Adjustment of Link Adaptation Parameter Based on Data and Control Channel Load

• US 20120300742A1
• Filed: 03/09/2010
• Published: 11/29/2012
• Est. Priority Date: 03/09/2010
• Status: Active Grant

• Current Assignee: Vivo Mobile Communication Co., Ltd. (Vivo Communication Technology Co. Ltd.)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Eriksson, Erik, Jersenius, Kristina
• Granted Patent: US 9,247,460 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 1/0004 applied to control information
• CPC Class Codes: H04L 1/0005 applied to payload information
• CPC Class Codes: H04L 1/001 applied to control information
• CPC Class Codes: H04L 1/0011 applied to payload information
• CPC Class Codes: H04L 1/0021 in which the algorithm uses adaptive thresholds
• CPC Class Codes: H04L 1/0033 arrangements specific to the transmitter
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 72/52 based on load

Abstract

A method for performing link adaptation in association with scheduling a data channel for a cell in a base station of a cellular communication system, and an arrangement, suitable for performing such a method. The link adaptation method has link adaptation optimization purpose which is achieved by updating a link adaptation parameter on the basis of the load on the data channel and on the basis of the load of a control channel controlling the data channel in the cell. The method obtains a better trade-off between the spectral efficiency and the delay, due to re-transmissions.

Claims

1-22. -22. (canceled)

23. A method for performing link adaptation in association with scheduling a data channel for a cell in a base station of a cellular communication system, the method comprising:

optimising the link adaptation by updating a link adaptation parameter based on;

a load of the data channel; and

a load of a control channel controlling the data channel in the cell.

24. The method of claim 23:

wherein the load is defined as a state of the cell with respect to the channels;

wherein the cell is in one of;

a Non Limited state (NL);

a Control Channel Limited (CCL) state;

a Data Channel Limited (DCL) state.

25. The method of claim 24, further comprising:

a) performing a scheduling of the data channel resources;

b) determining the load of the data channel and the load of the control channel controlling the data channel;

c) updating the link adaptation parameter based on of the load in response to the loads indicating that the cell is in the CCL state or the DCL state.

26. The method of claim 25 wherein step c) is conditional based on corresponding scheduled users being estimated not to be power limited.

27. The method of claim 25:

further comprising repeating steps a) and b) for a pre-defined number of consecutive schedulings prior to executing step c);

wherein in step c) the link adaptation parameter is updated based on an average load, the average load being based on statistics on the load determinations executed in association with the pre-defined number of consecutive schedulings.

28. The method of claim 25 wherein step a) comprises making a scheduling decision subsequent to having performed a scheduling.

29. The method of claim 25 wherein steps a), b) and c) are repeated until, in step b), the load indicates:

that the cell is in the Non Limited state;

a state transition from the CCL state to the DCL state between two most recent schedulings;

or

a state transition from the DCL state to the CCL state between the two most recent schedulings.

30. The method of claim 29 further comprising making a scheduling decision based on a most recent scheduling.

31. The method of claim 25 wherein during step c), the link adaptation parameter is updated such that:

the link adaptation becomes more robust in response to the load indicating that the cell is in the CCL state;

the link adaptation parameter becomes more aggressive in response to the load indicating that the cell is in the DCL state.

32. The method of claim 25:

further comprising, prior to executing step a), defining a default link adaptation parameter value to be used as a starting value for the link adaptation parameter;

wherein the parameter adaptation in step c) is performed such that the link adaptation parameter;

is increased by a predetermined updating value, in response to the cell being in one of the DCL state and the CCL state;

is decreased by the predetermined updating value in response to the cell being in the other of the DCL state and the CCL state;

remains unchanged in response to the cell being in the NL state.

33. The method of claim 23 wherein the link adaptation parameter is a Block Error Rate target of the data channel of the cell.

34. A base station of a cellular communication system for performing link adaptation in association with scheduling a data channel for a cell of the base station, the base station comprising:

a scheduler configured to perform the scheduling;

an updating unit configured to perform an optimized link adaptation at the scheduler by updating a link adaptation parameter based on;

a load on the data channel; and

a load of a control channel controlling the data channel in the cell.

35. The base station of claim 34:

further comprising a load determining unit configured to determine load by determining a state of the cell with respect to the channels;

wherein the cell can be in a Non Limited (NL) state, a Control Channel Limited (CCL) state or a Data Channel Limited (DCL) state.

36. The base station of claim 35 wherein the updating unit is configured to, in response to the cell being in the CCL state or the DCL state, update the link adaptation parameter based on load determined by the load determining unit subsequent to a scheduling of the data channel resources being performed by the scheduler.

37. The base station according to claim 36:

wherein the scheduler is further configured to estimate whether or not users which have been scheduled by the scheduler are power limited; and

wherein the updating unit is further configured to update the link adaptation parameter only when the scheduled users are estimated not to be power limited.

38. The base station of claim 36:

wherein the scheduler is configured to perform a pre-defined number of consecutive schedulings;

the updating unit is configured to update the link adaptation parameter subsequent to the final scheduling of the pre-defined number of consecutive schedulings based on an average load;

wherein the load determining unit is configured to determine the average load based on statistics on load determinations executed in association with the pre-defined number of consecutive schedulings.

39. The base station of claim 36 wherein the scheduler is further configured to make a scheduling decision subsequent to having performed a scheduling.

40. The base station of claim 36:

wherein the scheduler is configured to perform at least one repeated scheduling in response to being provided with a link adaptation parameter update from the updating unit;

wherein the load determining unit is configured to instruct the updating unit to update the link adaptation parameter subsequent to a scheduling, until;

the scheduler indicates to the load determining unit that the cell is in the NL state;

the load determining unit recognises that a state transition from the CCL state to the DCL state has occurred between two most recent schedulings;

or

the load determining unit recognises that a state transition from the DCL state to the CCL state has occurred between the two most recent schedulings.

41. The base station of claim 40 wherein the scheduler is further configured to make a scheduling decision based on a most recent scheduling.

42. The base station of claim 35 wherein the updating unit is configured to update the link adaptation parameter such that:

the link adaptation becomes more robust in response to the load indicating that the cell is in the CCL state;

the link adaptation parameter becomes more aggressive in response to the load indicating that the cell is in the DCL state.

43. The base station of claim 35:

wherein a default link adaptation parameter value is initially defined as a starting value for the link adaptation parameter;

wherein the updating unit is further configured to;

increase the link adaptation parameter by a predetermined updating value in response to the load determining unit indicating that the cell is in one of the DCL state or the CCL state;

decrease the link adaptation parameter by the predetermined updating value in response to the load determining unit indicating that the cell is in the other one of the DCL state or the CCL state;

maintain the link adaptation parameter unchanged in response to the load determining unit indicating that the cell is in the NL state.

44. The base station of claim 34 wherein the link adaptation parameter is a Block error Rate target for the data channel of the cell.