Method and apparatus for providing ternary power control in a communication system

• US 6,411,799 B1
• Filed: 12/04/1997
• Issued: 06/25/2002
• Est. Priority Date: 12/04/1997
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Padovani, Roberto
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Gesesse, Tilahun
• Application Number:
  US08/984,817
• Time in Patent Office: 1,664 Days
• Field of Search: 455/69, 455/63, 455/522, 455/13.4, 455/70, 455/226.1, 455/226.2
• US Class Current: 455/69
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 52/58 Format of the TPC bits

Abstract

A power control system for communication systems which utilizes a ternary signaling scheme to reduce or eliminate limit cycling which occurs as the result of using a binary signaling scheme is described. The power control values (each having one of three possible values) are not encoded and are punctured onto the data to improve the response time of the power control loop and allow for dynamic adjustment of the transmit power. The power up, power down, and do nothing commands are represented by positive, negative, and zero values (e.g., +1, −1, and 0), respectively. The remote station decreases its transmit power if any base station issues a power down command, maintains its transmit power if no base stations issue a power down command and at least one base station issues a do nothing command, and increases its transmit power if all base station issue power up commands.

Claims

1. A method for controlling a transmit power in a communication system comprising the steps of:

measuring a quality of a received signal;

comparing said quality of said received signal against a set of set points, said set of set points comprising a first set point and a second set point; and

generating a power control value in response to said comparing step;

wherein said power control value comprises one of three values, said three values corresponding to a power up command, a power down command, and a do nothing command, and wherein said power control value corresponds to said power up command if said quality of said received signal is above said first set point, to said power down command if said quality of said received signal is below said second set point, and to said do nothing command if said quality of said received signal is between said first and second set points;

transmitting said power control value to a destination station; and

wherein said transmit power of said destination station is adjusted in accordance with a received power control value;

processing a transmitted power control value at said destination station to provide said received power control value;

wherein said processing step comprises the steps of;

receiving at least one signal path corresponding to said transmitted power control value;

demodulating each of said at least one signal path to obtain a pilot signal and a filtered data;

computing a dot product of said pilot signal and said filtered data to obtain demodulated power control symbols; and

accumulating said demodulated power control symbols over a period of said power control value to obtain said received power control value.

2. The method of claim 1 wherein said quality of said received signal is based on a measured energy-per-bit-to-noise-plus-interference ratio E_b/I_o of said received signal.

3. The method of claim 1 wherein said set of set points is adjusted based on a performance requirement of said communication system.

4. The method of claim 3 wherein said performance requirement is based on a frame-error-rate of said received signal.

5. The method of claim 4 wherein said first set point is decreased if said frame-error-rate is higher than required.

6. The method of claim 4 wherein said second set point is increased if said frame-error-rate is lower than necessary.

7. The method of claim 1 wherein said first and second set points are set based on a measurement uncertainty of said quality of said received signal.

8. The method of claim 7 wherein a difference between said first and second set points is set equal to or greater than said measurement uncertainty of said quality of said received signal.

9. The method of claim 1 wherein said processing step further comprises the step of:

comparing an output from said accumulating step against a set of thresholds to obtain said received power control value.

10. The method of claim 1 wherein said power control value is not encoded.

11. The method of claim 1 wherein said power control value is punctured onto a data transmission.

12. The method of claim 1 wherein said power control value is pseudo-randomly positioned within a power control group.

13. A method for adjusting a transmit power in a communication system comprising the steps of:

receiving at least one transmitted power control value;

processing said at least one transmitted power control value to obtain a power control command; and

adjusting said transmit power in accordance with said power control command;

wherein said power control command comprises one of three values, said three values corresponding to a power up command, a power down command, and a do nothing command, and wherein said power control value corresponds to said power up command if a quality of a received signal at a base station transmitting said power control value is above a first set point, to said power down command if said quality of said received signal at said base station transmitting said power control values is below a second set point, and to said do nothing command if said quality of said received signal at said base station transmitting said power control value is between said first and second set points;

receiving at least one signal path corresponding to said at least one transmitted power control value;

demodulating each of said at least one signal path to obtain demodulated power control symbols;

accumulating said demodulated power control symbols over a period of said transmitted power control value;

combining identical power control values from said accumulating step to obtain independent power control values;

logically combining said independent power control values to obtain said power control command.

14. The method of claim 13 wherein said processing step further comprises the step of:

comparing independent power control values against corresponding sets of thresholds to obtain received power control values; and

wherein said logically combining step is performed on said received power control values to obtain said power control command.

15. The method of claim 13 wherein said transmit power is adjusted upward if at least one independent power control value is a power down command.

16. The method of claim 13 wherein said transmit power is maintained if no independent power control values are power down command and at least one independent power control value is a do nothing command.

17. The method of claim 13 wherein said transmit power is increased if all independent power control values are power up commands.