Detection and mitigation of satellite navigation spoofing

Abstract

A device for mitigating satellite navigation spoofing includes processing circuitry which detects correlation peaks for PRNs in a satellite navigation signal. The TOAs of subframes of navigation messages associated with each of correlation peaks are recorded and analyzed to determine if they fall within a specified time window. Based on the analysis, the correlation peaks are classified as legitimate or as spoofed. A correct geographic location is computed from the navigation data associated with the legitimate correlation peaks. Corresponding methods for mitigating satellite navigation spoofing may be embodied in a hardware-based GNSS receiver and in a software-based GNSS receiver.

What is claimed is: 
     
         1 . A device for mitigating satellite navigation spoofing, comprising processing circuitry adapted to:
 detect, in sampled navigation signal data, correlation peaks for a plurality of data sequences, said data sequences being associated with respective navigation satellites, at least two of said data sequences being associated with different navigation satellites;   classify correlation peaks having respective times of arrival outside a specified time window as spoofed correlation peaks; and   form a set of legitimate correlation peaks by removing said spoofed correlation peaks from said detected correlation peaks.   
     
     
         2 . A device for mitigating satellite navigation spoofing according to  claim 1 , further adapted to decode navigation messages extracted from said set of legitimate correlation peaks to a geographic location. 
     
     
         3 . A device for mitigating satellite navigation spoofing according to  claim 1 , wherein said specified time window is within a single subframe. 
     
     
         4 . A device for mitigating satellite navigation spoofing according to  claim 1 , wherein said times of arrival are arrival times of subframes of navigation messages. 
     
     
         5 . A device for mitigating satellite navigation spoofing according to  claim 4 , wherein said arrival time of a subframe of a navigation message comprises a time at which a specified data symbol of said subframe is received. 
     
     
         6 . A device according to  claim 1 , wherein a time interval between successive time windows comprises a duration of a subframe of a navigation message. 
     
     
         7 . A device according to  claim 1 , wherein a duration of said time window and a time interval between successive time windows are selected in accordance with characteristics of said satellite navigation signal. 
     
     
         8 . A device according to  claim 1 , wherein a duration of said time window is from 17 milliseconds to 23 milliseconds. 
     
     
         9 . A device according to  claim 1 , wherein said time window begins when a first one of said times of arrival is observed for a current subframe. 
     
     
         10 . A device according to  claim 1 , wherein said classifying further comprises:
 comparing at least one of clock correction data and ephemeris data in successive subframes of at least one navigation message extracted from a legitimate correlation peak; and   identifying spoofed correlation peaks based on changes in said at least one of clock correction data and ephemeris data between said successive subframes of said extracted navigation message.   
     
     
         11 . A device according to  claim 1 , wherein said device is embedded in a global navigation satellite system integrated circuit. 
     
     
         12 . A device according to  claim 1 , wherein said detecting is performed during acquisition of said navigation signal. 
     
     
         13 . A device according to  claim 1 , wherein said detecting comprises seeking a plurality of correlation peaks for at least one of said data sequences over an entire duration of a navigation message subframe. 
     
     
         14 . A method for mitigating satellite navigation spoofing, comprising:
 detecting, in sampled navigation signal data, correlation peaks for a plurality of data sequences, said data sequences being associated with respective navigation satellites, at least two of said data sequences being associated with different navigation satellites;   classifying correlation peaks having respective times of arrival outside a specified time window as spoofed correlation peaks; and   forming a set of legitimate correlation peaks by removing said spoofed correlation peaks from said detected correlation peaks.   
     
     
         15 . A method according to  claim 14 , further comprising decoding navigation messages extracted from said set of legitimate correlation peaks to a first geographic location. 
     
     
         16 . A method according to  claim 14 , further comprising decoding navigation messages associated with said spoofed correlation peaks to a second geographic location. 
     
     
         17 . A method according to  claim 14 , wherein said specified time window is within a single subframe. 
     
     
         18 . A method according to  claim 14 , wherein said times of arrival are arrival times of subframes of navigation messages. 
     
     
         19 . A method according to  claim 14 , wherein a time interval between successive time windows comprises a duration of a subframe of a navigation message. 
     
     
         20 . A method according to  claim 14 , wherein a duration of said time window and a time interval between successive time windows are selected in accordance with characteristics of said satellite navigation signal. 
     
     
         21 . A method according to  claim 14 , wherein a duration of said time window is 17 milliseconds to 23 milliseconds. 
     
     
         22 . A method according to  claim 14 , wherein said time window begins when a first one of said times of arrival is observed for a current subframe. 
     
     
         23 . A method according to  claim 14 , wherein said classifying further comprises:
 comparing at least one of clock correction data and ephemeris data in successive subframes of at least one navigation message extracted from a legitimate correlation peak; and   identifying spoofed correlation peaks based on changes in said at least one of clock correction data and ephemeris data between said subframes of said navigation messages between said successive subframes of said extracted navigation message.   
     
     
         24 . A method according to  claim 14 , wherein said detecting is performed during acquisition of said navigation signal. 
     
     
         25 . A method according to  claim 14 , wherein said detecting comprises seeking a plurality of correlation peaks for at least one of said data sequences over an entire duration of a navigation message subframe.