Method and system for characterizing propagation of radiofrequency signal

A method of forming a database for storing propagation characteristics of a radiofrequency signal transmitted from a transmitter at a fixed location in a three-dimensional environment comprising:

• a) identifying reflective features of said three-dimensional environment;
• b) establishing said three-dimensional environment from a terrain database having said reflective features of said three-dimensional environment stored therein;
• c) determining an angle of separation between adjacent ones of incident line segments representing propagation paths of said radiofrequency signal from said fixed location;
• d) projecting said radiofrequency signal along an azimuth and an elevation from said transmitter in response to said incident line segments;
• e) tracking said propagation paths in said three-dimensional environment, said propagation paths including straight-line paths and reflection paths;
• f) for each of said straight-line paths, storing a first one of said incident line segments in said database to represent said straight-line path;
• and
• g) for each of said reflection paths, storing a second one of said incident line segments and a reflection line segment in said database to represent said reflection path, said second incident line segment and said reflection line segment intersecting at an intersection location on a reflective feature in said three-dimensional environment.

A system for determining propagation characteristics of a radiofrequency signal between a transmitter location and each of a plurality of receiver locations in a three-dimensional environment comprising:

• a memory element having a database of propagation paths stored therein, said propagation paths being represented by a plurality of line segments, and said propagation paths originating at said transmitter location and radially projecting from said transmitter location along an azimuth and an elevation such that adjacent ones of said propagation paths are spaced apart by an angle of separation;
• a location coordinates receiver for receiving location coordinates for one of said receiver locations;
• and
• a segment selector for selecting, in response to said location coordinates, local line segments from said plurality of line segments in said database to establish a subset of said propagation paths, said local line segments being proximate said one of said receiver locations, and each of said propagation paths of said subset including one of said local line segments.

A method for identifying distinct multipath components from a set of propagation paths of a radiofrequency signal propagating between a transmitter at a fixed location and a receiver at a receiver location in a three-dimensional environment, said set of propagation paths being represented by line segments in a database, said method comprising the steps of:

• a) for each of said propagation paths, calculating a distance between said receiver location and a point on one of said line segments representing said propagation path that is substantially closest to said receiver location;
• b) for each of said propagation paths, determining a quantity of said line segments representing said propagation path between said fixed location and said point;
• c) distinguishing a first portion of said propagation paths in which said quantity is one;
• d) selecting one of said propagation paths of said first portion as one of said distinct multipath components;
• e) distinguishing a second portion of said propagation paths in which said quantity is at least two;
• f) determining a first quantity of said line segments representing a first propagation path from said second portion of said propagation paths;
• g) determining a second quantity of said line segments representing a second propagation path from said second portion of said propagation paths;
• and
• h) selecting said first and said second propagation paths as said distinct multipath components when said first quantity and said second quantity differ.