Multi-layer statistical wireless terminal location determination
Disclosed are embodiments for determining a location of a wireless terminal. The wireless terminal measures signal strength of a plurality of wireless transmitters. Based on this information, a plurality of location probability surfaces are generated. Each location probability surface indicates a plurality of probabilities that the wireless terminal is in each of a corresponding plurality of geographic regions. These probability surfaces are then averaged to determine a composite location probability surface. A motion probability surface is also determined, which stores a plurality of probabilities indicating variations of motion of the wireless terminal. The composite location probability surface is then updated based on the motion probability surface. A location estimate of the wireless terminal is then determined based on the updated composite location probability surface.
1. A system comprising:
a memory; and
processing circuitry in communication with the memory and configured to:
determine a first location probability surface for a location of a wireless terminal for a current time interval, the first location probability surface representing a first plurality of probabilities that the wireless terminal is within a plurality of regions, each probability of the first plurality of probabilities corresponding to a different region of the plurality of regions;
determine, based at least in part on a second location probability surface for the location of the wireless terminal at a previous time interval, a motion probability surface for a motion of the wireless terminal, the motion probability surface representing a second plurality of probabilities associated with a plurality of motion estimates of the wireless terminal, each probability of the second plurality of probabilities associated with a different motion estimate of the plurality of motion estimates; and
estimate, based on the first location probability surface for the location of the wireless terminal and the motion probability surface for the motion of the wireless terminal, the location of the wireless terminal to be within a particular region of the plurality of regions.
2. The system of claim 1 , wherein to estimate the location of the wireless terminal to be within the particular region of the plurality of regions, the processing circuitry is configured to:
determine, based on the first location probability surface for the location of the wireless terminal and the motion probability surface for the motion of the wireless terminal, a blended location probability surface for the location of the wireless terminal; and
estimate, based on the blended location probability surface for the location of the wireless terminal, the location of the wireless terminal to be within the particular region of the plurality of regions.
3. The system of claim 2 ,
wherein a second blended location probability surface for the location of the wireless terminal for the previous time interval is based at least in part on the second location probability surface for the location of the wireless terminal and a second motion probability surface for the motion of the wireless terminal determined for the previous time interval, and
wherein the processing circuitry is configured to determine the motion probability surface for the motion of the wireless terminal for the current time interval based on the second blended location probability surface for the location of the wireless terminal determined for the previous time interval.
4. The system of claim 1 , wherein the processing circuitry is configured to determine the first location probability surface for the location of the wireless terminal based at least in part on a difference, for each region of the plurality of regions, between an expected signal strength of a wireless signal received by the wireless terminal and a measured signal strength of the wireless signal received by the wireless terminal.
5. The system of claim 1 ,
wherein to determine the first location probability surface for the location of the wireless terminal, the processing circuitry is configured to determine a plurality of first location probability surfaces for the location of the wireless terminal, each first location probability surface of the plurality of first location probability surfaces determined with respect to a wireless signal received by the wireless terminal from a corresponding wireless transmitter of a plurality of wireless transmitters,
wherein the processing circuitry is further configured to aggregate the plurality of first location probability surfaces into a composite location probability surface for the location of the wireless terminal, and
wherein the processing circuitry is configured to estimate the location of the wireless terminal to be within the particular region of the plurality of regions based on the composite location probability surface for the location of the wireless terminal and the motion probability surface for the motion of the wireless terminal.
6. The system of claim 1 , wherein the processing circuitry is further configured to determine the motion probability surface for the motion of the wireless terminal based on motion information received from the wireless terminal.
7. The system of claim 1 , wherein the processing circuitry is further configured to determine the motion probability surface for the motion of the wireless terminal by applying a Gaussian distribution to motion information received from the wireless terminal.
8. The system of claim 1 , wherein each of the regions of the plurality of regions represents a two-dimensional geographic area or a three-dimensional geographic volume.
9. A method comprising:
determining, by processing circuitry, a first location probability surface for a location of a wireless terminal for a current time interval, the first location probability surface representing a first plurality of probabilities that the wireless terminal is within a plurality of regions, each probability of the first plurality of probabilities corresponding to a different region of the plurality of regions;
determining, by the processing circuitry and based at least in part on a second location probability surface for the location of the wireless terminal at a previous time interval, a motion probability surface for a motion of the wireless terminal, the motion probability surface representing a second plurality of probabilities associated with a plurality of motion estimates of the wireless terminal, each probability of the second plurality of probabilities associated with a different motion estimate of the plurality of motion estimates; and
estimating, by the processing circuitry and based on the first location probability surface for the location of the wireless terminal and the motion probability surface for the motion of the wireless terminal, the location of the wireless terminal to be within a particular region of the plurality of regions.
10. The method of claim 9 , wherein estimating the location of the wireless terminal to be within the particular region of the plurality of regions comprises:
determining, based on the first location probability surface for the location of the wireless terminal and the motion probability surface for the motion of the wireless terminal, a blended location probability surface for the location of the wireless terminal; and
estimating, based on the blended location probability surface for the location of the wireless terminal, the location of the wireless terminal to be within the particular region of the plurality of regions.
11. The method of claim 10 ,
wherein a second blended location probability surface for the location of the wireless terminal for the previous time interval is based at least in part on the second location probability surface for the location of the wireless terminal and a second motion probability surface for the motion of the wireless terminal determined for the previous time interval, and
wherein determining the motion probability surface for the motion of the wireless terminal comprises determining the motion probability surface for the motion of the wireless terminal for the current time interval based on the second blended location probability surface for the location of the wireless terminal determined for the previous time interval.
12. The method of claim 9 , wherein determining the first location probability surface for the location of the wireless terminal is based at least in part on a difference, for each region of the plurality of regions, between an expected signal strength of a wireless signal received by the wireless terminal and a measured signal strength of the wireless signal received by the wireless terminal.
13. The method of claim 9 ,
wherein determining the first location probability surface for the location of the wireless terminal comprises determining a plurality of first location probability surfaces for the location of the wireless terminal, each first location probability surface of the plurality of first location probability surfaces determined with respect to a wireless signal received by the wireless terminal from a corresponding wireless transmitter of a plurality of wireless transmitters,
wherein the method further comprises aggregating, by the processing circuitry, the plurality of first location probability surfaces into a composite location probability surface for the location of the wireless terminal, and
wherein the estimating of the location of the wireless terminal to be within the particular region of the plurality of regions is based on the composite location probability surface for the location of the wireless terminal and the motion probability surface for the motion of the wireless terminal.
14. The method of claim 9 , wherein the determining of the motion probability surface for the motion of the wireless terminal is further based on motion information received from the wireless terminal.
15. The method of claim 9 , wherein determining the motion probability surface for the motion of the wireless terminal further comprises applying a Gaussian distribution to motion information received from the wireless terminal.
16. A non-transitory, computer-readable medium comprising instructions that, when executed, are configured to cause processing circuitry of a computing system to:
determine a first location probability surface for a location of a wireless terminal for a current time interval, the first location probability surface representing a first plurality of probabilities that the wireless terminal is within a plurality of regions, each probability of the first plurality of probabilities corresponding to a different region of the plurality of regions;
determine, based at least in part on a second location probability surface for the location of the wireless terminal at a previous time interval, a motion probability surface for a motion of the wireless terminal, the motion probability surface representing a second plurality of probabilities associated with a plurality of motion estimates of the wireless terminal, each probability of the second plurality of probabilities associated with a different motion estimate of the plurality of motion estimates; and
estimate, based on the first location probability surface for the location of the wireless terminal and the motion probability surface for the motion of the wireless terminal, the location of the wireless terminal to be within a particular region of the plurality of regions.