Smart Sensor Node Impact  GPS leveraged for geo-referenced identity, and low power communications synchronization. Up to 100x communications power reduction.  Standard APIs implemented as Java class libraries and browser-based user interfaces provide code mobility, code reuse, and platform independence.  High-level spatial and context “anycast” addressing enables dynamic specialization for augmented awareness and collaborative consensus applications. New Ideas  Power-aware link and routing protocols. Exploit fine- grained power control of radios for energy efficient connectivity. Maximize sensor network’s operational lifetime through energy-aware routing.  GPS-aware link protocols. GPS-synchronized ultra-low-power communication.  Spatial addressing and connectivity. High-level addressing, unicast, multicast, anycast, and gathercast communication based on spatial referencing of the nodes.  Mobile code and web technology. Embedded Java APIs for code portability and browser-based topographical map interface for visualizing dynamic data from sensor net. Milestones Sensor Control API SpecificationFY00 Q1 Topographical Map Interface Definition FY00 Q1 Network Services API SpecificationFY00 Q2 GPS-Aware Link Protocol ExperimentFY01 Q4 Network Services PDA/Laptop ExperimentFY01 Q4 Integrated Sensor-Kit ExperimentFY02 Q4 Smart Sensor Node Event Target COTS PDA Brian Schott PI, Bob Parker (USC/ISI), Mani Srivastava (UCLA) Co-PI, Mark Jones (Virginia Tech) Co-PI Dynamic Sensor Networks

DSN Project Overview 1) Platform –GPS-synchronized ultra-low- power communication platform 2) Distribution & aggregation –network boot-up, low-power protocols, spatial addressing 3) Declarative language and execution environment –topographical map interface, Java APIs, sensor network emulation for rapid application development Distribution of node location and capabilities to neighborhood application query servers at boot-up and reconfiguration. Energy-efficient data distribution via low-power link protocols and power-aware routing Global spatial addressing that support referencing of individual or groups of sensor nodes by geographic location Node capability-based addressing in the local neighborhood. DSN network gateways for external IP-connectivity Sensor net simulation and emulation

Implementation Approach Run-time Environment Java-based API Applications Low-power link/MAC protocols Power-aware spatial routing Spatial & capability-based addressing Sensor Node Hardware Sensor N/W Emulation Simulation Low-power link/MAC protocols Power-aware spatial routing Spatial & capability-based addressing Sensor Node Model Sensor Node Model Protocols

Recent Work Architecture definition –platform definition –communication subsystem –system architecture Simulations in NS –node modeling (battery, radio, …) –sample MAC with radio shutdown management –low-power ad hoc routing

Architecture Ideas Explored “Query Servers” handle queries in a neighborhood dynamically elected on a rotating basis keep track of neighborhood nodes and their resources farm out tasks to sensor nodes to handle a query manage locally distributed signal processing to synthesize query reply »e.g. beam forming Smart intermediate nodes do caching synthesize replies for similar queries from cached data filter and/or combine query responses

Modeling in NS Mobile Node Link Layer MAC PHY Channel Routing Agent Buffer Mobile Node with Power Model Link Layer MAC with Power Management Model-aware PHY Channel Routing Agent Buffer Radio Battery CPU Sensor Node Model

Sensor Node Model Battery –often modeled as a “bucket of constant energy” –reality: delivered energy depends upon discharge rate (load current) e.g. C = k/I  discharge profile and duty cycle operating voltage and power level drained Radio baseband, RF frontend, and power amplifier Baseband + Link & MAC (digital, s/w) RF (analog) Power Amplifier Power Supply Battery DC-DC Converter P RF PEPE

Power-aware Routing Traditional ad hoc routing focuses on fast topology changes Using power-aware metrics and location information can provide power savings and network lifetime extension The cost (metric) of the route is determined based on the energy usage of each node

Short-term Issues Encountered Modeling of sensors –transducer models –sensor channel models Scenarios for driving the sensor net simulation –target mobility –user mobility –query traffic Better battery models –pulse discharge Computation energy consumption –energy consumed by protocols and signal processing

New Directions, Emphases, and Open Questions Techniques for robust distribution of location information –no or nonfunctional GPS, indoor etc. –approaches? terrestrial trilateration »angle of arrival »time of arrival »Signal strength support from radio using sensors using roaming users as carriers! Definition of APIs between application, query manager, and network protocol stack Sensor resource management in a neighborhood