1. A Throughput-Adaptive MAC Protocol for Wireless Sensor Networks Zuo Luo, Liu Danpu, Ma Yan, Wu Huarui Beijing University of Posts and Telecommunications Beijing, China IEEE WiCOM 2010

2. Outline Introduction System model TA-MAC Simulation Conclusion

3. Introduction All medium access control (MAC) protocols for wireless networks try to make sure that no node should interfere with other nodes

4. Introduction An additional consideration for wireless sensor networks is to manage radio's activity to conserve energy While traditional MAC protocols must balance throughput, delay and fairness

5. Introduction Energy consumption on sensor – Collision – Overhearing – Idle listening

6. Introduction In recent research efforts, a duty cycle is used in sensor nodes to reduce energy waste caused by idle listening – S-MAC – T-MAC

7. Introduction S-MAC active sleep Time active sleep Sensor A Sensor B

8. Introduction Drawbacks in S-MAC – Energy wasted – Packet dropped

9. Introduction T-MAC Time active sleep Sensor A

10. Introduction Drawbacks in T-MAC – Packet latency – Packet dropped

11. Goal Propose a new TA-MAC protocol in this paper – Adaptive contention window – BS packet

12. System model Duty cycle and synchronization Four way handshake Active period (AP) Contention window Transmission time of RTS Transmission time of CTS Short period between RTS and CTS Transmission time of BS

13. TA-MAC Adaptive contention window – Buffer threshold

14. TA-MAC A B C D E F Time RTSCTS RTS CTS ABC D EF BS waiting BS PS DATA ACK R C C R D DA A R C C R D DA A

15. Simulation Simulation setup ParameterValue Topology10 Line / 10*10 grid Active period20 ms Frame length650 ms Data packet size100 bytes Transmitting energy10 mA Receiving and idle energy4 mA Sleeping energy20 μA

16. Simulation result Line topology

17. Simulation result Line topology

18. Simulation result Grid topology

19. Simulation result Grid topology

20. Conclusion In this paper the authors proposed two new mechanisms to improve throughput and latency for WSNs The simulation results shows that TA-MAC protocol achieves significant trade-off on throughput and energy efficiency

21. 21 Thanks for your a ttention