无线网络wirelesssensornetworks08

1、Wireless Sensor Networks巨型机说：“我认为全球大概只需要五台计算机就够了”；PC机说：“每个家庭的桌面上都应该有一台电脑”;Pocket PC说：“太大了，应该每人口袋里放一台”;WSN说：“每粒沙子都应该是一台计算机”。1OutlineGeneral CommentsWireless Sensor Network ApplicationsArchitecture of WSNOverview of Sensor HardwareCharacteristic of WSNOur Work2OutlineGeneral CommentsWireless Sensor Ne

2、twork ApplicationsArchitecture of WSNOverview of Sensor HardwareCharacteristic of WSNHot IssuesOur Work3Sensor network: A new research hotspotAugust 2003 Business Week projects Sensors and Sensor Networks. to be one of 4 Key Technology Waves of the Future 国家中长期科学和技术发展规划纲要将传感器网络列为重点研究领域4Faster, Small

3、er, NumerousMoores Law“Stuff” (transistors, etc) doubling every 1-2 yearsBells LawNew computing class every 10 yearsyearlog (people per computer)Source: The Mote Revolution:Low Power Wireless Sensor Network DevicesStreaming Data to/from the Physical World5Whats are Wireless Sensor NetworksWireless n

4、etworks are usually composed of small, low-cost devices that communicate wirelessly and have the capabilities of Processing, Sensing and StoringThe purpose is to measure different physical parameters in a given environment, in order to characterize its properties, or to take decisions depending on t

5、hese measurements.6Enabling TechnologiesEmbeddedNetworkedSensingControl system w/Small form factorUntethered nodesExploitcollaborativeSensing, actionTightly coupled to physical worldEmbed numerous distributed devices to monitor and interact with physical worldNetwork devices to coordinate and perfor

6、m higher-level tasksExploit spatially and temporally dense, in situ, sensing and actuation7OutlineGeneral CommentsWireless Sensor Network ApplicationsArchitecture of WSNOverview of Sensor HardwareCharacteristic of WSNHot IssuesOUR WORK8Wireless Sensor Network ApplicationsMilitary ApplicationsEnviron

7、mental ApplicationsHealth ApplicationsHome ApplicationsIndustrial ApplicationsOther Commercial ApplicationsApplication WSN9Military Applicationsenemy tracking, battlefield surveillancetarget detection and classification10An Example:Counter Sniper SystemUsing the arrival times of the acoustic events

8、at different sensor locations, the shooter position can be accurately calculated using the speed of sound and the location of the sensors. 11民用领域土壤湿度、温度、成份监测，节点对土壤进行周期性采样将数据发送给远端用户森林防火：节点实时监测周围温度情况，并在探测到温度过高时发出警报。医疗看护：将传感器配置在身体上，可以将身体情况传输给远端监控中心。GE公司12科技领域了解火山习性研究鸟类习性海洋环境监测sensors and vehicles are d

9、eployed to perform collaborative monitoring tasks over a given area under ocean.Large number of sensor nodes collect data from the ocean and forward to a master node. 13Industrial Applications地面上的传感节点立柱上的传感节点无线传感网络原型系统拓扑图:矿井安全检测和防护系统From talk of Yunhao Luo14OutlineGeneral CommentsWireless Sensor Net

10、work Applications Architecture of WSNOverview of Sensor HardwareCharacteristic of WSNHot IssuesOUR WORK15Architecture of WSNSensor nodes are scattered in a sensor field(object field)Sensor nodes can self organize to form a sensor networkData are collected by these scattered nodes and routed back to

11、the sink in a multi-hop wayThe user communicate with the sink via Internet16Architecture of WSN(contd)nodes are still stationary.multiple, mobile sinks defined as users.sinks may collect data at any time, any place. 17无线传感网络接入网络核心网络Architecture of WSN(contd)From Talk of YunHao Luo18A general work pr

12、ocess of WSNDeployOrganize into networkSensing and monitoringData collection and dissemination19OutlineGeneral CommentsWireless Sensor Network ApplicationsArchitecture of WSNOverview of Sensor HardwareCharacteristic of WSNHot IssuesOUR WORK20Sensor HardwareFundamental ComponentsVarious Sensing,Proce

13、ssing,Storing, Transceiver,PowerApplication dependent components Locating, Mobilizer, Power generator21Sensor Node SamplesLWIM IIIUCLA, 1996Geophone, RFMradio, PIC, starnetworkAWAIRS IUCLA/RSC 1998Geophone, DS/SSRadio, strongARM,Multi-hop networksSensor MoteUCB, 2000RFM radio,AtmelMedusa, MK-2UCLA N

14、ESL200222Mote EvolutionSource: The Mote Revolution:Low Power Wireless Sensor Network Devices23OutlineGeneral CommentsWireless Sensor Network ApplicationsArchitecture of WSNOverview of Sensor HardwareCharacteristic of WSNHot IssuesOUR WORK24Characteristic of WSNResource Constraintsbattery equipped,re

15、charging the batteries is impossible or unfeasible Radio and embedded CPUSelf configuringRandomly deployed, unattended.Dynamic TopologyData centricDifferent from traditional networkUnique traffic modelApplication specific25Power ConsumptionPower is of most important and directly influencing the life

16、time of WSNConsumption in three domains:Sensing, communication and data processingEnergy consumed by Comm. is dominatingThe energy cost of transmitting 1Kb a distance of 100 m is approximately the same as that for executing 3 million instructions by a 100 million instructions per second (MIPS)/W pro

17、cessor. SDdkTx/Rc electronicsTx amplifier26MANET vs WSN: DifferencesLow density vs. high densityAddress centric (IP) vs. content centric (no IP)Resource (constraint vs critical)Mobile vs stationaryFirst criterion of performance (QoS vs. Power)27OutlineGeneral CommentsWireless Sensor Network Applicat

18、ions Architecture of WSNOverview of Sensor HardwareCharacteristic of WSNHot IssuesOUR WORK28Communication ProtocolsMAC ProtocolFairness vs. EnergyRouting ProtocolEnergy-aware routingGeo-routingTransport Control ProtocolCongestion ControlReliabilityEnd-to-end vs. Hop-by-hop EventSensor sourcesSensor

19、sinkDirected DiffusionA sensor field29Coverage ControlProblemGiven a set of sensors deployed in a target area, we want to determine if the area is sufficiently k-covered, in the sense that every point in the target area is covered by at least k sensors, where k is a predefined constant. Two Motivati

20、onsOne of the measurements of the QoSEnergy efficientTwo conflicting objectives:minimizing the number of active sensors to minimize the energy consumption.maintaining the coverage. Two metricsConnectivity and CoverageSensing radius Communicating radius30Data and Query DisseminationProblemThe sensor

21、network is a distributed database.How to collect or query the interested data detected by some nodes in a energy-efficient way?Application-specificArea-basedAttribute-basedPull vs. Push31OutlineGeneral CommentsWireless Sensor Network Applications Architecture of WSNOverview of Sensor HardwareCharact

22、eristic of WSNHot IssuesOUR WORK32自组织的无源无线ZigbeeWiFi输电线路在线监测监测功能图像采集：线下图像、塔架塔基图像、导线及绝缘子图像弧垂和导线温度的采集两级数据传输监测数据和报警信息从采集终端上传到塔架上监测子站采用无线Zigbee技术数据和信息从塔架监测子站接力上传到监控中心（运行值班、变电站）采用无线WiFi技术监控中心的控制命令可以下传监控功能监控中心采集监测数据、存储并进行综合分析处理33监测平台运行示意图34两层网络架构Zigbee802.11b/g35Geographic Routing for Sensor Networks36Mot

23、ivationA sensor net consists of hundreds or thousands of nodesScalability is the issueExisting ad hoc net protocols, e.g., DSR, AODV, ZRP, require nodes to cache e2e route informationDynamic topology changesMobilityReduce caching overheadHierarchical routing is usually based on well defined, rarely

24、changing administrative boundariesGeographic routingUse location for routingAssumptions Every node knows its locationPositioning devices like GPS LocalizationA source can get the location of the destination37Geographic Routing: Greedy RoutingSDClosest to DA Find neighbors who are the closer to the d

25、estination Forward the packet to the neighbor closest to the destination38Greedy Forwarding does NOT always work If the network is dense enough that each interior node has a neighbor in every 2/3 angular sector, GF will always succeedGF fails39Dealing with Void Apply the right-hand rule to traverse the edges of a voidPick the next anticlockwise edgeTraditionally used to get out of a maze40Impact of Sensing Coverage on Greedy Geographic Routing AlgorithmsGuoliang Xing, Chenyang Lu, R