Method and apparatus for synchronizing base stations

• US 20030147362A1
• Filed: 12/18/2002
• Published: 08/07/2003
• Est. Priority Date: 02/05/2002
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Dick, Stephen G., Miller, James M.
• Granted Patent: US 7,813,311 B2
• Time in Patent Office: Days
• US Class Current: 370/324
• CPC Class Codes: H04B 7/2687 Inter base stations synchronisation
• CPC Class Codes: H04B 7/269 Master/slave synchronisation

Abstract

Method and apparatus for synchronizing base stations employing an independent synchronizing source or identifying a base station as a master source. An RNC (C-RNC) or a base station may designate one base station or a UE to acquire measurements derived from base stations to achieve synchronization. Synchronization activities may be regularly scheduled or may be undertaken when periodic measurements indicate that a drift value exceeds a given threshold.

Claims

1. A method for time synchronizing a plurality of base stations in a wireless communication system, comprising:

a) detecting at least one of a plurality of out-of-sync base stations;

b) measuring a plurality of cell timing signals; and

c) correcting the at least one of a plurality of out-of-sync base stations.

2. The method of claim 1 wherein the step (a) comprises:

d) updating a covariant matrix database; and

e) determining at least one out-of-sync base station from the plurality of cell timing signals.

3. The method of claim 1 wherein step (b) comprises:

sending a request for a base station time of arrival (BSTOA) value from a radio network controller (RNC) to at least one of the out-of-sync base stations; and

transmitting said BSTOA value.

4. The method of claim 2 wherein step (b) comprises:

sending a request for a base station time of arrival (BSTOA) value from a radio network controller (RNC) to at least one of the out-of-sync base stations; and

transmitting said BSTOA value.

5. The method of claim 1 wherein the step (b) comprises:

f) sending a request for a base station time of arrival (BSTOA) value from a radio network controller'"'"'s (RNC'"'"'s) to at least one of a plurality of user equipment (UE) to measure the out-of-sync base stations; and

g) transmitting said BSTOA value.

6. The method of claim 2 wherein the step (b) comprises:

f) sending a request for a base station time of arrival (BSTOA) value from a radio network controller'"'"'s (RNC'"'"'s) to at least one of a plurality of User Equipment to measure the out-of-sync base stations; and

g) transmitting said BSTOA value.

7. The method of claim 3 wherein the step (c) correcting comprises:

comparing said BSTOA value with a stored BSTOA value;

generating a correction message;

transmitting said correction message to the out-of-sync base station;

transmitting a report from the out-of-sync base station to said RNC; and

updating said covariant matrix database.

8. The method of claim 4 wherein the step (c) correcting comprises:

comparing said BSTOA value with a stored BSTOA value;

generating a correction message;

transmitting said correction message to the out-of-sync base station;

transmitting a report from the out-of-sync base station to said RNC; and

updating said covariant matrix database.

9. The method of claim 7 further comprising maintaining the covariant matrix database on said RNC.

10. The method of claim 8 further comprising maintaining the covariant matrix database on said RNC.

11. The method of claim 9 wherein at least one out-of-sync base station or at least one UE is under control of at least two different RNCs, the method further comprising:

establishing a communications path between the at least two different RNCs; and

performing base station synchronizing.

12. The method of claim 10 wherein at least one out-of-sync base station or at least one UE is under control of at least two different RNCs, the method further comprising:

establishing a communications path between the at least two different RNCs; and

performing base station synchronizing.

13. A method for autonomous time synchronizing a pair of base stations in a wireless communication system, comprising:

detecting an adjacent out-of-sync base station;

measuring a plurality of cell timing signals; and

correcting the adjacent out-of-sync base station from values obtained from a RNC'"'"'s database.

14. A method for time synchronizing at least one of a plurality of base stations with an independent time reference in a wireless communication system, comprising:

generating a time synchronization message from a covariant matrix database and said independent time reference; and

transmitting the time synchronization message to at least one of a plurality of base stations.

15. A method for frequency synchronizing at least one of a plurality of base stations with an independent frequency reference in a wireless communication system, comprising:

generating a frequency synchronization message from a covariant matrix database and said independent frequency reference; and

transmitting said frequency synchronization message to at least one of a plurality of base stations.

16. A method for providing one of time and frequency synchronization in a plurality of slave base stations in a wireless communication system wherein an RNC estimates a plurality of correction values from a covariant matrix database, comprising:

synchronizing a time reference in a plurality of slave base stations;

generating estimates of a plurality of time and frequency values from said covariant matrix database; and

transmitting said plurality of time and frequency values to the plurality of slave base stations.

17. A method for time synchronizing a plurality of base stations in a wireless communication system minimizes a number of service interruptions, comprising:

a) scheduling a plurality of cell timing measurements of at least one of a plurality of base stations;

b) making said cell timing measurements;

c) developing a plurality of time drift factor values for the at least one of the plurality of base stations; and

d) scheduling periodic time update transmissions to the at least one of the plurality of base stations.

18. The method of claim 17 wherein step (b) comprises:

blanking a downlink physical synchronization channel in said plurality of base stations;

receiving a burst signal in one of a plurality of base stations; and

measuring said burst signal at said one of said plurality of base stations.

19. The method of claim 17 wherein step (d) comprises determining periodic time updates based upon the relationship of a drift value to a maximum allowable time difference.

20. A method for frequency synchronizing a plurality of base stations in a wireless communication system using a minimum number of service interruptions, comprising:

scheduling a plurality of frequency measurements of at least one of a plurality of base stations;

making said cell timing measurements;

developing a plurality of frequency drift pattern values for the at least one of the plurality of base stations; and

scheduling periodic frequency update transmissions to the at least one of the plurality of base stations.

21. The method of claim 20 wherein the step of making comprises:

blanking a downlink physical synchronization channel in said plurality of base stations;

receiving a burst signal in one of a plurality of base stations; and

measuring said burst signal at the one of a plurality of base stations.

22. A base station (BS) for a wireless digital system with the ability to time synchronize to at least one of a plurality of other base stations, said base station comprising:

means for detecting at least one of a plurality of out-of-sync base stations;

means for measuring a plurality of cell timing signal values; and

means for correcting the at least one of out-of-sync base stations.

23. The base station of claim 22 wherein said means for detecting includes:

updating a covariant matrix database with the plurality of cell timing signal values; and

further means for determining an out-of-sync base station from at least one of plurality cell timing signals.

24. The base station of claim 22 wherein said out-of-sync base station has means to measure and send a base station time of arrival (BSTOA) value.

25. The base station of claim 23 wherein said out-of-sync base station has means to measure and send a base station time of arrival (BSTOA) value.

26. The base station of claim 24 wherein said means for correcting includes:

means to compare the at least one out-of-sync base statiQon'"'"'s BSTOA value with a stored BSTOA value found in said covariant matrix database; and

said out-of-sync base station having;

means to receive a correction message and responding by transmitting a report and means for the out-of-sync base station to update the covariant matrix database from data from said report.

27. The base station of claim 25 wherein said means for correcting includes:

means to compare the at least one out-of-sync base station'"'"'s BSTOA value with a stored BSTOA value found in said covariant matrix database; and

said out-of-sync base station having;

means to receive a correction message and responding by transmitting a report and means for the out-of-sync base station to update the covariant matrix database from data from said report.

28. A base station (BS) for a wireless digital system with the ability to time synchronize a plurality of out-of-sync slave base stations to a master base station, said master base station comprising:

means for detecting at least one of a plurality of out-of-sync slave base stations;

means to measure a plurality of cell timing signals; and

means to correct the at least one of a plurality of out-of-sync slave base stations.

29. A base station (BS) for a wireless digital system with the ability to frequency synchronize a plurality of out-of-sync slave base stations to a master base station, said master base station comprising:

means for detecting at least one of a plurality of out-of-sync slave base stations;

means to measure a plurality of cell timing signals; and

means to correct the at least one of a plurality of out-of-sync slave base stations.

30. A base station (BS) for a wireless digital system with the ability to time synchronize a plurality of other base stations to an independent time reference, said base station comprising:

means for generate a time synchronization message; and

means to transmit to a plurality of other base stations said time synchronization message.

31. A base station (BS) for a wireless digital system with the ability to frequency synchronize a plurality of other base stations to an independent frequency reference, said base station comprising:

means for generating at a frequency synchronization message; and

means to transmit to a plurality of other base stations said frequency synchronization message.

32. A base station (BS) for a wireless digital system with the ability to time synchronize a plurality of other base stations, said base station comprising:

means to schedule a plurality of time sync measurements from at least one of a plurality of other base stations;

means to develop a time sync drift pattern for the at least one of the plurality of other base stations and; and

means to schedule periodic update transmissions to the at least one of the plurality of other base stations.

33. The base station of claim 32, comprising:

means for blanking a plurality of downlink physical synchronization channels in a plurality of base stations; and

means to send a burst signal to at least one of said plurality of base stations to measure a BSTOA value from at least one of said plurality of base stations.

34. A base station (BS) for a wireless digital system with the ability to time synchronize a plurality of other base stations and which minimizes service interruption needed to time synchronize, said base station comprising:

means to schedule a plurality of time sync measurements from at least one of a plurality of other base stations;

means to develop a time sync drift pattern for the at least one of the plurality of other base stations and; and

means for scheduling periodic frequency update transmissions to the at least one of the plurality of other base stations.

35. The base station of claim 34 further comprising:

means for blanking a plurality of downlink physical synchronization channels in a plurality of base stations; and

means for sending a burst signal to at least one of a plurality of base stations to measure a BSTOA value from at least one of a plurality of base stations.

43. The method of claim 34 wherein the step of measuring comprises:

sending a request for a base station time of arrival (BSTOA) value from the RNC to at least one of a plurality of User Equipment to measure the out-of-sync base stations; and

transmitting said BSTOA value to the RNC.

44. The method of claim 35 wherein the step of measuring comprises:

sending a request for a base station time of arrival (BSTOA) value from the RNC to at least one of a plurality of User Equipment to measure the out-of-sync base stations; and

transmitting said BSTOA value to the RNC.

45. The method of claim 43 wherein the step of correcting comprises:

comparing the BSTOA value with a stored BSTOA value within the RNC'"'"'s covariant matrix database;

transmitting a correction message to the out-of-sync base station;

transmitting a report from the out-of-sync base station to the RNC; and

updating the covariant matrix database.

46. The method of claim 44 wherein the step of correcting comprises:

comparing the BSTOA value with a stored BSTOA value within the RNC'"'"'s covariant matrix database;

transmitting a correction message to the out-of-sync base station;

transmitting a report from the out-of-sync base station to the RNC; and

updating the covariant matrix database.

47. The method of claim 45 wherein at least one out-of-sync base station or at least one UE is under control of at least two (2) different RNCs comprising the steps of:

establishing a communications path between the at least two different RNCs; and

performing time synchronizing.

48. The method of claim 46 wherein at least one out-of-sync base station or at least one UE is under control of at least two (2) different RNCs comprising the steps of:

establishing a communications path between the at least two different RNCs; and

performing time synchronizing.

36. A user equipment (UE) for a wireless digital system to synchronize one of a plurality of base stations in said system, said UE comprising:

means for receiving a request to synchronize a base station;

means for obtaining a BSTOA value for said one base station at least a remaining one of the plurality of base stations; and

means for transmitting said BSTOA values.

37. The UE of claim 36 having means for said plurality of base stations to be under control of a plurality of Radio Network Controllers (RNCs).

38. The UE of claim 37 further including means for transmitting the BSTOA values to one of the RNCS.

39. A method for time synchronizing in a wireless communication system, comprising:

detecting at least one of a plurality of out-of-sync base stations;

measuring a plurality of cell timing signals; and

correcting the at least one of a plurality of out-of-sync base stations.

40. The method of claim 39 wherein the step of detecting comprises:

updating a radio network controller'"'"'s (RNC'"'"'s) covariant matrix database; and

determining an out-of-sync base station from at least one of plurality cell timing signals.

41. The method of claim 40 wherein the step of measuring comprises:

sending a request for a base station time of arrival (BSTOA) value from the RNC to at least one of the out-of-sync base stations; and

transmitting said BSTOA value to the RNC.

42. The method of claim 41 wherein the step of measuring comprises:

sending a request for a base station time of arrival (BSTOA) value from the RNC to at least one of the out-of-sync base stations; and

transmitting said BSTOA value to the RNC.

49. A method for autonomous time synchronizing in a wireless communication system, the method comprising:

detecting an adjacent out-of-sync base station;

measuring a plurality of cell timing signals; and

correcting the at least one of a plurality of out-of-sync base stations from values from a RNC'"'"'s database.

50. A method for time synchronizing out-of-sync base stations to a master base station in a wireless communication system;

the method, comprising;

a) detecting at least one of said out-of-sync base stations;

b) measuring a plurality of cell timing signals; and

c) correcting the out-of-sync base stations based on step (b).

51. A method for frequency synchronizing one of a plurality of out-of-sync base stations to a master base station in a wireless communication system, comprising:

a) detecting said one of a plurality of out-of-sync base stations;

b) measuring a plurality of cell timing signals; and

c) correcting the at least one of a plurality of out-of-sync base stations based on step (b).

52. A method for time synchronizing base stations with predetermined time reference in a wireless communication system having an RNC;

comprising;

generating a time synchronization message from the RNC'"'"'s database; and

transmitting the time synchronization message to at least one of a plurality of base stations.

53. A method for frequency synchronizing base stations with a predetermined frequency reference in a wireless communication system having an RNC, comprising:

generating a frequency synchronization message from the RNC'"'"'s database; and

transmitting the time synchronization message to at least one of a plurality of base stations.

54. A method for obtaining one of time and frequency synchronization of base stations in a wireless communication system wherein an RNC estimates a plurality of correction values from a database, the method comprising:

synchronizing a time reference in a plurality of base stations;

generating estimates of a plurality of time and frequency values; and

transmitting the plurality of time and frequency values to the plurality of base stations.

55. The method of claim 54 wherein the RNC designates one of the base stations as a master base station and employs a given correction value to synchronize the plurality of base stations to said master base station.

56. A method for time synchronizing base stations in a wireless communication system in a reduced number of service interruptions, comprising:

scheduling a plurality of time sync measurements from at least one of the plurality of base stations;

developing a plurality of time sync drift pattern values for the at least one of the plurality of base stations; and

scheduling periodic update transmissions to the at least one of the plurality of base stations.

57. A method for frequency synchronizing base stations in a wireless communication system using a minimum number of service interruptions, comprising:

scheduling a plurality of frequency measurements from at least one of a plurality of base stations;

developing a plurality of frequency drift pattern values for the at least one of the plurality of base stations; and

scheduling periodic frequency update transmissions to the at least one of the plurality of base stations.

58. A method for providing one of time and frequency synchronization in a plurality of base stations in a wireless communication system wherein an RNC sends a correction value to a one of the plurality of base stations designated as a master station, comprising:

assigning a weight to each of the remaining base stations;

said master station sending a correction value to a highest weighted base station; and

the highest weighted base station sends a correction value to the next highest weighted base station.

59. The method of claim 58 wherein the remaining base stations having a weighted value less than the next highest weighted value receive correction values from a base station having a weighted value just above its weighted value and send correction values to the base station having a weighted value just below its weighted value.

60. A method for providing one of time and frequency synchronization in a plurality of base stations in a wireless communication system wherein an RNC sends a correction value;

said master base station sends correction values to all of the remaining base stations.