Wireless Sensor Network<br />Eng. MshariAlabdulkarim<br />
Energy saving in wireless sensor networks<br />Outline:<br /><ul><li>Studied Paper.
Introduction.
Power Consumption in WSNs.
Sleep-wake Scheduling.
MAC Protocol for WSN.
In-network Processing.
Network Coding.
Communication Protocol.</li></li></ul><li>Energy saving in wireless sensor networks<br />Studied Paper<br /><ul><li>Topic:...
Energy saving in wireless sensor networks<br />Introduction<br />Wireless Sensor Network?<br />A wireless sensor network i...
Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />What are the components of the wireless sensor?<b...
Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />What is the goal of the sensor node?<br />The goa...
Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />
Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />Wireless Sensor Network Applications:<br /><ul><l...
Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />Wireless Sensor Network Example (1):<br />
Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />Wireless Sensor Network Example (2):<br />
Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />Short Video<br />
Energy saving in wireless sensor networks<br />Power Consumption in WSNs<br />The power issue in the wireless sensor netwo...
Energy saving in wireless sensor networks<br />sources of power consumption:<br />Useful power consumption:<br /><ul><li>T...
Processing query requests.
Forwarding queries and data to the neighbors.</li></ul>Wasteful power consumption:<br /><ul><li>Idle listening to the chan...
Retransmitting because of collisions “e.g. two packets arrived at the same time at the same sensor”.
Overhearing “when a sensor received a packet doesn’t belong to it”.
 Generating and handling control packets.
Over-emitting “when a sensor received a packet while it is not ready”.</li></li></ul><li>Energy saving in wireless sensor ...
In-network Processing.
Network Coding.
Communication Protocol.</li></li></ul><li>Energy saving in wireless sensor networks<br />Sleep-wake scheduling<br />Wake S...
Energy saving in wireless sensor networks<br />Power consumption model:<br />Time<br />Wake<br />Wake<br />Sleep<br />Slee...
Energy saving in wireless sensor networks<br />
Energy saving in wireless sensor networks<br />On-demandScheme:<br />Strategy:<br />Sensor should be awakening just when i...
The best sleep-wake scheme for the applications with low duty cycle.</li></ul>Disadvantages:<br /><ul><li>Additional delay...
Not suitable for Disruption Tolerant Network (DTN).</li></li></ul><li>Energy saving in wireless sensor networks<br />Sched...
Energy saving in wireless sensor networks<br />Scheduled Rendezvous Scheme (Cont.):<br />Advantages:<br /><ul><li>All sens...
Energy saving in wireless sensor networks<br />Asynchronous Scheme (Cont.):<br />Advantages:<br /><ul><li>The sensors don’...
Allow each node in the WSN to set its own sleep/wake schedule independently.
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Power Saving in Wireless Sensor Networks

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Power Saving in Wireless Sensor Networks

  1. 1. Wireless Sensor Network<br />Eng. MshariAlabdulkarim<br />
  2. 2. Energy saving in wireless sensor networks<br />Outline:<br /><ul><li>Studied Paper.
  3. 3. Introduction.
  4. 4. Power Consumption in WSNs.
  5. 5. Sleep-wake Scheduling.
  6. 6. MAC Protocol for WSN.
  7. 7. In-network Processing.
  8. 8. Network Coding.
  9. 9. Communication Protocol.</li></li></ul><li>Energy saving in wireless sensor networks<br />Studied Paper<br /><ul><li>Topic: </li></ul>Energy saving in wireless sensor networks.<br /><ul><li>By: </li></ul>Hnin Yu Shew, JIANG Xiao-hong, Susumu Horiguchi<br />(Department of Computer Science, Graduate School of Information Science, Tohoku University, Sendai 980-8579, Japan) <br /><ul><li>Date: </li></ul>May 2009<br /><ul><li>Type: </li></ul>Survey on the main techniques used for energy saving in WSNs.<br />
  10. 10. Energy saving in wireless sensor networks<br />Introduction<br />Wireless Sensor Network?<br />A wireless sensor network is a collection of nodes “sensors” organized into a cooperative network. The nodes communicate wirelessly and often self-organize after being deployed in an ad-hoc fashion.<br />Base Station<br />Detection<br />Sensor Field<br />
  11. 11. Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />What are the components of the wireless sensor?<br />Processor.<br />Memory.<br />RF transceiver.<br />Power source.<br />Sensor.<br />
  12. 12. Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />What is the goal of the sensor node?<br />The goal from the sensor node is to collect the data at regular intervals, then transform the data into an electrical signal and finally send the signal to the sink or the base node. <br />
  13. 13. Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />
  14. 14. Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />Wireless Sensor Network Applications:<br /><ul><li>Monitoring Space.</li></ul>environmental and habitat monitoring, precision agriculture, indoor climate control, surveillance, treaty verification, and intelligent alarms.<br /><ul><li>Monitoring Objects.</li></ul>structural monitoring, condition-based equipment maintenance, medical diagnostics, and urban terrain mapping.<br /><ul><li>Monitoring Interactions of Objects and Space.</li></ul>wildlife habitats, disaster management, emergency response, ubiquitous computing environments, asset tracking, healthcare, and manufacturing process flow.<br />
  15. 15. Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />Wireless Sensor Network Example (1):<br />
  16. 16. Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />Wireless Sensor Network Example (2):<br />
  17. 17. Energy saving in wireless sensor networks<br />Introduction (Cont.)<br />Short Video<br />
  18. 18. Energy saving in wireless sensor networks<br />Power Consumption in WSNs<br />The power issue in the wireless sensor network is one of the biggest challenges, because the sensor has a limited source of power which is also hard to replace or recharge “e.g. sensors in the battle field, sensors in a large forest … etc”. <br />Why limited source of power?<br />Inexpensive nature.<br />Limited size and weight.<br />Redundant nature.<br />
  19. 19. Energy saving in wireless sensor networks<br />sources of power consumption:<br />Useful power consumption:<br /><ul><li>Transmitting or resaving data.
  20. 20. Processing query requests.
  21. 21. Forwarding queries and data to the neighbors.</li></ul>Wasteful power consumption:<br /><ul><li>Idle listening to the channel “waiting for possible traffic”.
  22. 22. Retransmitting because of collisions “e.g. two packets arrived at the same time at the same sensor”.
  23. 23. Overhearing “when a sensor received a packet doesn’t belong to it”.
  24. 24. Generating and handling control packets.
  25. 25. Over-emitting “when a sensor received a packet while it is not ready”.</li></li></ul><li>Energy saving in wireless sensor networks<br />How to minimize the energy consumption of sensor nodes while meeting the application requirements? <br /><ul><li>Sleep-wake Scheduling.
  26. 26. In-network Processing.
  27. 27. Network Coding.
  28. 28. Communication Protocol.</li></li></ul><li>Energy saving in wireless sensor networks<br />Sleep-wake scheduling<br />Wake State<br />Sleep State<br />Goal: reduce the time where the sensor is being idle.<br />Drawback: Additional delay because of waiting for the next-hop node to wake up.<br />
  29. 29. Energy saving in wireless sensor networks<br />Power consumption model:<br />Time<br />Wake<br />Wake<br />Sleep<br />Sleep<br />Sleep<br />Sleep and Wake Duty Cycle<br />
  30. 30. Energy saving in wireless sensor networks<br />
  31. 31. Energy saving in wireless sensor networks<br />On-demandScheme:<br />Strategy:<br />Sensor should be awakening just when it receives a packet from neighbors.<br />Advantages:<br /><ul><li>Minimize the power consumption.
  32. 32. The best sleep-wake scheme for the applications with low duty cycle.</li></ul>Disadvantages:<br /><ul><li>Additional delay incurred when a node has to wait for its next hop node to wake up.
  33. 33. Not suitable for Disruption Tolerant Network (DTN).</li></li></ul><li>Energy saving in wireless sensor networks<br />Scheduled Rendezvous Scheme:<br />Strategy:<br />All sensors should wake up at the same time. <br />Transmitter:<br />Wake<br />Wake<br />Sleep<br />Sleep<br />Sleep<br />Send Packets<br />Receiver:<br />Wake<br />Wake<br />Sleep<br />Sleep<br />Sleep<br />Receive Packets<br />
  34. 34. Energy saving in wireless sensor networks<br />Scheduled Rendezvous Scheme (Cont.):<br />Advantages:<br /><ul><li>All sensors are awake in the same time “which allowing the broadcast massages”.</li></ul>Disadvantages:<br /><ul><li>All sensors should be synchronized in order to wake and work in the same time.</li></li></ul><li>Energy saving in wireless sensor networks<br />Asynchronous Scheme:<br />Strategy:<br />All neighbors should have an overlapping between their wake periods. <br />Transmitter:<br />Wake<br />Sleep<br />Preamble<br />Data<br />Sleep<br />Send Packets<br />Receiver:<br />Wake<br />Sleep<br />Sleep<br />Data<br />Check the channel<br />Check the channel and receive<br />
  35. 35. Energy saving in wireless sensor networks<br />Asynchronous Scheme (Cont.):<br />Advantages:<br /><ul><li>The sensors don’t have to be synchronized together.
  36. 36. Allow each node in the WSN to set its own sleep/wake schedule independently.
  37. 37. The contention is reduced, because nodes wake up at different time instances.</li></li></ul><li>Energy saving in wireless sensor networks<br />MAC Protocol for WSN<br />
  38. 38. Energy saving in wireless sensor networks<br />S-MAC Protocol:<br />Stand for:<br />Sensors Medium Access Control.<br />Strategy:<br />All node follow a periodic sleep/wake cycle, where the waking time is about 10% of the sleeping time, and the nodes that are close to each other synchronize their active cycles together. <br />Listen<br />Listen<br />Sleep<br />Sleep<br />Time<br />T<br />
  39. 39. Energy saving in wireless sensor networks<br />S-MAC Protocol (Cont.):<br />Advantages:<br /><ul><li>Periodic Listen.
  40. 40. Collision Avoidance.
  41. 41. Overhearing Avoidance.
  42. 42. Message passing.</li></ul>Disadvantages:<br /><ul><li>Latency will be increase.</li></li></ul><li>Energy saving in wireless sensor networks<br />T-MAC Protocol:<br />Stand for:<br />Timeout Medium Access Control.<br />Strategy:<br />It adaptively adjusts the sleep and wake periods based on the estimated traffic flow.<br />Normal<br />Sleep<br />Sleep<br />Sleep<br />S-MAC<br />Sleep<br />Sleep<br />Sleep<br />T-MAC<br />
  43. 43. Energy saving in wireless sensor networks<br />Questions?<br />What S-MAC, T-MAC, B-MAC are doing?<br />Trying to minimize idle listen as mush as possible.<br />Why radio should listen the channel?<br />To minimize collisions.<br />How can we make collision free without listen the channel?<br />TDMA “Time Division Multiple Access”.<br />
  44. 44. Energy saving in wireless sensor networks<br />In-network Processing<br />After the sensors detect phenomena or change, they generate an event to the user and by that we will have a huge number of transmissions which will consume the power of the sensors.<br />Strategy:<br />Reduce the number of transmissions by aggregating several eventsinto a single event.<br />Aggregation takes place if the data arriving to the common node have same attributes of the phenomenon being sensed.<br />
  45. 45. Energy saving in wireless sensor networks<br />In-network Processing<br />Advantages:<br /><ul><li>Reduce the number of transmissions “which will help to reduce the consumption of power”.</li></ul>Disadvantages:<br /><ul><li>There is a potential of having greater delay.
  46. 46. Can’t be used in case if all the original packets are needed to be delivered to the destination nodes. </li></li></ul><li>Energy saving in wireless sensor networks<br />Network Coding<br />Goal: improve the throughput and save the bandwidth. <br />Strategy:allow to mix the data at the intermediate nodes.<br />Advantages:<br /><ul><li>Reduce the number of transmissions by mixing two packets together.
  47. 47. Improves throughput and saves bandwidth.</li></li></ul><li>Energy saving in wireless sensor networks<br />Network Coding<br />
  48. 48. Energy saving in wireless sensor networks<br />Communication Protocol<br />The goal from adjusting the communication protocol “Medium Access Control” is to avoid the collisions by scheduling nodes onto different sub-channels that are divided either by time “TDMA”, frequency “FDMA” or orthogonal codes “CDMA”.<br />
  49. 49. Energy saving in wireless sensor networks<br />Scheduled Protocol:<br />Strategy:<br />Prevent the collisions by reserving and scheduling the resources. <br />Example: <br />The best protocol considered as scheduled protocol is the TDMA “Time Division Multiple Access”, where the time is divided into N slots and each slot can be used by only one sensor.<br />Frame 1<br />Frame 2<br />1<br />2<br />3<br />N<br />1<br />2<br />3<br />N<br />Time<br />TDMA MAC Protocol<br />
  50. 50. Energy saving in wireless sensor networks<br />Scheduled Protocol (Cont.):<br />Advantages:<br /><ul><li>TDMA supports low-duty-cycle operations on sensors.
  51. 51. Saving the power from being wasted by turning off the radio out the allocated time slot.
  52. 52. Eliminating the possibility of collisions due contention and eliminating the possibility of overhearing.</li></ul>Disadvantages:<br /><ul><li>Not flexible to changes in sensor density or movements.
  53. 53. All sensors should be well synchronized.</li></li></ul><li>Energy saving in wireless sensor networks<br />Contention Protocol:<br />Strategy:<br />Before sending a message, a sensor listens to the medium. If it is busy, wait a random time then retry again and if it is free then it will send the message.<br />Advantages:<br /><ul><li>It can adapt for changes “in the node density, traffic load or the topology” better than the Scheduled protocol.
  54. 54. Support peer-to-peer communications.
  55. 55. The sensors don’t have to be synchronized together.</li></ul>Disadvantages:<br /><ul><li>It is the worst protocol among all the previous protocol from the power saving perspective, since all sensors listen to the channel all the time. </li></li></ul><li>Energy saving in wireless sensor networks<br />Conclusion<br />
  56. 56. Energy saving in wireless sensor networks<br />Thank you for listening<br />
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