Method and system for location-based power control in wireless communications

• US 7,260,415 B1
• Filed: 05/31/2001
• Issued: 08/21/2007
• Est. Priority Date: 05/31/2001
• Status: Expired due to Term

• Current Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Original Assignee: Sprint Spectrum LP (Deutsche Telekom AG)
• Inventors: Oh, Dae-Sik
• Primary Examiner(s): Urban; Edward F.
• Assistant Examiner(s): Dean; Raymond S.
• Application Number:
  US09/871,081
• Time in Patent Office: 2,273 Days
• Field of Search: 455/404.1, 455/404.2, 455/440, 455/522, 455/69, 455/456.1, 455/456.2, 455/456.3, 455/456.4, 455/456.5, 370/318
• US Class Current: 455/522
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile

Abstract

A method and system for power control in a wireless communication system. A base station determines the location of a mobile station and uses that location as a basis to select power control parameters, such as initial mobile station transmit power, initial base station transmit power, and reverse link setpoint. The base station instruct the mobile station to begin transmitting at the location-based initial mobile station transmit power, and the base station begins transmitting at the location-based initial base station transmit power. Power control then proceeds based on the location-based values. When the mobile station location changes, the process repeats, based on a new set of location-based power control parameters.

Claims

1. A method of controlling power used for communication between a mobile station and a base station, the method comprising:

the base station determining a location of the mobile station when the mobile station is going to engage in a call;

based on the location, the base station selecting an initial power level of a primary communication channel for communication from the mobile station to the base station;

starting at the initial power level, engaging in a power control process that regulates the power of the primary communication channel used for communication from the mobile station to the base station;

the base station detecting a changed location of the mobile station;

in response to detecting the changed location, the base station interrupting the power control process;

based on the changed location, the base station selecting a new initial power level; and

starting at the new initial power level, engaging in a new power control process that regulates the power of the primary communication channel used for communication from the mobile station to the base station.

2. The method of claim 1, wherein the base station selecting an initial power level of a primary communication channel for communication from the mobile station to the base station comprises:

the base station referring to a database that correlates locations with initial power levels; and

the base station selecting from the database an initial power level that is correlated with the location.

3. The method of claim 2, wherein engaging in a power control process that regulates the power of the primary communication channel used for communication from the mobile station to the base station comprises:

the base station sending to the mobile station an instruction to transmit at the selected initial power level,

whereby the mobile station responsively transmits at the selected initial power level.

4. A base station programmed to perform the functions of claim 1.

5. A method of controlling power of a primary communication channel for communications between a mobile station and a base station, the method comprising:

determining a location of the mobile station;

based on the location, the base station selecting a reverse link setpoint and an initial transmit power for the mobile station on the primary communication channel;

sending to the mobile station an instruction to transmit at the initial transmit power; and

adjusting mobile station transmit power on the primary communication channel so that a mobile station signal-to-noise ratio matches the reverse link setpoint.

6. The method of claim 5, wherein selecting a reverse link setpoint comprises:

referring to a database that correlates locations with reverse link setpoints; and

selecting from the database a reverse link setpoint that is correlated with the location.

7. The method of claim 5, wherein adjusting mobile station transmit power on the primary communication channel so that a mobile station signal-to-noise ratio matches the reverse link setpoint comprises:

measuring an energy level, E_b, of a signal received from the mobile station;

based on the energy level and an estimate of air interface noise, N_o, computing a measured value of E_b/N_o;

comparing the measured value of E_b/N_o with the reverse link setpoint; and

if the measured value of E_b/N_o does not match the reverse link setpoint, sending to the mobile station an instruction to adjust the mobile station transmit power on the primary communication channel.

8. The method of claim 5, further comprising:

receiving a signal at the base station from the mobile station;

measuring a frame error rate of the signal;

comparing the measured frame error rate to a threshold frame error rate;

if the measured frame error rate does not match the threshold frame error rate, adjusting the reverse link setpoint;

using the adjusted reverse link setpoint as a basis to manage mobile station transmit power on the primary communication channel.

9. The method of claim 8, further comprising:

based on the location, selecting a bounding value for a reverse link setpoint;

using the bounding value as a basis to limit the reverse link setpoint.

10. The method of claim 9, wherein selecting a bounding value for a reverse link setpoint comprises:

referring to a database that correlates locations with bounding values of reverse link setpoints; and

selecting from the database a reverse link setpoint that is correlated with the location.

11. A base station programmed to perform the functions of claim 5.

12. A method of controlling power of communications between a mobile station and a base station, the method comprising the following steps:

(a) determining a location of the mobile station;

(b) based on the location, the base station selecting a setpoint and a mobile station initial transmit power on a primary communication channel;

(c) instructing the mobile station to transmit at the mobile station initial transmit power on the primary communication channel;

(d) computing an energy-to-noise measure for a signal received from the mobile station;

(e) determining if the energy-to-noise measure matches the setpoint; and

(f) in response to a determination that the energy-to-noise measure does not match the initial setpoint, instructing the mobile station to adjust the mobile station transmit power.

13. The method of claim 12, further comprising:

(g) monitoring an error rate of signals received from the mobile station;

(h) determining if the error rate matches a predetermined threshold;

(i) in response to a determination that the error rate does not match the predetermined threshold, adjusting the setpoint.

14. The method of claim 13, further comprising:

periodically repeating steps (d)-(f) and (g)-(i).

15. The method of claim 14 further comprising:

detecting a new location of the mobile station; and

repeating steps (b)-(f) based on the new location.

16. A base station programmed to perform the functions of claim 12.

17. A power control system comprising:

a database that correlates locations with initial power levels; and

a base station controller (BSC) with access to said database, the BSC being configured so that when a mobile station is going to engage in a call, the BSC determines a location of the mobile station, selects from the database an initial power level based on the location of the mobile station, and instructs the mobile station to transmit at the initial power level, the BSC being further configured so that the BSC continually monitors the location of the mobile station and, in response to detecting a new location of the mobile station, the BSC selects from the database a new initial power level based on the new location of the mobile station and instructs the mobile station to transmit at the new initial power level.

18. The power control system of claim 17, further comprising:

a mobile positioning center (MPC), wherein the BSC queries the MPC to determine the location of the mobile station.