Method and apparatus for performing a fast downward move in a cellular telephone forward link power control system

• US 5,960,361 A
• Filed: 10/22/1996
• Issued: 09/28/1999
• Est. Priority Date: 10/22/1996
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chen, Tao
• Primary Examiner(s): Urban, Edward F.
• Application Number:
  US08/736,201
• Time in Patent Office: 1,071 Days
• Field of Search: 455/522, 455/126, 455/127, 455/69, 455/517, 455/524
• US Class Current: 455/522
• 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

Abstract

A base station of the cellular telephone forward link power control system transmits frames initially at a high default transmit power level, then decreases the power level incrementally until either a frame erasure is detected, triggering an immediate sharp increase in transmission power, or until a predetermined period of time has elapsed, after which the base station performs a fast downward move in the transmit power level. The fast downward move constitutes a sharp reduction in the transmit power level. In one example, the fast downward move is performed if one hundred consecutive frames are successfully transmitted without a frame erasure. By providing the fast downward move in transmit power, the power transmitted is decreased on the average. In particular, the fast downward move allows the amount of transmit power to be reduced significantly in circumstances where slow incremental decreases in power would result in excess power being employed. Method and apparatus embodiments are disclosed.

Claims

1. A signal transmission power control system comprising:

means for transmitting signals, said signals being transmitted initially at an initial transmit power level;

means for successively and gradually decreasing said transmit power level by a first amount;

means for receiving a signal indicating that said transmit power needs to be increased;

means, responsive to receipt of said signal, for increasing said transmit power level followed immediately by another successive and gradual decrease of said transmit power level by an amount substantially equal to said first amount such that said transmit power level follows a generally saw-toothed pattern; and

means for decreasing said transmit power level by a second amount, said second amount being greater than said first amount, following transmission of signals for a predetermined period of time without receipt of said signal indicating that said transmit power level needs to be increased.

2. The signal transmission power control system of claim 1

wherein said means for transmitting signals operates to transmit said signals in frames;

and

wherein said signal indicating that said transmit power needs to be increased is a feedback signal indicating that a frame erasure occurred within a device receiving said frames.

3. The signal transmission power control system of claim 2 wherein said frames are part of a forward link of a mobile telephone transmission configured in accordance with IS-95-A rate set 2 protocols and wherein said feedback signal is an error indicator bit (EIB) contained within a frame of a reverse link transmission.

4. A cellular telephone forward link power control system comprising:

means for transmitting frames, said frames being transmitted initially at an initial transmit power level;

means for successively and gradually decreasing forward link transmit power levels by a first amount;

means for receiving a signal indicating that a frame erasure occurred;

means, responsive to receipt of said signal, for increasing said transmit power level followed immediately by another successive and gradual decrease of said transmit power level by an amount substantially equal to said first amount such that said transmit power level follows a generally saw-toothed pattern; and

means for decreasing said forward link transmit power level by a second amount, greater than said first amount, following transmission of a predetermined number of consecutive frames without receipt of said signal indicating a frame erasure.

5. The cellular telephone forward link power control system of claim 4

wherein said frames are configured in accordance with IS-95-A rate set 2 protocols and wherein said feedback signal is an error indicator bit (EIB) contained within a frame of a reverse link transmission.

6. A method for controlling power within a signal transmission system comprising the steps of:

a) transmitting a signal at an initial power level;

b) receiving a responsive signal indicating whether the transmitted signal was successfully received;

c) if not successfully received, then transmitting a next signal at a power level that is significantly greater than a previous power level followed immediately by a successive and gradual decrease of said transmit power level such that said transmit power level follows a generally saw-toothed pattern; and

d) if successfully received, then transmitting additional signals at successively, gradually lower power levels until a predetermined period of time has elapsed then transmitting a next signal at a power level that is significantly below the power level of a most recently transmitted signal.

7. The method of claim 6

wherein said step of transmitting signals is performed to transmit said signals in frames;

and

wherein said signal indicating that said transmit power needs to be increased is a feedback signal indicating that a frame erasure occurred within a device receiving said frames.

8. The method of claim 7

wherein said frames are part of a forward link of a mobile telephone transmission configured in accordance with IS-95-A rate set 2 protocols and wherein said feedback signal is an error indicator bit (EIB) contained within a frame of a reverse link transmission.

9. A signal transmission power control system comprising:

means for transmitting signals, said signals being transmitted initially at an initial transmit power level;

means for successively and incrementally decreasing said transmit power level by a first amount;

means for receiving a signal indicating that said transmit power needs to be increased;

means, responsive to receipt of said signal, for increasing said transmit power level; and

means for decreasing said transmit power level by a second amount, said second amount being greater than said first amount, following transmission of signals for a predetermined period of time without receipt of said signal indicating that said transmit power level needs to be increased, wherein said means for decreasing said transmit power level by said second amount comprises;

means for transmitting one or more probe signals at said decreased power level;

means for determining whether said probe signals are successfully received by a receiving device; and

means, operative in response to said determination, for decreasing said transmit power level for subsequent signals if said probe signals are successfully received by an amount which is greater than if said probe signals are not successfully received.

10. The signal transmission power control system of claim 9

wherein said means for transmitting signals operates to transmit said signals in frames;

and

wherein said probe signals comprise one frame of signals.

11. A cellular telephone forward link power control system comprising:

means for transmitting frames, said frames being transmitted initially at an initial transmit power level;

means for successively and incrementally decreasing forward link transmit power levels by a first amount;

means for receiving a signal indicating that a frame erasure occurred;

means, responsive to receipt of said signal, for increasing said transmit power level; and

means for decreasing said forward link transmit power level by a second amount, greater than said first amount, following transmission of a predetermined number of consecutive frames without receipt of said signal indicating a frame erasure, wherein said means for decreasing said forward link transmit power level by said second amount comprises;

means for transmitting a probe frame at said decreased power level;

means for determining whether said probe frame is successfully received by a receiving mobile station; and

means, operative in response to said determination, for decreasing said transmit power level for subsequent frames if said probe frame is successfully received by an amount which is greater than if said probe frame is not successfully received.

12. A method for controlling power within a signal transmission system comprising the steps of:

a) transmitting a signal at an initial power level;

b) receiving a responsive signal indicating whether the transmitted signal was successfully received;

c) if not successfully received, then transmitting a next signal at a power level that is significantly greater than a previous power level; and

d) if successfully received, then transmitting additional signals at successively, incrementally lower power levels until a predetermined period of time has elapsed then transmitting a next signal at a power level that is significantly below the power level of a most recently transmitted signal, wherein said step of transmitting said next signal at a power level that is significantly below the power level of a most recently transmitted signal comprises the steps of;

transmitting probe signals at said decreased power level;

determining whether said probe signals are successfully received by a receiving device; and

decreasing said transmit power level for subsequent signals if said probe signals are successfully received by an amount which is greater than if said probe signals are not successfully received.

13. The method of claim 12

wherein said step of transmitting signals is performed to transmit said signals in frames;

and

wherein said probe signals comprise one frame of signals.