Detection of high velocity movement in a telecommunication system

• US 7,647,049 B2
• Filed: 07/12/2006
• Issued: 01/12/2010
• Est. Priority Date: 07/12/2006
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Andersson, Lennart, Engdahl, Karin
• Primary Examiner(s): Le; Danh C
• Application Number:
  US11/456,998
• Publication Number:
  US 20080014881A1
• Time in Patent Office: 1,280 Days
• Field of Search: 455/441, 455/426.1, 455/422.1, 370/342, 375/344, 342/461
• US Class Current: 455/441
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers
• CPC Class Codes: H04L 2027/0055 single phase
• CPC Class Codes: H04L 2027/0065 Frequency error detectors H04L2027/0067 takes precedence

Abstract

Whether relative velocity between a transmitter and a receiver is higher than a predetermined amount is detected. This involves using a Doppler estimation technique to generate an estimate of Doppler spread, {circumflex over (f)}_D⁽¹⁾, based on a received signal, and using an alternative velocity estimation technique to generate an estimate of velocity, {circumflex over (v)}, based on the received signal, wherein the alternative velocity estimation technique differs from the Doppler estimation technique. A plurality of estimates, including at least the estimate of Doppler spread and the estimate of velocity, are used to detect whether the relative velocity between the transmitter and the receiver is higher than the predetermined amount. The alternative velocity estimation technique may, for example, be a second Doppler estimation technique that differs from the other Doppler estimation technique.

Claims

1. A method of detecting that a relative velocity between a transmitter and a receiver in a telecommunications system is higher than a predetermined amount, the method comprising:

using a Doppler estimation technique to generate an estimate of Doppler spread, {circumflex over (f)}_D⁽¹⁾, based on a received signal;

using an alternative velocity estimation technique to generate an estimate of velocity, {circumflex over (v)}, based on the received signal, wherein the alternative velocity estimation technique differs from the Doppler estimation technique; and

using a plurality of estimates to detect whether the relative velocity between the transmitter and the receiver is higher than the predetermined amount, wherein the plurality of estimates includes at least the estimate of Doppler spread and the estimate of velocity.

2. The method of claim 1, wherein:

the Doppler estimation technique is a first Doppler estimation technique;

the estimate of Doppler spread, {circumflex over (f)}_D⁽¹⁾, is a first estimate of Doppler spread;

the alternative velocity estimation technique is a second Doppler estimation technique that differs from the first Doppler estimation technique; and

the estimate of velocity is a second estimate of Doppler spread, {circumflex over (f)}_D⁽²⁾.

3. The method of claim 2, wherein:

the first Doppler estimation technique comprises utilizing information about a part of the received signal associated with a strongest path between the transmitter and the receiver; and

the second Doppler estimation technique comprises;

excluding information about a part of the received signal associated with the strongest path between the transmitter and the receiver; and

utilizing information about a part of the received signal associated with a secondary path between the transmitter and the receiver.

4. The method of claim 3, wherein using the plurality of estimates to detect whether a relative velocity between the transmitter and the receiver is higher than the predetermined amount comprises:

concluding that the relative velocity between the transmitter and the receiver is higher than the predetermined amount if

({circumflex over (f)}_D⁽¹⁾>

τ

_high)OR(({circumflex over (f)}_D⁽²⁾>

τ

_high)AND(r({circumflex over (f)}_D⁽²⁾)>

τ

_r)); and

concluding that the relative velocity between the transmitter and the receiver is lower than the predetermined amount if

({circumflex over (f)}_D⁽¹⁾<

τ

_low)AND(({circumflex over (f)}_D⁽²⁾<

τ

_low)OR(r({circumflex over (f)}_D⁽²⁾)<

τ

_r)),

wherein r({circumflex over (f)}_D⁽²⁾) is a parameter indicating the reliability of {circumflex over (f)}_D⁽²⁾, τ

_high is a threshold representing a minimum Doppler value associated with a relative velocity between the transmitter and the receiver that is higher than the predetermined amount, τ

_low is a threshold representing a maximum Doppler value associated with a relative velocity between the transmitter and the receiver that is lower than the predetermined amount, and τ

_r is a threshold representing a minimum required value of reliability.

5. The method of claim 2, comprising:

detecting whether there exists uninterrupted rotation of a channel estimate over a predetermined period of time; and

in response to detecting the existence of uninterrupted rotation of the channel estimate over the predetermined period of time, concluding that the relative velocity between the transmitter and the receiver is higher than the predetermined amount.

6. The method of claim 5, comprising:

in response to detecting that the relative velocity between the transmitter and the receiver is higher than the predetermined amount, operating an automatic frequency controller at a high update rate; and

changing operation of the automatic frequency controller to a low update rate in response to determining that a magnitude of a frequency error generated by the automatic frequency controller has continuously remained below a predetermined threshold value for a predetermined period of time.

7. The method of claim 2, comprising:

determining a residual frequency offset value, f_err,f^(res), fε

F, wherein F represents a set of RAKE receiver fingers involved in automatic frequency control operation;

determining a function of the residual frequency offset value, ζ

(f_err,f^(res)); and

concluding that the relative velocity between the transmitter and the receiver is higher than the predetermined amount in response to determining that the function of the residual frequency offset value, ζ

(f_err,f^(res)), is greater than a predetermined threshold value.

8. The method of claim 1, wherein using the plurality of estimates comprises concluding that the relative velocity between the transmitter and the receiver is not higher than the predetermined amount only if none of the plurality of estimates indicates that the relative velocity between the transmitter and the receiver is higher than the predetermined amount.

9. The method of claim 1, wherein the alternative velocity estimation technique comprises:

detecting whether there exists uninterrupted rotation of a channel estimate over a predetermined period of time; and

in response to detecting the existence of uninterrupted rotation of the channel estimate over the predetermined period of time, concluding that the relative velocity between the transmitter and the receiver is higher than the predetermined amount.

10. The method of claim 1, wherein the alternative velocity estimation technique comprises:

determining a residual frequency offset value, f_err,f^(res), fε

F, wherein F represents a set of RAKE receiver fingers involved in automatic frequency control operation;

determining a function of the residual frequency offset value, ζ

(f_err,f^(res)); and

concluding that the relative velocity between the transmitter and the receiver is higher than the predetermined amount in response to determining that the function of the residual frequency offset value, ζ

(f_err,f^(res)), is greater than a predetermined threshold value.

11. The method of claim 10, wherein:

$\mathrm{\zeta <br><br>}<br><br>\left(f_{\mathrm{err},f}^{\left(\mathrm{res}\right)}\right)=\underset{f\in <br><br>F}{\max }<br><br>f_{\mathrm{err},f}^{\left(\mathrm{res}\right)}.$

12. The method of claim 10, wherein:

$\mathrm{\zeta <br><br>}<br><br>\left(f_{\mathrm{err},f}^{\left(\mathrm{res}\right)}\right)=\frac{1}{<br><br>F<br><br>}<br><br>\underset{f\in <br><br>F}{\sum <br><br>}<br><br>f_{\mathrm{err},f}^{\left(\mathrm{res}\right)}.$

13. The method of claim 1, comprising:

setting receiver parameters based on whether the relative velocity between the transmitter and the receiver is detected to be higher than the predetermined amount.

14. The method of claim 1, comprising:

setting automatic frequency control parameters based on whether the relative velocity between the transmitter and the receiver is detected to be higher than the predetermined amount.

15. The method of claim 1, wherein the method is performed in a user equipment.

16. The method of claim 1, wherein the method is performed in a base station of the telecommunication system.

17. The method of claim 1, wherein:

the telecommunication system is a Wideband Code Division Multiple Access (WCDMA) telecommunications system; and

the method is performed in a device associated with the WCDMA telecommunications system.

18. An apparatus for detecting that a relative velocity between a transmitter and a receiver in a telecommunications system is higher than a predetermined amount, the apparatus comprising:

a Doppler estimator that generates an estimate of Doppler spread, {circumflex over (f)}_D⁽¹⁾, based on a received signal;

an alternative velocity estimator that generates an estimate of velocity, {circumflex over (v)}, based on the received signal; and

logic that uses a plurality of estimates to detect whether the relative velocity between the transmitter and the receiver is higher than the predetermined amount,

wherein;

the plurality of estimates includes at least the estimate of Doppler spread and the estimate of velocity;

the Doppler estimator uses a Doppler estimation technique;

the alternative velocity estimator uses an alternative velocity estimation technique; and

the Doppler estimation technique differs from the alternative velocity estimation technique.

19. The apparatus of claim 18, wherein:

the Doppler estimation technique is a first Doppler estimation technique;

the estimate of Doppler spread, {circumflex over (f)}_D⁽¹⁾, is a first estimate of Doppler spread;

the alternative velocity estimation technique is a second Doppler estimation technique that differs from the first Doppler estimation technique; and

the estimate of velocity is a second estimate of Doppler spread, {circumflex over (f)}_D⁽²⁾.

20. The apparatus of claim 19, wherein:

the first Doppler estimator comprises logic that utilizes information about a part of the received signal associated with a strongest path between the transmitter and the receiver; and

the second Doppler estimation technique comprises;

excluding information about a part of the received signal associated with the strongest path between the transmitter and the receiver; and

utilizing information about a part of the received signal associated with a secondary path between the transmitter and the receiver.

21. The apparatus of claim 20, wherein the logic that uses the plurality of estimates to detect whether a relative velocity between the transmitter and the receiver is higher than the predetermined amount comprises:

logic that concludes that the relative velocity between the transmitter and the receiver is higher than the predetermined amount if

({circumflex over (f)}_D⁽¹⁾>

τ

_high)OR(({circumflex over (f)}_D⁽²⁾>

τ

_high)AND(r({circumflex over (f)}_D⁽²⁾)>

τ

_r)); and

logic that concludes that the relative velocity between the transmitter and the receiver is not higher than the predetermined amount if

({circumflex over (f)}_D⁽¹⁾<

τ

_low)AND(({circumflex over (f)}_D⁽²⁾<

τ

_low)OR(r({circumflex over (f)}_D⁽²⁾)<

τ

_r)),

wherein r({circumflex over (f)}_D⁽²⁾) is a parameter indicating the reliability of {circumflex over (f)}_D⁽²⁾, τ

_high is a threshold representing a minimum Doppler value associated with relative velocity between the transmitter and the receiver that is higher than the predetermined amount, τ

_low is a threshold representing a maximum Doppler value associated with a relative velocity between the transmitter and the receiver that is lower than the predetermined amount, and τ

_r is a threshold representing a minimum required value of reliability.

22. The apparatus of claim 19, comprising:

logic that detects whether there exists uninterrupted rotation of a channel estimate over a predetermined period of time; and

logic that, in response to detecting the existence of uninterrupted rotation of the channel estimate over the predetermined period of time, concludes that the relative velocity between the transmitter and the receiver is higher than the predetermined amount.

23. The apparatus of claim 22, comprising:

logic that, in response to detecting that the relative velocity between the transmitter and the receiver is higher than the predetermined amount, operates an automatic frequency controller at a high update rate; and

logic that changes operation of the automatic frequency controller to a low update rate in response to determining that a magnitude of a frequency error generated by the automatic frequency controller has continuously remained below a predetermined threshold value for a predetermined period of time.

24. The apparatus of claim 19, comprising:

logic that determines a residual frequency offset value, f_err,f^(res), fε

F, wherein F represents a set of RAKE receiver fingers involved in automatic frequency control operation;

logic that determines a function of the residual frequency offset value, ζ

(f_err,f^(res)); and

logic that concludes that the relative velocity between the transmitter and the receiver is higher than the predetermined amount in response to determining that the function of the residual frequency offset value, ζ

(f_err,f^(res)), is greater than a predetermined threshold value.

25. The apparatus of claim 18, wherein the logic that uses the plurality of estimates comprises logic that concludes that the relative velocity between the transmitter and the receiver is not higher than the predetermined amount only if none of the plurality of estimates indicates that the relative velocity between the transmitter and the receiver is higher than the predetermined amount.

26. The apparatus of claim 18, wherein the alternative velocity estimator comprises:

logic that detects whether there exists uninterrupted rotation of a channel estimate over a predetermined period of time; and

logic that, in response to detecting the existence of uninterrupted rotation of the channel estimate over the predetermined period of time, concludes that the relative velocity between the transmitter and the receiver is higher than the predetermined amount.

27. The apparatus of claim 18, wherein the alternative velocity estimator comprises:

logic that determines a residual frequency offset value, f_err,f^(res), fε

F, wherein F represents a set of RAKE receiver fingers involved in automatic frequency control operation;

logic that determines a function of the residual frequency offset value, ζ

(f_err,f^(res)); and

logic that concludes that the relative velocity between the transmitter and the receiver is higher than the predetermined amount in response to determining that the function of the residual frequency offset value, ζ

(f_err,f^(res)), is greater than a predetermined threshold value.

28. The apparatus of claim 27, wherein:

$\mathrm{\zeta <br><br>}<br><br>\left(f_{\mathrm{err},f}^{\left(\mathrm{res}\right)}\right)=\underset{f\in <br><br>F}{\max }<br><br>f_{\mathrm{err},f}^{\left(\mathrm{res}\right)}.$

29. The apparatus of claim 27, wherein:

$\mathrm{\zeta <br><br>}<br><br>\left(f_{\mathrm{err},f}^{\left(\mathrm{res}\right)}\right)=\frac{1}{<br><br>F<br><br>}<br><br>\underset{f\in <br><br>F}{\sum <br><br>}<br><br>f_{\mathrm{err},f}^{\left(\mathrm{res}\right)}.$

30. The apparatus of claim 18, comprising:

logic that sets receiver parameters based on whether the relative velocity between the transmitter and the receiver is detected to be higher than the predetermined amount.

31. The apparatus of claim 18, comprising:

logic that sets automatic frequency control parameters based on whether the relative velocity between the transmitter and the receiver is detected to be higher than the predetermined amount.

32. The apparatus of claim 18, wherein the apparatus is part of a user equipment.

33. The apparatus of claim 18, wherein the apparatus is part of a base station of the telecommunication system.

34. The apparatus of claim 18, wherein:

the telecommunication system is a Wideband Code Division Multiple Access (WCDMA) telecommunications system; and

the apparatus is part of a device associated with the WCDMA telecommunications system.