1. LLR-based Distributed Detection for Wireless Sensor Networks 後卓越進度報告 蔡育仁老師實驗室 2008/01/07

2. LLR: Log Likelihood Ratio The received signal Observation noise: assumed to be Binary Hypothesis Testing Low LLR High LLR

3. Distributed Detection Depends on Likelihood Ratio LLR can be treated as the reliability of a sample value Power allocation in WSNs Power allocation in each sensor based on the instantaneous observed signal Large absolute value of LLR  High reliability  Allocate more power; vice versa Sequential detection in WSNs Can reduce the number of required transmission with the similar detection performance Ordering the message transmission based on the LLR can further reduce the number of transmission Save more communication power

4. ……… …… Fusion Center Power Allocation Depends on Log Likelihood Ratio in WSNs

5. Sequential Detection Depends on Log Likelihood Ratio in WSNs The thresholds ln(A) and ln(B) depend on the target false alarm probability and miss detection probability H1H1 N LLR(N) lnA lnB H0H0 12345678

6. Simulation – LLR-based Power Allocation 10 -5 10 -4 10 -3 10 -2 10 0 10 20 30 40 50 60 70 80 90 100 Detection error probability Required power in percentage Scheme 1,  o =4 Scheme 1,  o =6 Scheme 1,  o =8 Scheme 1,  o =10 Scheme 2,  o =4 Scheme 2,  o =6 Scheme 2,  o =8 Scheme 2,  o =10

7. Simulation – LLR-based Sequential Detection FSS Real Value T-SPRT Ordered Real Value T-SPRT Detection error probability Required number of transmission Conventional Real Value T-SPRT Ordered Real Value T-SPRT

8. Publications Journal Paper Yuh-Ren Tsai, “Sensing Coverage for Randomly Distributed Wireless Sensor Networks in Shadowed Environments,” IEEE Transactions on Vehicular Technology, vol. 57, no. 1, Jan. 2008. (SCI, EI) Conference Paper Yuh-Ren Tsai, Kai-Jie Yang and Sz-Yi Yeh, “Non-uniform Node Deployment for Lifetime Extension in Large-scale Randomly Distributed Wireless Sensor Networks,” in Proc. of IEEE International Conference on Advanced Information Networking and Applications (AINA2008), Okinawa, Japan, March 2008. Yuh-Ren Tsai, and Jyun-Wei Syu, “Down-link CIR Spatial Correlation and CIR Prediction for CDMA Cellular Systems,” in Proc. of IEEE 2008 Vehicular Technology Conference (VTC- 2008 Spring), Singapore, May 2008.