Mobile device positioning in dynamic groupings of communication devices

Patent metadata

Field	Value
Publication number	US-9826361-B2
Application number	US-201615174953-A
Country	US
Kind code	B2
Filing date	Jun 6, 2016
Priority date	Jul 9, 2010
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

A RF based mobile positioning system determines mobile device positioning by count stamped packets communicated between the mobile device and access points according to a standard wifi protocol. Ad-hoc groups of wifi network nodes are formed and then broken with a mobile device as that mobile devices moves relative to fixed nodes, such as access points. Within an ad-hoc group, the nodes count stamp packets by latching a local counter within each node. Count-stamps are collected and used to generate ranges for a mobile device relative to nodes in an ad hoc group. A positioning services determines the position of the mobile device from the ranges.

First claim

The invention claimed is:

1. A radio frequency based mobile device positioning method, the method comprising:
at a mobile device, receiving receive messages transmitted from a plurality of other communication devices, a receive message including a transmit count stamp corresponding to a remote counter value at the transmission of the receive message from a corresponding communication device;
within the mobile device, generating receive count stamps for receive messages corresponding to a local counter value at receipt of the receive message from the other communication devices;
dynamically associating and disassociating the mobile device with a plurality of sub-groups of the plurality of other communication devices, based at least in part on receiving messages from a predetermined number of other communication devices for each sub-group; and
generating range estimates between the mobile device and the other communication devices in the sub-group currently associated with the mobile device, the range estimates based on a combination of the transmit count stamps and the receive count stamps; and wherein at least one of the range estimates is a mobile device range estimate between the mobile device and a second communication device that the mobile device is newly associated with in one of the sub-groups, and the mobile device range estimate is computed as function of count stamps previously communicated between the mobile device and other communication devices in the plurality of sub-groups.

2. The method of claim 1 , wherein each sub-group includes at least one non-mobile communication device.

3. The method of claim 1 , wherein the mobile device is operable to transmit messages, each transmit message including a transmit count stamp corresponding to the local counter value at the transmission of the transmit message.

4. The method of claim 1 , comprising:
propagating relationships among local clocks in the communication devices in the plurality of the sub-groups, including:
for each of the sub-groups, gathering count stamps for messages transmitted between nodes in the sub-group over a period of time;
from the count stamps gathered for a first sub-group, the programmed processor executing to determine clock differences for corresponding clocks in nodes of the first sub-group;
from the count stamps gathered for a second sub-group, determining clock differences for corresponding clocks in nodes of the second sub-group; and
diffusing a clock difference between nodes belonging only to the first sub-group and nodes belonging only to the second, through clock differences for nodes shared between the first and second sub-groups.

5. The method of claim 4 , comprising:
directly referencing a local time of at least one of the sub-groups to a standard time reference, and using the standard time reference to compute timing solutions for other nodes by relating differential solutions for the other nodes to the standard time reference.

6. The method of claim 1 , wherein each of the sub-groups include nodes with corresponding ping drivers, the ping drivers count stamping messages upon transmission or receipt of the messages with a counter value from a local, independent counter within a corresponding node.

7. A radio frequency based mobile device positioning method, the method comprising:
at a mobile device, receiving receive messages transmitted from a plurality of other communication devices, each receive message including a transmit identification datum which identifies a remote device creating the transmission of the receive message;
within the mobile device, generating a receive count stamp for each receive message corresponding to a local counter value at receipt of a receive message from the other communication devices;
dynamically associating and disassociating the mobile device with a plurality of sub-groups of the plurality of other communication devices, based at least in part on receiving messages from a predetermined number of other communication devices for each sub-group; and
generating range estimates between the mobile device and other communication devices in the sub-group currently associated with the mobile device, the range estimates based on a combination of the transmit identification datum and the receive count stamps; and wherein at least one of the range estimates is a mobile device range estimate between the mobile device and a second communication device that the mobile device is newly associated with in one of the sub-groups, and the mobile device range estimate is computed as a function of count stamps previously communicated between the mobile device and other communication devices in the plurality of sub-groups.

8. The method of claim 7 , wherein each sub-group includes at least one non-mobile communication device.

9. The method of claim 7 , wherein the mobile device is operable to transmit messages, each transmit message including a transmit count stamp corresponding to the local counter value at the transmission of the transmit message.

10. The method of claim 7 , comprising:
propagating relationships among local clocks in the communication devices in the plurality of the sub-groups, including:
for each of the sub-groups, gather count stamps for messages transmitted between nodes in the sub-group over a period of time;
from the count stamps gathered for a first sub-group, determining clock differences for corresponding clocks in nodes of the first sub-group;
from the count stamps gathered for a second sub-group, determining clock differences for corresponding clocks in nodes of the second sub-group; and
diffusing a clock difference between nodes belonging only to the first sub-group and nodes belonging only to the second sub-group, through clock differences for nodes shared between the first and second sub-groups.

Assignees

• Digimarc Corp

Inventors

• Rhoads Geoffrey B

Classifications

• H04W4/023 Primary

  using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds · CPC title

• H04W64/00

  Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management · CPC title

• H04W84/18

  Self-organising networks, e.g. ad-hoc networks or sensor networks · CPC title

• G01S5/0289

  of multiple transceivers, e.g. in ad hoc networks · CPC title

• H04W84/12

  WLAN [Wireless Local Area Networks] · CPC title