Asymmetric RTT ranging with multipath correction

• US 8,779,901 B2
• Filed: 04/12/2011
• Issued: 07/15/2014
• Est. Priority Date: 04/13/2010
• Status: Active Grant

• Current Assignee: Sunrise Micro Devices, Inc. (SoftBank Group Corp.)
• Original Assignee: Sunrise Micro Devices, Inc. (SoftBank Group Corp.)
• Inventors: Gorday, Paul E., Callaway, Edgar H. Jr., Martin, Frederick L.
• Primary Examiner(s): Bugg, George
• Assistant Examiner(s): SMALL, NAOMI J
• Application Number:
  US13/084,865
• Publication Number:
  US 20110250844A1
• Time in Patent Office: 1,190 Days
• Field of Search: 340/10.41, 340/539.13, 340/572.1, 342/47, 342/118, 702/158, 455/562.1, 370/329
• US Class Current: 340/10.41
• CPC Class Codes: H04B 17/364 Delay profiles

Abstract

A method, system, and device provide asymmetric round-trip-time (RTT) ranging with multipath correction. A RTT ranging determination using the resulting composite received signal contains multipath error, and compensation or correction of this error in a manner compatible with low-power, low-complexity devices, such as tag devices, is provided.

Claims

1. An asymmetric RTT ranging method for location determination between an interrogator device and a tag device, comprising:

the interrogator device transmitting a first wireless signal and initiating a time measurement;

the tag device receiving the first wireless signal and determining a composite arrival time of the first wireless signal and transmitting a second wireless signal after a predetermined period of time;

the interrogator device receiving the second wireless signal and determining a first arrival time and a composite arrival time of the second wireless signal, concluding the time measurement; and

compensating the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the second wireless signal wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device,

wherein a bandwidth of the first wireless signal transmitted by the interrogator device and a bandwidth of the second wireless signal transmitted by the tag device differ by a factor of approximately four or more with the bandwidth of the second wireless signal approximately four or more times the bandwidth of the first wireless signal.

2. The method of claim 1, wherein compensating the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the second wireless signal is performed by the interrogator device.

3. The method of claim 1, wherein compensating the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the second wireless signal further comprises:

the interrogator device transmitting a third signal that includes a time measurement value and arrival time information of the second wireless signal; and

a central processor receiving the third signal and compensating the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the second wireless signal.

4. An interrogator device, comprising:

a processor;

a transceiver coupled to the processor;

a timer coupled to the processor;

wherein as controlled by the processor, the transceiver transmits a first wireless signal and the timer initiates a time measurement;

the transceiver receives a second wireless signal from a tag device and provides it to the processor;

the processor determines a first arrival time and a composite arrival time of the second wireless signal and controls the timer to conclude the time measurement by the timer; and

the processor compensates the time measurement at least in part by the difference in time between the determined first arrival time and the determined composite arrival time of the second wireless signal where the compensated time measurement is useful to determine ranging between the interrogator device and the tag device, and

wherein a bandwidth of the first wireless signal transmitted by the interrogator device and a bandwidth of the second wireless signal received from the tag device differ by a factor of approximately four or more with the bandwidth of the second wireless signal approximately four or more times the bandwidth of the first wireless signal.

5. A wireless communication system, comprising:

a central processor, the central processor comprising;

a central processor processing element;

a central processor transceiver coupled to the central processor processing element;

an interrogator device that initiates a time measurement and is coupled to the central processor via a first communication link, the interrogator device comprising;

an interrogator processor;

an interrogator transceiver coupled to the interrogator processor;

an interrogator timer coupled to the interrogator processor;

a tag device coupled via a second communication link with the interrogator device, the tag device comprising;

a tag processor;

a tag transceiver coupled to the tag processor;

a tag timer coupled to the tag processor;

wherein the interrogator transceiver transmits a first wireless signal and the interrogator timer of the interrogator device initiates the time measurement;

the tag transceiver receives the first wireless signal and provides it to the tag processor that determines a composite arrival time of the first wireless signal;

as controlled by the tag timer the tag device waits a predetermined period of time and then the tag transceiver transmits a second wireless signal;

the interrogator transceiver receives the second wireless signal and the interrogator processor determines a first arrival time and a composite arrival time of the second wireless signal, concluding the time measurement;

the interrogator transceiver transmits a third signal that includes a time measurement value and arrival time information of the second wireless signal; and

the central processor transceiver receives the third signal and the central processor processing element compensates the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the second wireless signal, wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device, and

wherein a bandwidth of the first wireless signal transmitted by the interrogator transceiver and a bandwidth of the second wireless signal transmitted by the tag transceiver differ by a factor of approximately four or more with the bandwidth of the second wireless signal approximately four or more times the bandwidth of the first wireless signal.

6. An asymmetric RTT ranging method for location determination between a tag device and an interrogator device, comprising:

the tag device transmitting a first wireless signal and initiating a pre-compensated time measurement;

the interrogator device receiving the first wireless signal and determining a first arrival time and a composite arrival time of the first wireless signal;

the interrogator device waiting a predetermined period of time less the difference in time between the first arrival time and the composite arrival time of the first wireless signal;

the interrogator device transmitting a second wireless signal; and

the tag device receiving the second wireless signal and determining the composite arrival time of the second wireless signal, concluding the pre-compensated time measurement wherein the pre-compensated time measurement is useful to determine ranging between the tag device and the interrogator device,

wherein a bandwidth of the first wireless signal transmitted by the tag device and a bandwidth of the second wireless signal transmitted by the interrogator device differ by a factor of approximately four or more with the bandwidth of the first wireless signal approximately four or more times the bandwidth of the second wireless signal.

7. A wireless system, comprising:

an interrogator device comprising;

an interrogator processor;

an interrogator transceiver coupled to the interrogator processor;

an interrogator timer coupled to the an interrogator processor;

a tag device coupled via a communication link to the interrogator device that initiates a pre-compensated time measurement, the tag device comprising;

a tag processor;

a tag transceiver coupled to the tag processor;

a tag timer coupled to the tag processor;

wherein the tag transceiver transmits a first wireless signal and the tag timer of the tag device initiates the pre-compensated time measurement;

the interrogator transceiver receives the first wireless signal from the tag device, provides it to the interrogator processor of the interrogator device, and the interrogator processor determines a first arrival time and a composite arrival time of the first wireless signal;

as controlled by the interrogator timer the interrogator device waits a predetermined period of time less the difference in time between the first arrival time and the composite arrival time of the first wireless signal and the interrogator processor controls the interrogator transceiver of the interrogator device to transmit a second wireless signal;

the tag transceiver of the tag device receives the second wireless device and the tag processor determines the composite arrival time of the second wireless signal, concluding the pre-compensated time measurement, wherein the pre-compensated time measurement is useful to determine ranging between the interrogator device and the tag device, and

wherein a bandwidth of the first wireless signal transmitted by the tag transceiver and a bandwidth of the second wireless signal transmitted by the interrogator transceiver differ by a factor of approximately four or more with the bandwidth of the first wireless signal approximately four or more times the bandwidth of the second wireless signal.

8. An asymmetric RTT ranging method for location determination between an interrogator device and a tag device, comprising:

the tag device transmitting a first wireless signal and initiating a time measurement;

the interrogator device receiving the first wireless signal, determining arrival time information of the first wireless signal, and transmitting a second wireless signal after a predetermined period of time;

the tag device receiving the second wireless signal and the arrival time information of the first wireless signal and determining the composite arrival time of the second wireless signal, concluding the time measurement; and

compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device,

wherein a bandwidth of the first wireless signal transmitted by the tag device and a bandwidth of the second wireless signal transmitted by the interrogator device differ by a factor of approximately four or more with the bandwidth of the first wireless signal approximately four or more times the bandwidth of the second wireless signal.

9. The method of claim 8, wherein the arrival time information is comprised at least in part of a first arrival time and a composite arrival time of the first wireless signal.

10. The method of claim 8, wherein the second wireless signal includes the arrival time information of the first wireless signal.

11. The method of claim 8, comprising:

the tag device transmitting the first wireless signal and initiating the time measurement;

the interrogator device receiving the first wireless signal, determining the first arrival time and the composite arrival time of the first wireless signal, and transmitting the second wireless signal after a predetermined period of time;

the tag device receiving the second wireless signal and arrival time information of the first wireless signal and determining the composite arrival time of the second wireless signal, concluding the time measurement; and

compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal.

12. The method of claim 11, further comprising:

the tag device compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal.

13. The method of claim 11, wherein compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal further comprises:

the tag device transmitting a third signal that includes a time measurement value and arrival time information of the first wireless signal; and

a central processor receiving the third signal and compensating the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal.

14. The method of claim 8, further comprising:

the tag device receiving the second wireless signal and determining the composite arrival time of the second wireless signal;

after receiving the second wireless signal, the tag device receiving arrival time information of the first wireless signal, concluding the time measurement; and

the tag device compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device.

15. A tag device, comprising:

a processor;

a transceiver coupled to the processor;

a timer coupled to the processor;

wherein as controlled by the processor, the transceiver transmits a first wireless signal and the timer initiates a time measurement;

the transceiver receives from an interrogator device a second wireless signal and arrival time information of the first wireless signal and provides the second wireless signal and the arrival time information to the processor;

the processor determines a composite arrival time of the second wireless signal and controls the timer to conclude the time measurement by the timer wherein the time measurement is useful to determine ranging between the tag device and the interrogator device, and

wherein a bandwidth of the first wireless signal transmitted by the transceiver and a bandwidth of the second wireless signal received by the transceiver from the interrogator device differ by a factor of approximately four or more with the bandwidth of the first wireless signal approximately four or more times the bandwidth of the second wireless signal.

16. The tag device of claim 15, wherein the processor compensates the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal.

17. The tag device of claim 15, wherein the transceiver is controlled by the processor to transmit a third signal including a time measurement value and arrival time information of the second wireless signal.

18. A wireless communication system, comprising:

one or more interrogator devices, each interrogator device comprising;

an interrogator processor;

an interrogator transceiver coupled to the interrogator processor;

an interrogator timer coupled to the interrogator processor;

one or more tag devices coupled to one or more of the one or more interrogator devices via one or more communication links, each tag device comprising;

a tag processor;

a tag transceiver coupled to the tag processor;

a tag timer coupled to the tag processor;

wherein the tag transceiver transmits the first wireless signal and the tag timer initiates the time measurement;

the interrogator transceiver receives and provides the first wireless signal to the interrogator processor that determines the first arrival time and the composite arrival time of the first wireless signal, and the interrogator transceiver transmits the second wireless signal after a predetermined period of time;

the tag transceiver receives the second wireless signal and arrival time information of the first wireless signal and the tag processor determines the composite arrival time of the second wireless signal, concluding the time measurement, wherein the time measurement is useful to determine ranging between the interrogator device and the tag device and

wherein a bandwidth of the first wireless signal transmitted by the tag transceiver and a bandwidth of the second wireless signal transmitted by the interrogator transceiver differ by a factor of approximately four or more with the bandwidth of the first wireless signal approximately four or more times the bandwidth of the second wireless signal.

19. The system of claim 18, wherein the tag processor compensates the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal, wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device.

20. The system of claim 18, the system further comprising a central processor having:

a central processor processing element; and

a central processor transceiver coupled to the central processor processing element,

wherein the tag transceiver transmits a third signal that includes a time measurement value and arrival time information of the first wireless signal; and

the central processor transceiver receives the third signal and the central processor processing element compensates the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device.

21. An asymmetric RTT ranging method for location determination between an interrogator device and a tag device, comprising:

the tag device transmitting a first wireless signal and initiating a time measurement;

the interrogator device receiving the first wireless signal, determining a first arrival time and a composite arrival time of the first wireless signal, and transmitting a second wireless signal after a predetermined period of time;

the tag device receiving the second wireless signal and determining the composite arrival time of the second wireless signal, concluding the time measurement;

the tag device transmitting a third signal that contains the result of the time measurement; and

receiving the third signal and compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device,

wherein a bandwidth of the first wireless signal transmitted by the tag device and a bandwidth of the second wireless signal transmitted by the interrogator device differ by a factor of approximately four or more with the bandwidth of the first wireless signal approximately four or more times the bandwidth of the second wireless signal.

22. The method of claim 21, wherein receiving the third signal and compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal further comprises:

the interrogator device receiving the third signal and compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal.

23. The method of claim 21, wherein receiving the third signal and compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal further comprises:

the interrogator device receiving the third signal and transmitting a fourth signal that includes the time measurement value and arrival time information of the first wireless signal; and

a central processor receiving the fourth signal and compensating the time measurement at least in part by the difference in time between the first arrival time and the composite arrive time of the first wireless signal.

24. The method of claim 21, wherein receiving the third signal and compensating the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal further comprises:

a central processor receiving the third signal;

the interrogator device transmitting a fourth signal that includes arrival time information of the first wireless signal;

the central processor receiving the fourth signal; and

the central processor compensating the time measurement at least in part by the difference in time between the first arrival time and the composite arrive time of the first wireless signal.

25. A tag device, comprising:

a processor;

a transceiver coupled to the processor;

a timer coupled to the processor;

wherein as controlled by the processor, the transceiver transmits a first wireless signal and the timer initiates a time measurement;

the transceiver receives from an interrogator device a second wireless signal and provides it to the processor;

the processor determines a composite arrival time of the second wireless signal and controls the timer to conclude the time measurement by the timer; and

the processor controls the transceiver to transmit a third signal that contains the result of the time measurement wherein the time measurement is useful to determine ranging between the tag device and the interrogator device, and

wherein a bandwidth of the first wireless signal transmitted by the transceiver and a bandwidth of the second wireless signal received by the transceiver from the interrogator device differ by a factor of approximately four or more with the bandwidth of the first wireless signal approximately four or more times the bandwidth of the second wireless signal.

26. A wireless communication system, comprising:

one or more interrogator devices, each interrogator device comprising;

an interrogator processor;

an interrogator transceiver coupled to the interrogator processor; and

an interrogator timer coupled to the interrogator processor;

one or more tag devices coupled to one or more of the one or more interrogator devices, each tag device comprising;

a tag processor;

a tag transceiver coupled to the tag processor; and

a tag timer coupled to the tag processor;

wherein the tag transceiver transmits a first wireless signal and the tag timer initiates a time measurement;

the interrogator transceiver receives and provides the first wireless signal to the interrogator processor that determines a first arrival time and a composite arrival time of the first wireless signal and the interrogator timer controls the interrogator transceiver to transmit a second wireless signal after a predetermined period of time;

the tag transceiver receives and provides the second wireless signal to the tag processor that determines the composite arrival time of the second wireless signal;

the tag timer concludes the time measurement; and

the tag transceiver transmits a third signal that contains the result of the time measurement, wherein the time measurement is useful to determine ranging between the interrogator device and the tag device,

wherein a bandwidth of the first wireless signal transmitted by the tag transceiver and a bandwidth of the second wireless signal transmitted by the interrogator transceiver differ by a factor of approximately four or more with the bandwidth of the first wireless signal approximately four or more times the bandwidth of the second wireless signal.

27. The system of claim 26, wherein the interrogator transceiver receives and provides the third signal to the interrogator processor that compensates the result of the time measurement at least in part by the difference in time between the first arrival time and the composite arrival time of the first wireless signal, wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device.

28. The system of claim 26, the system further comprising a central processor having:

a central processor processing element; and

a central processor transceiver coupled to the central processor processing element,

wherein the interrogator transceiver receives the third signal and transmits a fourth signal that includes the time measurement value and arrival time information of the first wireless signal; and

the central processor transceiver receives the fourth signal and the central processor processing element compensates the time measurement at least in part by the difference in time between the first arrival time and the composite arrive time of the first wireless signal, wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device.

29. The system of claim 26, the system further comprising a central processor having:

a central processor processing element; and

a central processor transceiver coupled to the central processor processing element,

wherein the central processor transceiver receives the third signal;

the interrogator transceiver transmits a fourth signal that includes arrival time information of the first wireless signal;

the central processor transceiver receives the fourth signal; and

the central processor processing element compensates the time measurement at least in part by the difference in time between the first arrival time and the composite arrive time of the first wireless signal, wherein the compensated time measurement is useful to determine ranging between the interrogator device and the tag device.