Methods and apparatus for improving time of arrival determination
Devices, systems, and methods for improving performance in positioning systems. Performance may be improved using disclosed signal processing methods for separating eigenvalues corresponding to noise and eigenvalues corresponding to one or more direct path signal components or multipath signal components.
1. A method for determining location information associated with a receiver, the method comprising:
receiving information related to at least one of a direct path signal component or one or more multipath signal components associated with a positioning signal received by a receiver from a transmitter;
determining, using one or more processors, an estimated covariance of the positioning signal;
determining, using the one or more processors, a set of eigenvalues of the estimated covariance;
retrieving an estimated probability density associated with the set of eigenvalues, said estimated probability density having been obtained by combining a multiplicity of sets of eigenvalues of estimated covariances associated with a multiplicity of positioning signals;
separating, based on a threshold determined at least in part from the estimated probability density, the set of eigenvalues into a first subset of eigenvalues corresponding to the at least one of the direct path signal component or the one or more multipath signal components, and a second subset of eigenvalues corresponding to noise; and
determining, based at least in part on the separation of the set of eigenvalues into the first and second subsets, a distance between the transmitter and the receiver.
2. The method of claim 1 , wherein one eigenvalue, within the first subset of eigenvalues, and a corresponding eigenvector are associated with the direct path signal component.
3. The method of claim 2 , wherein the distance is determined based on a time of arrival of the direct path signal component.
4. The method of claim 1 , the method comprising:
determining an estimated location of the receiver, wherein the estimated location of the receiver is determined based on the determined distance and additional distances associated with two or more additional transmitters.
5. One or more non-transitory processor-readable media embodying program instructions that, when executed by one or more processors, cause the one or more processors to implement a method for determining location information associated with a receiver, the method comprising:
receiving information related to at least one of a direct path signal component or one or more multipath signal components associated with a positioning signal received by a receiver from a transmitter;
determining an estimated covariance of the positioning signal;
determining a set of eigenvalues of the estimated covariance;
retrieving an estimated probability density associated with the set of eigenvalues, said estimated probability density having been obtained by combining a multiplicity of sets of eigenvalues of estimated covariances associated with a multiplicity of positioning signals;
separating, based on a threshold determined at least in part from the estimated probability density, the set of eigenvalues into a first subset of eigenvalues corresponding to the at least one of the direct path signal component or the one or more multipath signal components, and a second subset of eigenvalues corresponding to noise; and
determining, based at least in part on the separation of the set of eigenvalues into the first and second subsets, a distance between the transmitter and the receiver.
6. The one or more non-transitory processor-readable media of claim 5 , wherein one eigenvalue, within the first subset of eigenvalues, and a corresponding eigenvector are associated with the direct path signal component.
7. The one or more non-transitory processor-readable media of claim 6 , wherein the distance is determined based on a time of arrival of the direct path signal component.
8. The one or more non-transitory processor-readable media of claim 5 , the method comprising:
determining an estimated location of the receiver, wherein the estimated location of the receiver is determined based on the determined distance and additional distances associated with two or more additional transmitters.
9. A system for determining location information associated with a receiver, the system comprising:
means, implemented in hardware, for receiving a positioning signal comprising at least one of a direct path signal component or one or more multipath signal components from a transmitter;
means, implemented in hardware, for determining an estimated covariance of the positioning signal;
means, implemented in hardware, for determining a set of eigenvalues of the estimated covariance;
means, implemented in hardware, for retrieving an estimated probability density associated with the set of eigenvalues, said estimated probability density having been obtained by combining a multiplicity of sets of eigenvalues of estimated covariances associated with a multiplicity of positioning signals;
means for separating, based on a threshold determined at least in part from the estimated probability density, the set of eigenvalues into a first subset of eigenvalues corresponding to the at least one of the direct path signal component or the one or more multipath signal components, and a second subset of eigenvalues corresponding to noise; and
means for determining, based at least in part on the separation of the set of eigenvalues into the first and second subsets, a distance between the transmitter and the receiver.
10. The system of claim 9 , wherein one eigenvalue, within the first subset of eigenvalues, and a corresponding eigenvector are associated with the direct path signal component.
11. The system of claim 10 , wherein the distance is determined based on a time of arrival of the direct path signal component.
12. The system of claim 9 , the system comprising:
means for determining an estimated location of the receiver, wherein the estimated location of the receiver is determined based on the determined distance and additional distances associated with two or more additional transmitters.
13. The system of claim 9 , wherein one or more processors are the means for determining an estimated covariance of the positioning signal, the means for determining a set of eigenvalues of the estimated covariance, the means for estimating a probability density of the set of eigenvalues, the means for separating, and the means for determining the distance between the transmitter and the receiver.
14. The system of claim 12 , wherein one or more processors are the means for determining an estimated covariance of the positioning signal, the means for determining a set of eigenvalues of the estimated covariance, the means for estimating a probability density of the set of eigenvalues, the means for separating, the means for determining the distance between the transmitter and the receiver, and the means for determining an estimated location of the receiver.