1 / 22

ECE/MAE 7750: Distributed Control Systems FISP: Focused Independent Study and Presentation

ECE/MAE 7750: Distributed Control Systems FISP: Focused Independent Study and Presentation. SMAC Protocol With Coordinate Sleeping for Ad-hoc Wireless Sensor Networks. Presenter: Abhishek Gupta Dept. of Electrical and Computer Engineering Utah State University Email: abhishek@cc.usu.edu

nguyet
Download Presentation

ECE/MAE 7750: Distributed Control Systems FISP: Focused Independent Study and Presentation

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. ECE/MAE 7750: Distributed Control SystemsFISP: Focused Independent Study and Presentation SMAC Protocol With Coordinate Sleeping for Ad-hoc Wireless Sensor Networks Presenter: Abhishek Gupta Dept. of Electrical and Computer Engineering Utah State University Email: abhishek@cc.usu.edu Date: February 02, 2005

  2. Outline • Introduction to Ad-hoc Wireless Sensor Networks • The problem and existing solutions • Introduction to S-MAC protocol • S-MAC design • Performance • Conclusion

  3. Introduction to Ad-hoc Wireless Sensor Networks • An Ad Hoc wireless sensor network is a network of sensor devices that are deployed in an ad hoc fashion and coordinate for sensing a physical phenomenon. • Each wireless sensing node typically includes • A Sensor • A processor • A radio • A battery

  4. Ad-hoc Wireless Sensor NetworkApplications Applications include • Traffic Surveillance • Military Applications • Fire Detection • Agricultural management • Structure and Earthquake monitoring • Industrial Control • Rescue Operations

  5. Attributes of Ad hoc Wireless Sensor Networks • Extremely power efficient • Batteries die over time • Cost of recharging nodes may exceed the cost of node itself. • Insensitive to change in network topology and node density. • New nodes can be added • Existing nodes can be relocated • Efficient use of bandwidth. • Fairness can be compromised for energy efficiency. • Inter-network data processing • Sending raw data to some end node for processing consume more energy.

  6. Energy Efficiency in Ad hoc Wireless Sensor Networks • Energy efficiency is the primary concern in a wireless sensor networks. • Causes of energy waste • Collisions • Takes place at the receiver • Increases Latency • Overhearing • Happens when the nodes pick up data destined to other nodes • Idle Listening • Listening to traffic that is not sent

  7. Energy Efficiency in Ad hoc Wireless Sensor Networks • Motes, which are used as nodes in wireless sensor networks, work on extremely low energy !!! Source: http://www.intel.com/research/exploratory/motes.htm

  8. MAC ProtocolsExisting Solution • Stands for Medium Access Control. • Determine when and how nodes should access the shared medium. • Two broad categories • Contention based protocols e.g. IEEE 802.11, CSMA etc. • Scheduled based protocols e.g. TDMA, FDMA etc

  9. MAC ProtocolsLimitations of Existing Solution • TDMA (Scheduled protocol) • Each node gets full bandwidth for a pre-allocated time in turns • Major drawback: Not suitable for networks whose node density changes. • FDMA (Scheduled protocol) • Each node gets a permanent share of bandwidth • Major drawback: Poor bandwidth utilization • IEEE 802.11 (Contention based protocol) • Each node contends for the medium as necessary • Major drawback: Wastes a lot of energy in idle listening

  10. SMAC ProtocolIntroduction • Stands for Sensors Medium Access Control • Specifically designed for Ad hoc wireless sensor networks • Primary goal: Energy Efficiency

  11. Latency Fairness Energy SMAC designFeatures Main features of SMAC include • Periodic Listen • Collision Avoidance • Overhearing Avoidance • Message Passing Tradeoffs

  12. Energy Latency SMAC DesignPeriodic Listen and Sleep • Problem: Idle listening consumes significant energy • Solution: Put all the nodes to sleep periodically Turn off radio when sleeping Reduce duty cycle to ~10% Preferable, neighboring nodes follow same schedule

  13. Schedule 1 Schedule 2 SMAC DesignChoosing and Maintaining Schedule • Nodes exchange their schedule by periodically broadcasting SYNC packet • Nodes take following 2 steps to choose their schedule • Listen for SYNC packets for a fixed amount of time • Case 1: No SYNC packets are received • Case 2: SYNC packet is received. • Case 3: Multiple SYNC packets are received. Border nodes with 2 schedule broadcast twice • Broadcast the chosen schedule by sending out SYNC packet.

  14. SMAC DesignListen and Sleep - Maintaining Synchronization • The listen time is divided into two parts: • For sending/receiving SYNC signal. • For sending/receiving Data.

  15. RTS CTS CTS SMAC DesignAdaptive listening • Used to reduces multi-hop latency due to periodic sleep. • Neighboring nodes wake up for a short period of time at the end of each transmission. 2 4 1 3

  16. SMAC DesignOverhearing Avoidance • All immediate neighbors of sender and receiver are put to sleep upon receiving RTS/CTS. • Neighbors do not overhear data packets and following ACKS. • The duration field in the packet indicates how long to sleep.

  17. DATA/ACK DATA/ACK DATA/ACK DATA/ACK DATA Unfairness Contention for medium SMAC designMessage Passing • SMAC reintroduces the concept of Message Passing • Long messages are converted into small fragment and are transmitted in bursts. • Receiver acknowledges each received fragment. Hidden terminal problem solved by ACK C SYNC A B corrupt

  18. SMAC DesignImplementation • To demonstrate the effectiveness of SMAC protocol compared to conventional protocols, they were implemented and tested on Motes. • Operating System used was TinyOS. • Three MAC modules were implemented on Rene Motes • An 802.11 like protocol without sleep • SMAC without periodic sleep • SMAC with period sleep UCB mote with whip Antenna

  19. SMAC DesignImplementation • Tests on a two hop network • Measures total energy overtime to send messages Idle listening rarely happens Periodic sleep for Idle listening The graph shows the mean energy on radios of source nodes

  20. SMAC DesignImplementation • Tests on a ten hop network The graph shows aggregate energy consumption in a 10-hop network

  21. SMAC DesignConclusion • SMAC offers significant energy efficiency over always listening MAC protocols. • SMAC is able to greatly prolong the network life, which is critical for real-world network applications.

  22. References: • Medium Access Control With Coordinated Adaptive Sleeping for Wireless Sensor Networks, by Wei Ye, John Heidemann, and Deborah Estrin (IEEE/ACM TRANSACTIONS ON NETWORKING, VOL. 12, NO. 3, JUNE 2004 ) • Presentation by Wei Ye on MAC Layer Design for Wireless Sensor Networks • Presentation by Ranjith Udayshankar on Medium Access Control With Coordinated Adaptive Sleeping for Wireless Sensor Networks • Figure of motes power spectrum obtained from http://www.intel.com/research/exploratory/motes.htm

More Related