Design And Research On Low Power Cost Of Nodes In Wireless Sensor Network

Wireless Sense Network (WSN) consists of a large number of sensor nodes, which are low-cost, tiny and deployed in the area. It is a multi-hop and self-organization network connected by the wireless communication. In this network, the supervisor can get the information everwhere in the network, and the data is transferred in the route build up by the nodes. Because of WSN, the way of exchanging between human beings and nature is changed. Different from the traditional network, in the WSN the nodes' power is limited. Moreover, the nodes are usually deployed in the high dangerous area or the district human beings can't reach. The node will no longer exist in WSN as soon as its power runs out. Therefore, the efficiency of energy is the key factor of WSN.In order to realize WSN of low power, the main work of this thesis include:1) Make the research on the ways in lowering power and find out the problems from them. At the moment, there are mainly five methods in this area. First, a low-power WSN node is the basic hardware. Second, by the MAC protocol the node's listening time can be adjusted so as to decrease the node's energy cost. Third, by the routing protocol the nodes' energy in the WSN can be cost averagely. Moreover, in the course of transferring data the nodes' energy can be saved by data combination. Finally, in the way of powe-control, the wireless communication module can be adjusted to save energy. However, these methods are blocked by such factors as power waste in wirless communication module, lack of adjustment in ducy cycle within MAC layer and so on. Therefore, this paper does some work on these factors.2) Node is the hardware foundation of WSN. In this thesis, the series of MSP430 and the chipcon of CC1100 are adopted as the processor module and wireless communication module respectively of the node. Based on this, a low-power node of WSN is made. In addition, a pair of nodes or a large number of nodes can be connected by wireless communication successfully. By computing, the node's expected life can meet the need of application to last long time with 2 AA batteries.3) In S-MAC protocol, it is unable to adjust the duty cycle according to the data flow in WSN. So we designed an Adaptive Duty Cycle MAC (ADC-MAC) protocol in which the amount of data flow is determined by the number of retry. By simulation in NS2, the ADC-MAC protocol works well in adjusting the duty cycle according to the data flow without changing anything in WSN. When the data flow in Network is large, the average delay time is reduced by 100 seconds. On the contrary, the average energy cost can be reduced by 20 percent.4) The protocols in the network layer of WSN only use one route to transfer the data and never change the route. As a result, the nodes' power in network can't be cost averagely. Therefore, based on the expected life of route in ESDSR, we adopted a multi-routing protocol. This protocol uses different route to transfer the data according to the routes' expected life. Therefore, the expected life is doubled.The way to save energy is mainly discussed in this paper. The technology and protocol in the physical layer, MAC layer and network layer is improved. All of these can be simulated in NS2. Therefore, the work in this paper is meaningful and helpful to the WSN.