Quickest Detection of GPS Spoofing Attack Z. Zhang, M. Trinkle, L. Qian, and H. Li MILCOM 2012 Nadia Adem 10/27/2014
Global Positioning System
GPS spoofing attacks
GPS Spoofing
Detecting GPS Spoofer
Outline Contributions Anti-spoofing system Experiment setup Problem formulation Detection techniques Performance evaluation Summary
Contributions Simple hardware installation Probabilistic-based detection
Anti-spoofing System
Experiment Setup Photo of the lab. and devices Lab. setup diagram
Probabilistic Detection Samples of signal to noise power ratios - the two antennas Distribution of standard deviation of the difference
Experiment Result Estimated PDF
Problem Formulation and Constraints Minimize worst case delay False alarm below a certain threshold
Hypothesis Testing Let the signal be y(t), model be h(t) Hypothesis testing: H0: y(t) = n(t) (no signal) H1: y(t) = h(t) + n(t) (signal) The optimal decision is given by the Likelihood ratio test (Nieman-Pearson Theorem), g is a threshold. Select H1 if L(y) = log(P(y|H1)/P(y|H0)) > g; otherwise select H0.
Signal detection paradigm
Receiver operating characteristic (ROC) curve Tradeoff between false alarm and detection probability
Cusum test (Page, 1966) gngn b Stopping time N This test minimizes the worst-average detection delay (in an asymptotic sense)
Performance Evaluation
My Comments Probabilistic knowledge about attacker Space Diversity
Summary GPS spoofing threat Proposed anti-sp0oing system Detection schemes Effectiveness of the proposed schem