# US 10,455,350 B2 · Method and system for radiolocation asset tracking via a mesh network

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- Number: US 10,455,350 B2
- Document ID: US10455350B2
- Status: Granted
- Kind: B2
- Application number: 15/644,717
- Filed: 2017-07-07
- Published: 2018-01-11
- Granted: 2019-10-22
- Earliest claimed: 2016-07-10
- Assignees: ZaiNar, Inc.
- Applicants: ZaiNar, Inc.
- Inventors: Philip A. Kratz; Daniel Jacker
- Web page: https://patentgrep.com/patent/US10455350B2

## CPC

- H04W 4/029: Location-based management or tracking services
- H04L 27/22: Demodulator circuits; Receiver circuits
- H04L 67/53: using third party service providers
- H04W 4/02: Services making use of location information
- H04W 56/002: {Mutual synchronization}
- H04W 64/00: Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management
- H04W 4/33: for indoor environments, e.g. buildings
- H04W 84/12: WLAN [Wireless Local Area Networks]
- H04W 84/18: Self-organising networks, e.g. ad-hoc networks or sensor networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A method of determining a reference clock in a mesh network includes receiving multiple signals, correlating the multiple signals with a local signal generated by the first node to determine a coarse set of time differences, refining the coarse set of time differences using a phase of a carrier signal of the multiple signals to produce a refined set of time differences, and using the refined set of time differences to define a reference clock.

## Claims

### Claim 1

A method of determining a reference clock for use in a mesh network, comprising:
generating, at the first node, a local signal;
receiving, at a first node in the mesh network, multiple signals from a second node in the mesh network;
demodulating the local signal to locate a local signal peak;
demodulating the multiple signals to locate multiple signal peaks;
correlating, at the first node, the local signal peak and the multiple signal peaks to determine an offset for the second node;
determining a coarse set of time differences using the offset for the second node;
refining the coarse set of time differences using a phase of a carrier signal of the multiple signals to produce a refined set of time differences; and
using the refined set of time differences to define the reference clock for use in the mesh network.

### Claim 2 (depends on 1)

The method of claim 1, wherein receiving the multiple signals comprises receiving pseudorandom ranging codes from the second node.

### Claim 3 (depends on 1)

The method of claim 1, wherein refining the coarse set of time differences comprises:
determining a frequency and phase of the carrier signal;
using the frequency and phase of the carrier signal to determine a fractional offset between carrier signal and the coarse set of time differences; and
using the fractional offset to adjust the coarse set of differences to a higher level of precision than the coarse set of differences.

### Claim 4 (depends on 1)

The method of claim 1, further comprising receiving, at the first node, multiple signals from at least a third node in the mesh network and performing the correlating, the refining and the using for at least the third node.

### Claim 5 (depends on 4)

The method of claim 4, wherein the correlating is performed between each node of the mesh network.

### Claim 6

A method of determining a reference clock for use in a mesh network:
receiving, at a first node in the mesh network, multiple signals from a second node in the mesh network;
correlating, at the first node, the multiple signals with a local signal generated by the first node to determine a coarse set of time differences;
determining a frequency and phase of the carrier signal;
using the frequency and phase of the carrier signal to determine a fractional offset between carrier signal and the coarse set of time differences; and
using the fractional offset to adjust the coarse set of differences to a higher level of precision than the coarse set of differences to produce a refined set of time differences; and
using the refined set of time differences to define the reference clock for use in the mesh network.

### Claim 7

A method of determining a reference clock for use in a mesh network:
receiving, at a first node in the mesh network, multiple signals from a second node in the mesh network;
receiving, at the first node in the mesh network, multiple signals from a third node in the mesh network;
correlating, at the first node, the multiple signals from the second node and the multiple signals from the third node with a local signal generated by the first node to determine a coarse set of time differences;
refining the coarse set of time differences using a phase of a carrier signal of the multiple signals from the second node and a phase of a carrier signal of the multiple signals from the third node to produce a refined set of time differences; and
using the refined set of time differences to define the reference clock for use in the mesh network.