Multiple code channel power control in a radio communication system

• US 6,173,162 B1
• Filed: 06/16/1997
• Issued: 01/09/2001
• Est. Priority Date: 06/16/1997
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Dahlman, Erik, Lundsjö, Johan, Johansson, Mathias
• Primary Examiner(s): Hunter, Daniel S.
• Assistant Examiner(s): ARMSTRONG, DARNELL R
• Application Number:
  US08/874,907
• Time in Patent Office: 1,303 Days
• Field of Search: 455/69, 455/522, 455/434, 455/515, 455/88, 455/572
• US Class Current: 455/69
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04W 52/12 Outer and inner loops
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels

Abstract

Methods of controlling the power levels of transmitted signals in telecommunication systems are described. A user may be assigned a plurality of radio bearers associated with a plurality of physical channels for communicating with a radiocommunication system. A fast power control loop monitors a reference channel and adjusts transmit power in accordance with an SIR target value. A plurality of slow power control loops adjust the SIR target value and also provide offset transmit power values associated with each physical channel to adapt the transmit powers in accordance with varying quality requirements between radio bearers.

Claims

1. A method for controlling transmit power in a radiocommunication system comprising the steps of:

assigning a plurality of physical channels to a user in said radiocommunication system;

measuring a characteristic of one of said plurality of physical channels which serves as a reference channel;

controlling transmit power associated with said reference channel based on said measured characteristic; and

adjusting transmit power of each of the plurality of physical channels other than said reference channel relative to the reference channel transmit power using individual power control loops.

2. The method of claim 1 wherein said reference channel is a physical control channel (PCCH) carrying control information.

3. The method of claims 1 wherein said step of measuring further comprises the step of:

measuring a signal-to-interference ratio (SIR) of said reference channel.

4. The method of claim 3 wherein said step of controlling transmit power further comprises the step of:

controlling the transmit power associated with said reference channel based on a comparison of the measured SIR and a target SIR value.

5. The method of claim 4, further comprising the step of:

adjusting said target SIR value according to quality measurements on the reference channel, where the target SIR value is decreased when the measured quality goes above a first threshold, and the target SIR value is increased when the measured quality falls below a second threshold.

6. The method of claim 5, wherein said target SIR value remains unchanged if said quality measurements are between said first and said second thresholds.

7. The method of claim 4 further comprising the steps of:

adjusting said target SIR value according to quality measurements on radio bearers that are assigned to the user, where the target SIR value is increased if the measured quality on at least one of the radio bearers falls below a first threshold associated with said at least one of the radio bearers, and the target SIR value is decreased if the measured quality on all radio bearers goes beyond a second threshold specific for each particular radio bearer.

8. The method of claim 1 wherein said step of adjusting transmit power of each of said plurality of physical channels other than said reference channel further comprises the steps of:

measuring a quality associated with each radio bearer mapped onto one or more of said plurality of physical channels; and

adjusting a transmit power of each of said plurality of physical channels other than said reference channel relative to the transmit power of said reference channel based on said measured quality.

9. The method of claim 5, wherein said step of adjusting transmit power of each of said plurality of physical channels other than said reference channel further comprises the steps of:

measuring a quality associated with each radio bearer mapped onto one or more of said plurality of physical channels; and

adjusting, at each update of said target SIR value, a transmit power of each of said plurality of physical channels other than said reference channel relative to the transmit power of said reference channel based on said measured quality by determining a change in difference between a transmit power of each physical channel other than said reference channel and a transmit power of said reference channel.

10. The method of claim 9, wherein said step of determining a change in difference further comprises the step of:

setting said difference equal to a difference between x dB and y dB, where;

x is positive if a measured quality on at least one radio bearer mapped onto a particular physical channel falls below a first threshold associated with said particular radio bearer;

x is negative if measured quality on all of the radio bearers that are mapped onto said particular physical channel goes beyond a respective second threshold associated with each particular radio bearer; and

y is the dB change in said target SIR value.

11. The method of claim 6, wherein said step of adjusting transmit power of each of said plurality of physical channels other than said reference channel further comprises the steps of:

measuring a quality associated with each radio bearer mapped onto one or more of said plurality of physical channels; and

adjusting, at each update of said target SIR value, a transmit power of each of said plurality of physical channels other than said reference channel relative to the transmit power of said reference channel based on said measured quality by determining a change in difference between a transmit power of each physical channel other than said reference channel and a transmit power of said reference channel.

12. The method of claim 11, wherein said step of determining a change in difference further comprises the step of:

setting said difference equal to a difference between x dB and y dB, where;

x is positive if a measured quality on at least one radio bearer mapped onto a particular physical channel falls below a first threshold associated with said particular radio bearer;

x is negative if measured quality on all of the radio bearers that are mapped onto said particular physical channel goes beyond a respective second threshold associated with each particular radio bearer; and

y is the dB change in said target SIR value.

13. A communication station comprising:

a receiving unit for receiving a transmit power control command and at least one power offset command;

a transmitter for transmitting data on a physical control channel and at least one physical data channel; and

a power control unit for adjusting a transmit power common to both said physical control channel and said at least one physical data channel using said power control command and for adjusting a relative transmit power between said physical control channel and said at least one physical data channel using said at least one power offset command.

14. The communication station of claim 13, wherein said communication station is a base station.

15. The communication station of claim 13, wherein said communication station is a mobile station.

16. The communication station of claim 13, wherein said transmitter further comprises:

a first spreading unit for spreading data associated with said physical control channel;

a second spreading unit for spreading data associated with said at least one physical data channel;

a variable gain amplifier connected to said second spreading unit for adjusting said relative transmit power; and

a summing device for combining an output of said first spreading unit and an output of said variable gain amplifier.

17. The communication station of claim 16, further comprising:

a scrambling unit for scrambling said combined outputs;

a second variable gain amplifier for adjusting said transmit power common to said physical control channel and said at least one physical data channel.