Granted Patent B2

US 12,560,437 · App. 18/322,874 · Granted Feb 24, 2026

Inventors: Michael Dormody (San Jose, CA); Badrinath Nagarajan (Cupertino, CA); Guiyuan Han (San Jose, CA); Arun Raghupathy (Bangalore, IN)

Assignee: NextNav, LLC

G01C21/206G01C5/06G01C21/3893H04W4/33

Abstract

Claims (75)

1 . A method, comprising:

selecting a set of altitude envelope distribution constraints for a physical building;

generating a set of a plurality of altitude envelope distributions for the physical building in accordance with the set of altitude envelope distribution constraints, each altitude envelope distribution comprising a plurality of first altitude envelopes, each of the first altitude envelopes corresponding to a respective estimated floor number of the physical building, each floor number corresponding to multiple altitude envelopes;

generating an aggregate altitude envelope distribution for the physical building using the set of the plurality of altitude envelope distributions and in accordance with the set of altitude envelope distribution constraints, the aggregate altitude envelope distribution comprising a plurality of second altitude envelopes, each of the second altitude envelopes corresponding to a respective estimated floor number of the physical building;

determining a reference altitude of the physical building; and

determining an absolute aggregate altitude envelope distribution using the reference altitude and the aggregate altitude envelope distribution, the absolute aggregate altitude envelope distribution comprising a plurality of third altitude envelopes, each of the third altitude envelopes corresponding to a respective estimated floor number of the physical building.

2 . The method of claim 1 , wherein:

generating a set of altitude envelope distributions for the physical building in accordance with the set of altitude envelope distribution constraints comprises:

generating an initial set of altitude envelope distributions using a first altitude envelope distribution constraint;

filtering the initial set of altitude envelope distributions using a second altitude envelope distribution constraint; and

using any remaining altitude envelope distributions of the initial set of altitude envelope distributions after the filtering as the set of altitude envelope distributions.

3 . The method of claim 2 , wherein:

the first altitude envelope distribution constraint is a maximum number of floors; and

the second altitude envelope distribution constraint is a maximum building height.

4 . The method of claim 2 , wherein:

the initial set of altitude envelope distributions comprises a plurality of altitude envelope distributions; and

each of the altitude envelope distributions comprises a minimum altitude value and a maximum altitude value associated with each floor number of that altitude envelope distribution.

5 . The method of claim 1 , wherein:

the set of altitude envelope distribution constraints is selected from a list of constraints comprising a minimum building height, a maximum building height, a minimum floor height, a maximum floor height, a minimum number of floors, and a maximum number of floors.

6 . The method of claim 5 , wherein:

selecting the set of altitude envelope distribution constraints comprises validating a set of initially selected altitude envelope distribution constraints individually and in combination based on a morphology of a region that includes the physical building.

7 . The method of claim 1 , further comprising:

identifying an estimated altitude of a mobile device;

for each floor number of the absolute aggregate altitude envelope distribution, upon determining that the estimated altitude is within an altitude envelope that corresponds to the floor number, adding that floor number to a list of estimated floor numbers; and

returning, to an endpoint, the list of estimated floor numbers.

8 . The method of claim 1 , further comprising:

identifying an estimated altitude of a mobile device;

for each floor number of the absolute aggregate altitude envelope distribution, calculating a vertical central tendency of an altitude envelope that corresponds to that floor number;

for each floor number of the absolute aggregate altitude envelope distribution, calculating a distance magnitude between the estimated altitude and the vertical central tendency that corresponds to that floor number;

for each floor number of the absolute aggregate altitude envelope distribution, conditionally adding that floor number to a list of estimated floor numbers based on the distance magnitude for that floor number; and

returning, to an endpoint, the list of estimated floor numbers.

9 . The method of claim 8 , wherein:

conditionally adding that floor number to a list of estimated floor numbers based on the distance magnitude for that floor number comprises:

adding that floor number to the list of estimated floor numbers if that floor number's corresponding distance magnitude is a smallest distance magnitude as compared to distance magnitudes corresponding to other floor numbers.

10 . The method of claim 8 , wherein:

conditionally adding that floor number to a list of estimated floor numbers based on the distance magnitude for that floor number comprises:

adding that floor number to the list of estimated floor numbers if that floor number's corresponding distance magnitude is less than a given threshold.

11 . The method of claim 8 , wherein:

conditionally adding that floor number to a list of estimated floor numbers based on the distance magnitude for that floor number comprises:

adding all possible floor numbers to the list of estimated floor numbers ordered by their respective distance magnitudes.

12 . The method of claim 1 , further comprising:

identifying estimated altitude data of a mobile device;

for each floor number of the absolute aggregate altitude envelope distribution, calculating an altitude overlap value using the estimated altitude data and an altitude envelope that corresponds to that floor number;

for each floor number of the absolute aggregate altitude envelope distribution, conditionally adding that floor number to a list of estimated floor numbers based on the calculated altitude overlap value for that floor number; and

returning, to an endpoint, the list of estimated floor numbers.

13 . The method of claim 12 , wherein:

conditionally adding that floor number to a list of estimated floor numbers based on the calculated altitude overlap value for that floor number comprises:

adding that floor number to the list of estimated floor numbers if the calculated altitude overlap value for that floor number is a largest calculated altitude overlap value as compared to calculated altitude overlap values corresponding to other floor numbers.

14 . The method of claim 12 , wherein:

conditionally adding that floor number to a list of estimated floor numbers based on the calculated altitude overlap value for that floor number comprises:

adding that floor number to the list of estimated floor numbers if that floor number's corresponding calculated altitude overlap value is greater than a given percentage threshold.

15 . The method of claim 12 , wherein:

conditionally adding that floor number to a list of estimated floor numbers based on the calculated altitude overlap value for that floor number comprises:

adding all possible floor numbers to the list of estimated floor numbers, ordered by their respective calculated altitude overlap values.

16 . The method of claim 1 , further comprising:

mapping each estimated floor number of the physical building to identically named estimated floor labels;

removing estimated floor labels from the mapping based on one or both of regional and cultural criteria;

adding additional estimated floor labels to the mapping; and

aligning the estimated floor numbers to the estimated floor labels.

17 . The method of claim 1 , further comprising:

identifying an estimated position of a mobile device and an estimated altitude of the mobile device;

identifying one or more physical buildings that correspond to the estimated position of the mobile device;

for each of the one or more physical buildings, identifying a respective absolute aggregate altitude envelope distribution that is associated with that building;

for each of the one or more physical buildings, determining a list of estimated floor numbers using the estimated altitude of the mobile device and the respective absolute aggregate altitude envelope distribution that is associated with that building; and

for each of the one or more physical buildings returning, to an endpoint, that list of estimated floor numbers.

18 . The method of claim 1 , wherein:

the reference altitude is an altitude of a ground floor of the physical building and is determined by i) querying altitudes of a terrain database within a footprint of the physical building and averaging the altitudes across the footprint of the physical building, or ii) retrieving the altitude of the ground floor of the physical building from a building database.

19 . The method of claim 1 , wherein:

the reference altitude is an altitude of a ground floor of the physical building and is determined by querying altitudes of a terrain database outside of a footprint of the physical building and averaging the altitudes.

20 . A system comprising one or more servers that are operable to:

select a set of altitude envelope distribution constraints for a physical building;

generate a set of a plurality of altitude envelope distributions for the physical building in accordance with the set of altitude envelope distribution constraints, each altitude envelope distribution comprising a plurality of first altitude envelopes, each of the first altitude envelopes corresponding to a respective estimated floor number of the physical building, each floor number corresponding to multiple altitude envelopes;

generate an aggregate altitude envelope distribution for the physical building using the set of the plurality of altitude envelope distributions and in accordance with the set of altitude envelope distribution constraints, the aggregate altitude envelope distribution comprising a plurality of second altitude envelopes, each of the second altitude envelopes corresponding to a respective estimated floor number of the physical building;

determine a reference altitude of the physical building; and

determine an absolute aggregate altitude envelope distribution using the reference altitude and the aggregate altitude envelope distribution, the absolute aggregate altitude envelope distribution comprising a plurality of third altitude envelopes, each of the third altitude envelopes corresponding to a respective estimated floor number of the physical building.

Assignments (2)

Continuity (2)

References Cited (11)