. Because of the non-empty intersection property of the prime grid, the mechanism can guarantee the connectivity of the network without using the time synchronization protocol even if the time of nodes is asynchronous. Simulation results show that the mechanism has significant advantages in scalability and energy efficiency.(3) To improve the scalability of the mine WSN and reduce the energy consumption of the nodes, the dissertation applies the EUCA and 3ASM to the mine monitoring system and uses the simulation software to verify the characteristics of the EUCA and 3ASM. Simulation results show that the EUCA and 3ASM can adapt to the mine working environment features and meet the needs of mine work.