1. 21 Apr 2006IPSN / SPOTS ‘06 Towards Radar-Enabled Sensor Networks Prabal Dutta prabal@cs.berkeley.edu http://www.cs.berkeley.edu/~prabal with Anish Arora and Steven Bibyk

2. 21 Apr 2006IPSN / SPOTS ‘06 For this Talk Radar  UWB Radar

3. 21 Apr 2006IPSN / SPOTS ‘06 Motivating Application – Intrusion Detection I detected a Radar Object I detect a Mag Object

4. 21 Apr 2006IPSN / SPOTS ‘06 Motivation Security applications that require –Personnel detection –Stealthy sensors –Low density The three goals of this talk –Shamelessly proselytize radar –Give you an intuitive appreciation for radar signals –Convince you to consider radar for detection applications

5. 21 Apr 2006IPSN / SPOTS ‘06 Lots of Sensor Options. Why Use Radar?

6. 21 Apr 2006IPSN / SPOTS ‘06 Simplified Theory of Operation – Doppler Sensors Radar transmits short (wideband) pulses with period T = 1/f Target with v r = v 0 reflects Doppler-shifted pulse f ’ Electronics “mix” TX and RX pulses and output Target radial velocity can be estimated Complication: Moving objects contain many surfaces

7. 21 Apr 2006IPSN / SPOTS ‘06 Sensor Electronics Dipole antenna UWB radar sensor –Range: 0 – 20 m –Power 3.4V – 6.0V @ 1mA 5.5V  1% @ 7.5mA –Output LPF Doppler baseband Bias: 1.25V (nominal) Range: 0 – 2.5V (VPP) –Wakeup: ~ 30 seconds! Mica Power Board –Input: 2.7V – 3.3V –Output: 3V – 40V –Preset: 3.6V, 5.5V Mica Sensor Board Mica2 Processor Board

8. 21 Apr 2006IPSN / SPOTS ‘06 Antenna Considerations Used default dipole antenna but it has several issues –Null in radiation pattern means a major blind spot –Considerable energy reflected by ground Discone addresses –Vertical polarization –Omni-directional –Wideband

9. 21 Apr 2006IPSN / SPOTS ‘06 Enclosure Design Orientation issues –Gimbal mechanism –Rotationally self-righting –Horizontally self-righting Transparent body –Passes solar radiation –Looks really cool! Weather Resistance –Water-tight enclosure –O-ring seals –Overheats in FL sun 

10. 21 Apr 2006IPSN / SPOTS ‘06 Sensor Traces – Noise

11. 21 Apr 2006IPSN / SPOTS ‘06 Sensor Traces – Person Walking

12. 21 Apr 2006IPSN / SPOTS ‘06 Sensor Traces – Person Running

13. 21 Apr 2006IPSN / SPOTS ‘06 Sensor Traces – Vehicle Driving

14. 21 Apr 2006IPSN / SPOTS ‘06 Signal Detection – NP Detector with CFAR

15. 21 Apr 2006IPSN / SPOTS ‘06 Conclusions and Future Work We –Motivated the application of a remarkably useful sensor –Showed feasibility of integrating UWB radar with motes –Demonstrated a simple CFAR NP signal detector –Highlighted some challenges with simple SP techniques Current work limited to –Single (or small number of) node(s) –Simple, local detection (and classification) –UWB Doppler motion sensors Future work –Address false alarm rates through robust detection –Explore collaborative signal processing –Explore low-complexity classification algorithms –Incorporate UWB rangefinders

16. 21 Apr 2006IPSN / SPOTS ‘06 Discussion