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US 10,091,754 B2Granted
Correcting interference of non-line-of-sight signals
AssigneeApple Inc.
InventorsIsaac Thomas Miller, Jonathan Schoenberg
Life of this patent
Estimating the term…
Abstract
Systems, methods, and computer program products for determining a location from non-line-of-sight (NLOS) signals are described. A processor can determine that multipath interferences of a signal reaching a receiver through different paths that are close in lengths may be mistakenly interpreted as additional time shift, (e.g., additional time delay or, in some cases, time advance) of the signal in calculating a timing of the signal. The processor can determine the possible differences between path lengths and then determine an amount of the additional time shift. The processor can determine a shift correction to remove effects caused by the additional time delay from the timing calculation.
Claims13
A method comprising:
- receiving, by a processor, an initial location bound of a radio frequency (RF) receiver, the initial location bound enclosing a plurality of candidate locations of the RF receiver;
- determining, by the processor, a respective set of feasible paths for an RF signal to reach from an RF transmitter to the RF receiver at each of the candidate locations, the set of feasible paths including different paths of the signal caused by the signal reflecting off different surfaces of physical objects, wherein determining the respective set of feasible paths includes:
- constructing a respective tree data structure for each candidate location, each tree data structure representing a plurality of hypothetical paths for the signal to reach from a location of the RF transmitter to the candidate location of the RF receiver;
- performing a feasibility check on each hypothetical path represented in the tree data structure;
- and
- designating hypothetical paths that pass the feasibility check as the feasible paths;
- determining that a difference between respective lengths of a first feasible path and a second feasible path is less than a threshold difference based on facet data representing one or more facets of one or more physical objects in an RF environment;
- determining a shift correction for adjusting a timing of the signal, the shift correction including an amount of an additional time shift to be removed from the timing of the signal, the amount of the additional time shift being determined according to the difference in lengths of the first and second feasible paths;
- and
- providing the shift correction to a navigation solver for determining a location of the RF receiver based on the timing of the signal and the shift correction for removing effects caused by the additional time shift.
7 more elements
A system comprising:
- one or more processors;
- and
- a non-transitory computer-readable medium storing instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising:
- receiving an initial location bound of a radio frequency (RF) receiver, the initial location bound enclosing a plurality of candidate locations of the RF receiver;
- determining a respective set of feasible paths for an RF signal to reach from an RF transmitter to the RF receiver at each of the candidate locations, the set of feasible paths including different paths of the signal caused by the signal reflecting off different surfaces of physical objects, wherein determining the respective set of feasible paths includes:
- constructing a respective tree data structure for each candidate location, each tree data structure representing a plurality of hypothetical paths for the signal to reach from a location of the RF transmitter to the candidate location of the RF receiver;
- performing a feasibility check on each hypothetical path represented in the tree data structure;
- and
- designating hypothetical paths that pass the feasibility check as the feasible paths;
- determining that a difference between respective lengths of a first feasible path and a second feasible path is less than a threshold difference based on facet data representing one or more facets of one or more physical objects in an RF environment;
- determining a shift correction for adjusting a timing of the signal, the shift correction including an amount of an additional time shift to be removed from the timing of the signal, the amount of the additional time shift being determined according to the difference in lengths of the first and second feasible paths;
- and
- providing the shift correction to a navigation solver for determining a location of the RF receiver based on the timing of the signal and the shift correction for removing effects caused by the additional time shift.
10 more elements
A non-transitory computer-readable medium storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:
- receiving an initial location bound of a radio frequency (RF) receiver, the initial location bound enclosing a plurality of candidate locations of the RF receiver;
- determining a respective set of feasible paths for an RF signal to reach from an RF transmitter to the RF receiver at each of the candidate locations, the set of feasible paths including different paths of the signal caused by the signal reflecting off different surfaces of physical objects, wherein determining the respective set of feasible paths includes:
- constructing a respective tree data structure for each candidate location, each tree data structure representing a plurality of hypothetical paths for the signal to reach from a location of the RF transmitter to the candidate location of the RF receiver;
- performing a feasibility check on each hypothetical path represented in the tree data structure;
- and
- designating hypothetical paths that pass the feasibility check as the feasible paths;
- determining that a difference between respective lengths of a first feasible path and a second feasible path is less than a threshold difference based on facet data representing one or more facets of one or more physical objects in an RF environment;
- determining a shift correction for adjusting a timing of the signal, the shift correction including an amount of an additional time shift to be removed from the timing of the signal, the amount of the additional time shift being determined according to the difference in lengths of the first and second feasible paths;
- and
- providing the shift correction to a navigation solver for determining a location of the RF receiver based on the timing of the signal and the shift correction for removing effects caused by the additional time shift.
7 more elements
Dependencies are inferred from the claim text.