Slide 1IntroductionSlide 3Why Sensor Platforms?Slide 5General WSN System ArchitectureSlide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Berkeley Motes [Hill+ 2000]Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Berkeley Motes [Hill+ 2000, TinyOS]Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28MANTIS [Abrach+ 2003]Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49System Architecture of Networked Sensor PlatformsWireless sensor networksWireless sensor networks (WSN) consists of group of sensor (WSN) consists of group of sensor nodes to perform distributed sensing task using wireless nodes to perform distributed sensing task using wireless medium.medium.CharacteristicsCharacteristics- low-cost, low-power, lightweight- low-cost, low-power, lightweight- densely deployed- densely deployed - prone to failures- prone to failures- two ways of - two ways of deploymentdeployment: randomly, pre-determined or engineered: randomly, pre-determined or engineered ObjectivesObjectives-- Monitor activitiesMonitor activities- Gather and fuse information- Gather and fuse information - Communicate with global data processing unit- Communicate with global data processing unitIntroduction–Recent sensor networks research involves almost all the layers and can Recent sensor networks research involves almost all the layers and can be categorized into the following three aspects: be categorized into the following three aspects: [Akyildiz+2002, [Akyildiz+2002, Elson+2002]:Elson+2002]:Energy Efficiency: Energy Efficiency: small devices, limited amount of energy, essential to prolong system small devices, limited amount of energy, essential to prolong system lifetimelifetimeScalability: Scalability: deployment of thousands of sensor nodes, low-costdeployment of thousands of sensor nodes, low-costLocality: Locality: smallest networks cannot depend on having global statessmallest networks cannot depend on having global statesIntroduction–Traditional mechanisms of exploring the network (analysis and Traditional mechanisms of exploring the network (analysis and simulation) are not satisfied for exploring such a large-scale, dynamic simulation) are not satisfied for exploring such a large-scale, dynamic and resource-constrained networks due to their difficulties to modeling and resource-constrained networks due to their difficulties to modeling every aspect of the system as a wholeevery aspect of the system as a whole–For example, energy consumption model of the hardware platforms, For example, energy consumption model of the hardware platforms, including sensing, computation and communication, is not fully including sensing, computation and communication, is not fully considered and overly-simplified assumptions have been madeconsidered and overly-simplified assumptions have been made–Application-specific property of WSN makes the existing research Application-specific property of WSN makes the existing research mechanisms even harder to obtain meaningful results mechanisms even harder to obtain meaningful results –Therefore, the demand to build a platform is increasing; e.g., Berkeley’s Therefore, the demand to build a platform is increasing; e.g., Berkeley’s motes and MANTISmotes and MANTISWhy Sensor Platforms?–Compared to analysis and simulation techniques, designing a system Compared to analysis and simulation techniques, designing a system platform has the following advantages:platform has the following advantages:Provides genuine executive environment: various proposed Provides genuine executive environment: various proposed algorithms can be exactly evaluated; good way to examine existing algorithms can be exactly evaluated; good way to examine existing design principles and discover new ones under different design principles and discover new ones under different configurationsconfigurationsMore attention can be focused on the application-layerMore attention can be focused on the application-layerA real system platform can accelerate the pace of research and A real system platform can accelerate the pace of research and developmentdevelopmentWhy Sensor Platforms?–Constructing a platform for WSN falls into the area of embedded system Constructing a platform for WSN falls into the area of embedded system development which usually consists of developing environment, hardware development which usually consists of developing environment, hardware and software platforms.and software platforms.1.1.Hardware PlatformHardware PlatformConsists of the following four components:Consists of the following four components:a) Processing Unita) Processing UnitAssociates with small storage unit (tens of kilo bytes order) and Associates with small storage unit (tens of kilo bytes order) and manages the procedures to collaborate with other nodes to carry out themanages the procedures to collaborate with other nodes to carry out theassigned sensing taskassigned sensing taskb) Transceiver Unitb) Transceiver UnitConnects the node to the network via various possible transmissionConnects the node to the network via various possible transmissionmedias such as infra, light, radio and so onmedias such as infra, light, radio and so onGeneral WSN System Architecture1.1.Hardware PlatformHardware Platformc) Power Unitc) Power UnitSupplies power to the system by small size batteries which makes the Supplies power to the system by small size batteries which makes the energy a scarce resourceenergy a scarce resourced) Sensing Unitsd) Sensing UnitsUsually composed of two subunits: sensors and analog-to-digitalUsually composed of two subunits: sensors and analog-to-digitalConverters (ADCs). The analog signal produced by the sensors areConverters (ADCs). The analog signal produced by the sensors areconverted to digital signals by the ADC, and fed into the processing unitconverted to digital signals by the ADC, and fed into the processing unite) Other Application Dependent Componentse) Other Application Dependent ComponentsLocation finding system is needed to determine the location of sensor Location finding system is needed to determine the location of sensor nodes with high accuracy; mobilizer may be needed to move sensor nodes with high accuracy; mobilizer may be needed to move sensor nodes when it is required to carry out the tasknodes when it is required to carry out the