1 / 19

Prepared by A. ABOUZEID

ESRT: Event-to-Sink Reliable Transport in Wireless Sensor Networks[Sankarasubramaniam et. al, ACM MobiHoc 2003]. Prepared by A. ABOUZEID. Event Detection in a WSN. A sensor node that can sense the event. Event!. Sink wants reliable event detection with minimum energy expenditure .

talen
Download Presentation

Prepared by A. ABOUZEID

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ESRT: Event-to-Sink Reliable Transport in Wireless Sensor Networks[Sankarasubramaniam et. al, ACM MobiHoc 2003] Prepared by A. ABOUZEID RPI ECSE-6962

  2. Event Detection in a WSN A sensor node that can sense the event Event! Sink wants reliable event detection with minimum energy expenditure A sensor node RPI ECSE-6962

  3. Motivation • A sink is only interested in the collective information from a number of source nodes and not in individual sensor reports • Event-to-sink communication • Different from traditional notion of end-to-end communication • Energy-efficient • Congestion resolution RPI ECSE-6962

  4. Problem Statement • To configure the reporting rate f of source nodes so as to achieve the required event detection reliabilityRat the sink with minimum resource utilization • Also resolve congestion RPI ECSE-6962

  5. Linear increase with f Typical Behavior at a Sink Network gets congested sooner with increasing number of source nodes Congestion: Reliability level is always lower than the peak point RPI ECSE-6962

  6. Five characteristic regions Not Congested Congested Higher reliability than required Lower reliability than required Goal: To stay in OOR where energy expenditure is optimal OOR RPI ECSE-6962

  7. Congestion Detection • Congestion status is required at the sink to determine the network state • Based on expectation of buffer overflow at sensor nodes • During a single interval, f and n do not change much • If pending congestion is detected CN bit is set in event reports RPI ECSE-6962

  8. ESRT Actions RPI ECSE-6962

  9. ESRT State Diagram Not all transitions are possible (e.g. From (C,HR), ESRT cannot transition to (NC,LR)) RPI ECSE-6962

  10. Stability of ESRT • ESRT converges to OOR from any of four initial states {(NC,LR), (NC,HR), (C,HR), (C,LR)} • From (NC,HR), ESRT stays in the state until converges to OOR • Convergence time depends on ε – smaller ε causes longer convergence time RPI ECSE-6962

  11. Simulation Setup • Ns-2 simulator • 200 sensor nodes • 100m x 100m area • 40m transmission range • 30 byte packets • 65 packets IFQ • 10 sec decision interval (τ) RPI ECSE-6962

  12. From (NC,LR) Reaches OOR in two intervals RPI ECSE-6962

  13. From (NC,HR) ESRT stays in (NC,HR) until reaching OOR in five intervals RPI ECSE-6962

  14. (C,HR) to (NC,HR) then OOR RPI ECSE-6962

  15. (C,LR) to (NC,LR) then OOR RPI ECSE-6962

  16. Power savings from (NC,HR) Reporting rate gets reduced conservatively while maintaining reliability RPI ECSE-6962

  17. Conclusion • ESRT provides a reliable event-to-sink communication • Self-configuration • Energy awareness • Uses minimum energy while achieving required reliability • Congestion control • Collective identification • Individual sensor ID is not necessary • Biased implementation • Almost entirely in sink RPI ECSE-6962

  18. Questions • Definition of reliability as number of received packets? • Is ESRT congestion detection accurate and reliable? • ESRT action heavily depends on the congestion state • What if the congestion reports are inconsistent due to partial congestion or underlying path oscillation? • What is the effect of inaccurate congestion state detection on ESRT? • Is it reasonable assumption that a sink is capable of broadcasting to all the source nodes ? • what if R is higher than the peak point? RPI ECSE-6962

  19. Questions continued • Out of band? • If in-band, how to deal with congestion? • What if the density of source nodes is too low to meet the required reliability with fast reporting? • In other words, RPI ECSE-6962

More Related