Granted Patent B2

US 12,513,643 · App. 18/764,745 · Granted Dec 30, 2025

Inventors: Tommi Ylamurto (Redwood City, CA); Philip A. Kratz (Redwood City, CA)

Assignee: ZaiNar, Inc.

H04W56/009H04B7/0626H04J3/0658H04L5/0053

Abstract

Claims (257)

1 . A method comprising:

selecting a first node as a master node based on a first position of the first node relative to a set of nodes;

at the first node in the set of nodes:

receiving a first signal transmitted from a target device;

recording a first receive time of the first signal at the first node;

transmitting a second signal from the first node in response to selecting the first node as the master node; and

recording a transmit time of the second signal from the first node;

at a second node in the set of nodes:

receiving the first signal transmitted from the target device;

recording a second receive time of the first signal at the second node;

receiving the second signal transmitted from the first node;

recording a third receive time of the second signal at the second node; and

based on the second signal, recording a first partial channel state information characterizing a communication channel between the first node and the second node for a second time period;

accessing a first channel response characterizing the communication channel between the first node and the second node for a first time period preceding the second time period;

in response to the first signal, calculating a time bias between the first node and the second node based on:

the transmit time of the second signal from the first node;

the third receive time of the second signal at the second node;

the first channel response; and

the first partial channel state information; and

estimating a target position of the target device based on:

the first receive time of the first signal at the first node;

the second receive time of the first signal at the second node; and

the time bias.

2 . The method of claim 1 , further comprising, during the first time period:

at the first node:

transmitting a first ranging signal to the second node; and

recording a second transmit time of the first ranging signal from the first node;

at the second node:

in response to receiving the first ranging signal, recording a fourth receive time of the first ranging signal at the second node;

based on the first ranging signal, recording a second partial channel state information characterizing the communication channel;

transmitting a second ranging signal to the first node; and

recording a third transmit time of the second ranging signal from the second node;

at the first node:

in response to receiving the second ranging signal, recording a fifth receive time of the second ranging signal at the first node; and

based on the second ranging signal, recording third partial channel state information characterizing the communication channel; and

calculating the first channel response based on:

the second partial channel state information;

the third partial channel state information;

the second transmit time of the first ranging signal;

the third transmit time of the second ranging signal;

the fourth receive time of the first ranging signal; and

the fifth receive time of the second ranging signal.

3 . The method of claim 1 , further comprising, during the first time period:

in response to receiving a third signal from the first node, recording a second partial channel state information characterizing the communication channel based on the third signal; and

calculating the first channel response based on the second partial channel state information and a first distance between the first node and the second node.

4 . The method of claim 1 :

further comprising:

at a third node in the set of nodes:

receiving the first signal transmitted from the target device;

recording a fourth receive time of the first signal at the third node;

receiving the second signal transmitted from the first node;

recording a fifth receive time of the second signal at the third node; and

based on the second signal, recording a second partial channel state information characterizing a second communication channel between the first node and the third node for the second time period;

accessing a second channel response characterizing the second communication channel between the first node and the third node for the first time period;

in response to the first signal, calculating a second time bias between the first node and the third node based on:

the transmit time of the second signal from the first node;

the fifth receive time of the second signal at the third node;

the second channel response; and

the second partial channel state information;

estimating a first time-difference-of-arrival of the first signal at the first node and the second node based on:

the first receive time of the first signal at the first node;

the second receive time of the first signal at the second node; and

the time bias; and

estimating a second time-difference-of-arrival of the first signal at the first node and the third node based on:

the first receive time of the first signal at the first node;

the fourth receive time of the first signal at the third node; and

the second time bias; and

wherein estimating the target position comprises estimating the target position of the target device based on:

the first time-difference-of-arrival of the first signal at the first node and the second node; and

the second time-difference-of-arrival of the first signal at the first node and the third node.

5 . The method of claim 1 :

further comprising:

at the second node:

receiving a third signal transmitted from the target device; and

recording a fourth receive time of the third signal at the second node;

at a third node in the set of nodes:

receiving a third signal transmitted from the target device;

recording a fifth receive time of the third signal at the third node;

receiving the second signal transmitted from the first node;

recording a sixth receive time of the second signal at the third node; and

based on the second signal, recording a second partial channel state information characterizing a second communication channel between the first node and the third node for the second time period;

accessing a second channel response characterizing the second communication channel between the first node and the third node for the first time period;

calculating a second time bias between the first node and the third node based on:

the transmit time of the second signal from the first node;

the sixth receive time of the second signal at the third node;

the second channel response; and

the second partial channel state information;

estimating a first time-difference-of-arrival of the first signal at the first node and the second node based on:

the first receive time of the first signal at the first node;

the second receive time of the first signal at the second node; and

the time bias; and

estimating a second time-difference-of-arrival of the third signal at the second node and the third node based on:

the fourth receive time of the third signal at the second node;

the fifth receive time of the third signal at the third node; and

the second time bias; and

wherein estimating the target position comprises estimating the target position of the target device based on:

the first time-difference-of-arrival of the first signal at the first node and the second node; and

the second time-difference-of-arrival of the third signal at the second node and the third node.

6 . The method of claim 1 , wherein calculating the time bias comprises calculating the time bias based on:

the transmit time of the second signal from the first node;

the third receive time of the second signal at the second node; and

a quotient of the first partial channel state information and the first channel response.

7 . The method of claim 1 , wherein calculating the time bias comprises:

calculating a first square of the first partial channel state information;

calculating a second square of the first channel response; and

calculating the time bias based on:

the transmit time of the second signal from the first node;

the third receive time of the second signal at the second node;

the first square of the first channel state information; and

the second square of the first channel response.

8 . The method of claim 1 , wherein calculating the time bias comprises:

calculating a first duration between the second receive time, of the first signal at the second node, and the third receive time of the second signal at the second node; and

calculating the time bias in response to the first duration falling below a threshold duration.

9 . The method of claim 1 :

wherein transmitting the second signal comprises transmitting the second signal comprising a multicast synchronization signal in response to receiving the first signal at the first node; and

wherein calculating the time bias comprises calculating the time bias based on:

the transmit time of the multicast synchronization signal from the first node;

the third receive time of the multicast synchronization signal at the second node;

the first channel response; and

the first partial channel state information.

10 . The method of claim 1 :

wherein receiving the first signal at the first device comprises receiving the first signal comprising an acknowledgement signal responsive to the second signal transmitted from the first node; and

wherein estimating a target position comprises estimating the target position of the target device based on:

the first receive time of the acknowledgement signal at the first node;

the second receive time of the acknowledgement signal at the second node; and

the time bias.

11 . The method of claim 1 :

wherein recording the first receive time comprises recording the first receive time of the first signal at the first node based on a first timing reference characterized by a first clock frequency;

wherein recording the second receive time comprises recording the second receive time of the first signal at the second node based on a second timing reference characterized by a second clock frequency different from the first clock frequency;

wherein calculating the time bias comprises calculating a clock phase difference based on:

the transmit time of the second signal from the first node;

the third receive time of the second signal at the second node;

the first channel response; and

the first partial channel state information; and

wherein estimating the target position of the target device comprises:

calculating a clock frequency offset based on the first clock frequency and the second clock frequency; and

estimating the target position of the target device based on:

the first receive time of the first signal at the first node;

the second receive time of the first signal at the second node;

the clock phase difference; and

the clock frequency offset.

12 . The method of claim 1 :

wherein accessing the first channel response comprises:

during a third time period preceding the second time period, storing the first channel response in the second node; and

during the second time period, accessing the first channel response at the second node; and

wherein calculating the time bias comprises calculating the time bias at the second node.

13 . The method of claim 1 , wherein calculating the time bias comprises:

accessing a first distance between the first node and the second node; and

calculating the time bias between the first node and the second node based on:

the transmit time of the second signal from the first node;

the third receive time of the second signal at the second node;

the first channel response;

the first partial channel state information; and

the first distance between the first node and the second node.

14 . The method of claim 1 :

wherein receiving the first signal at the second node comprises receiving a set of signals transmitted from the target device, the set of signals comprising the first signal and a third signal;

wherein recording the second receive time of the first signal comprises recording a set of receive times of the set of signals at the second node, the set of receive times comprising:

the second receive time of the first signal at the second node; and

a fourth receive time of the third signal at the second node;

further comprising:

based on the set of signals, recording a set of partial channel state information characterizing a second communication channel between the second node and the target device;

calculating combined partial channel state information relative to the third signal based on the set of partial channel state information;

estimating a first time difference and a first phase difference for the first signal based on the combined partial channel state information; and

calculating an adjusted second receive time of the first signal based on:

the second receive time of the first signal at the second node;

the first time difference; and

the first phase difference; and

wherein estimating the target position comprises estimating the target position of the target device based on:

the first receive time of the first signal at the first node;

the adjusted second receive time of the first signal; and

the time bias.

15 . A method comprising:

at a first node in a set of nodes:

receiving a first subset of signals in a set of signals transmitted from a target device, the first subset of signals comprising a first signal and excluding a third signal;

recording a first set of receive times of the first subset of signals at the first node, the first set of receive times comprising a first receive time of the first signal at the first node;

transmitting a second signal from the first node; and

recording a transmit time of the second signal from the first node;

at a second node in the set of nodes:

receiving a second subset of signals in the set of signals transmitted from the target device, the second subset of signals comprising the first signal and the third signal;

recording a second set of receive times of the second subset of signals at the second node, the second set of receive times comprising:

a second receive time of the first signal at the second node; and

a fourth receive time of the third signal at the second node;

receiving the second signal transmitted from the first node;

recording a third receive time of the second signal at the second node; and

based on the second signal, recording a first partial channel state information characterizing a communication channel between the first node and the second node for a second time period;

at a third node in the set of nodes:

in response to receiving a third subset of signals, in the set of signals and comprising the third signal, recording a third set of receive times of the third subset of signals at the third node, the third set of receive times comprising a fifth receive time of the third signal at the third node; and

in response to receiving the second signal transmitted from the first node, recording a sixth receive time of the second signal at the third node;

accessing a first channel response characterizing the communication channel between the first node and the second node for a first time period preceding the second time period;

in response to the first signal, calculating a time bias between the first node and the second node based on:

the transmit time of the second signal from the first node;

the third receive time of the second signal at the second node;

the first channel response; and

the first partial channel state information;

estimating a first time-difference-of-arrival of the first signal at the first node and the second node based on:

the first set of receive times of the first subset of signals at the first node;

the second set of receive times of the second subset of signals at the second node; and

the time bias;

estimating a second time-difference-of-arrival of the third signal at the second node and the third node based on:

the second set of receive times of the second subset of signals at the second node;

the third set of receive times of the third subset of signals at the third node;

the time bias between the first node and the second node; and

a second time bias between the first node and the third node; and

estimating a target position of the target device based on:

the first time-difference-of-arrival of the first signal at the first node and the second node; and

the second time-difference-of-arrival of the third signal at the second node and the third node.

16 . The method of claim 15 , further comprising:

at the third node, based on the second signal, recording a second partial channel state information characterizing a second communication channel between the first node and the third node for the second time period; and

calculating the second time bias between the first node and the third node based on:

the transmit time of the second signal from the first node;

the sixth receive time of the second signal at the third node;

a second channel response characterizing the second communication channel between the first node and the third node; and

the second partial channel state information.

17 . A method comprising:

at a sniffer node in a set of nodes:

receiving a first signal transmitted from a target device;

recording a second receive time of the first signal at the sniffer node;

receiving a second signal transmitted from a master node in the set of nodes;

recording a third receive time of the second signal at the sniffer node; and

based on the second signal, recording a first partial channel state information characterizing a communication channel between the master node and the sniffer node for a second time period;

during a first time period preceding the second time period:

in response to receiving a third signal from the master node, recording a fourth receive time of the third signal at the sniffer node;

based on the third signal, recording a second partial channel state information characterizing the communication channel; and

calculating a first channel response based on the second partial channel state information and a first distance between the master node and the sniffer node;

accessing the first channel response characterizing the communication channel between the master node and the sniffer node for the first time period;

in response to the first signal, calculating a clock phase difference between the master node and the sniffer node based on:

a transmit time of the second signal from the master node;

the third receive time of the second signal at the sniffer node;

the first channel response; and

the first partial channel state information; and

estimating a target position of the target device based on:

a first receive time of the first signal at the master node;

the second receive time of the first signal at the sniffer node; and

the clock phase difference.

18 . A method comprising:

at a first node in a set of nodes:

receiving a first signal transmitted from a target device;

recording a first receive time of the first signal at the first node;

transmitting a second signal from the first node; and

recording a transmit time of the second signal from the first node;

at a second node in the set of nodes:

receiving the first signal transmitted from the target device;

recording a second receive time of the first signal at the second node;

receiving the second signal transmitted from the first node;

recording a third receive time of the second signal at the second node; and

based on the second signal, recording a first partial channel state information characterizing a communication channel between the first node and the second node for a second time period;

accessing a first channel response characterizing the communication channel between the first node and the second node for a first time period preceding the second time period;

in response to the first signal, calculating a time bias between the first node and the second node based on:

the transmit time of the second signal from the first node;

the third receive time of the second signal at the second node;

the first channel response;

the first partial channel state information; and

a first distance between the first node and the second node; and

estimating a target position of the target device based on:

the first receive time of the first signal at the first node;

the second receive time of the first signal at the second node; and

the time bias.

Assignments (1)

Continuity (3)

References Cited (10)