Method and system for performing ranging functions in an ultrawide bandwidth system
View Patent ↗A process is provided for determining the distance between two devices by sending ranging packets between them. The local device sends a first ranging packet, which the remote device sends holds for a first hold time before sending a second ranging packet in return. The local device also sends a third ranging packet, which the remote device sends holds for a second hold time before sending a fourth ranging packet in return. If the second hold time is twice the first hold time, then the propagation time for signals between the two devices can be determined solely by time measurements made by the local device. For received signals, these time measurements can be adjusted to provide accurate time estimates for a direct line of sight signal, which corresponds to a shortest transmission distance between the two devices. The propagation time can then be used to determine distance between the devices.
1. A method of determining a propagation time in a signal path of a wireless network, comprising:
sending a first ranging packet from the local device to the remote device at a first time;
receiving the first ranging packet at the remote device at a second time, where the second time is equal to the first time plus the propagation time;
sending a second ranging packet from the remote device to the local device at a third time, where the third time is equal to the second time plus a first hold time;
receiving the second ranging packet at the local device at a fourth time, where the fourth time is equal to the third time plus the propagation time;
sending a third ranging packet from the local device to the remote device at a fifth time;
receiving the third ranging packet at the remote device at a sixth time, where the sixth time is equal to the fifth time plus the propagation time;
sending a fourth ranging packet from the remote device to the local device at a seventh time, where the seventh time is equal to the sixth time plus a second hold time, the second hold time being different from the first hold time;
receiving the fourth ranging packet at the local device at a eighth time, where the eighth time is equal to the seventh time plus the propagation time; and
calculating the propagation time at the local device as a function of the first time, the fourth time, the fifth time, the eighth time, and a proportion between the first hold time and the second hold time.
2. A method of determining a propagation time in a signal path of a wireless network, as recited in claim 1 , further comprising calculating a distance between the local device and the remote device to be equal to the propagation time multiplied by the speed of light.
3. A method of determining a propagation time in a signal path of a wireless network, as recited in claim 1 , wherein the second hold time is twice the first, hold time.
4. A method of determining a propagation time in a signal path of a wireless network, as recited in claim 3 , wherein the propagation time is equal to the difference between the fourth time and the first time minus half the difference between the eighth time and the fifth time.
5. A method of determining a signal path distance in a wireless network, as recited in claim 1 ,
wherein the first ranging packet comprises a plurality of multipath components arriving at different times at the remote device, and
wherein the second time represents an earliest received time at which an earliest multipath component from the plurality of multipath components arrives at the remote device.
6. A method of determining a signal path distance in a wireless network, as recited in claim 5 , further comprising:
acquiring an acquired multipath component at the remote device from the plurality of multipath components, the acquired multipath component being different from the earliest received multipath component;
determining the earliest received time by processing the acquired multipath component and the plurality of received multipath components to locate the earliest received multipath component, and identify the earliest received time associated with the earliest received multipath component; and
determining the second time to be the earliest received time.
7. A method of determining a signal path distance in a wireless network, as recited in claim 6 , wherein the step of determining the earliest received multipath component further comprises:
identifying all incoming signals received at the remote device within a maximum duration prior to receiving the acquired multipath component;
comparing the received incoming signals to a noise threshold;
locating an earliest received incoming signal that is above the noise threshold; and
determining the earliest received incoming signal to be the earliest received, multipath component.
8. A method of determining a signal path distance in a wireless network, as recited in claim 1 ,
wherein the second ranging packet comprises a plurality of multipath components arriving at different times at the local device, and
wherein the fourth time represents an earliest received time at which an earliest multipath component from the plurality of multipath components arrives at the local device.
9. A method of determining a signal path distance in a wireless network, as recited in claim 8 , further comprising:
acquiring an acquired multipath component at the local device from the plurality of multipath components, the acquired multipath component being different from the earliest received multipath component;
determining the earliest received time by processing the acquired multipath component and the plurality of received multipath components to locate the earliest received multipath component, and identify the earliest received time associated with the earliest received multipath component; and
determining the fourth time to be the earliest received time.
10. A method of determining a signal path distance in a wireless network, as recited in claim 9 , wherein the step of determining the earliest received multipath component further comprises:
identifying all incoming signals received at the local device within a maximum duration prior to receiving the acquired multipath component;
comparing the received incoming signals to a noise threshold;
locating an earliest received incoming signal that is above the noise threshold; and
determining the earliest received incoming signal to be the earliest received multipath component.
11. A method of determining a signal path distance in a wireless network, as recited in claim 1 ,
wherein the third ranging packet comprises a plurality of multipath components arriving at different times at the remote device, and
wherein the fifth time represents an earliest received time at which an earliest multipath component from the plurality of multipath components arrives at the remote device.
12. A method of determining a signal path distance in a wireless network, as recited in claim 11 , further comprising:
acquiring an acquired multipath component at the remote device from the plurality of multipath components, the acquired multipath component being different from the earliest received multipath component;
determining the earliest received time by processing the acquired multipath component and the plurality of received multipath components to locate the earliest received multipath component, and identify the earliest received time associated with the earliest received multipath component; and
determining the fifth time to be the earliest received time.
13. A method of determining a signal path distance in a wireless network, as recited in claim 12 , wherein the step of determining the earliest received multipath component further comprises:
identifying all incoming signals received at the remote device within a maximum duration prior to receiving the acquired multipath component;
comparing the received incoming signals to a noise threshold;
locating an earliest received incoming signal that is above the noise threshold; and
determining the earliest received incoming signal to be the earliest received multipath component.
14. A method of determining a signal path distance in a wireless network, as recited in claim 1 ,
wherein the fourth ranging packet comprises a plurality of multipath components arriving at different times at the local device, and
wherein the eighth time represents an earliest received time at which an earliest multipath component from the plurality of multipath components arrives at the local device.
15. A method of determining a signal path distance in a wireless network, as recited in claim 14 , further comprising:
acquiring an acquired multipath component at the local device from the plurality of multipath components, the acquired multipath component being different from the earliest received multipath component;
determining the earliest received time by processing the acquired multipath component and the plurality of received multipath components to locate the earliest received multipath component, and identify the earliest received time associated with the earliest received multipath component; and
determining the eighth time to be the earliest received time.
16. A method of determining a signal path distance in a wireless network, as recited in claim 15 , wherein the step of determining the earliest received multipath component further comprises:
identifying all incoming signals received at the local device within a maximum duration prior to receiving the acquired multipath component;
comparing the received incoming signals to a noise threshold;
locating an earliest received incoming signal that is above the noise threshold; and
determining the earliest received incoming signal to be the earliest received multipath component.