Synchronization of forward link base station power levels during handoff between base station sectors in a mobile radio communication system

• US 6,366,778 B1
• Filed: 07/22/1999
• Issued: 04/02/2002
• Est. Priority Date: 02/19/1998
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Bender, Paul E., Padovani, Roberto
• Primary Examiner(s): Vo, Nguyen T.
• Assistant Examiner(s): LY, NGHI H
• Application Number:
  US09/360,296
• Time in Patent Office: 985 Days
• Field of Search: 455/445, 455/522, 455/561, 455/69, 370/331
• US Class Current: 455/442
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0068 by puncturing
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/208 involving signal re-encoding
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 52/44 in connection with interruption of transmission
• CPC Class Codes: H04W 52/58 Format of the TPC bits
• CPC Class Codes: H04W 52/60 using different transmission rates for TPC commands
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like

Abstract

A method and apparatus for controlling the transmit power levels of first and second base station transceivers, wherein the first and second base station transceivers are respectively associated with first and second sectors of a cell. The received signal strength of a communication signal arriving at the mobile station is initially determined. A power control value that is based on the received signal strength is then transmitted from the mobile station to the first and second base station transceivers. A first received power control value is next generated by attempting to receive the transmitted power control value at the first base station transceiver, and a second received power control value is generated by attempting to receive the transmitted power control value at the second base station transceiver. A common transmit power value is calculated at a base station controller for the first and second base station transceivers when the first and second received power control values are unequal. The communication signal is then transmitted from the first and second base station transceivers in accordance with the common transmit power value.

Claims

1. In a telephone system having a base station controller associated with a sectorized cell, a first base station transceiver associated with a first sector of the cell and a second base station transceiver associated with a second sector of the cell, and a mobile station, a method for controlling the transmit power level of the first and second base station transceivers, comprising the steps of:

(a) determining the received signal strength of a communication signal arriving at the mobile station;

(b) transmitting a power control value based on the received signal strength to the first base station transceiver and the second base station transceiver;

(c) generating a first received power control value by attempting to receive the transmitted power control value at the first base station transceiver;

(d) generating a second received power control value by attempting to receive the transmitted power control value transmitted from the mobile station at the second base station transceiver;

(e) calculating, at the base station controller, a common transmit power value for the transceivers if the first and second received power control values are unequal; and

(f) transmitting the communication signal from the first and second based station transceivers in accordance with the common transmit power value.

2. The method of claim 1, wherein the received signal strength is determined by measuring the difference between an expected signal to noise ratio and an actual signal to noise ratio.

3. The method of claim 1, wherein the mobile station also communicates to the controller whether the received signal strength is valid.

4. The method of claim 3, wherein the common transmit power value is not changed if no received signal strength is valid.

5. The method of claim 1, wherein the received signal strength communicated to the controller with a reverse frame n is used by the controller to generate the common transmit power value communicated to the first and second base station transceivers for a forward frame n+2+Tbackhaul, where Tbackhaul represents a processing delay in frames caused by the base controller.

6. The method of claim 1, wherein the common transmit power value corresponds to a gain applied to the communication signal sent from the first and second base station transceivers.

7. The method of claim 1, wherein step (c) further comprises adjusting, during a first frame, a gain of the communication signal transmitted from the first base station transceiver in accordance with the first received power control value, and step (f) further comprises adjusting, during a second frame subsequent to the first frame, the gain of the communication signal transmitted from the first base station transceiver in accordance with a difference between the common transmit power value and the first received power control value.

8. The method of claim 7, wherein step (c) further comprises adjusting, during the first frame, a gain of the communication signal transmitted from the second base station transceiver in accordance with the second received power control value, and step (f) further comprises adjusting, during the second frame subsequent to the first frame, the gain of the communication signal transmitted from the second base station transceiver in accordance with a difference between the common transmit power value and the second received power control value.

9. In a cellular communication system having a base station controller associated with a sectorized cell, a first base station transceiver associated with a first sector of the cell and a second base station transceiver associated with a second sector of the cell, and a mobile station, an apparatus for controlling the transmit power level of the first and second base station transceivers, comprising:

(a) means for determining the received signal strength of a communication signal arriving at the mobile station;

(b) means for transmitting a power control value based on the received signal strength to the first base station transceiver and the second base station transceiver;

(c) means for generating a first received power control value by attempting to receive the power control value transmitted from the mobile station at the first base station transceiver;

(d) means for generating a second received power control value by attempting to receive the power control value transmitted from the mobile station at the second base station transceiver;

(e) means for calculating at the base station controller, a common transmit power value for the first and second base station transceivers if the first and second received power control values are unequal; and

(f) means for transmitting the communication signal from the first and second base station transceivers in accordance with the common transmit power value.

10. In a cellular or personal communication system having a base station controller associated with a sectorized cell, a first base station transceiver associated with a first sector of the cell and a second base station transceiver associated with a second sector of the cell transceiver, and a mobile station, an apparatus for controlling the transmit power level of the first and second base station transceivers, comprising:

(a) a processor in the mobile station that determines the received signal strength of a communication signal arriving at the mobile station;

(b) a transmitter that transmits a power control value based on the received signal strength to the first base station transceiver and the second base station transceiver;

(c) a processor in the first receiver that generates a first received power control value in response to the power control value transmitted from the mobile station;

(d) a processor in the second receiver that generates a second received power control value in response to the power control value transmitted from the mobile station;

(e) processing circuitry in the base station controller that generates a common transmit power value for the first and second base station transceivers if the first and second received power control values are unequal; and

(f) a transmitter in the first base station transceiver and a transmitter in the second base station transmitter that transmit the communication signal in accordance with the common transmit power value.