Research On Coverage Control Algorithm For Underwater Sensor Networks

With the growing importance of ocean resources and the rise of ocean economy in the world,research on Underwater sensor networks (UWSNs) has become a hotspot in the field of sensornetworks. To monitor and obtain information better in Underwater sensor networks, sensingcoverage over the targeted region is necessary. Thus, the first problem to be solved in Underwatersensor networks is the node deployment strategy or coverage control method to adopt, which isrelated to the allocation of communication bandwidth, computing ability, power and other limitedresources. Coverage preservation is one of the most essential functions to guarantee quality ofservice (QoS) in Underwater sensor networks.To deal with the problems mentioned above, this paper studies the coverage control approachsfrom two perspectives: initial deployment achieving k-coverage degree and coverage preservingduring the operation of the networks. The main works in the thesis are as follows:(1)We propose a probabilistic sensing based deployment scheme for Underwater MobileSensor Networks (PSDS). We consider two related deployment problems: how to place the sensornodes in order to achieve full coverage (k-coverage degree) and how to dispatch the sensor nodesto the locations which have been calculated in the former problem. For the first problem, a greedystrategy is used to determine the locations of the sensor nodes by iteration until achieve fullcoverage (k-coverage degree) or reach a preset upper limit on the number of sensor nodes. Thesimulation results show that the proposed deployment scheme needs less sensor nodes to achievefull coverage compared to random deployment scheme and uniform deployment scheme(k-coverage degree). For the second problem, it aims to reduce energy consumption as little aspossible owing to the movement of sensor nodes. We propose three schemes including a centralizeddispatch strategy, a distribution dispatch strategy and a random dispatch strategy. Finally, weanalyze the performances of the three schemes.(2) We first propose a single-hop coverage-preserving routing algorithm for UWSNs (SCPR).This algorithm first defines a coverage redundancy metric (CR), and selects the cluster headsaccording to this metric. A cluster head sends the aggregated data from its cluster members directlyto the Sink. To guarantee energy balance and achieve better network coverage, we also propose amulti-hop coverage-preserving routing algorithm (MCPR), where each cluster head prefers to selectits parent node with higher CR as its next hop routing. Finally, the aggregated datas are sent to theSink using multi-hop routing. Simulation results show that both the SCPR and MCPR algorithms improve the network coverage ratio, reduce network energy consumption and extend networklifetime compared to the LEACH-Coverage-U algorithm.(3) We propose a full-coverage required coverage-preserving algorithm for Underwater SensorNetworks (FCCP). At first, the algorithm elects the root node by constructing a cover set, eachelement of the cover set could cover the sensing region of the node partially or completely. Then,make the redundant nodes of the network sleep, each node chooses the node with the highest CRin the parent nodes as the next hop node, and form a tree routing. Finally, each node sends thesensed data to the Sink node using multi-hop routing. Compared to the energy-awarecoverage-preserving hierarchical routing protocol (ECHR) for the purpose of full coverage, FCCPeffectively reduces network energy consumption and extends the network lifetime of full coverage.