The Node Scheduling Algorithm Under The Constraints Of Maintaining Field Coverage And Network Connectivity In Wireless Sensor Networks

Area coverage and network connectivity are basic requirements of wireless sensor network (WSN). Area coverage is that the sensors can sense or detect the monitoring area to collect information, while network connectivity guarantees the information gathered can be delivered between every two active sensors. In applications which the sensors are deployed randomly, the node density is high to meet the demands of specific application. The existence of redundant nodes complicates the network topology and data routing protocol, aggravates the competition of the already limited channel, wastes the sensor energy to forward the redundant data caused by the relevant nodes. So, it's of great importance to improve the performance and extend the lifespan of the network through node scheduling algorithm.According to the specific requirement of the application, the nodes can be randomly grouped into K uncovered groups while each group works in turn to provide the basic area coverage. But the sensors randomly grouping can't guarantee network connectivity sometimes, so some rule must be adapted to make some nodes work in more than one turn for maintaining the network connectivity. One another effective approach to conserving system energy in WSN is to keep only a minimal number of sensors active at the same time. But if any node in the minimal active sensor set suffers malfunction or being dead, the"blind point"problem that some place is not in the monitoring range of any active nodes occurs. Let one more minimal active sensor sets work together to increase the robustness and the coverage strength of the application. Given the WSN provides area coverage, analyze the detecting moving object in wireless sensor network, make some improvement of the sensor detecting mode, propose the undetectable speed and partially detectable speed which provide the referring range for WSN applications.Node scheduling which switches nodes to sleep and wakes them up when necessary is an important mean to prolong wireless sensor network's lifetime. This paper presents a minimal-hop-to-sink based node-scheduling algorithm (MBNS) under the constraints of field coverage and network connectivity. Using the collision-avoiding strategy to prevent one more neighboring nodes turning off at the same time to avoid the occurrence of blind point; using the probing mechanism to wake sleeping nodes up to maintain network performance. At last, the theoretical analysis and simulation results prove the correctness and effectiveness of the algorithm.The network performance can be improved through the mobile sensor second- deployment algorithm. Each node moves to the new location under the virtual force of its neighboring nodes and surrounding environment to maximize field coverage and maintain network connectivity. Compare and analyze the three usual sensor second-deployment ways based on virtual force. The analysis results show"distributed computing, move after computing"method can reduce the total moving distance greatly after adopting the"relative move"optimization, which is of great opplication value.