Research On Energy-Saving Mechanism Of Wireless Sensor Networks

Wireless sensor network (WSN) is self-organizing, low cost and structurally flexible,which makes it widely applied in both the military and civilian domains and it has become one of the most popular researched subjects in the IT field. A vital goal of the research on WSN is to prolong the network lifetime on the premise of network application, thus energy saving is one of the key technologies in WSN. This dissertation focuses on the energy saving mechanism from the following aspects:the circuit structure of physical layer, the timing operation mechanism of MAC layer and the control methods of topology of network.First, based on the performance characteristic of periodic sleep of WSN, this dissertation proposes a control method of energy saving-layered and the scheme of circuit design for each energy consumption layer by analyzing the time characteristic of the circuit start-up process. To save energy consumption, the WSN nodes go to sleep periodically. Because higher layer protocol of WSN could not control the start-up process of physical layer, the start-up energy consumption of physical layer is often neglected. The process of receiving and processing signals of WSN nodes in this dissertation is divided into three phases: wireless receiving phase, frame format decision phase and MAC layer processing phase. The three phases correspond to the energy consumption of the three layers. Energy saving is implemented by controlling the working order of the three energy consumption layers.Secondly, this dissertation proposes two energy saving MAC protocols to decrease the energy consumption for idle listening by combining the MAC layer and physical layer. One is the Adaptive Wake On Radio (AWOR) which is fit for the Master-slave network and the other is improved low power consumption quasi-synchronization MAC protocol for distributed network. The AWOR protocol is based on quick field strength detection mechanism and can adjust the window size of listening adaptively in the wireless interference environment to decrease the energy consumption of idle listening. In the low energy power consumption quasi-synchronous MAC protocol, the dynamic prediction mechanism of clock drift is applied to rectify the clock drift and avoid data conflict to ensure the operation of quasi synchronous mechanism. This improved low energy consumption distributed quasi synchronous MAC protocol has strong invulnerability and better power saving performance.Thirdly, this dissertation proposes a novel Cluster topological control algorithm to solve the energy consumption caused by the interference among the nodes in dense Wireless Sensor Networks. The cluster head is made much more powerful, partitioning a cluster into two rings. The outer ring is further divided into smaller sectors. This topology control algorithm has advantages of both high efficiency in controlling cluster head center, and flexibility of multi-hops. Moreover, this algorithm possesses the efficiency to improve the system throughput, decrease the interferences of nodes and save energy.Furthermore, this dissertation proposes an improved low energy consumption WSN multi-channel MAC protocol based on the problem of the higher energy consumption of traditional protocols. This improved protocol reaches the goal of saving energy by adjusting the size of work window dynamically with the prior time slot allocation mechanism and make nodes into sleep mode timely. The wireless multiple channels of WSN has great improvement in energy consumption and time delay.Finally, this dissertation designs a system of low energy consumption WSN network applied in the gas meter. This system applies the AWOR protocol and designs an automatic meter reading system and achieved good effect of saving energy.