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8/9/2019 Future of Wsn
1/17
Sensor networksOpportunities for theory
The future
Sensor Networks and the Future of Networked
Computation
James AspnesYale University
February 16th, 2006
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
http://find/http://goback/8/9/2019 Future of Wsn
2/17
Sensor networksOpportunities for theory
The future
RationaleClassical networksSensor networksThe presentThe future
Why wireless sensor networks?
Question: If a tree falls inthe forest, how do we hearit?
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
http://find/http://goback/8/9/2019 Future of Wsn
3/17
Sensor networksOpportunities for theory
The future
RationaleClassical networksSensor networksThe presentThe future
Why wireless sensor networks?
Question: If a tree falls inthe forest, how do we hearit?
Answer: nail a sensor to
every tree.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
http://find/http://goback/8/9/2019 Future of Wsn
4/17
Sensor networksOpportunities for theory
The future
RationaleClassical networksSensor networksThe presentThe future
The central dogma of sensor networks
Distributed sensing is necessary to detect rare, localizedevents.
Abundant sensors must be cheap.Short-hop radio is the obvious communication mechanism.
The more computation we can do in the network itself, theless communication we need.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
R i l
http://find/http://goback/8/9/2019 Future of Wsn
5/17
Sensor networksOpportunities for theory
The future
RationaleClassical networksSensor networksThe presentThe future
Classical networks
Classical networks are made of big, expensive devices:
Routers.
Wires (or equivalent fixed point-to-point connections).
Power cables running to the routers.
Network administrators standing next to the routers.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
R ti l
http://find/http://goback/8/9/2019 Future of Wsn
6/17
Sensor networksOpportunities for theory
The future
RationaleClassical networksSensor networksThe presentThe future
Sensor networks
Sensor networks are made of small, cheap devices:
Sensors.Short-distance radio broadcast.
Weak power sources: batteries, solar cells, RF antennas.
No network administrators!
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
Rationale
http://find/http://goback/8/9/2019 Future of Wsn
7/17
Sensor networksOpportunities for theory
The future
RationaleClassical networksSensor networksThe presentThe future
Sensor networks
Sensor networks are made of small, cheap devices:
Sensors.Short-distance radio broadcast.
Weak power sources: batteries, solar cells, RF antennas.
No network administrators!
Every feature of sensor networks is likely to become typical of mostnetworked computing devices.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
Rationale
http://find/http://goback/8/9/2019 Future of Wsn
8/17
Sensor networksOpportunities for theory
The future
RationaleClassical networksSensor networksThe presentThe future
Where we are evolving from
Existing sensor network applications.
Weather stations.Networks of strain gauges on ships.
Ecological sensor networks.B-52-launched tank detectors.
Active RFID chips.
Mostly used for inventory tracking.Many are writable.
Some already can record temperature extremes or suddendrops.
New hardware technologies like proximity interconnect andchip-based networks.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
Rationale
http://find/http://goback/8/9/2019 Future of Wsn
9/17
Sensor networksOpportunities for theory
The future
RationaleClassical networksSensor networksThe presentThe future
Where we are evolving to
Sensors/RFID chips that talk to each other.
Computers without wires.
Cheap sensors everywhere.
Long view: smart molecules?
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
http://find/http://goback/8/9/2019 Future of Wsn
10/17
Sensor networksOpportunities for theory
The future
Classic network problems revisitedNew problemsNew models
Classic network problems revisited
Consensus, leader election, clock synchronization withsevere resource constraints.
New geographical routing algorithms that require no externalconfiguration and respect sensors limitations.
Internet-scale problems on much smaller scales.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
http://find/http://goback/8/9/2019 Future of Wsn
11/17
Sensor networksOpportunities for theory
The future
Classic network problems revisitedNew problemsNew models
Data aggregation
The central problem in sensor networks.
Still an active area of research.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
http://find/http://goback/8/9/2019 Future of Wsn
12/17
Sensor networksOpportunities for theory
The future
Classic network problems revisitedNew problemsNew models
Localization
How do we know where oursensors are?
Triangulation/trilateration.
NP-hard in the worst case.
Good algorithms for densenetworks.
Error propagation still needswork.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
http://find/http://goback/8/9/2019 Future of Wsn
13/17
Sensor networksOpportunities for theory
The future
Classic network problems revisitedNew problemsNew models
Mobility
Controlled mobility creates a need for planning.Uncontrolled mobility requires tolerance of a rapidly-changingnetwork structure (or maybe no consistent network structure).
Details: see previous talk.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
http://find/http://goback/8/9/2019 Future of Wsn
14/17
Sensor networksOpportunities for theory
The future
Classic network problems revisitedNew problemsNew models
Security
How do we keep dumb sensors from being hijacked or misused?
Controversy over adding RFID tags to US passportsexemplifies issues of control.
Most RFID and sensor network applications rely on physicaldistance to limit access.
Such reliance may not be reasonable as sensors become
ubiquitous.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
S k Cl i k bl i i d
http://find/http://goback/8/9/2019 Future of Wsn
15/17
Sensor networksOpportunities for theory
The future
Classic network problems revisitedNew problemsNew models
New models
Population protocols model collections of very weak devicesusing networks of finite-state automata.
Unstructured case is now very well understood.Bounded-degree networks are in principle equivalent toLINSPACE Turing machines.Speedy algorithms are still needed.
Can we build continuous models that are good approximations
to discrete physical systems?Battery life, geographical constraints, and sensor unreliabilityneed to be incorporated into models at a fundamental level.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
S t k
http://find/http://goback/8/9/2019 Future of Wsn
16/17
Sensor networksOpportunities for theory
The future
The future
There are many morebacteria than people (even
by weight).The same economicssuggests we can expectmany more tiny computersthan big ones.
Sensor networks are thevanguard of this revolution.
0 0 0 00 0 0 00 0 0 00 0 0 00 0 0 00 0 0 00 0 0 00 0 0 01 1 1 11 1 1 11 1 1 11 1 1 11 1 1 11 1 1 11 1 1 11 1 1 1ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
Sensor networks
http://find/http://goback/8/9/2019 Future of Wsn
17/17
Sensor networksOpportunities for theory
The future
The future
There are many morebacteria than people (even
by weight).The same economicssuggests we can expectmany more tiny computersthan big ones.
Sensor networks are thevanguard of this revolution.
ToNC workshop, February 16th, 2006 Sensor Networks and the Future of Networked Computation
http://find/http://goback/