【作者】 王蔚沄；

【导师】 唐明浩；

【作者基本信息】 东华大学 ， 控制理论与控制工程， 2008， 硕士

【摘要】 无线传感器网络(Wireless Sensor Network,简称WSN)是由部署在监测区域内大量的廉价微型传感器节点组成,通过无线通信方式形成的一个多跳的自组织的网络系统,其目的是协作地感知、采集和处理网络覆盖区域中感知对象的信息,并发送给观察者。无线传感器网络就是将逻辑上的信息世界与客观上的物理世界融合在一起,改变了人类与自然界的交互方式。它不同于传统网络,其能量受限制,而且该网络中的节点一般被布置在高危区域或无人值守区域,供电电池在电能耗尽后无法更换,导致节点退出网络。因此,能量的高效性成为无线传感器网络首要的性能指标。本文围绕实现低功耗无线传感器网络的目标,主要开展了以下几方面的研究:1)研究分析了无线传感器网络低功耗实现途径,并论述了各技术目前所面临的问题。目前在该研究领域中,主要有5种低功耗技术分别是构建低功耗的无线传感器网络节点;利用MAC层协议调节节点的工作机制,降低节点能量消耗;利用路由层协议实现整个无线传感器网络的能量均衡消耗;通过在数据传输过程中的数据融合,减少数据冗余达到减少能量消耗的目的;利用功率控制技术减少节点无线通信模块的能量消耗。可是由于在无线通信模块上的耗能,MAC层协议缺少自适应调整占空比,在路由协议中缺少多路径机制等瓶颈限制了这些技术的发展,本文基于这些问题做了些有益的探索。2)节点是构建无线传感器网络的硬件基础,WSN中的节点由于能量受限,往往不能长时间地在无人区域完成监测任务,无法满足应用需求。鉴于此,本文提出了以MSP430系列单片机和CC1100无线通信芯片分别作为节点的处理器模块和无线通信模块的设计方案,制作完成了基于此方案的低功耗无线传感器网络节点,实现了节点间点对点和组网的无线通信,最后分析计算了节点的生存期,结果表明本文设计的节点能够在2节AA电池供电的条件下保持较长的工作时间;3)针对MAC层上S-MAC协议不能根据网络中的数据流量自适应调整占空比的缺陷,本文提出了根据平均重传次数判断网络的数据流量大小,调整占空比的ADC-MAC协议,并通过在NS2网络仿真环境中进行仿真实验,验证了在不牺牲网络中各性能指标的前提下,ADC-MAC协议能有效地根据网络中的数据流量调节占空比,在网络中数据流量较大时,大大降低了数据收发的时延,平均减少了100秒左右的时间;当网络负载流量较轻时,由于减少了侦听时间的占空比,减少了空闲状态下的能量消耗,平均减少了相当于采用S-MAC和A-SMAC时消耗能量的20%左右;4)针对传统网络中路由层上协议在数据传输过程中只利用一条路径进行传输,无法均衡网络能耗的问题,本文在ESDSR路径生存期的基础上,结合无线传感器网络的特点,提出了能量多路径路由协议,在该协议中利用排除法和平均法对可能出现的网络拓扑结构进行了处理,实现数据传输过程中路径的切换,从而保证网络中各节点能量均衡消耗,使整个网络的生存期在网络中数据流量较小的情况下延长了1倍;本文主要研究了无线传感器网络实现低功耗的节能技术,针对节点物理层,MAC层和网络层三个方面中的节能方法和协议提出了改进,并在NS2网络仿真环境平台中进行仿真实验,结果达到预期目标。本文的研究对无线传感器网络的能量高效性做了有益的探索,能够在一定程度上解决制约其投入应用的能耗瓶颈。更多还原

【Abstract】 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.更多还原