Nyoman Adhiarna

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Global Sensor Network A Survey

• Nyoman Adhiarna
• Deo Kumar Pradhan

ICE 0602 Ubiquitous Networking
Instructor Prof. Lee Young Hee
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Outlines

• What are Wireless Sensor Networks
• WSN Components
• Applications
• Current challenges
• Kindle Innovation Strategy
• Protocol stack of Sensor Network
• Reading Devices Comparisons
• Global Sensing Infrastructure (GSI)
• Conclusions

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What are wireless sensor networks (WSNs)?

• Networks of typically small, battery-powered,
  wireless devices.
• Random deployment of nodes
• Cooperative sensor nodes
• Fault tolerance.

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WSN node components

• Low-power processor.
• Limited processing.
• Memory.
• Limited storage.
• Radio.
• Low-power.
• Low data rate.
• Limited range.
• Sensors.
• Scalar sensors temperature, light, etc.
• Cameras, microphones.
• Power.

P O W E R
Sensors
Storage
Processor
Radio
WSN device schematics
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Applications
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Current Challenges

• Typically, severely energy constrained.
• Limited energy sources (e.g., batteries).
• Trade-off between performance and lifetime.
• Self-organizing and self-healing.
• Remote deployments.
• Scalable.
• Arbitrarily large number of nodes.

• Heterogeneity.
• Devices with varied capabilities.
• Different sensor modalities.
• Hierarchical deployments.
• Adaptability.
• Adjust to operating conditions and changes in
  application requirements.
• Security and privacy.
• Potentially sensitive information.
• Hostile environments.

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Sensor Network Architecture

• Layered Base station, one-hop layer, 2-hop
  layer, ...
• Clustered Nodes elect and communicate through
  cluster heads

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Comparisons with Other Networks
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Protocol Stack of Sensor Network
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Comparisons between Sensor and Ad-Hoc Networks
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Routing Protocols

• Routing protocols in wireless ad hoc networks are
  not well suited to WSNs.
• Hundreds to thousands of nodes, or more
• Densely deployed
• Prone to failure
• Topology changes frequently
• Limited in power, computation capacities, and
  memory
• May not have global id because of the large
  amount of overhead

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Sensor Protocols for information via Negotiation
(SPIN)
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Directed Diffusion
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Low Energy Adaptive Clustering Hierarchy (LEACH)

• Clustering-based protocols to minimize energy
  dissipation (gradual depletion).
• Energy dissipation to communicate with the base
  station is spread out to all nodes.
• Randomly select sensor nodes as clusterheads by
  an algorithm.

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Comparison between SPIN, LEACH, and Directed
Diffusion
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Global Sensing Infrastructure

• Purposes Integration of wireless sensor networks
  through internet to create more prevalent and
  interconnected network.
• Issues
• Multiple applications to share the same sensing
  substrate.
• Integration of sensor and IP network
• Integration of new components
• Flexibility (platform-specific services?)

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Global Sensing Infrastructure (2)
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Sensor Technology and constraints

• Sensor are getting smaller and smarter due to the
  advancement of MEMS(micro miniature sensor
  technology)
• Sensor are moving away from providing analogue
  signals to digital data to facilitate accurate
  data processing and transmission.
• Smart sensors are becoming prevalent due to lower
  cost and demand for distributed sensing and
  control across all industries.
• The individual devices in a wireless senor
  network (WSN) are inherently resource
  constrained
• They have limited processing speeds, storage
  capacity and communication bandwidth.
• These devices have substantial processing
  capability in the aggregate, but not
  individually, so we must combine their many
  vantage points on the physical phenomena within
  the network itself.

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Two ways of communications

• A) Nodes directly communicate with the gateway in
  its cluster.
• B) nodes use chaining in order to communicate
  with the gateway. Using chaining reduces the
  energy used in transmission, but increases the
  energy used in processing. Continuous operation
  or query mode
• - in continuous operation mode, the node is
  continuously sensing the environment and sending
  the data (or processed data) to neighboring or a
  central node.
• -in query mode, the node is usually powered down
  waiting for a command from a central node, or
  neighboring node.
• Multihop communication is widely used in sensor
  networks, not only to reduce power consumption
  but is more immune to shadowing which makes it an
  attractive solution in sensor networks.

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• Data aggregation
• In wireless networks data are collected by the
  sensors and reported to an end user.
• Doing processing locally and sending only the
  results increases the energy used by the
  processor and decreases the energy of data
  transmission.
• Sending raw data decreases the energy consumed in
  processing and increases the energy of
  transmission.
• Data aggregation and fusion play a very important
  role in energy saving.
• As there are many sensor, some of the data may be
  redundant. Messages routed through the nodes can
  be combined to reduce the overall traffic in the
  network, thus improving the performance and
  reducing the power used in transmitting messages.
  

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What are WSNs and MANETs?

• Sensor networks are a class of wireless networks
  whose primary motive is environment sensing. They
  could consist of nodes with sensing and
  communication devices embedded in them.
• A Wireless Sensor Network (WSN for short) is a
  distributed system consisting of a base station
  and a number of wireless sensors nodes endowed
  with radio transceivers. The data being sensed by
  the sensor nodes in the network is eventually
  transmitted to a base station, where the
  information can be accessed.
• Mobile Ad hoc Networks, or MANETs, are a class of
  networks which are infrastructure less in nature,
  and require no pre-deployed set up to
  communicate. These are self collaborative in
  nature, and can automatically set up a network
  and discover routes to a destination on the fly.
  These use intermediate nodes to route data to a
  destination not directly reachable. Or in other
  words, they use multiple short hops rather than
  a single hop from source to destination.

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Routing challenges

• The two main challenges are the varying topology
  nature of sensor networks, and the low power
  requirement on sensor networks.

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Proposed GSI

• Problem current architecture
• Difficult to program applications
• Limited integration between WSN protocols and
  services due to inconsistent assumptions on H/W
  and S/W
• Needs to integrate WSN and internet
• No adaptability of applications toward platform
  and changing environment.

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Challenges of GSI

• Application Concurrency
• Service description
• Service Discovery
• Device Heterogeneity
• Inconsistent Resource Availability
• Basic Service Set
• Coordination
• Event Distribution

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Irisnet Worldwide Sensor Web

• Issues of Irisnet
• Planet-wide local data collection (numerous
  devices and vast amount of data)
• Real-time adaptation of collection and processing
  (due to data sensing and processing routines)
• Sensor device as a single unit supporting
  high-level rich query language
• Queries posed anywhere on the Internet
• Data integrity and privacy
• Robustness (devices failure will occur often)

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Irisnet An Architecture for a Worldwide Sensor
Web

• Service store specific-purpose data in a
  distributed network.
• Organizing agents (OAs) implement the
  distribution database.
• Single OA participate in only one sensing
  service.
• Prototype applications Parking-service finders
  (identification of nearest available parking
  space)

SA Sensing agent OA Organizing agent
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Conclusions

• Realization of wide range of applications of
  sensor networks needs to satisfy the constraints
  particularly fault tolerance, scalability, cost,
  hardware, topology change, environment and power
  consumption.
• Since the constraints are scarcity of resources
  and may rapidly change, new networking techniques
  should be developed.
• Global Sensing Infrastructure can offer sensing
  capabilities much greater than single WSN.
  Therefore, a new software architecture must be
  developed allowing independent software
  components could be developed.
• There are many proposed architecture for a WW
  Sensor Web.

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References

• Akyildiz, Ian, F. et.al, A Survey on Sensor
  Networks, IEEE Communication Magazine, August
  2002.
• Fok, Chien-Liang, et. al., Towards A Flexible
  Global Sensing Infrastructure, IEEE
  Communication, June 2005.
• Gibbons, Phillip B, IrisNet An Architecture for
  A World Wide Sensor Web, IEEE Pervasive
  Computing, 2003

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Thank You