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An Improved CDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks

An Improved CDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks. Guangyu Fan, Huifang Chen, Lei Xie , Kuang Wang. IEEE WICOM 2011. Introduction. The world's oceans cover over 70 % of its surface Underwater Wireless Sensor Networks (UWSNs). Introduction.

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An Improved CDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks

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  1. An Improved CDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks GuangyuFan, HuifangChen, Lei Xie, KuangWang IEEE WICOM 2011

  2. Introduction • The world's oceans cover over 70 % of its surface • Underwater Wireless Sensor Networks (UWSNs)

  3. Introduction • Underwater sensor network technology can be applied in many fields • Environment monitoring • Geographic data collection • Offshore exploration • Assisted navigation • Disaster prevention • Tactical surveillance

  4. Introduction B A A B Propagation delay • Transmission rate • WSN:3x 108 m/s • UWSN: 1500 m/s • Propagation delay

  5. Introduction A RTS CTS DATA B RTS CTS DATA RTS C RTS CTS • Problem • Long propagation delay

  6. Introduction • CDMA-based protocols • Transmitter-oriented code assignment (TOCA) • Receiver-oriented code assignment (ROCA) • Path-oriented code assignment (POCA)

  7. RTS CTS DATA RTS CTS RTS DATA RTS CTS DEFERS TRANSMISSIONS Related works A B Maximum Propagation Delay+CTS C Waste time ! Slotted FAMA

  8. Related works RIPT

  9. Related works Collision Disadvantage

  10. Goal • In the paper, POCA-CDMA-MAC is proposed for UWASNs. • It utilizes a round-robin method and CDMA technology to reduce collisions of packets.

  11. Network environment • Assumption • Sink can receive packets from multiple neighbors at the same time • Routes will be built • All sensor nodes are equipped with a half-duplex, omni-directional transceiver

  12. POCA-CDMA-MAC Surface station AP1 Sink CP7 BP1 AP6 BP6 AP2 AP5 CP6 BP2 BP4 BP5 BP3 CP2 CP5

  13. POCA-CDMA-MAC (s1,s2,s3,s4,s5,s6,s7) AP1 Sink CP7 BP1 AP6 BP6 AP2 AP5 CP6 BP2 BP4 BP5 BP3 CP2 CP5

  14. POCA-CDMA-MAC (s2,s3,s4,s5,s6,s7) s1 AP1 Sink CP7 BP1 AP6 BP6 AP2 AP5 CP6 BP2 BP4 BP5 BP3 CP2 CP5

  15. POCA-CDMA-MAC (s2,s3,s4,s5,s6,s7) AP1 Sink s1 CP7 BP1 AP6 BP6 AP2 AP5 CP6 BP2 BP4 BP5 BP3 CP2 CP5

  16. POCA-CDMA-MAC (s5,s6,s7) AP1 Sink s1 CP7 BP1 AP6 s3 BP6 AP2 • s4 s2 AP5 CP6 BP2 BP4 BP5 BP3 CP2 CP5

  17. POCA-CDMA-MAC (s5,s6,s7) AP1 Sink s1 CP7 BP1 AP6 BP6 AP2 AP5 CP6 BP2 BP4 BP5 BP3 CP2 CP5 s2 s3 • s4

  18. POCA-CDMA-MAC AP1 Sink s1 s7 CP7 BP1 AP6 BP6 AP2 AP5 CP6 BP2 s6 BP4 BP5 BP3 CP2 CP5 s2 s3 • s4 s5

  19. POCA-CDMA-MAC Sink AP2 BP2 CP2 CP2 BP2 AP2 Sink

  20. POCA-CDMA-MAC Sink AP2 BP2 CP2 CP2 BP2 AP2 Sink

  21. POCA-CDMA-MAC Sink AP2 BP2 CP2 CP2 BP2 AP2 Sink

  22. POCA-CDMA-MAC Sink AP2 BP2 CP2 CP2 BP2 AP2 Sink

  23. POCA-CDMA-MAC Sink AP2 BP2 CP2 CP2 BP2 AP2 Sink Problem

  24. POCA-CDMA-MAC Sink AP2 BP2 CP2 CP2 Passing token BP2 AP2 Sink Solution

  25. Simulation

  26. Simulation

  27. Simulation

  28. Simulation

  29. Conclusion • In the proposed MAC protocol prevent collision of packets and the length of the spreading sequence codes is shortened by using • round-robin method • CDMA technology • Each node encodes its packets with a spreading sequence, so the sink can receive packets from multiple neighbors at the same time.

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