WSN

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WSN Wireless Sensor Networksand Applications
Dwight Borses Member of the Technical
Staff National Semiconductor, Irvine, CA
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Wireless Sensor NetworksDescription

• Consists of a large number of sensor nodes
• Nodes are extremely small, low-cost, low-power
• Nodes communicate over RF or lasers
• Network collect environmental data which they
  forward to infrastructure processing nodes
• Acoustics
• Light
• Humidity
• Temperature
• Imaging
• Seismic, etc

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Gather information about unknown area
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Fire Fighting

• Wearable computing systems that are integrated
  into standard fire-fighting masks show the wearer
  a postage-stamp-size "You Are Here" map of the
  building-floor.
• The same map can be seen on the Fire Chiefs
  laptop as they coordinate the fire with the
  deployed fire crew.
• Such tracking allows further coordination with
  the Chief's laptop that monitors the main
  location of fire and smoke. Improved designs of
  wireless smoke and CO alarms are also integral to
  the project.

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Combined Sewer Outflow (CSO)

• In an estimated 772 U.S. cities in the Midwest,
  Northeast and on West Coast, storm and sanitary
  sewers are connected.
• Under normal circumstances, waste water traveling
  through the combined systems is diverted to
  sewage treatment plants at a given point along
  the system, while storm water continues on for
  discharge into streams and rivers.
• During major storms the systems often are
  overloaded and storm water and raw sewage mix
  together.
• In order to prevent raw sewage from backing up
  into homes and businesses, municipalities often
  direct the excess sewage directly into open
  streams or rivers, thereby creating a CSO event.

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Federal Mandate

• The Environmental Protection Agency (EPA) has
  recognized the water quality issues resulting
  from CSOs and in 1994 placed all municipalities
  with CSO problems under federal mandate to take
  corrective action.
• Sewer system separation, which involves the
  construction of new sewers and the redirection of
  storm water into the new sewer, is one solution
  to the problem.
• However, the high construction costs and serious
  community disruptions involved in this approach
  have made it unfeasible for most municipalities.
• "It would cost the city of South Bend an
  estimated 200 million, and Indianapolis roughly
  1 billion, to complete sewer system separation,"
  "Just imagine the cost and disruption involved in
  using this approach in a major metropolitan area
  like Boston or New York City."

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WSN to the Rescue?

• Jeffrey W. Talley, an assistant professor of
  civil engineering and geological sciences, is
  leading a team of researchers in an effort to
  develop a novel technology to address the problem
  of combined sewer outflow (CSO).
• As an alternative solution, Talley's team has
  proposed addressing the CSO problem through the
  use of embedded wireless sensor networks
  (EmNets).
• Such networks consist of a series of small,
  playing card-sized sensors controlled by embedded
  micro-processors and run by solar energy.
• The sensors have antennas attached which enable
  them to exchange information over a wireless
  communication network.

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Detecting a Developing CSO Event

• The network provides measurements that can be
  accessed by engineers in real time via the
  Internet and used to control a sewer system's
  response to a storm.
• During a storm, the sensors can detect a
  developing CSO event and indicate where it will
  occur.
• A series of "smart valves" would then divert
  combined sewage into holding reservoirs along the
  system until water levels return to normal and
  the system can once again safely separate sewage
  from storm water.
• "This active control allows for the reduction of
  CSO events while making only minor modifications
  into existing sewer infrastructure."

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Infrastructure Contaminant flow monitoring
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UCLA Wildlife Habitat Monitoring

• Instrumented with cameras and microphones
• Task is to detect presence of bird and photograph
  it
• One approach
• Use microphones to detect birdcall and estimate
  location
• Then, select a camera that has the bird in field
  of view

Species Detection and Tracking
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Method Accuracy Error Properties Power cost Environment
Active acoustic ranging Sub-cm LOS gaussian, independent of distance NLOS large non-gaussian bias High cost for TX, near passive RX idle Tolerant of many envioronments
Stereo image sensors A few cm LOS angular error is a function of resolution. Detection error is non-gaussian. NLOS N/A If image sensors are distributed, high comm cost
RSSI Feet? Long-term averaging can counteract fading. Indoor multipath problematic Piggybacked on radio TX Best in predictable environments
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Wireless Sensor Networks for Habitat Monitoring
p88-mainwaring.pdf
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UCB Mote
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Lots of Dots
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First-Generation Dust Mote
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Optical Communication UsingPassive Dust Mote
Transmitters
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Optical Communication UsingPassive Dust Mote
Transmitters (cont.)

• Requires each dust mote to have a line-of-sight
  path to the base station.
• Uplink transmissions are multiplexed using
  space-division multiplexing.

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Active dust mote transmitter
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Optical Communication UsingActive Dust Mote
Transmitters

• Base station uses CCD or CMOS camera (up to 1
  Mbps)
• Using multi-hop routing, not all dust motes need
  to have a line-of-sight path to the base station.

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Two-axis beam steering assembly

• Beams should have divergence ltlt 1º and be
  steerable over a hemisphere.

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Fiber Coupled Microsphere Laser
All optical fiber delivery of pump power and
extraction of lasing emission ? avoids difficult
fiber-to-chip coupling. Lasing emission in the
1500 nm telecom band ? compatibility with
existing fibercom systems. Tandem laser
oscillators on a single fiber ? potential
application as a multi-wavelength source.
Vahala Group
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Fiber-coupled microsphere laser
Erbium doped silica microsphere
40 mm
Optical fiber taper
Green excited stated emission from fundamental
whispering gallery mode
Vahala Group
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Wisenet_SubSys_Blocks_v2.pdf
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SINA Sensor Information Networking Architecture
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Overlap-Problem
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Response-Implosion-Problem
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ADV new data advertisement REQ request for
data DATA data message
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What, Where, How Perlegos.pdf
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Routing

• Proactive vs. Reactive
• proactive continuously evaluate network
  connectivity
• reactive invoke a route determination procedure
  on-demand.
• Right balance between proactive and reactive

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Examples

• Proactive Protocols
• Destination sequenced distance vector (DSDV)
• Reactive Protocols
• Dynamic source routing (DSR)
• Ad hoc on-demand distance vector routing (AODV)
• Temporally ordered routing algorithms (TORA)

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Tiny OS

• Intel Mote software is based on Tiny OS, a
  component-based operating system designed for
  deeply embedded systems that require
  concurrency-intensive operations and which have
  minimal hardware resources.

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TinyDB

• How do you extract the valuable nuggets of
  information from a sensor network's firehose of
  raw data?
• Database system developed by CITRIS in
  collaboration with the Intel Research Laboratory
  Berkeley
• TinyDB is a query processing system for
  extracting information from a network of TinyOS
  sensors.
• TinyDB provides a simple, SQL-like interface to
  specify the data you want to extract, along with
  additional parameters, like the rate at which
  data should be refreshed -- much as you would
  pose queries against a traditional database.
• Given a query specifying your data interests,
  TinyDB collects that data from motes in the
  environment, filters it, aggregates it together,
  and routes it out to a PC.
• TinyDB does this via power-efficient in-network
  processing algorithms.

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Background on CITRIS

• Governor Gray Davis launched this effort with the
  Center for Information Technology Research in the
  Interest of Society (CITRIS), a California
  partnership of university, industry, and
  government .
• Centered at UC Berkeley, CITRIS sponsors research
  on issues having major impact on the economy,
  quality of life, and future success of
  California
• Conserving energy education saving lives,
  property, and productivity in the wake of
  disasters boosting transportation efficiency
  advancing diagnosis and treatment of disease and
  expanding business growth through much richer
  personalized information services.
• More than 100 faculty members in engineering,
  science, social science, and other disciplines at
  four UC campuses will collaborate with
  researchers at more than 20 supporting companies
  on CITRIS research.

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Thank you!