System and method for channel information exchange for time of flight range determination

Patent metadata

Field	Value
Publication number	US-9261580-B2
Application number	US-201314127385-A
Country	US
Kind code	B2
Filing date	Sep 18, 2013
Priority date	Mar 6, 2013
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

A system for time-of-flight (ToF) positioning in an IEEE 802.11 network comprises an initiating station that transmits a request frame over a channel to a responding station for a ToF position measurement. The responding station may respond with an offloading of the channel information, request frame receipt time, and response frame transmit time back to the initiating station to enable the initiating station to calculate the ToF position with respect to the responding station.

First claim

What is claimed is:

1. A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors to configure a wireless communication device to perform time-of-flight position calculations, the instructions:
transmit a request frame over a first channel from an initiating station to a responding station;
receive a response frame from the responding station over a second channel from the responding station to the initiating station, the response frame comprising first channel information for the first channel;
the initiating station determines second channel information of the second channel; and
the initiating station determines the ToF positioning at least partially in response to a time-of-departure of the request frame, a time-of-arrival of the response frame, and a sum of channel corrections from the first channel information and the second channel information.

2. The non-transitory computer-readable medium of claim 1 wherein the request frame is transmitted from the initiating station at a first time and received by the responding station at a second time, the operations further:
receive, at a fourth time, a first acknowledgement frame transmitted, at a third time, from the responding station to the initiating station in response to the request frame; and
the initiating station transmits a second acknowledgement frame to the responding station in response to the response frame.

3. The non-transitory computer-readable medium of claim 2 wherein the operation that receives the response frame further receives the response frame comprising the first channel information, the second time, and the third time.

4. The non-transitory computer-readable medium of claim 3 wherein the operation that the initiating station determines the ToF positioning further determines the ToF positioning in response to the first channel information, the second channel information, the first time, the second time, the third time, and the fourth time.

5. The non-transitory computer-readable medium of claim 4 wherein the operation that the initiating station determines the ToF positioning comprises the operation that the initiating station determines the ToF positioning by:
determination of a round trip time as a difference between the fourth time and the first time;
determination of a responder delay as a difference between the third time and the second time;
determination of a difference between the round trip time and the responder delay; and
determination of half of a sum of the difference between the round trip time and the responder delay and a sum of channel corrections from the first and second channel information.

6. The non-transitory computer-readable medium of claim 3 wherein the response frame further comprises a symbol start time t symbStart within the request frame of a particular symbol.

7. The non-transitory computer-readable medium of claim 6 and the operations further:
the initiating station determines a time of arrival of the response frame by t symbStart +Dt−t HW-delay , where Dt represents a time different between t symbStart and receipt of a first line of sight peak of a signal from the responding station and t HW-delay represents a delay imposed by the responding station.

8. The non-transitory computer-readable medium of claim 2 wherein the second time is a time of receipt of a training frame associated with the request frame and the fourth time is a time of receipt of a training frame associated with the first acknowledgement frame, the operations further:
determine an actual time of arrival of the request frame after correction of the request frame from the first channel information; and
determine an actual time of arrival of the first acknowledgement frame after correction of the first acknowledgement frame from the second channel information.

9. The non-transitory computer-readable medium of claim 1 wherein the ToF positioning is performed continuously.

10. The non-transitory computer-readable medium of claim 1 wherein the request frame comprises a first null data packet frame and the response frame comprises a second null data packet frame.

11. A non-transitory computer-readable medium that stores instructions for execution by one or more processors to configure a wireless communication device to perform time-of-flight (ToF) positioning in a wireless network, the instructions:
a responding station receives, from an initiating station, a request frame over a first channel;
the responding station calculates the ToF positioning in response to a time-of-departure of a previous request frame, a time-of-arrival of a previous response frame, and a sum of channel corrections from previous first channel information and previous second channel information as determined by the previous request frame and the previous response frame, respectively, in a previous ToF positioning request transmitted prior to the request frame; and
transmit a response frame over a second channel to the initiating station, the response frame comprising the ToF positioning of the initiating station.

12. The non-transitory computer-readable medium of claim 11 wherein the responding station that calculates the ToF positioning comprises the responding station calculates the ToF positioning in response to [D (k−1) +(t′ 4 (k−1) −t 1 (k−1) )−(t 3 (k−1) −t′ 2 (k−1) )]/2 where D (k−1) represents the sum of channel corrections from the previous first channel information and the previous second channel information, t 1 (k−1) represents the time-of-deparure of the previous request frame, t′ 2 (k−1) represents a receipt time of the previous request frame by the responding station, t 3 (k−1) represents a transmission time of the previous response frame, and t′ 4 (k−1) represents the time-of-arrival of the previous response frame by the initiating station.

13. The non-transitory computer-readable medium of claim 12 wherein the request frame comprises the previous first channel information, t′ 4 (k−1) , and t 1 (k−1) .

14. The non-transitory computer-readable medium of claim 11 wherein the instructions further perform a subsequent ToF positioning in response to first channel information of the first channel and second channel information of the second channel.

15. An initiating station to determine a time-of-flight (ToF) position with respect to a responding station in an 802.11 network, the initiating station comprising:
a physical layer to transmit a request frame to a responding station, over a first channel, for measurement of the ToF position and receive a response frame from the responding station, over a second channel, comprising first channel information, a received time of the request frame, and a transmit time of the response frame; and
a processing layer to calculate the ToF position in response to the received time of the request frame, a transmit time of the request frame, a received time of the response frame, the transmit time of the response frame, and a sum of channel corrections from the first channel information and second channel information of the second channel.

16. The initiating station of claim 15 wherein the initiating station comprises a wireless mobile station.

17. The initiating station of claim 15 wherein the responding station comprises an access point.

18. The initiating station of claim 15 wherein the physical layer is further to transmit an action frame to the responding station wherein the action frame comprises the second channel information, a received time of an acknowl

Assignees

• Intel Corp

Inventors

• Banin Leor
• Amizur Yuval
• Schatzberg Uri

Classifications

• G01S5/0244

  Accuracy or reliability of position solution or of measurements contributing thereto · CPC title

• G01S5/14

  Determining absolute distances from a plurality of spaced points of known location · CPC title

• H04W84/12

  WLAN [Wireless Local Area Networks] · CPC title

• G01S5/10 Primary

  Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements {, e.g. omega or decca systems}(G01S5/12 takes precedence {; beacons and receivers cooperating therewith G01S1/306, G01S1/308}) · CPC title

• G01S5/06

  Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements (G01S5/12 takes precedence) · CPC title