Future Directions in GNSS Research

1. Future Directions in GNSS Research Todd Humphreys | Aerospace Engineering The University of Texas at Austin GPS World Webinar | November 15, 2012

2. Acknowledgements • University of Texas Radionavigation Lab graduate students JahshanBhatti, Kyle Wesson, Ken Pesyna, Zak Kassas, Daniel Shepard, and Andrew Kerns

3. PNT Desiderata Precise and Accurate Available Everywhere Cost Effective Instantaneous Fix Low Power Secure & Robust KanwarChadha, Texas Wireless Summit, Oct. 26, 2012

4. State of Art: uBlox UC530M Precise and Accurate 2.0 m CEP with SBAS Available Everywhere -148 dBmacq, -165 dBmtrk Cost Effective ~$30 - $50 Instantaneous Fix 1 second hot TTFF Low Power 66 mW continuous Secure & Robust CW interference removal

5. Promising Directions for University Research Precise and Accurate 2.0 m CEB with SBAS Available Everywhere -148 dBmacq, -165 dBmtrk Cost Effective ~$30 - $50 Instantaneous Fix 1 second hot TTFF Low Power 66 mW continuous Secure & Robust CW interference removal

6. (Practically) Closed Problems • 2-meter insecure rural outdoor location • Elimination of ionospheric delay • Multi-frequency open civil signals eliminate 1st-order effects • 2nd-order effects at mm level • Ray-tracing models available for single-freq. networked RX • Broadcast model obsolete • Data-aided carrier tracking • Half-cycle carrier tracking (e.g. Costas-loop tracking) is outmoded • GPS L1 C/A is >99% predictable – build on-the-fly database or get one over network • Other GNSS signals have pilot channels • One remaining open problem: Exploit coding on L2 CM to improve L2C carrier tracking Precise and Accurate Available Everywhere Instantaneous Fix Low Power Secure & Robust

7. Open Problems (1 of 4) • Move sub-centimeter positioning into the mainstream • Precise positioning applications are much bigger than surveying, mining, and geodesy – there are myriad consumer applications • Precise positioning is not intrinsically expensive – primary cost is in non-recurring engineering • Mainstreaming of cm-positioning will be enormously disruptive for established precise positioning providers Precise and Accurate Available Everywhere Instantaneous Fix Low Power Secure & Robust

11. CDGNSS-Enabled Precise Augmented Reality

13. AR Video

14. Open Problems (1 of 4) • Move sub-centimeter positioning into the mainstream • Robustify and increase sensitivity of carrier-phase differential GNSS (current state of art can’t handle even heavy foliage) • Overlay CDGPS engine on vectorized tracking (VDLL/VFLL + phase recovery), or, better yet … • Integrate CDGPS engine within vector tracking architecture • Difference correlators offer improved robustness and greater sensitivity. See T. Pany et al. “Difference Correlators,” May/June 2012. • Exploit non-RF sensors to move indoors • IMUs • Cameras are cheap, pervasive. Camera central to precise augmented reality, for which IMUs may be unnecessary. • “Green” carrier-phase recovery – low power will enable consumer applications Precise and Accurate Available Everywhere Instantaneous Fix Low Power Secure & Robust

15. Open Problems (2 of 4) • Move toward cooperative signal-opportunistic PNT • Indoor problem won’t be solved by GNSS signals alone • Might as well assume all future PNT devices will be networked • Natural evolution of processing platform: • Navigation processing on chip •  Navigation processing on host processor •  Navigation processing on cloud • Natural evolution of tracking architecture: • Single-channel scalar tracking •  Single-receiver vector tracking •  Multi-receiver vector tracking Precise and Accurate Available Everywhere Instantaneous Fix Low Power Secure & Robust

16. Cooperative Opportunistic Vectorized Tracking for Robust PNT

17. Open Problems (3 of 4) • Civil GNSS receivers insecure • No commercial GNSS receiver has yet been built with security in mind • Open GNSS signals are predictable  spoofable • Vast majority of receivers in critical national infrastructure are GPS L1 C/A receivers • Securing GNSS across a wide variety of application domains (e.g., low-power, low-cost, space-constrained) will remain a challenge for years to come Precise and Accurate Available Everywhere Instantaneous Fix Low Power Secure & Robust

18. GNSS Spoofing

19. UT June 2012 Spoofing Demo

20. Spoofing Defenses Non-Cryptographic Cryptographic SSSC on L1C (Scott) J/N Sensing (Ward, Scott, Calgary) Stand-Alone NMA on L2C, L5, or L1C (MITRE, Scott, UT) Sensor Diversity Defense (DARPA, BAE, UT) SSSC or NMA on WAAS (Scott, UT) Single-Antenna Spatial Correlation (Cornell, Calgary) Correlation Anomaly Defense (TENCAP, Ledvina, Torino, UT) P(Y) Cross-Correlation (Stanford, Cornell) Networked Multi-Element Antenna Defense (Keys, Montgomery, DLR, Stanford)

21. Open Problems (4 of 4) • Move GPS dot from fiction to non-fiction • Dime-sized tracking device accurate to two feet anywhere on the globe Precise and Accurate Available Everywhere Instantaneous Fix Low Power Secure & Robust

22. The GPS Dot

24. Open Problems (4 of 4) • Move GPS dot from fiction to non-fiction • Dime-sized tracking device accurate to two feet anywhere on the globe • Competing goals ensure that dots will offer interesting research challenges for years to come: • High sensitivity vs. small size • High sensitivity vs. low-power • Dots could cooperate in a wireless sensor network Precise and Accurate Available Everywhere Instantaneous Fix Low Power Secure & Robust

25. radionavlab.ae.utexas.edu