1. Collaborative Sensing over Smart Sensors Vassileios Tsetsos, Nikolaos Silvestros & Stathes Hadjiefthymiades Pervasive Computing Research Group Dept of Informatics and Telecommunications National and Kapodistrian University of Athens October 2009 @ 2nd Student Workshop on Wireless Sensor Networks

2. IPAC Platform  Integrated Platform for Autonomic Computing (EU FP7)  Middleware, service execution and creation environment  Collaborative sensing, plug short range communications  Probabilistic broadcasting and epidemic information dissemination  Applications/Trials: Autonomic networked objects in industry Intelligent Transportation Crisis Situations / Peace Keeping Military Operations

3. Introduction & Motivation  Nomadic computing Embedded devices with limited resources Frequent node relocation / ad hoc communications Broadcast-based data dissemination Context-aware applications  Real-world problems: Not all nodes have sensors Each node’s sensors are of different technology and not interoperable (at all levels)

4. Proposed Solutions (in brief)  Collaborative Sensing Nodes exchange sensor information (on demand)… …in an efficient way  Smart Sensors Sensors that adopt standard interfaces are used Sensor plug ‘n’ play is supported ○ Plug in new sensors of the same or different platform (Sun SPOT, Xbow Mica2, …)

5. Collaborative Sensing

6. Context Modeling Environmental Situation User Situation InsideBuildingHappy Situation is-a Fire Action Rules: Fire  BroadcastAlert (100) Situation Classification Rules (SCR): Temperature>80 ^ Humidity<10  Fire (100, 10) Spatial Validity Environmental Context Temperature User Context Location Mood Context is-a Temporal Validity Declarative context description

7. Overall Architecture Context-aware Nomadic Applications Short Range Communications Context Foraging Context Modeling & Reasoning Node Architecture Sensors CR CRel CP CR: Context Requestor CP: Context Provider CRel: Context Relay CRel CP  Nodes are moving in random trajectories  Nodes have location sensors  Short range communications: WiFi, WiseMac, DSRC, IEEE 1609 WAVE, ZigBee  Not all nodes have sensors  Nodes are willing to cooperate

8. Context Request Formation & Dissemination CR CRel CP CRel CP SV CReq = 100 Temperature>80 ^ Humidity<10  Fire (100, 10) Spatial Validity Temporal Validity Local conditionRemote condition Humidity<10 (100, 10) CReq: SCR: CReq is retransmitted every 10 time units and within a range of 100 space units 1 1 2

9. Context Providers  Nodes with sensors  They have an index structure that is used:  as a registry of all event filters received through context requests,  as a mechanism that matches incoming sensor values with event filters (context request conditions)  Index resembles a message forwarding engine of content- based network routers  Context Response  CRes := val i = V  Spatial validity: equal to the request’s value

10. Context Providers’ Index 1. Context Request (Event filters) 2. Sensor value 3. Context Response Humidity = 7 Humidity < 10 The responses are aggregated

11. Performance Results # of CR40 # of CP40 Comparison with a polling scheme (CPol) # of nodes100 Mobility model Random waypoint # of SCR per CR 2 SV of SCRs110 Comm. range50

12. Smart Sensors

13. The IEEE 1451 Standards  A Family of standards that define all aspects of smart transducers (sensors, actuators)  The only available standard …but still evolving  Specifies: Transducer Electronic DataSheets (TEDS) Hardware/Software interfaces Commands, Messages, States, …

14. A IEEE 1451 smart sensor

15. Smart Sensors in IPAC TCP HTTP IPAC HW OS IPAC MW SEC Proxy TIM IPAC APPLICATION IPAC node USB NCAP Sun SPOT Java Virtual Machine IEEE 1451.2 IEEE 1451.0 IEEE 1451.2 IEEE 1451.0

16. Conclusions & Future Work  IPAC adopts a novel and pragmatic approach to context-aware computing  Many applications can benefit: VANETs and ITS, Crisis Management, …  Interoperability at the sensor level is still a challenge  Hardware implementations of IEEE 1451 are required…any volunteers?!