UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 1 Wireless Sensor Networks Ramesh Govindan Lab Home Page: Personal Home Page:

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 2 The Progress of Technology Platforms with –Processors –Memory (flash, RAM) –Low-power radios –Sensors! »Temperature »Light »Humidity »Acceleration Battery operated

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 3 Networked Embedded Sensing Put many of these nodes close to phenomena Network them –Wireless, multi-hop »Deployment becomes easy! Computation and processing is necessarily distributed –Nodes are battery-powered –… and communication requires energy … and likely to stay that way

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 4 Application Areas Seismic Structure response Contaminant Transport Marine Microorganisms Ecosystems, Biocomplexity Structural Condition Assessment Computers in the Physical World!

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 5 Where are we today?

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UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 7 Sensor Data Logger

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UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 9 Where’s the Computer Science in this? To build a software infrastructure for developing networked embedded sensing applications

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 10 An Example Treat a sensor network as a database and use in-network storage. Provide an efficient solution for multi-dimensional range queries. –e.g. List all events whose temperature lies between 70 and 80 and whose light levels are between 10 and 15. Useful for searching and correlating events of interests with multiple attributes. –Drill-down searching, trigger and action, … Fascinating example of the confluence between databases and networking!

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 11 Distributed Index for Multi-Dimensional Data (DIM) Functionality –Efficient range query for multidimensional data. Approaches –Divide sensor field into bins. –Locality preserving mapping from m-d space to geographic locations. –Use geographic routing such as GPSR. Assumptions –Nodes know their locations and network boundary –No node mobility E 2 = E 1 = Q 1 =

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 12 Building Zones Divide network into zones. Each node mapped to one zone. Encode zones based on division. Each zone has a unique code. Map m-d space to zones. Zones organized into a virtual binary tree L  [1/2, 1)L  [0, 1/2) T  [1/2, 1) T  [0, 1/2) L  [0, 1/4) L  [1/4, 1/2)L  [1/2, 3/4) L  [3/4, 1) T  [3/4, 1) T  [1/2, 3/4) T  [1/4, 1/2) T  [0, 1/4) L: Light, T: Temperature

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory Virtual Binary Tree L  [1/2, 1) L  [0, 1/4) 110 L  [0, 1/2) T  [1/2, 1) T  [0, 1/2) L  [1/4, 1/2)L  [1/2, 3/4) L  [3/4, 1) T  [3/4, 1) T  [1/2, 3/4) T  [1/4, 1/2) T  [0, 1/4)

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 14 Data Insertion Encode events Compute geographic destination Hand to GPSR Intermediate nodes can refine the destination estimation L  [1/2, 1) L  [0, 1/4) L  [0, 1/2) T  [1/2, 1) T  [0, 1/2) L  [1/4, 1/2)L  [1/2, 3/4) L  [3/4, 1) T  [3/4, 1) T  [1/2, 3/4) T  [1/4, 1/2) T  [0, 1/4) E 1 =   Store E 1 L: Light, T: Temperature

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 15 Query Split a large query into smaller subqueries. Encode each subquery. Process subqueries separately, resolving locally or forwarding to other nodes based on their codes L  [1/2, 1) L  [0, 1/4) L  [0, 1/2) T  [1/2, 1) T  [0, 1/2) L  [1/4, 1/2)L  [1/2, 3/4) L  [3/4, 1) T  [3/4, 1) T  [1/2, 3/4) T  [1/4, 1/2) T  [0, 1/4)   Q 10 = Q 1 = Q 12 = Q 11 = L: Light, T: Temperature

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 16 Implementation on the Motes Use TinyDB Schema Tuple Storage on Flash/RAM –Insertion, deletion, search GPSR implemented with priority-based hop-by-hop reliability –Favor query and reply messages different over other messages. DIM’s components –Zone, Query, Insertion, –Dispatcher ZoneQueryInsertion GPSR Protocol- Independent Routing Shim Flash/ RAM Tuple Storage TinyDB Schema DIM Dispatcher

UNIVERSITY OF SOUTHERN CALIFORNIA Embedded Networks Laboratory 17 Some Screenshots