Power presetting in a radio communication system

• US 6,067,446 A
• Filed: 07/11/1996
• Issued: 05/23/2000
• Est. Priority Date: 07/11/1996
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Thornberg, Carl Magnus, Rahman, Anisur M., Persson, Anders H.ang.kan, Butovitsch, Paul Peter, Turcotte, Joseph Eric
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US08/678,313
• Time in Patent Office: 1,412 Days
• Field of Search: 455/69, 455/70, 455/67.1, 455/67.3, 455/522, 455/63, 370/252, 370/331, 370/332, 370/335, 370/342, 375/200, 375/206
• US Class Current: 455/69
• CPC Class Codes: H04W 52/18 TPC being performed according to specific parameters
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 distributing total power among users or channels
• CPC Class Codes: H04W 52/362 Aspects of the step size
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/44 in connection with interruption of transmission

Abstract

A radio communication method and system employs power level presetting to mitigate the increase in interference caused by the discontinuous transmission of mobile stations. In the downlink, power presetting entails detecting the entry (or removal) of mobile stations to a cell, and in response thereto, calculating a plurality of power adjustment values for each mobile station within the cell. In the uplink, power presetting entails estimating an increase in interference caused by the entry (or removal) of mobile stations to a cell, and using this estimate for calculating an updated power target for each mobile station within the cell. Power presetting is also initiated in response to one or more mobile stations switching from high data-rate mode to low data-rate mode, or vice versa.

Claims

1. A power control method for a radiocommunication system, including the steps of:

transmitting signals from a base station to each of a plurality of mobile stations using a respective plurality of transmitting power levels to satisfy predetermined target reception requirements at said respective mobile stations, said plurality of mobile stations forming a set of mobile stations;

detecting a change in said set of mobile stations; and

in response to said step of detecting, calculating a plurality of power preset adjustment values for application to said respective plurality of transmitting power levels, based on said predetermined target reception requirements which are known in advance of said change in said set of mobile stations, to compensate said plurality of transmitting power levels for said change in said set of mobile stations, wherein said calculating is preemptively performed to reduce disturbances in interference which would be caused by said change based on a predictive assessment of said disturbances in interference, wherein each of said power preset adjustment values is individually provided so that a corresponding mobile station will continue to have its target reception requirements met subsequent to said change in said set of mobile stations.

2. The power control method of claim 1, wherein said change in said set of mobile station comprises the introduction of at least one new mobile station to said set of mobile stations, or the removal of at least one mobile station from said set of mobile stations.

3. The power control method of claim 2, where said introduction of at least one mobile station occurs when at least one mobile station switches from a passive to an active state, and said removal of at least one mobile station occurs when at least one mobile station switches from an active to a passive state.

4. The power control method of claim 2, wherein said introduction of at least one mobile station occurs when at least one mobile station enters a cell associated with said base station, and said removal of at least one mobile station occurs when at least one mobile station leaves a cell associated with said base station.

5. The power control method of claim 1, wherein said change in said set of mobile stations includes a change in operating characteristics in at least one mobile station in said set.

6. The power control method of claim 5, wherein said change in operating characteristics in at least one station in said set comprises said one station switching from a low data-rate mode of operation to a high data-rate mode of operation, or from a high data-rate mode of operation to a low data-rate mode of operation.

7. The power control method of claim 1, wherein said plurality of reception requirements comprise a plurality of target signal-to-interference ratios associated with said plurality of mobile stations, wherein said method further includes the step of:

obtaining said plurality of target signal-to-interference ratios associated with said plurality of mobile stations, wherein said presetting step uses said plurality of signal-to-interference ratios to compute said plurality of power adjustment levels.

8. The power control method of claim 7, wherein said base station receives said plurality of signal-to-interference ratios from said plurality of mobile stations, or said base station estimates said plurality of signal-to-interference ratios.

9. The power control method of claim 1, wherein said calculating step employs a matrix processing step.

10. The power control method of claim 9, wherein said power adjustment values are computed according to the relationship:

##EQU9## where;

.increment.P_N is a vector which provides said power adjustment values;

P_N+1 is a power level imposed by said change at time t+.increment.t; and

##EQU10## where SIR₁ through SIR_N refer to target signal-to-interference ratios of mobile stations 1-N, respectively.

11. The power control method of claim 1, wherein said calculating step iteratively calculates said plurality of power adjustment values.

12. The power control method of claim 11, wherein said power adjustment values are calculated by:

a) selecting a set of power adjustment values in response to said change;

b) determining intracell interference associated with said selected set of power adjustment values;

c) selecting another set of power adjustment values on the basis of said determined intracell interference; and

d) repeating steps (a)-(c) at least once.

13. The power control method of claim 1, wherein said calculating step is performed when said change in said set exceeds a prescribed threshold.

14. A radiocommunication system employing power control presetting, comprising:

a plurality of mobile stations comprising a set of mobile stations;

a base station associated with said plurality of mobile stations, said base station communicating with said plurality of mobile stations using respective power levels to satisfy predetermined target reception requirements at said respective mobile stations; and

a power control unit;

said power control unit including control logic for detecting a change in said set of mobile stations, and in response thereto, calculating a plurality of power preset adjustment values, based on said predetermined target reception requirements which are known in advance of said change in said set of mobile stations, for application to said plurality of respective power levels, wherein said calculating is performed to reduce disturbances in interference which would be caused by said change based on a predictive assessment of said disturbances in interference, wherein each of said power preset adjustment values is individually provided so that a corresponding mobile station will continue to have its target reception requirements met subsequent to said change in said set of mobile stations.

15. The radiocommunication system of claim 14, wherein said change in said set of mobile station comprises the introduction of at least one new mobile station to said set of mobile stations, or the removal of at least one mobile station from said set of mobile stations.

16. The radiocommunication system of claim 15, where said introduction of at least one mobile station occurs when at least one mobile station switches from a passive to an active state, and said removal of at least one mobile station occurs when at least one mobile station switches from an active to a passive state.

17. The radiocommunication system of claim 15, wherein said introduction of at least one mobile station occurs when at least one mobile station enters a cell associated with said base station, and said removal of at least one mobile station occurs when at least one mobile station leaves a cell associated with said base station.

18. The radiocommunication system of claim 14, wherein said change in said set of mobile stations includes a change in operating characteristics in at least one mobile station in said set.

19. The radiocommunication system of claim 18, wherein said change in operating characteristics in at least one station in said set comprises said one station switching from a low data-rate mode of operation to a high data-rate mode of operation, or from a high data-rate mode of operation to a low data-rate mode of operation.

20. The radio communication system of claim 14, wherein said plurality of reception requirements comprise a series of target signal-to-interference ratios associated with said plurality of mobile stations, wherein said control logic computes said power adjustment values using said series of target signal-to-interference ratios associated with said plurality of mobile stations.

21. The radio communication system of claim 20, wherein said base station receives said plurality of signal-to-interference ratios from said plurality of mobile stations, or said base station estimates said plurality of signal-to-interference ratios.

22. The radio communication system of claim 14, wherein said control logic employs matrix processing to compute said power adjustment values.

23. The radiocommunication system of claim 22, wherein said power adjustment values are computed according to the relationship:

##EQU11## where;

.increment.P_N is a vector which provides said power adjustment values;

P_N+1 is a power level imposed by said change at time t+.increment.t; and

##EQU12## where SIR₁ through SIR_N refer to target signal-to-interference ratios of mobile stations 1-N, respectively.

24. The radio communication system of claim 14, wherein said control logic employ iterative processing to compute said power adjustment values.

25. The radiocommunication system of claim 24, wherein said power adjustment values are calculated by said control unit by:

a) selecting a set of power adjustment values in response to said change;

b) determining intracell interference associated with said selected set of power adjustment values;

c) selecting another set of power adjustment values on the basis of said determined intracell interference; and

d) repeating steps (a)-(c) at least once.

26. The radio communication system of claim 14, wherein said control logic is performed in response to said change exceed a prescribed threshold.

27. A power control unit for use in a radiocommunication system comprising:

logic for computing a plurality of power levels associated with a plurality of mobile stations, said plurality of power levels setting a power at which a base station transmits information to said plurality of mobile stations to satisfy predetermined target reception requirements at said respective mobile stations, wherein said plurality of mobile stations form a set of mobile stations; and

control logic for detecting a change in said set of mobile stations, and in response thereto, calculating a plurality of power preset adjustment values based on said predetermined target reception requirements which are known in advance of said change in said set of mobile stations, for application to said plurality of power levels, wherein said calculating is performed to reduce disturbances in interference which would be caused by said change based on a predictive assessment of said disturbances in interference, wherein each of said power preset adjustment values is individually provided so that a corresponding mobile station will continue to have its target reception requirements met subsequent to said change in said set of mobile stations.

28. The power control unit of claim 27, wherein said change in said set of mobile stations comprises the introduction of at least one new mobile station to said set of mobile stations, or the removal of at least one mobile station from said set of mobile stations.

29. The power control unit of claim 28, where said introduction of at least one mobile station occurs when at least one mobile station switches from a passive to an active state, and said removal of at least one mobile station occurs when at least one mobile station switches from an active to a passive state.

30. The power control unit of claim 28, wherein said introduction of at least one mobile station occurs when at least one mobile station enters a cell associated with said base station, and said removal of at least one mobile station occurs when at least one mobile station leaves a cell associated with said base station.

31. The power control unit of claim 27, wherein said change in said set of mobile stations includes a change in operating characteristics in at least one mobile station in said set.

32. The power control unit of claim 31, wherein said change in operating characteristics in at least one station in said set comprises said one station switching from a low data-rate mode of operation to a high data-rate mode of operation, or from a high data-rate mode of operation to a low data-rate mode of operation.

33. The power control unit claim 27, wherein said plurality of reception requirements comprise a series of target signal-to-interference ratios associated with said plurality of mobile stations, wherein said control logic computes said power adjustment values using said series of target signal-to-interference ratios associated with said plurality of mobile stations.

34. The power control unit of claim 33, wherein said base station receives said plurality of signal-to-interference ratios from said plurality of mobile stations, or said base station estimates said plurality of signal-to-interference ratios.

35. The power control unit of claim 27, wherein said control logic employs matrix processing to compute said power adjustment values.

36. The power control unit of claim 35, wherein said power adjustment values are computed according to the relationship:

##EQU13## where;

.increment.P_N is a vector which provides said power adjustment values;

P_N+1 is a power level imposed by said change at time t+.increment.t; and

##EQU14## where SIR₁ through SIR_N refer to the target signal-to-interference ratios of mobile stations 1-N, respectively.

37. The power control unit of claim 27, wherein said control logic employ iterative processing to compute said power adjustment values.

38. The power control unit of claim 37, wherein said power adjustment values are calculated by said control logic by:

a) selecting a set of power adjustment values in response to said change;

b) determining intracell interference associated with said selected set of power adjustment values;

c) selecting another set of power adjustment values on the basis of said determined intracell interference; and

d) repeating steps (a)-(c) at least once.

39. The power control unit of claim 27, wherein said control logic is invoked when said change exceeds a prescribed threshold.

40. A power control method for a radiocommunication system, said radiocommunication system including at least one cell, said cell containing a base station in communication with a plurality of mobile stations, said plurality of mobile stations forming a set of mobile stations, said method including the steps of:

detecting a change in said set of mobile stations;

estimating an impact of said change in said set of mobile stations on an interference measure, said estimating step producing an interference estimate;

calculating power targets for said respective mobile stations within said cell based on said interference estimate and signal-to-interference target values for said respective mobile stations;

receiving signals from said mobile stations within said cell to produce received signals and assessing power levels of said respective received signals;

comparing said power levels of said received signals for said respective mobile stations with said corresponding power targets for said mobile stations and producing comparison results; and

on the basis of said comparison results, transmitting at least one power command from said base station to at least one of said mobile stations within said cell, said at least one power command instructing said at least one mobile station to increase or decrease its transmitting power.

41. The power control method according to claim 40, wherein said change in said set of mobile stations comprises one or more of the following events:

a mobile station entering a cell;

a mobile station leaving a cell;

a mobile station switching from passive to active state;

a mobile station switching from active to passive state;

a mobile station switching from high data-rate mode to low data-rate mode;

a mobile station switching from low data-rate mode to high data-rate mode.

42. The power control method according to claim 40, wherein said detecting step assesses said change in said set of mobile stations from a control preamble received from one or more mobile stations.

43. The power control method according to claim 40, wherein said detecting step assesses said change in said set of mobile stations from the transmission of data from one or more mobile stations.

44. A radiocommunication system employing power control, said system including:

at least one radiocommunication cell, said one cell including a base station in communication with a plurality of mobile stations, said plurality of mobile stations comprising a set of mobile stations;

detector logic for detecting a change in said set of mobile stations;

an estimator for estimating the impact which said change in said set of mobile stations will have on an interference measure within said cell, said estimator producing an interference estimate;

calculating logic for calculating power targets for said respective mobile stations within said cell based on said interference estimate and signal-to-interference target values for said respective mobile stations within said cell;

a base station receiver for receiving signals from each of said mobile stations within said cell to produce received signals and assessing power levels of said respective received signals;

a comparator for comparing said power levels of said received signals for said respective mobile stations with said corresponding power targets for said mobile stations, said comparator producing a comparison results; and

on the basis of said comparison results, transmitting at least one power command from said base station to at least one of said mobile stations within said cell, said at least one power command instructing said at least one mobile stations to increase or decrease its transmitting power.

45. The radio communication system according to claim 44, wherein said change in said set of mobile stations comprises one or more of the following events:

a mobile station entering a cell;

a mobile station leaving a cell;

a mobile station switching from passive to active state;

a mobile station switching from active to passive state;

a mobile station switching from high data-rate mode to low data-rate mode;

a mobile station switching from low data-rate mode to high data-rate mode.

46. The radio communication system according to claim 44, wherein said detecting logic assesses said change in said set of mobile stations from a control preamble received from one or more mobile stations.

47. The radio communication system according to claim 44, wherein said detecting logic assesses said change in said set of mobile stations from the transmission of data from one or more mobile stations.