Methods for locating transmitters using backward ray tracing
First Claim
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1. A method for locating a transmitter, the method comprising:
- generating, at a receiver, a plurality of candidate locations for the transmitter based on signal ray characteristics of a plurality of signal rays, the candidate locations being points along an estimated path traversed by the plurality of signal rays from the transmitter to the receiver;
calculating, for each candidate location, at least one weighted metric by summing a plurality of location metrics associated with each respective candidate location;
locating the transmitter based on the at least one weighted metric associated with each candidate location;
launching a simulated virtual ray toward a first point of incidence on the reverse path of a received signal ray, the first point being a last point traversed by a received signal ray, a point of incidence being a point at which a signal ray impinges with a structure or wall of a building; and
simulating a reverse path of the received signal ray until a stopping condition is met; and
calculating a predicted power for the simulated virtual ray at the first point of incidence, wherein the stopping condition is met if the predicted power is greater than or equal to a transmission power of the received signal ray,wherein a location metric for a first candidate location among the plurality of candidate locations is calculated, at least in part, based on a comparison between a prediction metric for a signal ray at the first candidate location and a prediction metric for the signal ray at a second of the plurality of candidate locations.
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Abstract
According to a method for localizing a transmitter inside a building, a transmitter emits rays which undergo multiple reflections with the walls, ceilings and floors of the building. Each of K receivers receives rays from the transmitter, and the receivers estimates the AOA (Angle of arrival), TOA (Time of Arrival) and power of each ray. At least one of the receivers uses a known blueprint of the building and material characteristics of the walls to localize the transmitter to a higher degree of accuracy by applying a backward ray tracing algorithm.
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Citations
16 Claims
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1. A method for locating a transmitter, the method comprising:
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generating, at a receiver, a plurality of candidate locations for the transmitter based on signal ray characteristics of a plurality of signal rays, the candidate locations being points along an estimated path traversed by the plurality of signal rays from the transmitter to the receiver; calculating, for each candidate location, at least one weighted metric by summing a plurality of location metrics associated with each respective candidate location; locating the transmitter based on the at least one weighted metric associated with each candidate location; launching a simulated virtual ray toward a first point of incidence on the reverse path of a received signal ray, the first point being a last point traversed by a received signal ray, a point of incidence being a point at which a signal ray impinges with a structure or wall of a building; and simulating a reverse path of the received signal ray until a stopping condition is met; and calculating a predicted power for the simulated virtual ray at the first point of incidence, wherein the stopping condition is met if the predicted power is greater than or equal to a transmission power of the received signal ray, wherein a location metric for a first candidate location among the plurality of candidate locations is calculated, at least in part, based on a comparison between a prediction metric for a signal ray at the first candidate location and a prediction metric for the signal ray at a second of the plurality of candidate locations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16)
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11. A transceiver for locating a transmitter, the transceiver comprising:
a location estimation unit configured to, generate a plurality of candidate locations for the transmitter based on signal ray characteristics of a plurality of signal rays, the candidate locations being points along an estimated path traversed by the plurality of signal rays from the transmitter to the receiver, calculate, for each candidate location at least one weighted metric summing a plurality of location metrics associated with each respective candidate location, and locate the transmitter based on the at least one weighted metric associated with each candidate location;
whereina location metric for a first candidate location among the plurality of candidate locations is calculated, at least in part, based on a comparison between a prediction metric for a signal ray at the first candidate location and a prediction metric for the signal ray at a second of the plurality of candidate locations. - View Dependent Claims (12, 13, 14)
Specification