Transmission power control method, base station, mobile station and mobile communication system

• US 7,010,320 B2
• Filed: 02/06/2002
• Issued: 03/07/2006
• Est. Priority Date: 02/16/2001
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Komatsu, Masahiro
• Primary Examiner(s): Gesesse, Tilahun
• Assistant Examiner(s): TRINH, TAN H
• Application Number:
  US10/066,767
• Publication Number:
  US 20020115465A1
• Time in Patent Office: 1,490 Days
• Field of Search: 455/522, 455/69, 455/226.1, 455/515, 455/238
• US Class Current: 455/522
• CPC Class Codes: H04W 52/08 Closed loop power control
• CPC Class Codes: H04W 52/221 using past power control commands
• CPC Class Codes: H04W 52/223 predicting future states of the transmission
• CPC Class Codes: H04W 52/226 using past references to control power, e.g. look-up-table
• CPC Class Codes: H04W 52/282 taking into account the speed of the mobile
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile

Abstract

This invention is to prevent deterioration in communication quality of closed loop transmission power control, which may occur when the change in transmission power cannot keep up with a sudden change in the state of a transmission path. Transmission power control command extractor 4 extracts a transmission power control command from the uplink signal that has been received by receiver 2. Mobile position predictor 7 predicts the future position of the mobile station from its present position as recognized by mobile position recognizer 5 and from its present rate of movement as recognized by mobile velocity recognizer 6. Database 8 records the state of the downlink transmission path as a function of mobile position. Transmission power controller 9 looks up database 8 on the basis of the predicted future position of the mobile station and controls the downlink transmission power of base station BS on the basis of (i) the result of this lookup, and (ii) the transmission power control command. Transmitter 11 transmits at the downlink transmission power that has been instructed by transmission power controller 9.

Claims

1. A base station which uses uplink transmission power control commands transmitted from the base station via a downlink to control the uplink transmission power of a mobile station in such manner that the uplink receiving state at this base station becomes good:

which is characterized by comprising;

a receiver for receiving uplink radio signals that have been transmitted via the uplink;

an uplink receiving state estimator for estimating the receiving state of the uplink from the received uplink signal;

a mobile position recognizer for recognizing the present position of the mobile station from the received uplink signal;

a mobile velocity recognizer for recognizing the present rate of movement of the mobile station from the received uplink signal;

a mobile position predictor for predicting the future position of the mobile station from its present position and present rate of movement;

a database in which the state of the uplink transmission path has been recorded as a function of mobile position;

an uplink transmission power control command generator for looking up the database on the basis of the predicted future position of the mobile station, and for generating an uplink transmission power control command for controlling the uplink transmission power of the mobile station on the basis of (i) the future state of the uplink transmission path obtained as a result of the lookup, and (ii) the aforementioned estimated uplink receiving state;

a mixer for outputting the mixed signal obtained by mixing the downlink data with the aforementioned generated uplink transmission power control command; and

a transmitter for transmitting the mixed signal.

2. The base station claimed in claim 1, wherein the database records the state of the uplink transmission path as a function of the position of the mobile station, where the state of the uplink transmission path is evaluated from the level of the received uplink signal.

3. The base station claimed in claim 1, wherein the database records the state of the uplink transmission path as a function of the position of the mobile station, where the state of the uplink transmission path is evaluated from the SIR of the data after the received uplink signal has been demodulated.

4. The base station claimed in claim 1, wherein the database records the state of the uplink transmission path as a function of the position of the mobile station, where the state of the uplink transmission path is evaluated from the BER of the data after the received uplink signal has been demodulated.

5. The base station claimed in claim 1, wherein the database records the state of the uplink transmission path as a function of the position of the mobile station, where the state of the uplink transmission path is evaluated from the FER of the data after the received uplink signal has been demodulated.

6. The base station claimed in claim 1, wherein the database records the state of the uplink transmission path as a function of the position of the mobile station, where the state of the uplink transmission path is evaluated from the estimated state of the transmission path.

7. The base station claimed in claim 1, wherein, when it is predicted that the state of the uplink transmission path will deteriorate, the uplink transmission power control command generator generates an uplink transmission power control command that increases the uplink transmission power in advance.

8. The base station claimed in claim 1, wherein, when it is predicted that the state of the uplink transmission path will become very poor, the uplink transmission power control command generator generates an uplink transmission power control command that does not increase the uplink transmission power.

9. The base station claimed in claim 1, wherein the database controls transmission power during diversity handover by sharing information with a plurality of base stations.

10. A mobile station which uses uplink transmission power control commands transmitted from a base station via a downlink to control its uplink transmission power in such manner that the uplink receiving state at the base station becomes good:

which is characterized by comprising;

a receiver for receiving downlink radio signals that have been transmitted via the downlink;

an uplink transmission power control command extractor for extracting the aforementioned uplink transmission power control commands from the received downlink signal;

a mobile position recognizer for recognizing the present position of the mobile station;

a mobile velocity recognizer for recognizing the present rate of movement of the mobile station;

a mobile position predictor for predicting the future position of the mobile station from its present position and present rate of movement;

a database in which the state of the uplink transmission path has been recorded as a function of mobile position;

an uplink transmission power controller for looking up the database on the basis of the predicted future position of the mobile station, and for controlling the uplink transmission power of the mobile station on the basis of (i) the future state of the uplink transmission path obtained as a result of the lookup, and (ii) the aforementioned uplink transmission power control commands; and

a transmitter for transmitting at the uplink transmission power instructed by the uplink transmission power controller.

11. The mobile station claimed in claim 10, wherein, when it is predicted that the state of the uplink transmission path will deteriorate, the uplink transmission power controller increases the uplink transmission power in advance within a range that does not exceed the maximum transmission power.

12. The mobile station claimed in claim 10, wherein when it is predicted that the state of the uplink transmission path will become very poor, the uplink transmission power controller does not increase the uplink transmission power.