Y. Zhou, E. Ngai, M. Lyu, and J. Liu Group Meeting 2006-11-21

1. POWER-SPEED A Power-ControlledReal-Time Data Transport Protocolfor Wireless Sensor-Actuator Networks(Based on the work submitted to WCNC 2007) Y. Zhou, E. Ngai, M. Lyu, and J. Liu Group Meeting 2006-11-21 Dept. of Computer Science & Engineering

2. Outline • Introduction • Protocol Design • Simulation Study • Conclusions

3. Introduction • An example wireless sensor network

4. I, robot I, robot Introduction An example wireless sensor-actuator network (WSAN)

5. Introduction • Features of WSANs • Real-time data transport • Mobile data sinks, i.e., the actuator nodes • Stateless protocol is highly desired • Battery-powered sensor nodes • Energy-efficiency is still a critical issue

6. Introduction • Existing protocols for WSANs and WSNs • Timeliness-domain QoS-guaranteed protocols • SPEED, MMSPEED • PREI (in MASS’06, by us) • Feedback control packets are required • To select fitful paths • If feedback control packets can be avoided, … • It would be • This is the focus of this work

7. Introduction • Existing protocols for WSANs and WSNs • GRP: Geographic Routing Protocol • No feedback packets are required. • No QoS guarantee

8. Outline • Introduction • Protocol Design • Simulation Study • Conclusions

9. Protocol Design • Selecting next hop neighbor to which packets are forwarded • Guarantee in-time delivery • Achieve energy-efficiency • Examples • GRP • Shortest-path based protocol

10. Protocol Design • Estimating QoS conditions of downstream links • No feedback packets • unaware of real QoS data • Perform estimation • Space domain: delay of upstream links • Time domain: historical link delay

11. Protocol Design • Observation • Encapsulate data in packet is more energy-efficient than send them individually • Example • Sending two 32-byte packets cost twice as much energy as sending one 64-byte packet • Data on upstream-link conditions can be easily encapsulated in sensor reporting packets

12. Protocol Design • Part of POWER-SPEEDpacket header

13. Protocol Design • Link delay estimation • Time domain • Space domain • SPEED • Max hops

14. Protocol Design • Estimate the number of hops if delivering packet to a specific neighbor • Candidate • Those • Required energy to send a packet to this neighbor • Energy consumption estimation • So, next-hop neighbor is the one that achieves minimum

15. Protocol Design • Summaries • POWER-SPEED selects the next-hop neighbor based on the estimation of downstream path quality and the latency-bound requirement of packets. Adaptively it sends a packet • that will expire in a longer period of time with lower transmitter power level to save energy • that will expire sooner with higher transmitter power level, which results in fewer hop numbers between senders to destination actuators, and thus guarantees that the packet can reach its destination in a shorter period of time.

16. Outline • Introduction • Protocol Design • Simulation Study • Conclusions

17. Simulations

18. Simulations • Randomly place 100 nodes. Compare the performance of GRP and POWER-SPEED in terms of energy consumptions

19. Simulations • Randomly place 100-250 nodes. Compare the performance of GRP and POWER-SPEED in terms of energy consumptions

20. Simulations • Compare the performance of GRP and POWER-SPEED in terms of in-time packet delivery rate

21. Outline • Introduction • Protocol Design • Simulation Study • Conclusions

22. Conclusion • We show a way to achieve real-time data transport without feed-back control packets • We propose POWER-SPEED and show the effectiveness of the protocol

23. Q & A Thank You