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Understanding the Gap between the IEEE 802.11 Protocol Performance and the Theoretical Limits.

Understanding the Gap between the IEEE 802.11 Protocol Performance and the Theoretical Limits. Pawel Tomasik Martikel-Nr 3431263. Wireless Sensor Networks. Plan. Introduction About IEEE 802.11 Main problems Summary Questions. Wireless Sensor Networks. Introduction.

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Understanding the Gap between the IEEE 802.11 Protocol Performance and the Theoretical Limits.

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  1. Understanding the Gap between the IEEE 802.11 Protocol Performance and the Theoretical Limits. Pawel Tomasik Martikel-Nr 3431263 Wireless Sensor Networks

  2. Plan • Introduction • About IEEE 802.11 • Main problems • Summary • Questions Wireless Sensor Networks

  3. Introduction • What is this 802.11 protocol? • The IEEE 802.11 MAC protocol is probably the most widely used MAC protocol for ad hoc networks which is still developing. Wireless Sensor Networks

  4. Notions • RTS - Request-To-Send • CTS - Clear-To-Send • ACK - ACKnowledgment • NAV - Network Allocation Vector Wireless Sensor Networks

  5. How does it work?? Wireless Sensor Networks

  6. Implementation Wireless Sensor Networks

  7. Limits – Physical Layer • Spatial Reuse – the number of succesful simultaneous transmissions per spatial unit. • Fairness Index – the max value is 1 when all nodes access the cannel equally Wireless Sensor Networks

  8. Problems • The gagged node • The jammed node • The focused node Wireless Sensor Networks

  9. The gagged node A node is silenced by repeated Request-To-Send (RTS) messages that are not followed by a data packet transmission. Wireless Sensor Networks

  10. The gagged node Wireless Sensor Networks

  11. The gagged node Wireless Sensor Networks

  12. The jammed node A node is jammed by data packet transmitted between two other nodes and cannot extract valuable state informations in control messages sent concurrently. Wireless Sensor Networks

  13. The jammed node Wireless Sensor Networks

  14. The jammed node Wireless Sensor Networks

  15. The focused node A node focuses its transmission attempts on a single of its neighboring nodes that experiences high contention Wireless Sensor Networks

  16. Summary After suppression this 3 situations we can observe the performance of the 802.11 protocol with RTS-CTS within 10% of the optimal spatial reuse. Wireless Sensor Networks

  17. The end. Questions?? Wireless Sensor Networks

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