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A Multiple Rendezvous Multichannel MAC Protocol for Underwater Sensor Networks

A Multiple Rendezvous Multichannel MAC Protocol for Underwater Sensor Networks. Chih -Min Chao and Yao- Zong Wang Department of Computer Science and Engineering National Taiwan Ocean University, Taiwan IEEE WCNC 2010. Outline. Introduction Relate Work Goal MM-MAC Simulation Conclusion.

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A Multiple Rendezvous Multichannel MAC Protocol for Underwater Sensor Networks

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  1. A Multiple Rendezvous Multichannel MAC Protocolfor Underwater Sensor Networks Chih-Min Chao and Yao-Zong Wang Department of Computer Science and Engineering National Taiwan Ocean University, Taiwan IEEE WCNC 2010

  2. Outline • Introduction • Relate Work • Goal • MM-MAC • Simulation • Conclusion

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

  4. Introduction • Underwater Environment • Long propagation delay • The propagation speed for an acoustic link is 1500 meters/sec • 2 × 105 times lowerthan the speed of a radio link • Expensive transmitting power consumption • The transmit power is 10 W • Lower available bandwidth

  5. Introduction • Underwater Environment + Multichannel • Enhance network throughput • Achieves low average delay

  6. Goal • This paper proposes a multichannel MAC protocolfor UWSNs • Receiver-based protocol • Only one transceiver is needed • To solve the missing receiver problem in multichannel protocols • Data packets will not be collided by control packets • Enhances the network performance in a multi-hop UWSN • Fairness

  7. Assumptions • Totally m equal-bandwidth channels are available. • Each node is equipped with one half-duplex modem which is able to switch to any channel dynamically. • Nodes are time synchronized. • Each node knows the identifications (IDs) of its one hop neighbors.

  8. System Model … … Superframe Superframe Superframe Channel 1 Superframe … … … Superframe Superframe 2 Superframe 0 1 Data ACK Channel 2 Control period Data period … … Superframe Superframe Superframe Channel 3 …

  9. System Model C B A D Control period Data period A Home-channel=1 2 0 1 Data ACK 5 3 4 B Home-channel=2 2 0 1 Data ACK 5 3 4 C Home-channel=3 2 0 1 Data ACK 5 3 4 D Home-channel=4 2 0 1 Data ACK 5 3 4

  10. Challenges • how to decide the slots which the node should stay in its home-channel. • how does the sender know the slots which the receiver stay in its home-channel. • How to overcome the long propagation delay in the UWSNs.

  11. MM-MAC • Default slots • A node will stay on its default channel, waiting for transmission requests. • Switching slots • A node may switch to its intended receiver’s default channel to initiate a transmission Superframe … 2 0 1 Data ACK Control period Data period

  12. MM-MAC • Cyclic Quorum Systems • Zn : n = 4 ~ 111 The number of slots Z8 G0 = {0,1,2,4} G1 = {1,2,3,5} G2 = {2,3,4,6} G3 = {3,4,5,7} G4 = {4,5,6,0} G5 = {5,6,7,1} G6 = {6,7,0,2} G7 = {7,0,1,3} Z6 G0 = {0,1,3} G1 = {1,2,4} G2 = {2,3,5} G3 = {3,4,0} G4 = {4,5,1} G5 = {5,0,2} Plus one each time any difference set under Zn

  13. MM-MAC • Superframe # 1 Superframe Slot 0 1 2 3 4 5 DCA=1 … 2 0 1 Data ACK 1 1 1 A DSA={2,3,5} Control period Data period DCB=2 B 2 2 2 DSB={3,4,0} Z6 G0 = {0,1,3} G1 = {1,2,4} G2 = {2,3,5} G3 = {3,4,0} G4 = {4,5,1} G5 = {5,0,2} 2+1=3G3={3,4,0} switching slot default slot

  14. MM-MAC Maximum Propagation Delay+CTS Superframe … 2 0 1 Data ACK Control period Data period

  15. MM-MAC A B C D • Example • Superframe # 5 control period data period 0 1 2 3 4 5 DATA DATA DATA DATA NTF NTF NTF NTF RTS DCA = 3 DSA = {2,3,5} 2 2 2 2 2 2 2 2 2 NTF NTF NTF NTF ACK CTS DCB = 2 DSB = {1,2,4} 2 2 2 2 2 2 RTS DATA DATA DATA DATA RTS DCC = 1 DSC = {0,1,3} 0 0 0 0 2 0 Z6 G0 = {0,1,3} G1 = {1,2,4} G2 = {2,3,5} G3 = {3,4,0} G4 = {4,5,1} G5 = {5,0,2} CTS ACK DCD = 0 DSD = {0,2,5} 0 0 x i switching slot default slot packet X sent through channel i

  16. Simulation

  17. RTS CTS DATA RTS CTS RTS DATA RTS CTS DEFERS TRANSMISSIONS Simulation • Slotted FAMA A B Maximum Propagation Delay+CTS C In a multihop environment, the RTS/CTS packets may collide with data packets.

  18. Simulation • Multiple Sinks Model

  19. Simulation • Single Sink Model

  20. Conclusion • The proposed MM-MAC protocol • Is a multiple rendezvous • Only one modem is required for each node • Solves the missing receiver problem. • Reduce the collision probability of data packets • Achieves higher throughput and keeps the retransmission overhead low

  21. Thank You

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