MEASUREMENT OF TIME OF ARRIVAL

• US 20110286505A1
• Filed: 05/25/2009
• Published: 11/24/2011
• Est. Priority Date: 05/26/2008
• Status: Active Grant

• Current Assignee: Commonwealth Scientific & Industrial Research Organisation (Commonwealth Of Australia As Represented By Department Of Industry, Innovation, Climate Change, Science, Research And Tertiary Education)
• Original Assignee: Commonwealth Scientific & Industrial Research Organisation (Commonwealth Of Australia As Represented By Department Of Industry, Innovation, Climate Change, Science, Research And Tertiary Education)
• Inventors: Hedley, Mark, Humphrey, David
• Granted Patent: US 9,295,021 B2
• Time in Patent Office: Days
• US Class Current: 375/224
• CPC Class Codes: G01S 5/02213 Receivers arranged in a network for determining the position of a transmitter
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Disclosed is a method of measuring time of arrival of a signal transmitted from a transmitter (120) to reciever (110-n). The method comprises: modulating a plurality of narrowband signal portions onto different carrier frequencies; transmitting by the transmitter, each modulated signal portion to the receiver; receiving, by the receiver, the transmitted signal portions; estimating the channel impulse response by combining (610) the received signal portions; and measuring (620) the time of arrival using the estimated channel impulse response. Further disclosed is a method of measuring a time of arrival of a signal transmitted from a transmitter to a receiver. The method comprises: estimating a noise level (1310) in an impulse response of a channel between the transmitter and the receiver; finding a first peak (1330) in the channel impulse response that is not noise or a side lobe of a subsequent peak, using the estimated noise level; and measuring the time of arrival (1220) using the first peak.

Claims

1. A method of measuring time of arrival of a signal transmitted from a transmitter to a receiver over a channel, said method comprising:

modulating a plurality of narrowband signal portions onto different carrier frequencies;

transmitting, by said transmitter, each said modulated signal portion to said receiver;

receiving, by said receiver, the transmitted signal portions;

estimating an impulse response of the channel by combining the received signal portions; and

measuring the time of arrival using the estimated channel impulse response.

2. A method according to claim 1, wherein each said signal portion has substantially equal power at all frequencies within the band of the signal portion, and a limited peak to average power ratio in the time domain.

3. A method according to claim 1, wherein the frequency responses of at least two of said modulated signal portions overlap in the frequency domain.

4. A method according to claim 1, wherein said estimating comprises:

determining a frequency response for each said received signal portion;

applying a correction to the phase of each said frequency response;

combining the corrected channel frequency responses into a wideband frequency response; and

transforming the wideband frequency response into the channel impulse response.

5. The method according to claim 4, wherein the correction is applied such that the wideband frequency response is continuous in phase.

6. The method according to claim 4, wherein the correction is applied such that overlapping portions of adjacent frequency responses have matching phases.

7. The method according to claim 6, wherein the applying comprises:

computing, for each frequency response, a complex constant that minimises the sum of the squared error between the overlapping values of the frequency response and an adjacent frequency response; and

multiplying the frequency response values by the complex constant.

8. The method according to claim 4, wherein the correction is further applied to the magnitude of each said frequency response.

9. The method according to claim 4, wherein said determining comprises compensating each frequency response for the distortive effect of the transmitter and the receiver.

10. The method according to claim 4, wherein the transforming comprises:

applying an inverse Fourier transform to the wideband frequency response to form the channel impulse response.

19. The method according to claim 1, wherein the measuring comprises:

estimating a noise level in said impulse response;

finding a first peak in said impulse response that is not noise or a side lobe of a subsequent peak, using said estimated noise level; and

measuring the time of arrival using said first peak.

11. A method of measuring a time of arrival of a signal transmitted from a transmitter to a receiver, said method comprising:

estimating a noise level in an impulse response of a channel between said transmitter and said receiver;

finding a first peak in the channel impulse response that is not noise or a side lobe of a subsequent peak, using said estimated noise level; and

measuring the time of arrival using said first peak.

12. The method according to claim 11, wherein said measuring comprises:

interpolating one or more samples on the leading edge of the first peak; and

locating a first sample on said interpolated leading edge with a monotonic rise and with a value greater than a predetermined constant factor multiplied by the value of the first peak.

13. The method according to claim 11, wherein said measuring comprises:

extracting a predetermined number of samples on a leading edge of said first peak;

looking up a database of stored time of arrival offset values using said extracted leading edge samples; and

obtaining the time of arrival from said database lookup.

14. The method according to claim 13, further comprising, before said extracting, resampling said channel impulse response such that one of the sampling points coincides with the location of said first peak.

15. The method according to claim 13, wherein the database is hierarchical.

16. The method according to claim 13, further comprising extracting a lower dimensional feature from the extracted leading edge samples before said database lookup.

17. The method according to claim 13, wherein the database is constructed using channel impulse responses generated by a channel model, wherein the parameters of the model are derived from measurements.

18. The method according to claim 13, wherein the database contains additional information about the time of arrival including:

one or more further estimates of times of arrival for each impulse response;

the likelihood of each time of arrival estimate; and

the uncertainty in each time of arrival estimate.

20. A method of measuring time of arrival of a signal transmitted from a transmitter to a receiver over a channel, said method comprising:

receiving, by said receiver, a plurality of transmitted narrowband signal portions, each signal portion having been modulated onto a different carrier frequency;

estimating an impulse response of the channel by combining the received signal portions; and

measuring the time of arrival using the estimated channel impulse response.

21. A system adapted to measure time of arrival, the system comprising:

a transmitter adapted to;

modulate a plurality of narrowband signal portions onto different earner frequencies; and

transmit each said modulated signal portion by said transmitter to said receiver over a channel; and

a receiver adapted to;

receive the transmitted signal portions;

estimate an impulse response of the channel by combining the received signal portions; and

measure the time of arrival using the estimated channel impulse response.

22. A receiver adapted to measure time of arrival of a signal transmitted from a transmitter to a receiver over a channel, the receiver being adapted to:

receive a plurality of transmitted narrowband signal portions, each signal portion having been modulated onto a different carrier frequency;

estimate an impulse response of the channel by combining the received signal portions; and

measure the time of arrival using the estimated channel impulse response.