Mobile station speed estimation

• US 20040097197A1
• Filed: 08/13/2003
• Published: 05/20/2004
• Est. Priority Date: 02/14/2002
• Status: Active Grant

• Current Assignee: Nokia Corporation
• Original Assignee: Nokia Corporation
• Inventors: Juncker, Carsten, Morch, Niels Jacob Sand, Toft, Peter
• Granted Patent: US 7,218,934 B2
• Time in Patent Office: Days
• US Class Current: 455/67.11
• CPC Class Codes: G01S 11/10 using Doppler effect
• CPC Class Codes: H04B 17/20 of receivers
• CPC Class Codes: H04B 7/01 Reducing phase shift

Abstract

The Doppler spreads of the received signals in a MIMO, SIMO or MISO mobile communication system are estimated from the derivatives of the path transfer function envelopes for the received signals. The estimated Doppler spreads is used to estimate the speed of the mobile station.

Claims

1. A method of estimating the speed of a mobile station in a MIMO, SIMO or MISO wireless communication system, the method comprising:

concurrently receiving a plurality of radio signals;

deriving a value for the derivative of the envelope of the path transfer function for each radio signal;

computing an estimate of the Doppler spread of each of said radio signals from said derivative values; and

deriving a value for the speed of said mobile station from said Doppler spread estimates.

2. A method according to claim 1, wherein said values for the derivatives of said envelopes are derived by low-pass filtering an envelope signal representing the corresponding path transfer function envelope to band limit it and filtering the band-limited envelope signal using an IIR or FIR filter.

3. A method according to claim 2, wherein said envelope signals comprise respective sequences of samples representing the corresponding path transfer function envelope.

4. A method according to claim 2, wherein the computing of said estimates of the Doppler spreads comprises determining the variances of said derivative values.

5. A method according to claim 4, wherein the computing of said estimates of the Doppler spreads comprises determining a value indicative of the received powers of said radio signals.

6. A method according to claim 5, wherein the Doppler spread estimates are each calculated by determining the square root of the result of dividing twice the corresponding variance by the value indicative of the received power of the respective radio signal.

7. A method according to claim 6, wherein the Doppler spread estimates are each calculated in accordance with the formula:

8. A method according to claim 1, wherein the speed of the mobile station is calculated in accordance with the formula:

9. A method according to claim 1, wherein the speed of the mobile station is calculated as the mean of speeds calculated for a plurality of said signals in accordance with the formula:

10. A method according to claim 1, wherein the speed of the mobile station is calculated as a weighted sum of speeds calculated for a plurality of said signals in accordance with the formula:

11. A method according to claim 1, wherein the speed of the mobile station is calculated as the median of speeds calculated for a plurality of said signals in accordance with the formula:

12. A method of estimating the speed of a mobile station in a MIMO, SIMO or MISO wireless communication system, the method comprising:

concurrently receiving a plurality of radio signals;

deriving first and second values for the derivative of the envelope of the path transfer function for each radio signal;

computing first and second estimates of the Doppler spread of each of said radio signals from said derivative values; and

deriving a value for the speed of said mobile station from said Doppler spread estimates.

13. A method according to claim 12, wherein said first value for the derivative of the envelope of each of said radio signals is derived by derived by low-pass filtering an envelope signal representing the corresponding path transfer function envelope to band limit it and filtering the band-limited envelope signal using an IIR or FIR filter and said second value for the derivative of the envelope of each of said radio signals is derived by low-pass filtering an envelope signal representing the path transfer function envelope to band limit it and filtering the band-limited envelope signal using an IIR or FIR filter, the first values being derived using a low-pass filter characteristic having a lower cut-off frequency than that of the low-pass filter characteristic used for deriving said second values.

14. A method according to claim 13, wherein the low-pass filtering for the first values is followed by downsampling.

15. A method according to claim 13, wherein said envelope signals comprise sequences of samples representing the respective path transfer function envelopes.

16. A method according to claim 13, wherein the computing of said first and second estimates of the Doppler spreads comprises determining the variances of said first and second derivative values respectively.

17. A method according to claim 16, wherein the computing of each of said estimates of the Doppler spread comprises determining a value indicative of the received power of the corresponding radio signal.

18. A method according to claim 17, wherein the first and second Doppler spread estimates are calculated by determining the square root of the result of dividing twice the respective variance by said value indicative of the received power of the respective radio signal.

19. A method according to claim 12, wherein the Doppler spread estimatea are each calculated in accordance with the formula:

20. A method according to claim 12, comprising deriving first and second speed estimates values from the first and second Doppler spreads respectively and selecting the first or second speed estimate value in dependent on the magnitude of the first or second speed estimate value to provide said speed estimate.

21. A method according to claim 20, wherein the first and second speed estimates are calculated in accordance with the formula:

22. A method according to claim 20, wherein the first and second speed estimates are calculated as the mean of speeds calculated for a plurality of said signals in accordance with the formula:

23. A method according to claim 20, wherein the first and second speed estimates are calculated as a weighted sum of speeds calculated for a plurality of said signals in accordance with the formula:

24. A method according to claim 20, wherein the first and second speed estimates are calculated as the median of speeds calculated for a plurality of said signals in accordance with the formula:

25. A mobile station of a MIMO, SIMO or MISO wireless communication network, the mobile station including radio receiver means having at least one antenna for receiving a plurality of radio signals and outputting corresponding baseband signals and processing means for processing said baseband signals, wherein the processing means is configured for estimating the Doppler spread of a radio signal by:

deriving a value for the derivative of the envelope of the path transfer function for each received radio signal;

computing an estimate of the Doppler spread of each of said radio signals from said derivative values; and

deriving a value for the speed of said mobile station from said Doppler spread estimates.

26. A mobile station according to claim 25, wherein said processing means is configured such that said values for the derivatives of said envelopes are derived by low-pass filtering an envelope signal representing the corresponding path transfer function envelope to band limit it and filtering the band-limited envelope signal using an IIR or FIR filter.

27. A mobile station according to claim 25, wherein the radio receiver means outputs said baseband signals as respective sequences of samples .

28. A mobile station according to claim 25, wherein the processing means is configured such that the computing of said estimates of the Doppler spreads comprises determining the variances of said derivative values.

29. A mobile station according to claim 28, wherein the processing means is configured such that the computing of said estimates of the Doppler spreads comprises determining a value indicative of the received powers of said radio signals.

30. A mobile station according to claim 29, wherein the processing means is configured such that the Doppler spread estimates are each calculated by determining the square root of the result of dividing twice the corresponding variance by the value indicative of the received power of the respective radio signal.

31. A mobile station according to claim 25, wherein the processing means is configured such that the Doppler spread estimates are each calculated in accordance with the formula:

32. A method according to claim 25, wherein the processing means is configured such that the speed of the mobile station is calculated in accordance with the formula:

33. A method according to claim 25, wherein the processing means is configured such that the speed of the mobile station is calculated as the mean of speeds calculated for a plurality of said signals in accordance with the formula:

34. A method according to claim 25, wherein the processing means is configured such that the speed of the mobile station is calculated as a weighted sum of speeds calculated for a plurality of said signals in accordance with the formula:

35. A method according to claim 25, wherein the processing means is configured such that the speed of the mobile station is calculated as the median of speeds calculated for a plurality of said signals in accordance with the formula:

36. A mobile station of a MIMO, SIMO or MISO wireless communication network, the mobile station including radio receiver means having at least one antenna for concurrently receiving a plurality radio signals and outputting corresponding baseband signals and processing means for processing said baseband signals, wherein the processing means is configured for estimating the Doppler spread of a radio signal by:

deriving first and second values for the derivative of the envelope of the path transfer function for each radio signal;

computing first and second estimates of the Doppler spread of each of said radio signals from said derivative values; and

deriving a value for the speed of said mobile station from said Doppler spread estimates.

37. A mobile station according to claim 36, wherein said processing means is configured such that said first value for the derivative of the envelope of each of said radio signals is derived by derived by low-pass filtering an envelope signal representing the corresponding path transfer function envelope to band limit it and filtering the band-limited envelope signal using an IIR or FIR filter and said second value for the derivative of the envelope of each of said radio signals is derived by low-pass filtering an envelope signal representing the path transfer function envelope to band limit it and filtering the band-limited envelope signal using an IIR or FIR filter, the first values being derived using a low-pass filter characteristic having a lower cut-off frequency than that of the low-pass filter characteristic used for deriving said second values.

38. A mobile station according to claim 37, wherein the processing means is configured such that the low-pass filtering for the first values is followed by downsampling.

39. A mobile station according to claim 36, wherein the radio receiver means outputs said baseband signals as sequences of samples representing the respective path transfer function envelopes.

40. A mobile station according to claim 37, wherein the processing means is configured such that the computing of said first and second estimates of the Doppler spreads comprises determining the variances of said first and second derivative values respectively.

41. A mobile station according to claim 40, wherein the processing means is configured such that the computing of each of said estimates of the Doppler spread comprises determining a value indicative of the received power of the corresponding radio signal.

42. A mobile station according to claim 41, wherein the processing means is configured such that the first and second Doppler spread estimates are calculated by determining the square root of the result of dividing twice the respective variance by said value indicative of the received power of the respective radio signal.

43. A mobile station according to claim 37, wherein the processing means is configured such that the Doppler spread estimates are each calculated in accordance with the formula:

44. A mobile station according to claim 36, wherein the processing means is configured for deriving first and second speed estimates values from the first and second Doppler spreads respectively and selecting the first or second speed estimate value in dependent on the magnitude of the first or second speed estimate value to provide said speed estimate.

45. A mobile station according to claim 44, wherein the processing means is configured such that the first and second speed estimates are calculated in accordance with the formula:

46. A mobile station according to claim 44, wherein the processing means is configured such that the first and second speed estimates are calculated as the mean of speeds calculated for a plurality of said signals in accordance with the formula:

47. A mobile station according to claim 44, wherein the processing means is configured such that the first and second speed estimates are calculated as a weighted sum of speeds calculated for a plurality of said signals in accordance with the formula:

48. A mobile station according to claim 44, wherein the processing means is configured such that the first and second speed estimates are calculated as the median of speeds calculated for a plurality of said signals in accordance with the formula: