Research On Data Collectiom With Multiple Mobile Elements In Wireless Sensor Networks

Mobile Elements (MEs) are widely employed for data collection in Wireless Sensor Networks (WSNs) to balance the energy consumption and prolong the network lifetime. Traditionally, data collection was carried out through multi-hop wireless transmissions among sensor nodes. The sensor nodes near the sink transmit their own data, as well as relaying data for the distant nodes, which drains the nodes’ energy and lead to the topology holes in the WSNs. The data collection, especially for the data converged at the nodes around the holes, depends on the data relaying by the nodes on the boundary of the hole, which may result in the exhaustive energy consumption of the involved nodes, enlarging the hole and even breaking the network.To address the issues of the multi-hop transmission, researchers introduce MEs to sweep data. The sensor nodes can reduce and balance the energy consumption without relaying data for others, prolonging the network lifetime. Furthermore, making MEs move around the holes can reduce the amount of the transmission tasks on the hole, which can save the energy of nodes and prevent the expansion of the hole effectively. However, the limited travel speed of the MEs causes a large data collection latency, which in turn degrades the performance of the data collection task and weakens the applicability of the data collection schemes. Thus, balancing the network energy, while reducing the data collection latency, is meaningful to the research and application of MEs in WSN.Our work improves the data collection efficiency by utilizing multiple MEs. We set the concentric deterministic trajectories in WSNs to reduce the data collection latency and adjust the transmission range of sensor nodes to reduce the energy consumption. Furthermore, we expand the algorithm into three dimensional WSN and propose an new algorithm to restrain the expansion of topology holes, improve the data collection latency and prolonging the network life time.Our main work is shown below:1) Propose the data collection algorithm with the assistance of the multiple MEs. After analyzing the current trajectory planning schemes, we found that by setting the concentric circle-like trajectories, adjacent MEs meet at a regular interval and relay data, thus, reducing the data collection latency.2) Study the hole detection algorithm in 3D WSN. After analyzing the energy consumption of the current hole detection schemes, we proposed a new hole detection algorithm by utilizing clustering to reduce the energy consumption and obtain a reasonable result.3) Design the data collection algorithm in 3D WSN. We expand our current work to restrain the expansion of holes. By making the MEs move around the hole, we construct a half-ball as the shield to protect the topology hole from expansion, ensuring the collectivity of the network and prolonging the network life time.