Determining multipath in a positioning system
Methods, systems, computer-readable media, and apparatuses for determination of multipath for determining a location of user equipment (UE) are presented. In some embodiments, the UE may, based on a first indication of signal strength associated with a first polarization type, and a second indication of signal strength associated with a second polarization type, determine an indication of multipath reflection along a path of signal propagation between a space vehicle (e.g., GNSS satellite) and the UE. Circularly polarized positioning signals may be received by the UE via natively present linearly polarized antennas and converted into circularly polarized signals. Converted circularly polarized signals may include right-handed and left-handed components, and signal strengths for each component may be compared to determine the presence of multipath. Positioning signals may be given a weight or disregarded based on the multipath determination when determining the position of the UE.
1. A method for multipath estimation at a mobile device, the method comprising:
receiving, using one or more antennas at the mobile device, one or more signals from a Global Navigation Satellite System (GNSS) satellite, the one or more signals comprising a right-handed circularly polarized (RHCP) signal and a left-handed circularly polarized (LHCP) signal, wherein the RHCP signal and the LHCP signal are received over a single signal path from an antenna subsystem of the mobile device;
generating a first indication of signal strength from the RHCP signal;
generating a second indication of signal strength from the LHCP signal;
determining an indication of multipath reflection along a path of signal propagation between the GNSS satellite and the mobile device based on the first indication and the second indication; and
determining a presence of signal spoofing source associated with the one or more signals received from the GNSS satellite based on the first indication and polarization characteristics of the RHCP signal, the second indication and polarization characteristics of the LHCP signal, and a multipath characteristic associated with the one or more signals received from the GNSS satellite, wherein the multipath characteristic comprises a relationship between the first indication of signal strength and the second indication of signal strength, and wherein the presence of a spoofing signal source is determined by evaluating the polarization characteristics of the RHCP signal, the polarization characteristics of the LHCP signal, and the multipath characteristic associated with the one or more signals received from the GNSS satellite.
2. The method of claim 1 , wherein the determining of the presence of signal spoofing source comprises distinguishing a spoofed signal from a true signal based at least on the multipath characteristic associated with the one or more signals received from the GNSS satellite.
3. The method of claim 2 , wherein the determining of the presence of signal spoofing source comprises comparing the multipath characteristic associated with the one or more signals received from the GNSS satellite with at least one other multipath characteristic associated with one or more signals received from at least one other GNSS satellite.
4. The method of claim 3 , wherein the distinguishing of the spoofed signal from the true signal is based on, according to the comparing, the multipath characteristic associated with the one or more signals received from the GNSS satellite being substantially identical with the at least one other multipath characteristic associated with one or more signals received from at least one other GNSS satellite.
5. The method of claim 2 , wherein the distinguishing of the spoofed signal from the true signal is based on a polarization profile, the polarization profile comprising a relationship among at least the first indication of signal strength, the second indication of signal strength, the multipath characteristic associated with the one or more signals received from the GNSS satellite, or a combination thereof.
6. The method of claim 1 , wherein the RHCP signal and the LHCP signal are received as frequency-multiplexed signals or time-multiplexed signals over the single signal path from the antenna subsystem.
7. The method of claim 1 , further comprising:
selecting, at a first time, the one or more signals received from the GNSS satellite; and
selecting, at a second time, one or more second wireless signals different from the one or more signals received from the GNSS satellite, the one or more second wireless signals received at the mobile device using the one or more antennas.
8. The method of claim 7 , wherein the one or more second wireless signals comprise wide area network (WAN) signals.
9. The method of claim 1 , wherein the determining of the indication of multipath reflection is further based on prior measurement data relating to the first indication of signal strength and the second indication of signal strength, the prior measurement data having been obtained by one or more other mobile devices and being accessible to the mobile device.
10. A user equipment comprising:
one or more antennas;
an antenna subsystem configured to perform signal communication with at least a Global Navigation Satellite System (GNSS) satellite;
one or more memory; and
one or more processors communicatively coupled to the antenna subsystem and the one or more memory, and configured to:
receive, using the one or more antennas, one or more signals from the GNSS satellite, the one or more signals comprising a right-handed circularly polarized (RHCP) signal and a left-handed circularly polarized (LHCP) signal, wherein the RHCP signal and the LHCP signal are received over a single signal path from the antenna subsystem;
generate a first indication of signal strength from the RHCP signal;
generate a second indication of signal strength from the LHCP signal;
determine an indication of multipath reflection along a path of signal propagation between the GNSS satellite and the user equipment based on the first indication and the second indication; and
determine a presence of signal spoofing source associated with the one or more signals received from the GNSS based on the first indication and polarization characteristics of the RHCP signal, the second indication and polarization characteristics of the LHCP signal, and a multipath characteristic associated with the one or more signals received from the GNSS satellite, wherein the multipath characteristic includes a relationship between the first indication of signal strength and the second indication of signal strength, wherein the multipath characteristic comprises a relationship between the first indication of signal strength and the second indication of signal strength, and wherein the presence of a spoofing signal source is determined by evaluating the polarization characteristics of the RHCP signal, the polarization characteristics of the LHCP signal, and the multipath characteristic associated with the one or more signals received from the GNSS satellite.
11. The user equipment of claim 10 , wherein the determination of the presence of signal spoofing source comprises distinguishing of a spoofed signal from a true signal based at least on the multipath characteristic associated with the one or more signals received from the GNSS satellite.
12. The user equipment of claim 11 , wherein the determination of the presence of signal spoofing source comprises comparison of the multipath characteristic associated with the one or more signals received from the GNSS satellite with at least one other multipath characteristic associated with one or more signals received from at least one other GNSS satellite.
13. The user equipment of claim 12 , wherein the distinguishing of the spoofed signal from the true signal is based on, according to the comparison, the multipath characteristic associated with the one or more signals received from the GNSS satellite being substantially identical with the at least one other multipath characteristic associated with one or more signals received from at least one other GNSS satellite.
14. The user equipment of claim 11 , wherein the distinguishing of the spoofed signal from the true signal is based on a polarization profile, the polarization profile comprising a relationship among at least the first indication of signal strength, the second indication of signal strength, the multipath characteristic associated with the one or more signals received from the GNSS satellite, or a combination thereof.
15. The user equipment of claim 10 , wherein the RHCP signal and the LHCP signal are received as frequency-multiplexed signals or time-multiplexed signals over the single signal path from the antenna subsystem.
16. The user equipment of claim 10 , further comprising:
selecting, at a first time, the one or more signals received from the GNSS satellite; and
selecting, at a second time, one or more second wireless signals different from the one or more signals received from the GNSS satellite, the one or more second wireless signals received at the user equipment using the one or more antennas.
17. The user equipment of claim 16 , wherein the one or more second wireless signals comprise wide area network (WAN) signals.
18. The user equipment of claim 10 , wherein the determining of the indication of multipath reflection is further based on prior measurement data relating to the first indication of signal strength and the second indication of signal strength, the prior measurement data having been obtained by one or more other devices and being accessible to the user equipment.
19. A user equipment (UE) apparatus comprising:
means for receiving, using one or more antennas at the apparatus, one or more signals from a Global Navigation Satellite System (GNSS) satellite, the one or more signals comprising a right-handed circularly polarized (RHCP) signal and a left-handed circularly polarized (LHCP) signal, wherein the RHCP signal and the LHCP signal are received over a single signal path from an antenna subsystem of the apparatus;
means for generating a first indication of signal strength from the RHCP signal;
means for generating a second indication of signal strength from the LHCP signal;
means for determining an indication of multipath reflection along a path of signal propagation between the GNSS satellite and the apparatus based on the first indication and the second indication; and
means for determining a presence of signal spoofing source associated with the one or more signals received from the GNSS satellite based on the first indication and polarization characteristics of the RHCP signal, the second indication and polarization characteristics of the LHCP signal, and a multipath characteristic associated with the one or more signals received from the GNSS satellite, wherein the multipath characteristic comprises a relationship between the first indication of signal strength and the second indication of signal strength, and wherein the presence of a spoofing signal source is determined by evaluating the polarization characteristics of the RHCP signal, the polarization characteristics of the LHCP signal, and the multipath characteristic associated with the one or more signals received from the GNSS satellite.
20. The UE apparatus of claim 19 , wherein the means for determining of the presence of signal spoofing source comprises means for distinguishing a spoofed signal from a true signal based at least on the multipath characteristic associated with the one or more signals received from the GNSS satellite.
21. The UE apparatus of claim 20 , wherein the means for determining of the presence of signal spoofing source comprises means for comparing the multipath characteristic associated with the one or more signals received from the GNSS satellite with at least one other multipath characteristic associated with one or more signals received from at least one other GNSS satellite.
22. The UE apparatus of claim 21 , wherein the means for distinguishing of the spoofed signal from the true signal is based on, according to the means for comparing, the multipath characteristic associated with the one or more signals received from the GNSS satellite being substantially identical with the at least one other multipath characteristic associated with one or more signals received from at least one other GNSS satellite.
23. The UE apparatus of claim 20 , wherein the means for distinguishing the spoofed signal from the true signal is based on a polarization profile, the polarization profile comprising a relationship among at least the first indication of signal strength, the second indication of signal strength, the multipath characteristic associated with the one or more signals received from the GNSS satellite, or a combination thereof.
24. The UE apparatus of claim 19 , wherein the RHCP signal and the LHCP signal are received as frequency-multiplexed signals or time-multiplexed signals over the single signal path from the antenna subsystem.
25. The UE apparatus of claim 19 , further comprising:
means for selecting, at a first time, the one or more signals received from the GNSS satellite; and
means for selecting, at a second time, one or more second wireless signals different from the one or more signals received from the GNSS satellite, the one or more second wireless signals received at the apparatus using the one or more antennas.
26. The UE apparatus of claim 25 , wherein the one or more second wireless signals comprise wide area network (WAN) signals.
27. The UE apparatus of claim 19 , wherein the means for determining of the indication of multipath reflection is further based on prior measurement data relating to the first indication of signal strength and the second indication of signal strength, the prior measurement data having been obtained by one or more other mobile devices and being accessible to the mobile device.