Research On Sensor Scheduling Algorithm Based On Multi-demand Of Coverage In Directional Sensor Networks

Directional Sensor Networks(DSNs), as an advanced form of Wireless Sensor Networks(WSNs), has been widely applied in many scenarios. However, most of DSNs work in the wireless way and the energy of sensor node can’t be replenished, reasonable sensor scheduling schema is essential to largely increase the efficiency of sensors and extend the lifetime of the networks on the premise of network coverage demand. In practical application, lots of deployment area may be very large and the different subareas in this area may have different coverage demand. Therefore, it is necessary and applicable to take multi-coverage area into consideration and schedule each area independently when designing the scheduling algorithm. When deploying the DSNs, one monitoring sites may use different types of sensor node, which may make differences in the radius and angles of sense ability. Thus, heterogeneity of sensors should be considered, such as the different sense radius, different sense angles, different sense directions and so on. The proposed scheduling algorithm must adapt to the directional sensor nodes that can adjust their sense directions.Based on the sensors which can’t adjust their sense directions, this thesis divides the monitored area into different small subareas according to their different coverage demand and proposes a new sensor scheduling algorithm DSSA(Distributed Subarea Sensor-schedule Algorithm). DSSA is a kind of greed algorithm that uses the least sensors to provide each subareas with the corresponding coverage demand. DSSA also takes the overall network connectivity into consideration. The simulation shows that DSSA can provide the longer lifetime of subarea and overall network lifetime, also the sensor selection efficiency of DSSA is better when compared with other algorithm. Furthermore, DSSA still performs well when the sensor number is halved and doubled.Focus on the sensors which can adjust their sense direction, this thesis proposes an efficient grid division algorithm DASA(Direction Adjustable Sensor-schedule Algorithm) based on multi-coverage. DSNs uses the greedy algorithmic idea to choose the working node and the working direction based on the coverage contributions of different neighbor nodes and different sense direction. In the simulation, DASA performs better in subarea lifetime, overall network lifetime and sensor selection efficiency compared with other algorithms.