Synchronization for cellular telecommunications network

• US 6,373,834 B1
• Filed: 06/11/1998
• Issued: 04/16/2002
• Est. Priority Date: 12/19/1997
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Nesic, Jasmina, Lundh, Peter Carl Birger
• Primary Examiner(s): Vincent, David R.
• Assistant Examiner(s): Phunkulh, Bob A.
• Application Number:
  US09/095,585
• Time in Patent Office: 1,405 Days
• Field of Search: 370/328, 370/329, 370/335, 370/336, 370/337, 370/342, 370/389, 370/395, 370/345, 370/347, 370/350, 370/498, 370/503, 370/509, 370/510, 370/310.1, 370/310.2, 375/356, 375/358, 455/502
• US Class Current: 370/350
• CPC Class Codes: H04B 7/269 Master/slave synchronisation
• CPC Class Codes: H04J 3/0667 Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays arrangements for monitoring round trip delays in packet switching networks H04L43/0864
• CPC Class Codes: H04J 3/0697 Synchronisation in a packet node

Abstract

Synchronization is effected in a cellular telecommunications network (20) between a master timing unit (60) located at control node (30) of the network and a slave timing unit (STU) located either at the control node or a controlled node, e.g., base station (22), of the network. In accomplishing the synchronization, one of the master timing unit or the slave timing unit serves as an initiating timing unit for transmitting a synchronization analysis command message including a first parameter (t₁) to the other of the timing units which serves as a responding timing unit. In response, the responding timing unit sends a synchronization analysis response message which includes at least second parameter (t₂) and preferably a third parameter (t₃) to the initiating timing unit. The initiating unit uses e.g., parameters extracted from the synchronization analysis response message to determine a synchronization adjustment value for the slave timing unit. When the master timing unit is the initiating timing unit, the master timing unit transmits the synchronization adjustment value in a synchronization updating command message to the slave timing unit.

Claims

1. A cellular telecommunications network comprising:

a master timing unit located at a control node of the network;

a slave timing unit located at the control node or a controlled node of the network;

wherein one of the master timing unit and the slave timing unit serves as an initiating timing unit for transmitting a synchronization analysis command message including a first parameter to a responding timing unit, the responding timing unit being the other of the master timing unit and the slave timing unit the first parameter being a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit;

wherein in response to the synchronization analysis command the responding timing unit sends a synchronization analysis response message including a second parameter to the initiating timing unit, the second parameter being a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit;

wherein the initiating timing unit uses the first parameter and the second parameter included in the synchronization analysis response message to determine a synchronization adjustment for the slave timing unit.

2. The network of claim 1, wherein the initiating timing unit is the master timing unit, and wherein the master timing unit transmits the synchronization adjustment in a synchronization adjustment command message to the slave timing unit.

3. The network of claim 1, wherein the initiating timing unit is the slave timing unit, and wherein the slave timing unit uses the synchronization adjustment value to synchronize a clock of the slave timing unit with a clock of the master timing unit.

4. The network of claim 1, wherein the synchronization adjustment is a synchronization offset value.

5. The network of claim 1, wherein the initiating timing unit is located in a control node that controls a base station node, and the responding timing unit is located in the base station node.

6. The network of claim 1, wherein the responding timing unit is located in a control node that controls a base station node, and the initiating timing unit is located in the base station node.

7. The network of claim 1, wherein the initiating timing unit is located in a control node that controls a base station node.

8. The network of claim 1, wherein the network is code division multiple access (CDMA) cellular telecommunications network, and wherein the slave timing unit is located in a diversity handover unit situated at the control node.

9. The network of claim 1, wherein at least one of the synchronization analysis command message, the synchronization analysis message, and the synchronization adjustment command message are encapsulated in an asynchronous transfer mode (ATM) cell.

10. The network of claim 1, wherein prior to transmitting the synchronization adjustment command message, wherein the initiating timing unit is the master timing unit, wherein the master timing unit uses the synchronization analysis message to determine whether a slave counter value maintained by a slave counter in the slave timing unit is within a predetermined range of a master counter value maintained by a master counter in the master timing unit, and wherein if the slave counter value is not within the predetermined range of the master counter value, the master timing unit sends a set slave counter command message for loading a value related to the master counter value in the slave counter.

11. The network of claim 10, wherein if the slave counter value is not within the predetermined range of the master counter value, the master timing unit sends a series of synchronization analysis messages to the slave timing unit, and using a corresponding series of synchronization analysis messages determines a mean value of the round trip delay (RTD).

12. The network of claim 1, wherein the initiating timing unit transmits a series of synchronization analysis command messages and wherein the responding timing unit responsively sends a corresponding series of synchronization analysis response messages, and wherein the initiating timing unit performs at least one of filtering and averaging of parameter values ascertained from the synchronization analysis response messages to determine an appropriate synchronization adjustment value for the slave timing unit.

13. The network of claim 1, wherein the synchronization analysis response message includes both the first parameter and the second parameter.

14. A cellular telecommunications network comprising:

a master timing unit located at a control node of the network;

a slave timing unit located at the control node or a controlled node of the network;

wherein one of the master timing unit and the slave timing unit serves as an initiating timing unit for transmitting a synchronization analysis command message including a first parameter to a responding timing unit, the responding timing unit being the other of the master timing unit and the slave timing unit;

wherein in response to the synchronization analysis command the responding timing unit sends a synchronization analysis response message including a second parameter to the initiating timing unit;

wherein the initiating timing unit determines a synchronization adjustment for the slave timing unit by using the first parameter and the second parameter included in the synchronization analysis response message and by comparing the second parameter included in the synchronization analysis response message with a predicted second parameter.

15. The network of claim 14, wherein the first parameter is a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit and the second parameter is a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit.

16. The network of claim 15, wherein the synchronization analysis response message sent by the responding timing unit to the initiating timing unit includes a third time stamp value t₃ related to the time that the synchronization analysis response message is sent from the responding timing unit, wherein the initiating timing unit determines a fourth time stamp value t₄ indicative of a time of reception of the synchronization sequence response message at the initiating timing unit, and wherein the predicted second time stamp value t_2-predicted is determined as:

17. The network of claim 16, wherein the synchronization adjustment value is determined as t_2-predicted−

t₂.

18. A cellular telecommunications network comprising:

a master timing unit located at a control node of the network;

a slave timing unit located at the control node or a controlled node of the network;

wherein one of the master timing unit and the slave timing unit serves as an initiating timing unit for transmitting a synchronization analysis command message including a first parameter to a responding timing unit, the responding timing unit being the other of the master timing unit and the slave timing unit;

wherein in response to the synchronization analysis command the responding timing unit sends a synchronization analysis response message including a second parameter to the initiating timing unit;

wherein the initiating timing unit determines a synchronization adjustment for the slave timing unit by using the first parameter and the second parameter included in the synchronization analysis response message and by comparing the first parameter included in the synchronization analysis response message with predicted first parameter.

19. The network of claim 18, wherein the first parameter is a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit and the second parameter is a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit.

20. The network of claim 19, wherein the synchronization analysis response message sent by the responding timing unit to the initiating timing unit includes a third time stamp value t₃ related to the time that the synchronization analysis response message is sent from the responding timing unit, wherein the initiating timing unit determines a fourth time stamp value t₄ indicative of a time of reception of the synchronization sequence response message at the initiating timing unit, and wherein the predicted first time stamp value t_1-predicted is determined as:

21. The network of claim 20, wherein the synchronization adjustment is determined as t_1-predicted−

t₁.

22. A method of operating cellular telecommunications network comprising:

transmitting a synchronization analysis command message including a first parameter from an initiating timing unit to a responding timing unit, the initiating timing unit being one of a master timing unit located at control node of the network and a slave timing unit located at the control node or a controlled node of the network, the responding timing unit being the other of the master timing unit and the slave timing unit, the first parameter being a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit;

sending from the responding timing unit to the initiating timing unit, and in response to the synchronization analysis command message, a synchronization analysis response message including a second parameter, the second parameter being a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit;

using, at the initiating time unit, the first parameter and the second parameter included in the synchronization analysis response message to determine a synchronization adjustment value for the slave timing unit.

23. The method of claim 22, wherein the initiating timing unit is the master timing unit, and wherein the method further comprises transmitting the synchronization adjustment value in a synchronization adjustment command message to the slave timing unit.

24. The method of claim 22, wherein the synchronization adjustment is a synchronization offset value.

25. The method of claim 22, wherein the initiating timing unit is located in a control node that controls a base station node, and the responding timing unit is located in the base station node.

26. The method of claim 22, wherein the responding timing unit is located in a control node that controls a base station node, and the initiating timing unit is located in the base station node.

27. The method of claim 22, wherein the master timing unit is located in a control node that controls a base station node.

28. The method of claim 22, wherein the network is code division multiple access (CDMA) cellular telecommunications network, and wherein the slave timing unit is located in a diversity handover unit situated at the control node.

29. The method of claim 22, further comprising encapsulating at least one of the synchronization analysis command message, the synchronization analysis response message, and the synchronization adjustment command message in an asynchronous transfer mode (ATM) cell.

30. The method of claim 22, further comprising, prior to transmitting the synchronization adjustment command message, the steps of:

using the synchronization analysis response message to determine whether a slave counter value maintained by a slave counter in the slave timing unit is within a predetermined range of a master counter value maintained by a master counter in the master timing unit; and

if the slave counter value is not within the predetermined range of the master counter value, sending from the master timing unit a set slave counter command message for loading a value related to the master counter value in the slave counter.

31. The method of claim 30, further comprising, if the slave counter value is not within the predetermined range of the master counter value, the steps of:

sending from the master timing unit a series of synchronization analysis command messages to the slave timing unit;

using a corresponding series of synchronization analysis return messages to determine a mean value of the round trip delay (RTD).

32. The method of claim 22, further comprising

transmitting, from the initiating timing unit, a series of synchronization analysis command messages;

responsively sending, from the responding timing unit, a corresponding series of synchronization analysis response messages; and

performing at least one of filtering and averaging of parameter values ascertained from the synchronization analysis response messages to determine an appropriate synchronization adjustment value for the slave timing unit.

33. The method of claim 22, further comprising including in the synchronization analysis response message both the first parameter and the second parameter.

34. A method of operating cellular telecommunications network comprising:

transmitting a synchronization analysis command message including a first parameter from an initiating timing unit to a responding timing unit, the initiating timing unit being one of a master timing unit located at control node of the network and a slave timing unit located at the control node or a controlled node of the network, the responding timing unit being the other of the master timing unit and the slave timing unit;

sending from the responding timing unit to the initiating timing unit, and in response to the synchronization analysis command message, a synchronization analysis response message including a second parameter;

determining, at the initiating time unit, a synchronization adjustment value for the slave timing unit by using the first parameter and the second parameter included in the synchronization analysis response message and by comparing the second parameter included in the synchronization analysis response message with a predicted second parameter.

35. The method of claim 34, wherein the first parameter is a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit and the second parameter is a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit.

36. The method of claim 35, wherein the method further comprises:

including in the synchronization analysis message sent by the responding timing unit to the initiating timing unit a third time stamp value t₃ related to the time at which the synchronization analysis response message is sent from the responding timing unit; and

determining at the initiating timing unit a fourth time stamp value t₄ indicative of a time of reception of the synchronization a analysis response message at the initiating timing unit; and

determining the predicted second time stamp value t_2-predicted using the following relation;

37. The method of claim 36, wherein the synchronization adjustment value is determined as t_2-predicted−

t₂.

38. A method of operating cellular telecommunications network comprising:

transmitting a synchronization analysis command message including a first parameter from an initiating timing unit to a responding timing unit, the initiating timing unit being one of a master timing unit located at control node of the network and a slave timing unit located at the control node or a controlled node of the network, the responding timing unit being the other of the master timing unit and the slave timing unit;

sending from the responding timing unit to the initiating timing unit, and in response to the synchronization analysis command message, a synchronization analysis response message including a second parameter;

determining, at the initiating time unit, a synchronization adjustment value for the slave timing unit by using the first parameter and the second parameter included in the synchronization analysis response message and by comparing the first parameter included in the synchronization analysis response message with a predicted first parameter.

39. The method of claim 38, wherein the first parameter is a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit and the second parameter is a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit.

40. The method of claim 39, wherein the method further comprises:

including in the synchronization analysis message sent by the responding timing unit to the initiating timing unit a third time stamp value t₃ related to the time at which the synchronization analysis response message is sent from the responding timing unit; and

determining at the initiating timing unit a fourth time stamp value t₄ indicative of a time of reception of the synchronization analysis response message at the initiating timing unit; and

determining the predicted first time stamp value t_1-predicted using the following relation;

41. The method of claim 40, wherein the synchronization adjustment value is determined as t_1-predicted−

t₁.

42. A cellular telecommunications network comprising:

a master timing unit located at control node of the network;

a slave timing unit located at the control node or a controlled node of the network;

wherein one of the master timing unit and the slave timing unit serves as an initiating timing unit for transmitting a synchronization analysis command message including a first parameter to a responding timing unit, the responding timing unit being the other of the master timing unit and the slave timing unit;

wherein in response to the synchronization analysis command the responding timing unit sends a synchronization analysis response message including a second parameter to the initiating timing unit, the second parameter indicative of a time at which the synchronization analysis command message was received at the responding timing unit;

wherein the initiating timing unit uses the synchronization analysis response message to determine a synchronization adjustment for the slave timing unit.

43. A method of operating cellular telecommunications network comprising:

transmitting a synchronization analysis command message including a first parameter from an initiating timing unit to a responding timing unit, the initiating timing unit being one of a master timing unit located at control node of the network and a slave timing unit located at the control node or a controlled node of the network, the responding timing unit being the other of the master timing unit and the slave timing unit;

sending from the responding timing unit to the initiating timing unit, and in response to the synchronization analysis command message, a synchronization analysis response message including a second parameter indicative of when the synchronization analysis command message was received at the responding timing unit;

using the synchronization analysis response message at the initiating timing unit to determine a synchronization adjustment value for the slave timing unit.

44. A cellular telecommunications network comprising:

a master timing unit located at control node of the network;

a slave timing unit located at the control node or a controlled node of the network;

wherein one of the master timing unit and the slave timing unit serves as an initiating timing unit for transmitting a synchronization analysis command message including a first parameter to a responding timing unit, the responding timing unit being the other of the master timing unit and the slave timing unit;

wherein in response to the synchronization analysis command the responding timing unit sends a synchronization analysis response message including a second parameter to the initiating timing unit;

wherein the initiating timing unit uses the synchronization analysis response message to determine a synchronization adjustment for the slave timing unit; and

wherein the initiating timing unit determines the synchronization updating value by comparing the second parameter included in tie synchronization analysis response message with a predicted second parameter.

45. The network of claim 44, wherein the first parameter is a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit and the second parameter is a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit.

46. A cellular telecommunications network comprising:

a master timing unit located at control node of the network;

a slave timing unit located at the control node or a controlled node of the network;

wherein one of the master timing unit and the slave timing unit serves as an initiating timing unit for transmitting a synchronization analysis command message including a first parameter to a responding timing unit, the responding timing unit being the other of the master timing unit and the slave timing unit;

wherein in response to the synchronization analysis command the responding timing unit sends a synchronization analysis response message including a second parameter to the initiating timing unit;

wherein the first parameter is a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit and the second parameter is a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit;

wherein the initiating timing unit uses the synchronization analysis response message to determine a synchronization adjustment for the slave timing unit;

wherein the synchronization analysis response message sent by the responding timing unit to the initiating timing unit includes a third time stamp value t₃ related to the time that the synchronization analysis response message is sent from the responding timing unit, wherein the initiating timing unit determines a fourth time stamp value t₄ indicative of a time of reception of the synchronization sequence response message at the initiating timing unit, and wherein the predicted second time stamp value t_2-predicted is determined as;

47. The network of claim 46, wherein the synchronization adjustment value is determined as t_2-predicted−

t₂.

48. A cellular telecommunications network comprising:

a master timing unit located at control node of the network;

a slave timing unit located at the control node or a controlled node of the network;

wherein one of the master timing unit and the slave timing unit serves as an initiating timing unit for transmitting a synchronization analysis command message including a first parameter to a responding timing unit, the responding timing unit being the other of the master timing unit and the slave timing unit;

wherein in response to the synchronization analysis command the responding timing unit sends a synchronization analysis response message including a second parameter to the initiating timing unit;

wherein the initiating timing unit uses the synchronization analysis response message to determine a synchronization adjustment for the slave timing unit; and

wherein the initiating timing unit determines the synchronization updating value by comparing the first parameter included in the synchronization analysis response message with a predicted first parameter.

49. The network of claim 48, wherein the first parameter is a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit and the second parameter is a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit.

50. The network of claim 49, wherein the synchronization analysis response message sent by the responding timing unit to the initiating timing unit includes a third time stamp value t₃ related to the time that the synchronization analysis response message is sent from the responding timing unit, wherein the initiating timing unit determines a fourth time stamp value t₄ indicative of a time of reception of the synchronization sequence response message at the initiating timing unit, and wherein the predicted first time stamp value t_1-predicted is determined as:

51. The network of claim 50, wherein the synchronization adjustment value is determined as t_1-predicted−

t₁.

52. A method of operating cellular telecommunications network comprising:

transmitting a synchronization analysis command message including a first parameter from an initiating timing unit to a responding timing unit, the initiating timing unit being one of a master timing unit located at control node of the network and a slave timing unit located at the control node or a controlled node of the network, the responding timing unit being the other of the master timing unit and the slave timing unit;

sending from the responding timing unit to the initiating timing unit, and in response to the synchronization analysis command message, a synchronization analysis response message including a second parameter;

using the synchronization analysis response message at the initiating timing unit to determine a synchronization adjustment value for the slave timing unit;

wherein the first parameter is a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit and the second parameter is a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit;

including in the synchronization analysis message sent by the responding timing unit to the initiating timing unit a third time stamp value t₃ related to the time at which the synchronization analysis response message is sent from the responding timing unit; and

determining at the initiating timing unit a fourth time stamp value t₄ indicative of a time of reception of the synchronization analysis response message at the initiating timing unit; and

determining the predicted second time stamp value t_2-predicted using the following relation;

53. The method of claim 52, wherein the synchronization adjustment value is determined as t_2-predicted−

t₂.

54. A method of operating cellular telecommunications network comprising:

transmitting a synchronization analysis command message including a first parameter from an initiating timing unit to a responding timing unit, the initiating timing unit being one of a master timing unit located at control node of the network and a slave timing unit located at the control node or a controlled node of the network, the responding timing unit being the other of the master timing unit and the slave timing unit;

sending from the responding timing unit to the initiating timing unit, and in response to the synchronization analysis command message, a synchronization analysis response message including a second parameter;

using the synchronization analysis response message at the initiating timing unit to determine a synchronization adjustment value for the slave timing unit;

wherein the first parameter is a first time stamp value t₁ related to the time that the synchronization analysis command message is transmitted from the initiating timing unit and the second parameter is a second time stamp value t₂ related to the time that the synchronization analysis command message is received at the responding timing unit;

including in the synchronization analysis message sent by the responding timing unit to the initiating timing unit a third time stamp value t₃ related to the time at which the synchronization analysis response message is sent from the responding timing unit; and

determining at the initiating timing unit a fourth time stamp value t₄ indicative of a time of reception of the synchronization analysis response message at the initiating timing unit; and

determining the predicted first time stamp value t_1-predicted using the following relation;

55. The method of claim 54, wherein the synchronization adjustment value is determined as t_1-predicted−

t₁.