Apparatus and method for controlling the transmission power of the forward link of a wireless communication system

• US 6,609,007 B1
• Filed: 09/14/1999
• Issued: 08/19/2003
• Est. Priority Date: 09/14/1999
• Status: Expired due to Fees

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Eibling, Edward Ellis, Weaver, Carl Francis, Kamel, Raafat Edward, Kuo, Wen-Yi, Thomas, Mathew
• Primary Examiner(s): VO, NGUYEN THANH
• Application Number:
  US09/395,494
• Time in Patent Office: 1,435 Days
• Field of Search: 455/69, 455/522, 455/67.1, 455/67.3, 455/561, 455/424, 455/425, 370/342
• US Class Current: 455/522
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/226 using past references to control power, e.g. look-up-table

Abstract

A method that adjusts the power level of a set of forward-link signals of a base station responsive to the loading of the forward link as determined by a power level measurement of the signal set. One power level measurement is a pilot fraction of the forward link. Other power level measurements, such as the signal set'"'"'s power level, can be used, alone or in combination, instead of or in addition to the pilot fraction of the forward link to adjust the power level of the signal set. The power level of the signal set can be changed in any manner, including by scaling it by a scaling factor, or by increasing the power level by a fixed or a variable amount. The power level measurement of the signal set is obtained during a current time period. The scaling factor that will be used in the subsequent time period is determined using the power level measurement. In one embodiment of the invention, the scaling factor can be obtained from a look-up table that is based on the power level measurement. If the cell containing the base station includes several sectors, the power level of the signal set in a sector is adjusted when the power level measurement in that sector indicates that the power level should be adjusted.

Claims

1. A method for controlling a power level of signals transmitted over a forward link by a base station in a wireless system, the base station having a signal set of a plurality of forward link signals, each forward link signal of the plurality having an individual power control, the method comprising the step of:

adjusting the power levels of each of the forward link signals of the plurality as a function of the extent to which the forward link is loaded, the adjusting of the power level of each of the forward link signals being independent of the individual power control of the forward link signal being adjusted.

2. The method of claim 1, wherein the extent to which the forward link is loaded is determined as a function of a pilot fraction of the forward link.

3. The method of claim 1, wherein the extent to which the forward link is loaded is determined as a function of the signal set'"'"'s power level.

4. The method of claim 1, wherein the signal set comprises all signals in a sector of a cell containing the base station.

5. The method of claim 1,

further comprising the steps of:

obtaining a power level of the signal set for a time period;

obtaining a power level of a pilot for the time period; and

determining a pilot fraction for the time period as a function of the obtained power levels; and

wherein the adjusting step comprises;

scaling the power levels of each of the forward link signals of the plurality using a scaling factor which is a function of the pilot fraction, the scaling of the power level of each of the forward link signals being independent of the individual power control of the forward-link signal being scaled.

6. The method of claim 5, further comprising the step of determining the scaling factor by looking up the scaling factor in a look-up table that relates the pilot fraction to the scaling factor.

7. The method of claim 5, wherein the time period comprises a frame.

8. The method of claim 5, wherein the time period comprises a plurality of frames.

9. The method of claim 5, wherein the scaling step comprises scaling the power level of each of the forward link signals of the plurality during a subsequent time period using the scaling factor.

10. The method of claim 5, wherein the scaling step comprises scaling the power level of each of the forward link signals of the plurality during the time period using the scaling factor.

11. The method of claim 5, wherein:

a cell containing the base station comprises a first sector and a second sector;

the base station further having a second signal set of a second plurality of forward link signals, the signal set corresponding to the first sector and the second signal set corresponding to the second sector;

the step of obtaining the power level of the signal set comprises obtaining a power level for the signal set for the time period and obtaining a power level for the second signal set for the time period;

the step of determining the pilot fraction comprises determining a pilot fraction for the signal set for the time period and determining a pilot fraction for the second signal set for the time period; and

the scaling step comprises scaling the power level of each of the forward link signals of the plurality of the signal set using a scaling factor which is a function of the pilot fraction determined for the signal set and scaling the power level of each of the forward link signals of the second plurality of the second signal set using a scaling factor which is a function of the pilot fraction determined for the second signal set.

12. The method of claim 5, wherein the scaling factor increases as the pilot fraction increases.

13. The method of claim 1,

further comprising the steps of:

obtaining a power level of the signal set for a time period;

obtaining a power level of a pilot for the time period; and

determining an average pilot fraction for the time period as a function of the obtained power levels; and

wherein the adjusting step comprises;

scaling the power levels of each of the forward link signals of the plurality using the scaling factor which is a function of the average pilot fraction, the scaling of the power level of each of the forward link signals being independent of the individual power control of the forward-link signal being scaled.

14. The method of claim 13, wherein the average pilot fraction for the time period is based on a ratio of the pilot'"'"'s power level to the signal set'"'"'s power level for the time period, and an average pilot fraction for a previous time period.

15. The method of claim 13, further comprising the step of determining the scaling factor by looking up the scaling factor in a look-up table that relates the pilot fraction to the scaling factor.

16. The method of claim 13, wherein the time period comprises a frame.

17. The method of claim 13, wherein the time period comprises a plurality of frames.

18. The method of claim 13, wherein the scaling step comprises scaling the power level of each of the forward link signals of the plurality during a subsequent time period using the scaling factor.

19. The method of claim 13, wherein the scaling step comprises scaling the power level of each of the forward link signals of the plurality during the time period using the scaling factor.

20. The method of claim 13, wherein a cell containing the base station comprises a plurality of sectors, each corresponding to at least one signal set and wherein:

the step of obtaining the power level of the signal set comprises obtaining a power level for each signal set for the time period;

the step of determining the average pilot fraction comprises determining an average pilot fraction for each signal set for the time period; and

the scaling step comprises scaling the power level of each signal set using a scaling factor which is a function of the average pilot fraction for that set.

21. The method of claim 13, wherein the scaling factor increases as the average pilot fraction increases.

22. The method of claim 1, wherein the adjusting step comprises scaling the power levels of each of the plurality of the forward link signals of the signal set using a scaling factor that increases as the load of the base station decreases.

23. The method of claim 1,

further comprising the step of combining each of the of the forward link signals of the plurality to form a combined-baseband signal;

and

wherein the adjusting step comprises adjusting the power levels of each of the forward link signals of the plurality by adjusting the combined-baseband signal.