Method to control base station transmit power drift during soft handoffs

• US 20020077140A1
• Filed: 12/20/2000
• Published: 06/20/2002
• Est. Priority Date: 12/20/2000
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Rege, Kiran M., Monogioudis, Pantelis
• Granted Patent: US 7,006,841 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/061 using feedback from receiving side
• CPC Class Codes: H04B 7/0636 Feedback format
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

A UNMTS (universal mobile telecommunications system) based system comprises a common control point, a number of base stations, K, and a mobile terminal. During a soft handoff involving the K base stations and the mobile terminal, the common control point receives individual user channel transmit powers from each of the K base stations. In addition, the common control point receives two parameters from the mobile terminal—the identity of that base station involved in the soft handoff that has the strongest received signal at the mobile terminal and, on an average, a value representing how much stronger the received SNR was in comparison to the SNR target maintained by the mobile terminal. The common control point then decides on a downlink reference user channel transmit power for each of the base stations as a function of the individual user channel transmit powers reported by each base station involved in the soft handoff and the information provided from the mobile terminal.

Claims

1. A method for use in wireless equipment, the method comprising the steps of:

receiving user channel transmit power information from base stations involved in a soft handoff with user equipment; and

receiving information from the user equipment;

wherein the wireless equipment determines a reference user transmit power level for use by the base stations as a function of the received user channel transmit power information and the received information from the user equipment.

2. The method of claim 1 wherein the received information from the user equipment comprises at least one parameter that is a function of a measured signal-to-noise ratio in the user equipment.

3. The method of claim 1 wherein the received information from the user equipment comprises a value representative of an excess signal-to-noise ratio determined as a function of a target signal-to-noise ratio value and a signal-to-noise ratio associated with a received user channel transmit power signal that is stronger than at least some of the base stations.

4. A method for use in wireless equipment, the method comprising the steps of:

receiving user channel transmit power information from base stations involved in a soft handoff with user equipment; and

receiving information from the user equipment, wherein the information comprises an identifier of that base station with a received signal at the user equipment stronger than other base stations and a signal-to-noise ratio value associated with the identified base station;

determining a downlink reference power from the received user channel transmit power information and the received information from the user equipment; and

transmitting the determined downlink reference power to the base stations.

5. A method of claim 4 wherein the signal-to-noise ratio value represents an excess signal to noise ratio value determined as a function of a target signal-to-noise ratio value and a signal-to-noise ratio value associated with the identified base station.

6. A method for use in wireless equipment during a soft handoff with a number of base stations, the method comprising the steps of:

identifying that base station with a received signal at the wireless equipment stronger than other base stations; and

calculating a signal-to-noise ratio value associated with the identified base station; and

transmitting the identify of the identified base station and the calculated signal-to-noise ratio to a control point of a wireless system.

7. The method of claim 6 wherein the control point is a common control point.

8. The method of claim 6 wherein the calculated signal-to-noise ratio value represents an excess signal to noise ratio value determined as a function of a target signal-to-noise ratio value and a signal-to-noise ratio value associated with the received signal from the identified base station.

9. Apparatus for use in wireless equipment, the apparatus comprising:

a receiver for receiving user channel transmit power information from base stations involved in a soft handoff with user equipment, and receiving information from the user equipment; and

a processor for determining a reference user transmit power level for use by the base stations as a function of the received user channel transmit power information and the received information from the user equipment.

10. The apparatus of claim 9 wherein the received information from the user equipment comprises at least one parameter that is a function of a measured signal-to-noise ratio in the user equipment.

11. The apparatus of claim 9 wherein the received information from the user equipment comprises a value representative of an excess signal-to-noise ratio determined as a function of a target signal-to-noise ratio value and a signal-to-noise ratio associated with a received user channel transmit power signal that is stronger than at least some of the base stations.

13. The apparatus of claim 12 wherein the signal-to-noise ratio value represents an excess signal to noise ratio value determined as a function of a target signal-to-noise ratio value and a signal-to-noise ratio value associated with the identified base station.

15. The apparatus of claim 14 wherein the control point is a common control point.

16. The apparatus of claim 14 wherein the calculated signal-to-noise ratio value represents an excess signal to noise ratio value determined as a function of a target signal-to-noise ratio value and a signal-to-noise ratio value associated with the received signal from the identified base station.

18. The transmission frame of claim 17 wherein the transmission frame is conveyed via a radio resource control based protocol.

19. The transmission frame of claim 17 wherein the transmission frame is conveyed via physical layer signaling.

12. Apparatus for use in wireless equipment, the apparatus comprising:

a transceiver for (a) receiving user channel transmit power information from base stations involved in a soft handoff with user equipment, (b) receiving information from the user equipment, wherein the information comprises an identifier of that base station with a received signal at the user equipment stronger than other base stations and a signal-to-noise ratio value associated with the identified base station, (c) transmitting a downlink reference power to the base stations; and

a processor for use in determining the downlink reference power from the received user channel transmit power information and the received information from the user equipment.

14. Apparatus for use in wireless equipment during a soft handoff with a number of base stations, the apparatus comprising:

a processor for use in (a) identifying that base station with a received signal at the wireless equipment stronger than other base stations, and (b) calculating a signal-to-noise ratio value associated with the identified base station; and

a transmitter for transmitting the identify of the identified base station and the calculated signal-to-noise ratio to a control point of a wireless system.

17. A transmission frame representing data embodied in a wireless transmission signal, the transmission frame comprising:

a first portion of a field comprising at least one bit for conveying data representative of an identifier for identifying a base station whose received signal at a user equipment is stronger than other received signals from other base stations at the user equipment; and

a second portion of the field comprising at least one bit for conveying data representative of a value associated with a signal-to-noise measure of the received signal from the identified base station at the user equipment.