An Energy-Aware Medium-Access-Control Protocol with Frequent Sleeps for Wireless Sensor Networks

1. An Energy-Aware Medium-Access-Control Protocol with Frequent Sleeps for Wireless Sensor Networks Christopher K. Nguyen And Anup Kumar Mobile Information Networks & Distributed Systems Lab Department of Computer Engineering & Computer Science University of Louisville IEEE Symposium on Computers and Communications (ISCC 2005) Speaker: Yung-Ling Yu

2. Outline • Introduction • TEA-MAC protocol design • Simplified version of 802.11 MAC frames • Radio modes and sensor states • The complete TEA-MAC scheme • Evaluations and simulation results • Conclusion

3. Introduction • WSN require that the energy consumption in sensors should be as low as possible • Saving energy always compromises the utilization and performance of WSN • The Throughput and Energy-Aware MAC(TEA-MAC) focuses on • High throughput utilization of WSN • Ensuring low consumption of energy

4. Introduction • The proposed protocol has two main contributions • Wake up as soon as a communication is requested • Because just-in-time wake-ups reduce latency • Sleep as soon as it becomes idle • Because instant sleeps reduce consumption of energy

5. TEA-MAC protocol design • The proposed scheme alleviate • Idle listening • Control-packet overhead • Overhearing • Using two main issues • Frequent sleeps • Minimize idle listening • Reduce overhearing • Short sleeps • Maximize the throughput by reducing latency

6. Simplified version of 802.11 MAC frames • For WSN, the prevalent communication is broadcast • The overhead problem grows significant when the broadcast data propagate • The shaded regions create unnecessary overhead • Every node is the recipient of the transmission

7. Simplified version of 802.11 MAC frames • From inspection of the 802.11 data frame • The wastage percentage is • (4*6)/(2+2+6+6+6+2+6+2312+4) = 1.02 % • From inspection of the 802.11 control frame • The wastage percentage is 1.for RTS (2*6)/(2+2+6+6+4) = 60% 2.for CTS or ACK 6 / (2+2+6+4) = 42.86%

8. Radio modes and sensor states • Three radio modes • Sleep • Receive • Transmit

9. Radio modes and sensor states • Two sensor states • Sleep • Awake

10. The complete TEA-MAC scheme

11. The complete TEA-MAC scheme

12. The complete TEA-MAC scheme

13. Evaluations and simulation results • Simulator • SENSE(Sensor Network Simulation and Emulator) • 500 sensor nodes • Communication types • Broadcast, multicast, and unicast mixed • Broadcast and unicast intervals were set at 5s and 10s, respectively • The power • Transmission 1.6W • Reception 1.2W • Idle listen 1.15W

14. Evaluations and simulation results

15. Evaluations and simulation results

16. Conclusion • TEA-MAC is a practical approach for two reasons • First, sensors are inexpensive • It is not cost-ineffective to deploy sensors in great numbers • Second, Technological advances provide sensors with much longer life • The problem of energy consumption will eventually be less significant