Method for controlling exchanges of frames between a control unit and at least one radio station, and control unit for implementing the method

• US 20030219005A1
• Filed: 04/25/2003
• Published: 11/27/2003
• Est. Priority Date: 04/30/2002
• Status: Abandoned Application

• Current Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Dijkerman, Robert W., Tam, Shedman, Zhao, Jian G., Peng, Quanying, Ratovelomanana, Frederic, Isnard, Olivier, Calmel, Jean-Marie
• Application Number:
  US10/423,285
• Publication Number:
  US 20030219005A1
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: H04B 7/2678 Time synchronisation
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 92/10 between terminal device and access point, i.e. wireless air interface

Abstract

Each radio station (2) has a receiving window associated with each frame, positioned according to a time marker inserted in the said frame by a control unit (1). The frames include data frames (5), in which the time marker is inserted for synchronization with a radio terminal (4), and signalling frames. Each radio station indicates a data frame received outside the associated receiving window, and responds to a signalling frame by returning to the control unit a synchronization parameter representing a time of arrival of the said signalling frame. In a period of transmission of successive data frames: signalling frames are transmitted to each radio station simultaneously; returned synchronization parameters are processed; and times of transmission of successive data frames are controlled according to the processed parameters.

Claims

1. Method for controlling the transmission of frames from a control unit to at least one radio station, in which method each radio station has a respective receiving window associated with each frame, positioned in time according to a time marker inserted in the said frame by the control unit, in which method the frames include data frames, in which data frames the time marker is inserted by the control unit for synchronization with a radio terminal to which each radio station transmits data of the said data frames, and signalling frames, and in which method each radio station is arranged for indicating to the control unit a data frame received outside the associated receiving window, and for responding to a signalling frame by returning to the control unit a synchronization parameter representing a time of arrival of the said signalling frame with respect to the associated receiving window, the method including the following steps executed by the control unit in a period of transmission of successive data frames:

transmission of signalling frames to each radio station simultaneously;

processing of the returned synchronization parameters; and

controlling the times of transmission of successive data frames according to the processed parameters.

2. Method according to claim 1, in which the transmission of signalling frames to each radio station is periodic.

3. Method according to claim 2, in which the transmission of signalling frames to each radio station has a variable periodicity in time.

4. Method according to claim 1, in which the signalling frames are transmitted to each radio station in a proportion that depends on a number of frames returned to the control unit by at least some of the radio stations to indicate a data frame received outside the associated receiving window over a period of transmission of successive data frames.

5. Method according to claim 1, in which a transport link between the control unit and a radio station is determined as failing when the said radio station does not return to the control unit a synchronization parameter representing a time of arrival, in response to signalling frames.

6. Method according to claim 1, in which the said processing of synchronization parameters returned in response to a signalling frame includes a comparison of the said synchronization parameters at predetermined time-instants with respect to an associated time of arrival window endpoint.

7. Method according to claim 6, in which the said predetermined time-instants are start points of respectively the receiving window (TOAWS) and a receiving sub-window (RNCWS) positioned at the time of arrival window endpoint.

8. Method according to claim 7, in which RNCWS is set beforehand according to a service type requested by the said radio terminal.

9. Method according to claim 7, in which the processing of synchronization parameters returned in response to a signalling frame includes a determination, at the control unit, of an estimation of times of arrival, for each radio station, based on the last N synchronization parameters returned, where N is an integer that is greater than or equal to 1, and a determination among the said estimations of a maximum value TOAMX corresponding to the earliest time-instant estimation and a minimum value TOAMIN corresponding to the latest time-instant estimation, the two values TOAMIN and TOAMAX being able to be equal, in which method an adjustment value is determined, such as:

if TOAMAX−

TOAMIN is greater than TOAWS, the adjustment value is set at TOAWS−

TOAMAX;

if TOAMAX−

TOAMIN is less than or equal to TOAWS,

if TOAMIN is greater than RNCWS or if TOAMIN is negative,

if TOAMAX+(RNCWS−

TOAMIN) is less than or equal to TOAWS, the adjustment value is set at RNCWS−

TOAMIN,

if TOAMAX+(RNCWS−

TOAMIN) is greater than TOAWS, the adjustment value is set at TOAWS−

TOAMAX;

if TOAMIN is positive or zero and less than or equal to RNCWS,

if TOAMAX is less than or equal to TOAWS, the adjustment value is zero,

if TOAMAX is greater than TOAWS, the adjustment value is set at TOAWS−

TOAMAX;

and in which method the means for controlling times of transmission of successive data frames includes a translation according to the said determined adjustment value.

10. Method according to claim 9, in which the estimation of times of arrival for each radio station is a sliding average performed on the last N synchronization parameters returned by the said radio station.

11. Method according to claim 1, in which, after processing, the synchronization parameters returned to the control unit are modified, according to the same controlling means as for the times of transmission of successive data frames.

12. Method according to claim 1, in which, after processing of the synchronization parameters, a synchronization parameter returned to the control unit in response to a signalling frame transmitted by the control unit before the processing of the synchronization parameters is ignored.

13. Method according to claim 1, in which, after processing of the synchronization parameters returned to the control unit, a synchronization parameter returned to the control unit in response to a signalling frame transmitted by the control unit before processing of the synchronization parameters is modified, the said modification including the same controlling means as for the times of transmission of successive data frames.

14. Method for controlling the reception and combination of frames at a control unit, the frames being transmitted from at least one radio station, in which method the control unit has a receiving window associated with each frame, positioned in time according to a time marker inserted in the said frame by each radio station, in which method the frames include data frames, in which data frames the time marker is inserted by each radio station for synchronization with a radio terminal transmitting data of the said data frames, in which method the control unit is arranged for detecting a data frame received outside the associated receiving window, and for determining a time of arrival of a data frame with respect to the associated receiving window, and in which method the control unit is arranged for combining data frames received from at least some of the radio stations and containing the same time marker, at a date of expiry of a respective timer, and this, date of expiry is positioned in time according to the associated receiving window, the method including the following steps executed by the control unit in a period of reception of successive data frames:

processing of the determined times of arrival;

controlling the date of expiry of the timer according to the processed times of arrival.

15. Method according to claim 14, in which the said processing of the determined times of arrival includes a comparison of the said determined times of arrival of a data frame at predetermined time-instants with an associated time of arrival window endpoint.

16. Method according to claim 15, in which the said predetermined time-instants are start points respectively of the receiving window (ULTOAWS) and of a receiving sub-window (ULRNCWS) positioned at the time of arrival window endpoint.

17. Method according to claim 16, in which ULRNCWS is set beforehand according to a service type requested by the said radio terminal.

18. Method according to claim 16, in which the processing of times of arrival determined for a data frame includes a determination, at the control unit, of an estimation of times of arrival, for each radio station, of the last N determined times of arrival, where N is an integer greater than or equal to 1, and a determination, among the said estimations, of a maximum value ULTOAMAX corresponding to the earliest time-instant estimation and a minimum value ULTOAMIN corresponding to the latest time-instant estimation, the two values ULTOAMIN and ULTOAMAX being able to be equal, in which method an adjustment value is determined such as:

if ULTOAMAX−

ULTOAMIN is greater than ULTOAWS, the adjustment value is set at ULTOAWS−

ULTOAMAX;

if ULTOAMAX−

ULTOAMIN is less than or equal to ULTOAWS,

if ULTOAMIN is greater than ULRNCWS or if ULTOAMIN is negative,

if ULTOAMAX+(ULRNCWS−

ULTOAMIN) is less than or equal to ULTOAWS, the adjustment value is set at ULRNCWS−

ULTOAMIN,

if ULTOAMAX+(ULRNCWS−

ULTOAMIN) is greater than ULTOAWS, the adjustment value is set at ULTOAWS−

ULTOAMAX;

if ULTOAMIN is positive or zero and less than or equal to ULRNCWS,

if ULTOAMAX is less than or equal to ULTOAWS, the adjustment value is zero,

if ULTOAMAX is greater than ULTOAWS, the adjustment value is set at ULTOAWS−

ULTOAMAX;

and in which method the means for controlling the date of expiry of the timer according to the processed times of arrival includes a translation according to the said determined adjustment value.

19. Method according to claim 18, in which the estimation of times of arrival for a radio station is a sliding average performed on the last N times of arrival determined for the said radio station.

20. Method according to claim 14, in which, after processing, the times of arrival of data frames received at the control unit before processing are modified, according to the same controlling means as for the date of expiry of the timer.

21. Control unit including means of transmission of frames to at least one radio station and means of insertion of a time marker in each frame, each radio station having a respective receiving window associated with each frame, positioned in time according to the said time marker, the transmitted frames including data frames, in which data frames the time marker is inserted for synchronization with a radio terminal to which each radio station transmits the data of the said data frames, and signalling frames, the receiving unit additionally including means for receiving from each radio station an indication of reception of a data frame outside the associated receiving window and means of receiving a synchronization parameter returned by a radio station in response to a signalling frame, the said synchronization parameter representing a time of arrival of the said signalling frame with respect to the associated receiving window, the control unit including:

means for transmitting signalling frames to each radio station simultaneously, in a period of transmission of successive data frames;

means for processing the synchronization parameters returned; and

means for controlling the times of transmission of successive data frames according to processed parameters.

22. Control unit according to claim 21, in which the transmission of signalling frames to each radio station is periodic.

23. Control unit according to claim 22, in which the transmission of signalling frames to each radio station has a variable periodicity in time.

24. Control unit according to claim 21, in which the transmission of signalling frames to each radio station is in a proportion that depends on a number of frames returned to the control unit by at least some of the radio stations to indicate a data frame received outside the associated receiving window over a period of transmission of successive data frames.

25. Control unit according to claim 21, in which the means of processing of synchronization parameters returned in response to a signalling frame include a comparison of the said synchronization parameters at predetermined time-instants with respect to an associated time of arrival window endpoint.

26. Control unit according to claim 25, in which the $ said predetermined time-instants are start points of respectively the receiving window (TOAWS) and a receiving sub-window (RNCWS) positioned at the time of arrival window endpoint.

27. Control unit according to claim 26, in which RNCWS is set beforehand according to a service type requested by the said radio terminal.

28. Control unit according to claim 26, in which the means of processing of synchronization parameters returned in response to a signalling frame include a determination of an estimation of times of arrival, for each radio station, based on the last N synchronization parameters returned, where N is an integer that is greater than or equal to 1, and a determination among the said estimations of a maximum value TOAMX corresponding to the earliest time-instant estimation and a minimum value TOAMIN corresponding to the latest time-instant estimation, the two values TOAMIN and TOAMAX being able to be equal, the control unit additionally having means for determining an adjustment value such as:

if TOAMAX−

TOAMIN is greater than TOAWS, the adjustment value is set at TOAWS−

TOAMAX;

if TOAMAX−

TOAMIN is less than or equal to TOAWS,

if TOAMIN is greater than RNCWS or if TOAMIN is negative,

if TOAMAX+(RNCWS−

TOAMIN) is less than or equal to TOAWS, the adjustment value is set at RNCWS−

TOAMIN,

if TOAMAX+(RNCWS−

TOAMIN) is greater than TOAWS, the adjustment value is set at TOAWS−

TOAMAX;

if TOAMIN is positive or zero and less than or equal to RNCWS,

if TOAMAX is less than or equal to TOAWS, the adjustment value is zero,

if TOAMAX is greater than TOAWS, the adjustment value is set at TOAWS-TOAMAX;

and in which method the means for controlling the times of transmission of successive data frames include a translation according to the said determined adjustment value.

29. Control unit according to claim 28, in which the estimation of times of arrival for each radio station is a sliding average performed on the last N synchronization parameters returned by the said radio station.

30. Control unit according to claim 21, including means for modifying, after processing, the synchronization parameters returned, according to the same controlling means as for the times of transmission of successive data frames.

31. Control unit according to claim 21, including means for ignoring, after processing of the synchronization parameters, a synchronization parameter returned in response to a signalling frame transmitted before the processing of the synchronization parameters.

32. Control unit according to claim 21, including means for modifying, after processing of the returned synchronization parameters, a synchronization parameter returned to the control unit in response to a signalling frame transmitted by the control unit before processing of the synchronization parameters, the said modification including the same means for controlling as for the times of transmission of successive data frames.

33. Control unit including means for receiving and combining frames, the frames being transmitted from at least one radio station, the control unit having a receiving window associated with each frame, positioned in time according to a time marker inserted in the said frame by each radio station, the frames including data frames, in which data frames the time marker is inserted by each radio station for synchronization with a radio terminal transmitting data of the said data frames, the control unit having means for detecting a data frame received outside the associated receiving window, and for determining a time of arrival of a data frame with respect to the associated receiving window, the control unit additionally including means for combining data frames received from at least some of the radio stations and containing the same time marker, at a date of expiry of a respective timer, positioned in time according to the associated receiving window, the control unit also including:

means for processing the determined times of arrival, in a period of reception of successive data frames;

means for controlling the date of expiry of the timer according to the processed times of arrival.

34. Control unit according to claim 33, in which the means of processing of the determined times of arrival include a comparison of the said determined times of arrival of a data frame at predetermined time-instants with respect to an associated time of arrival window endpoint.

35. Control unit according to claim 34, in which the said predetermined time-instants are start points respectively of the receiving window (ULTOAWS) and of a receiving sub-window (ULRNCWS) positioned at the time of arrival window endpoint.

36. Control unit according to claim 35, in which ULRNCWS is set beforehand according to a service type requested by the said radio terminal.

37. Control unit according to claim 35, in which the means of processing of times of arrival determined for a data frame include a determination of an estimation of times of arrival, for each radio station, of the last N determined times of arrival, where N is an integer greater than or equal to 1, and a determination, among the said estimations, of a maximum value ULTOAMAX corresponding to the earliest time-instant estimation and a minimum value ULTOAMIN corresponding to the latest time-instant estimation, the two values ULTOAMIN and ULTOAMAX being able to be equal, the control unit additionally having means for determining an adjustment value such as:

if ULTOAMAX−

ULTOAMIN is greater than ULTOAWS, the adjustment value is set at ULTOAWS−

ULTOAMAX;

if ULTOAMAX−

ULTOAMIN is less than or equal to ULTOAWS,

if ULTOAMIN is greater than ULRNCWS or if ULTOAMIN is negative,

if ULTOAMAX+(ULRNCWS−

ULTOAMIN) is less than or equal to ULTOAWS, the adjustment value is set at ULRNCWS−

ULTOAMIN,

if ULTOAMAX+(ULRNCWS−

ULTOAMIN) is greater than ULTOAWS, the adjustment value is set at ULTOAWS−

ULTOAMAX;

if ULTOAMIN is positive or zero and less than or equal to ULRNCWS,

if ULTOAMAX is less than or equal to ULTOAWS, the adjustment value is zero,

if ULTOAMAX is greater than ULTOAWS, the adjustment value is set at ULTOAWS−

ULTOAMAX;

and in which method the means for controlling the date of expiry of the timer according to the processed times of arrival include a translation according to the said determined adjustment value.

38. Control unit according to claim 37, in which the estimation of times of arrival for a radio station is a sliding average performed on the last N times of arrival determined for the said radio station.

39. Control unit according to claim 33, including means for modifying, after processing, the times of arrival of data frames received at the control unit before processing, according to the same controlling means as for the date of expiry of the timer.