Method and apparatus for adaptive power control in a wireless voice and data communication system

• US 20050197150A1
• Filed: 02/14/2005
• Published: 09/08/2005
• Est. Priority Date: 06/21/2000
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Jou, Yu-Cheun, Sarkar, Sandip
• Granted Patent: US 7,881,739 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 11/10 using Doppler effect
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/282 taking into account the speed of the mobile

Abstract

A method and apparatus for adaptively controlling the power level of transmissions from a remote station by determining the velocity of the remote station. A general classification of the velocity of the remote station can be used to selectively implement a closed loop power control scheme. Power level parameters are used to determine velocity. In accordance with a classification of stationary, low speed, or high speed, the closed loop power control is selectively operated. Velocity can be determined by either the base station or the remote station through various methods. One method is the use of power control bits and/or average power to determine level crossings and excursion times.

Claims

1. A method for adaptively controlling reverse link transmission power levels within a wireless communication system, comprising:

determining a mobility profile of a remote station within the range of a base station, wherein the remote station transmits a plurality of signals to the base station at various transmission power levels by using an open loop power control scheme and a closed loop power control scheme; and

turning off the closed loop power control scheme if the mobility profile is unfavorable.

2. The method of claim 1, wherein said determining the mobility profile of the remote station comprises:

using an average transmission power level associated with a frame of the plurality of signals to determine a level crossing value and an excursion time;

using the level crossing value and the excursion time to determine a velocity classification for the remote station, wherein the velocity classification is either a high speed, a low speed or a static speed; and

designating the mobility profile as unfavorable if the velocity classification is high speed or static speed.

3. The method of claim 2, wherein said using the level crossing value and the excursion time value to determine a velocity classification for the remote station comprise:

(a) comparing the level crossing value to a first threshold value;

(b) if the level crossing value is greater than the first threshold value, then comparing the excursion time value to a second threshold value;

(i) if the excursion time value is less than the second threshold value, then setting the velocity classification as static, else setting the velocity classification as high speed;

(c) if the level crossing value is less than or equal to the first threshold value, then comparing the level crossing value to a third threshold value;

(i) if the level crossing value is less than the third threshold value, then performing;

comparing the excursion time value to the second threshold value; and

if the excursion time value is greater than the second threshold value, then determining the number of times the excursion time value is greater than the second threshold value in a given period;

if the number of times the excursion time value is greater than the second threshold value in the given period is more than an assigned number, then setting the velocity classification as low speed, else setting the velocity classification as high speed; and

(i) if the level crossing value is greater than or equal to the third threshold value, then setting the velocity classification as high speed.

4. The method of claim 1, wherein said determining the mobility profile of the remote station comprises:

using a plurality of transmitted power control bits to determine a level crossing value and an excursion time value;

using the level crossing value and the excursion time value to determine a velocity classification for the remote station, wherein the velocity classification is either a high speed, a low speed or a static speed; and

designating the mobility profile as unfavorable if the velocity classification is high speed or static speed.

5. The method of claim 4 wherein said using the level crossing value and the excursion time value to determine a velocity classification for the remote station comprise:

(a) comparing the level crossing value to a first threshold value;

(b) if the level crossing value is greater than the first threshold value, then comparing the excursion time value to a second threshold value;

(i) if the excursion time value is less than the second threshold value, then setting the velocity classification as static, else setting the velocity classification as high speed;

(c) if the level crossing value is less than or equal to the first threshold value, then comparing the level crossing value to a third threshold value;

(i) if the level crossing value is less than the third threshold value, then performing;

comparing the excursion time value to the second threshold value; and

if the excursion time value is greater than the second threshold value, then determining the number of times the excursion time value is greater than the second threshold value in a given period;

if the number of times the excursion time value is greater than the second threshold value in the given period is more than an assigned number, then setting the velocity classification as low speed, else setting the velocity classification as high speed; and

(i) if the level crossing value is greater than or equal to the third threshold value, then setting the velocity classification as high speed.

6. The method of claim 1, wherein said determining the mobility profile of the remote station comprises:

using a plurality of transmitted power control bits to determine a level crossing value;

multiplying the level crossing value, a carrier signal frequency, and a constant, e, to generate a product;

dividing the product by the square root of 2π

to generate an approximate velocity value; and

designating the mobility profile as unfavorable if the approximate velocity value is zero (0) kph or over 120 kph.

7. The method of claim 1, wherein said determining the mobility profile of the remote station comprises estimating an approximate velocity of the remote station by using a covariance approximation technique.

8. The method of claim 1, wherein said turning off the closed loop power control scheme is performed by the base station, wherein the base station ignores closed loop power control requests from the remote station.

9. The method of claim 1, wherein said turning off the closed loop power control scheme is performed by the base station, wherein the base station transmits a command to the remote station to make the closed loop power control scheme ineffectual.

10. The method of claim 1, wherein the mobility profile is unfavorable if the mobility profile indicates a high speed or a static speed.

11. A method for adaptively controlling transmission power levels of a remote station, comprising:

determining whether the remote station is stationary, travelling at low speed, or travelling at high speed; and

refraining from implementing a closed loop power control scheme if the remote station is stationary or travelling at high speed, wherein the closed loop power control scheme is used to adjust an open loop power control scheme.

12. The method of claim 11, wherein said determining whether the remote station is stationary, travelling at low speed, or travelling at high speed comprises:

determining a plurality of level crossing values, a plurality of excursion time values, and a plurality of excursion depth values from a set of power statistics;

inputting the plurality of level crossing values, the plurality of excursion time values, and the plurality of excursion depth values into an adaptive algorithm to determine a velocity value, wherein the adaptive algorithm uses a Recursive Least Squares (RLS) estimation process and the velocity value indicates whether the remote station is stationary, travelling at low speed, or travelling at high speed.

13. The method of claim 11, wherein said determining whether the remote station is stationary, travelling at low speed, or travelling at high speed comprises:

determining a plurality of level crossing values, a plurality of excursion time values, and a plurality of excursion depth values from a set of power statistics;

inputting the plurality of level crossing values, the plurality of excursion time values, and the plurality of excursion depth values into an adaptive algorithm to determine a future velocity value, wherein the adaptive algorithm uses a Recursive Least Squares (RLS) estimation process and the future velocity value indicates whether the remote station will be stationary, travelling at low speed, or travelling at high speed.

14. The method of claim 11, wherein said determining whether the remote station is stationary, travelling at low speed, or travelling at high speed comprises:

determining a first probability density function (PDF) associated with a plurality of level crossing values, a second PDF associated with a plurality of excursion time values, and a third PDF associated with a plurality of excursion depth values from a set of power statistics;

inputting the first PDF, the second PDF, the third PDF, the plurality of level crossing values, the plurality of excursion time values, and the plurality of excursion depth values into an adaptive algorithm to determine a velocity value, wherein the adaptive algorithm uses a Least Mean-Squared (LMS) estimation process and the velocity value indicates whether the remote station is stationary, travelling at low speed, or travelling at high speed.

15. An apparatus for adaptively controlling reverse link transmission power levels within a wireless communication system, comprising a processor within a base station configured to determine a mobility profile of a remote station within the range of the base station, wherein the remote station transmits a plurality of signals to the base station at various transmission power levels by using an open loop power control scheme and a closed loop power control scheme, wherein the processor is further configured to turn off the closed loop power control scheme if the mobility profile is unfavorable.

16. The apparatus of claim 15, wherein the processor is coupled to a processor-readable storage element containing an instruction set executable by the processor to determine the mobility profile of the remote station and to turn off the closed loop power control scheme.

17. An apparatus for adaptively controlling reverse link transmission power levels within a wireless communication system, comprising:

means for determining a mobility profile of a remote station within the range of a base station, wherein the remote station transmits a plurality of signals to the base station at various transmission power levels by using an open loop power control scheme and a closed loop power control scheme; and

means for turning off the closed loop power control scheme if the mobility profile is unfavorable.