How to reduce the energy on the Sensor Network

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How to reduce the energy on the Sensor Network

• Donghoon Kim
• Computer Science Software Engineering
• Auburn University

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Wireless Networks

• Involves wireless communication media not
  necessarily mobile Aloha network
• Problems
• Shared media
• Increased bit error rate(BER)
• Lower radio transmission power

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Problems cont

• Shared media
• Low bandwidth
• Technique for increasing bandwidth
• Divide into cells(sub-networks) overlap cells
  on different wavelength (scarce spectrum) and
  reuse channels from cell to cell
• Reduce range to increase number of cells ( fewer
  objects per cell)
• Compression and logging(combine short messages
  into long ones)

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Problems cont

• Increased bit error rate(BER) due to
• Fading multipath and long-term fading
• Noise quality of transmission media
• Interference concurrent usage of communication
  media
• Frequent disconnection

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Problems cont

• Lower radio transmission power
• Scarce energy resource in mobile units
• Limits transmission power to avoid interference
• Signal strength decrease with inverse square of
  distance
• Higher frequency(3-5 GHz) increase attenuation
  and decrease range

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Mobile Networks

• Supports mobility of users, hosts, devices not
  necessarily wireless
• Problems
• Movement from cell to cell
• Change physical network address
• Replication at many cells
• Motion

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Mobile Networks

• Problems cont
• Mobility increase fading and bit error rate
• Lower throughput and higher delay
• Awareness of mobile computing environment
• Location of mobile unit
• (e.g. route information services, local yellow
  pages)
• Tariff switch to different interface for
  various functions
• (e.g. email, ftp)
• Variable bandwidth and device/interface
• Disconnected operations

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Technical Issues in Mobile Networks(1)

• Mobility network layer must
• Know where a user is
• Problem host IP name is bound to its network
  address and we can determine the network address
  but not the physical location
• When a host moves, techniques to determine its
  recent address are
• Broadcast
• Central Services(GSM Global System for Mobile
  Communications)
• Home base(Mobile IP)
• Route message to mobile users
• Store info about current location of users
• Mobile IP solution
• Cellular phone network solution

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Technical Issues in Mobile Networks(2)

• Ad-hoc networking
• Mobile hosts form networks without fixed
  infrastructure
• Dynamic topology structure
• Dynamic source routing use cached info and
  route discovery protocol

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Technical Issues in Mobile Networks(3)

• Portability
• Low power
• Power saving methods
• Risk of data loss
• Replicate to more secure site
• Small user interface
• Handwriting recognition
• Speech recognition
• Pen-point devices
• Small storage capacity
• No disk use ROM
• Script language reduces program size

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Multihop Network
Using several short intermediate hops to send a
bit is more energy-efficient than using one
longer hop.1
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Energy trade-offs in network protocols

• Nodes cannot know a priori the optimal route to
  other nodes
• This path changes as nodes move, enter, or leave
  the network.
• The network protocol coordinates the discovery
  and tracking of routes in the network.

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Energy trade-offs in network protocols(cont)

• Discovery and tracking consumes energy
• It requires communication between nodes.
• The network discovery and maintenance overhead
  may well dominate the energy consumed for data
  transmission itself.
• With low data rates and the relatively fast
  dynamics of some nodes

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Energy trade-offs in network protocols(cont)

• This is actually the case for a large number of
  the ad hoc networking protocols currently in
  vogue
• The general ways to do this tracking and
  discovery are proactive and reactive routing

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Energy trade-offs in network protocols(cont)

• Proactive routing
• The network layer .
• periodically updates routes
• has an up-to-date picture of the optimal routes
• A proactive network finds the routes between many
  nodes at once in an efficient manner.
• It consumes less energy than finding each
  particular route separately

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Energy trade-offs in network protocols(cont)

• Reactive routing
• Reactive routing discovers routes only when the
  network needs them.
• The network generally does not maintain routes
  until it uses them.
• To communicate infrequently with a small number
  of nodes, there is no advantage to maintaining
  infrequently used routes.

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Energy trade-offs in network protocols(cont)

• Hybrid solutions
• Sensor networks are best served by content-and
  localization-based addressing schemes
• Directed diffusion routing, geographical routing,
  and swarm-intelligence are just a few of the
  techniques to watch.

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Energy trade-offs at the MAC Layer

• The MAC layer affects the energy efficiency in a
  number of ways
• MAC-layer power management can minimize the
  standby power of the network
• Careful control of access to the aether reduces
  the number of wasted (re)transmissions corrupted
  by interference from neighboring nodes in the
  network.
• To reach our ultra-low energy target, we need a
  MAC protocol that lets radios sleep most of the
  time and yet lets them awaken precisely when they
  need to transmit or receive data

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Energy Scavenging

• Solar cells can just barely serve as the sole
  energy source for Piconodes.
• Harvesting energy from vibration is promising for
  this application.
• Raised floors and dropped ceilings in most office
  buildings exhibits measurable vibrations
• (from trucks driving down nearby streets and
  people walking on the raised floors)

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Directed Diffusion Routing

• A simplified schematic for directed diffusion

• Interest propagation

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Directed Diffusion Routing

• A simplified schematic for directed diffusion

(b)Initial gradients set up
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Directed Diffusion Routing

• A simplified schematic for directed diffusion

( c ) Data delivery along reinforced path
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Directed Diffusion Routing

• Evaluation of diffusion
• Directed diffusion has the potential for
  significant energy efficiency.
• Even with relatively unoptimized path selection,
  it outperforms an idealized traditional data
  dissemination scheme like omniscient multicast.
• Diffusion mechanisms are stable under the ranges
  of network dynamics
• For directed diffusion to achieve its full
  potential, however, careful attention has to be
  paid to the design of sensor radio MAC layers.

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ASCENT Adaptive Self-Configuring sEnsor
Networks Topologies

• ASCENT
• is not a routing or data dissemination protocol.
• Simply decides which nodes should join the
  routing infrastructure.
• has potential for significant reduction of
  message loss and increase in energy efficiency
• is responsive and stable under systematically
  varied conditions

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ASCENT how does it work ?

• The nodes can be in active or passive state
• Active nodes are part of the topology and forward
  data packets
• Nodes in passive state can be sleeping or
  collecting network measurements. They do not
  forward any packets.
• Each node measures the number of neighbors and
  message loss locally

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ASCENT how does it work ?
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ASCENT how does it work ?
Join Decision Engine
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ASCENT

• Reduction of message loss and increase in energy
  efficiency.
• Problem
• To find the right density of nodes that build the
  basic topology.

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My Future Work

• How do I decide the optimal path using ASCENT
  Directed diffusion ?

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My Future Work

• Focus on the energy efficiency
• Find the right density of nodes
• Add energy status in each node
• ns-2 for simulation

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References

• J. Rabaey, J. Ammer, L.da Silva Jr., D.Patel
• PicoRadioAd-hoc wireless Networking of
  Ubiquitous Low-Energy Sensor/Monitor Nodes
• Dr. Lim Mobile Computing spring2002
• Alberto Cerpa And Deborah Estrin
• ASCENT Adaptive Self-Configuring sEnsor
  Networks Topologies.
• 4. C. Intanagonwiwat, R.Govindan, and D.Estrin
• Directed Diffusion A Scalable and Robust
  Communication Paradigm for Sensor Networks Proc.
  ACM MobiCom2000

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Thank you