Study On Energy Efficient Data Gathering Technology Of Wireless Sensor Networks

Wireless sensor network (WSN) is a brand-new way for mankind to extend their recognition of the world. A WSN consists of many wireless sensor nodes distributed randomly or artificially in the monitoring region, these wireless sensor nodes form a multi-hop self-organizing networks by wireless communication, through this network the data information of the object within the covering range can be cooperatively sensed, calculated and collected, and then the data information will be delivered to the Sink node and the end-users in the network. Thus, data gathering not only is the fundamental function of WSN, but also is the foundation of wide applications. WSN has such characteristics as large scale, self-organizing, random distribution, complex environment, limited nodes resources and dynamically changing network topology, especially the node is generally powered by battery, so WSN has limited energy. Just because of the factors mentioned above, researching high energy-efficiency data gathering protocol to improve the effective utilizing rate of the nodes'power and extend the network lifetime has become a hotspot for the emergency surveillance WSN application.Starting from the intensely active area of research in wireless sensor network,the issues about the data gathering protocol are studied in this thesis. The main innovative achievements and results of this dissertation are listed as follows.1.A WSN model fitting for emergency surveillance application was proposed, the node with dual radio structure is adopted. Considering the character of the emergency surveillance WSN application, the operation mode of the two communication channel in the node is defined. The periodic synchronization listening of the node in wakeup channel is applied in this model to ensure the local connectivity degree of the networks and reduce the energy consumption of the idle listening.2.A new geographic high energy-efficient data gathering protocol REEGF was proposed. On the basis of the original geographic routing GeRaF protocol, combining the WSN's S-MAC protocol and the heuristic topology control STEM protocol, the energy saving strategy based on the topology control is supplemented while the selection method of the candidate relay nodes is revised. Through integrating routing, topology control and MAC into a layer, the idle energy consumption and the communication control overheads are greatly reduced, so that the data delivery rate is obviously improved and the multi-hop latency and energy-consumption are reduced, the network lifetime is prolonged considerably. Theoretical analysis and simulation results fully prove the effectiveness of REEGF protocol.3.In order to improve the efficiency of the relay node selection of data gathering protocol for multi-hop wireless sensor networks, an energy efficient relay node fast selection algorithm (EERNFS) was proposed. In EERNFS, time-sharing channel was adopted to maintain time synchronization of WSN and periodically update the information of the neighbor network node. The network nodes could be activated synchronously in any network listening/sleeping cycle according to a certain probability, thus the real-time consistency and the stability of the nodes'connectivity degree in WSN were guaranteed. Based on the geographic priority, the value of the nodes and the distribution estimation of the route-link quality, the relay node is selected through the competition method and the competing between the candidate relay nodes was reduced through gradually multiplying time window method. Theoretical analysis and simulation results fully prove the superiority of the EERNFS in improving the performance of the networks.4.A high energy-efficient cooperative data delivery protocol ESCDD for large scale multi-hop WSN was proposed. ESCDD adopts the sleeping scheduling strategy of the nodes depending on the local information to control the connectivity degree of the nodes and reduce the idle listening time; ESCDD adopts greedy mechanism based on the geographic information which is similar to GeRaF to select the relay nodes, the data delivery average hops are reduced; ESCDD selects a single cooperative node through the physical layer power control to collaborate on data transmission and resume the data information according to the rule of maximum ratio incorporation, keep implementing the cooperative communication to accomplish multi-hop data delivery. ESCDD drastically improves the data delivery rate, reduces the average multi-hop latency of data delivery, saves the average energy consumption of the nodes through the single node cooperative mechanism and makes the energy consumed by each node more balance. The effectiveness of ESCDD is demonstrated through comprehensive simulation studies.