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A Reliable and Efficient MAC Protocol for Underwater Acoustic Sensor Networks

A Reliable and Efficient MAC Protocol for Underwater Acoustic Sensor Networks. Junjie Xiong , Michael R. Lyu , and Kam -Wing Ng. Speaker : Chuan-Heng , Chi. International Journal of Distributed Sensor Networks 2011. Outline. Introduction Goals Network environment RAS Protocol

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A Reliable and Efficient MAC Protocol for Underwater Acoustic Sensor Networks

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  1. A Reliable and Efficient MAC Protocol for Underwater Acoustic Sensor Networks JunjieXiong, Michael R. Lyu, and Kam-Wing Ng Speaker : Chuan-Heng, Chi International Journal of Distributed Sensor Networks 2011

  2. Outline Introduction Goals Network environment RAS Protocol RRAS Protocol Simulation Conclusion

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

  4. Introduction • Underwater sensor network technology can be applied in many fields • Data acquisition • Underwater exploration • Unattended environmental monitoring systems • Prevention of natural disasters • Military purpose

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

  6. Goals We design an efficient priority scheduling protocol called RAS at the MAC layer of BS We propose RRAS to improve the network reliability

  7. Network environment • The typical application we discuss is the ocean bottom surveillance application • All nodes generate the same amount of data and send them to the BS

  8. RAS Protocol BS • Initialization phase • (1) Synchronization • (2) Construct tree topology and static routing • (3) BS knows all of the transmission requirements

  9. RAS Protocol • Scheduling Principle • The transceiver cannot receive when it is transmitting • DR: data receive • DT: data transmit • IR: interference receive • (A)~(F)

  10. RAS Protocol T B A A Data T Data Data B Data (A) A DR duration must not overlap any DT duration

  11. RAS Protocol B T1 T2 A Data T1 T2 B Data A Data (B) A DR duration must not overlap any IR duration Data

  12. RAS Protocol T1 A B Data B T1 Data Data A Data (C) A DR duration must not overlap any other DR duration

  13. RAS Protocol B T1 T2 A Data T1 T2 B Data A Data (D) A DT duration and IR duration(s) can overlap Data

  14. RAS Protocol (E) No DR from ith hop node to (i+ 1)th hop node (F) A node considers DR duration as the scheduling basis rather than DT or IR duration

  15. RAS Protocol BS Step 1: Schedule the BS’s DR from 1-hop nodes

  16. RAS Protocol ‧‧‧ BS Step 2:

  17. RAS Protocol Sequence:{PA1, PB1, PA2, PB2, PA3, PB3} BS BS B A B A PA1,PA2,PA3 PB1,PB2,PB3 Step 3:

  18. RAS Protocol • Problem • Since packet loss is very common in UWASNs, RAS is not reliable.

  19. RRAS Protocol • This paper focus on the packet loss caused by the volatile wireless environment • RRAS utilizes the NACK-retransmission mechanism to improve the overall system reliability

  20. RRAS Protocol

  21. RRAS Protocol Sequence:{PA1, PB1, PA2, PB2, PA3, PB3} n A B PA1,PA2,PA3 PB1,PB2,PB3 One node loss packet

  22. RRAS Protocol Sequence:{PA1, PB1, PA2, PA3, PB3} n A B PA1,PA2,PA3 PB1,PB2,PB3 One node loss packet

  23. RRAS Protocol Sequence:{PA1, PB1, PA2, PA3, PB3} n NACK A B PA1,PA2,PA3 PB1,PB2,PB3 One node loss packet

  24. RRAS Protocol Sequence:{PA1, PB1, PA2, PA3, PB3} n PB2 retransmission A B PA1,PA2,PA3 PB1,PB2,PB3 One node loss packet

  25. RRAS Protocol n A B C D Multiple nodes loss packets

  26. RRAS Protocol n NACK A B C D Multiple nodes loss packets

  27. RRAS Protocol n retransmission packet A B C D Multiple nodes loss packets

  28. RRAS Protocol n NACK A B C D Multiple nodes loss packets

  29. RRAS Protocol n retransmission packet A B C D Multiple nodes loss packets

  30. RRAS Protocol • Problem • Since the control frame exchanges deteriorate the UWASN efficiency greatly

  31. RRAS Protocol • This paper employ simple ALOHA that is, a node could transmit a packet when it is not receiving or transmitting • More efficient

  32. RRAS Protocol We define the states of a node after the data transmission period as (α, β)

  33. RRAS Protocol When does the retransmission packet send back to parent? (N,N)no retransmission (N,Y)waiting for NACK (Y,N)sending NACK to child (Y,Y)waiting for NACK from parent sending NACK to child

  34. RRAS Protocol parent Retransmission data NACK child • Analysis of retransmission time • If it does not adopt ALOHA

  35. RRAS Protocol parent Retransmission data NACK child • Analysis of retransmission time • If it adopt ALOHA • ALOHA allows parallel transmission among NACKs from different node

  36. RRAS Protocol • Analysis of retransmission time • If it adopt ALOHA

  37. Simulation

  38. Simulation • UW-FLASHR • UW-FLASHR uses control frame handshaking to reserve parallel transmissions

  39. Simulation

  40. Simulation

  41. Simulation

  42. Simulation

  43. Conclision • In this paper, we propose RAS protocol in UWASNs • To improve the efficiency • The reliable RAS is implemented to achieve a tradeoff between the reliability and efficiency

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