Method and system for radiolocation asset tracking via a mesh network

• US 10,455,350 B2
• Filed: 07/07/2017
• Issued: 10/22/2019
• Est. Priority Date: 07/10/2016
• Status: Active Grant

• Current Assignee: Kratz Jacker LLC
• Original Assignee: Zainar, Inc.
• Inventors: Kratz, Philip A., Jacker, Daniel
• Primary Examiner(s): Trinh, Sonny
• Application Number:
  US15/644,717
• Publication Number:
  US 20180014151A1
• Time in Patent Office: 837 Days
• CPC Class Codes: H04L 27/22 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 67/53 using third party service providers
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 4/33 for indoor environments, e.g. buildings
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

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

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.

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

3. 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.

4. 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.

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

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.

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.