Control of transmission power in wireless packet data transfer

• US 5,995,496 A
• Filed: 06/16/1997
• Issued: 11/30/1999
• Est. Priority Date: 06/17/1996
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Honkasalo, Zhichun, Jokinen, Harri, Hamalainen, Jari, Fehlmann, Richard
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): Ho, Tuan Q
• Application Number:
  US08/876,677
• Time in Patent Office: 897 Days
• Field of Search: 370/318, 370/328, 370/335, 370/311, 370/342, 370/391, 370/332, 370/333, 370/320, 370/317, 370/352, 370/389, 370/353, 370/354, 370/356, 370/441, 455/69, 455/134, 455/126, 455/135, 455/226
• US Class Current: 370/318
• CPC Class Codes: H04W 52/06 TPC algorithms
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/228 using past power values or information
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment

Abstract

In packet switched data transfer of the cellular radio system, the control of the transmission power comprises characteristics as well of the closed-loop control and the open-loop control. Before forming the connection and during long pauses between the packets, the terminal device measures the control signal transmitted by the base station and compares its signal power (R0) to the target level (t0), that is included by the base station in the control signal as a parameter. The base station informs in the control signal also the transmission power, whereby the terminal device sets the same power to be its transmission power, corrected by the difference between the target level and the measured quality of the link (t0-R0). In addition, also the measured quality of the link (RXQUAL) is transmitted in the acknowledgment messages of the packets, whereby the transmitting device changes its transmission power so that the quality will be controlled to the certain target level. The biggest step of the change is determined by the length of the packets. In the packet transfer downlink, the base station uses first the maximum power and corrects then its transmission power based on the measuring information included in the acknowledgment messages transmitted by the terminal device.

Claims

1. A method for controlling transmission power in a terminal device of a cellular radio system, a radio connection of which with a certain base station comprises an alternative first state (10) and second state (11), in the first state of which the terminal device receives (30) signals transmitted regularly by the base station and in the second state of which the terminal device additionally g transmits (34) data as packets to the base station, characterized in that in said first state the control of the default value of the transmission power in said terminal device is based on measuring (31, 32) of the signals transmitted regularly by the base station, and in said second state the control of the transmission power in said terminal device is based both on a feedback transmitted by the base station on the quality of a data transfer link (35, 36, 37, 39) and on measuring of other signals transmitted regularly by the base station.

2. A method in accordance with claim 1, characterized in that in said first state the control of the default value of the transmission power in said terminal device is based on measuring of the signal power (R0) of the signals transmitted regularly by the base station.

3. A method in accordance with claim 2, characterized in that when the transmission power (SB) with which said base station transmits said signals that it regularly transmits, and the target level (t0) of a link quality, with which it is advantageous for said base station to receive packets transmitted by said terminal device, are known by said terminal device, it corrects the default value of its transmission power to correspond to the value Si(ti) that is determined by the formula

4. A method in accordance with claim 1, characterized in that in said first state the control of the default value of the transmission power in said terminal device is based on measuring of the C/I ratio of the signals transmitted regularly by the base station.

5. A method in accordance with claim 1, characterized in that in said second state the meaning of the feedback being carried by a certain acknowledgment message transmitted by said base station and expressing the quality of the data transfer link, for the control of the transmission power of said terminal device, is the smaller the longer the time is that has passed from the reception of the feedback in question by said terminal device.

6. A method in accordance with claim 1, characterized in that the terminal device that is in said second state moves to the first state when a certain predetermined time limit from reception of the feedback on the latest transmitted packet has expired, without the terminal device having started to transmit the next packet (TIMEOUT).

7. A method in accordance with claim 6, characterized in that said predetermined time limit is the longer the more seldom the transmission power has been corrected earlier during the same packet switched radio connection.

8. A method in accordance with claim 1, characterized in that in said second state, the value of the transmission power calculated for the next packet at a certain moment follows the formula

9. A method in accordance with claim 1, characterized in that when the terminal device has determined the value of a certain new transmission power, it changes its transmission power from the previous value of the transmission power towards said new value of the transmission power not more than by a certain marginal factor.

10. A method in accordance with claim 9, characterized in that said marginal factor is determined based on the size of the packets to be transmitted in the data transfer link.

11. A method in accordance with claim 10, characterized in that said marginal factor is the bigger the longer the packets to be transmitted in the data transfer link are.

12. A method in accordance with claim 1, characterized in that if said terminal device does not get in said second state any acknowledgment at all to a certain packet that it has transmitted, it increases its transmission power.

20. A method in accordance with any of the foregoing claims, characterized in that if said base station does not get in said second state any acknowledgement at all to a certain packet transmitted by it, it increases its transmission power.

22. A method in accordance with claim 1, wherein the second state, the value of the transmission power of a terminal device of a packet switched cellular radio base station calculated at a certain moment follows the formula

13. A method for controlling a transmission power in a base station of a cellular radio system, a radio connection of which at least with one terminal device comprises an alternative first state (10) and a second state (11), in the first state of which the base station transmits regularly control signals and in the second state of which the base station additionally transmits data as packets to a certain terminal device, characterized in that in said first state the default value of the transmission power in said base station is the same as the maximum transmission power of the base station and in said second state the control of the transmission power in said base station is based as well on the feedback of the quality of a data transfer link (35, 36, 37, 39) said feedback being transmitted by the terminal device, as on the time passed from the reception of a previous acknowledgement message by the base station from said terminal device.

14. A method in accordance with claim 13, characterized in that in said second state the meaning of a certain feedback transmitted by said terminal device and indicating the quality of the data transfer link is the smaller the longer the time is that has passed from the reception of the feedback in question by said base station.

15. A method in accordance with claim 13, characterized in that the base station that is in said second state moves to the first state when a certain predefined time limit from reception of the feedback on the latest transmitted packet has expired without the base station having started to transmit the next packet (TIMEOUT).

16. A method in accordance with claim 15, characterized in that said predefined time limit is the longer the more seldom the transmission power has been corrected earlier during the same packet switched radio link.

17. A method in accordance with claim 13, characterized in that when the base station has determined the value of the certain new transmission power, it changes its transmission power from the previous value of the transmission power towards said new value of the transmission power not more than by a certain marginal factor.

18. A method in accordance with claim 17, characterized in that said marginal factor is determined based on the size of the packets to be transmitted in the data transfer link.

19. A method in accordance with claim 18, characterized in that said marginal factor is the bigger the longer the packets to be transmitted in the data transfer link are.

23. A method in accordance with claim 13, wherein said alternative first state (10) and said alternative second state (11), the value of transmission power of a packet switched cellular radio base station calculated for the next packet to a certain terminal device at a certain moment, characterized in that said first state of which the packet switched cellular radio base station regularly transmits control signals and in said second state of which the packet switched cellular radio base station additionally transmits feedback data as packets to a certain terminal device, characterized in that in said first state the default value of the transmission power in said packet switched cellular radio base station is the same as the maximum transmission power of the packet switched cellular radio base station and in said second state the control of the transmission power in said packet switched cellular radio base station is based on the quality of the data transfer link (35, 36, 37, 39) derived from the feedback data, said feedback data being transmitted by the terminal device, and on the time passed from the reception of previous feedback data transmitted by the terminal device.

21. A method for controlling transmission power in a terminal device of a packet switched radio communication system comprising steps of:

a) establishing an initial state radio connection with a certain packet switched radio communication base, wherein a default value of the transmission power of the terminal device is based on a measuring of signals regularly transmitted by the base station; and

b) switching to an alternative packet reception state radio connection with a certain packet switched radio communication base station, wherein the terminal device receives additional feedback acknowledgment data from the base station, wherein the transmission power of the terminal device is based both on feedback acknowledgment data and on a measuring of signals regularly transmitted by the base station, wherein the feedback acknowledgment data contains information on the quality and age of packets received and transmitted by the base station.