Method and system for controlling the transmission power of certain parts of a radio transmission

• US 6,603,773 B2
• Filed: 04/07/1999
• Issued: 08/05/2003
• Est. Priority Date: 04/08/1998
• Status: Expired due to Term

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Salonaho, Oscar, Laakso, Janne
• Primary Examiner(s): Hsu, Alpus H.
• Assistant Examiner(s): Tran, Thien D
• Application Number:
  US09/287,844
• Publication Number:
  US 20030099209A1
• Time in Patent Office: 1,581 Days
• Field of Search: 370/320, 370/332, 370/333, 370/335, 370/342, 370/441, 370/503, 370/506, 370/508, 375/295, 375/296, 375/130, 455/134, 455/38.3, 455/522, 455/68, 455/69
• US Class Current: 370/441
• 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 52/325 Power control of control or pilot channels
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

A data transmission system comprises a first device and a second device and a duplex data transmission connection therebetween. The first device sends to the second device user data on a data channel and control information on a control channel. The transmission is arranged in frames that comprise a user data field corresponding to a data channel and at least a first and a second control information field corresponding together to a control channel. In order to realise the control of the transmission power, there is determined a first transmission power level, a second transmission power level and a third transmission power level. From the second device to the first device there is transmitted a frame by applying said first transmission power level to the transmission of the user data field, said second transmission power level to the transmission of the first control information field and said third transmission power level to the transmission of the second control information field.

Claims

1. A method for controlling transmission power in a data transmission system comprising a first device and a second device and in between them a two-way data transmission connection that employs Code Division Multiple Access, where the first device transmits to the second device user data on a data channel, and the second device transmits to the first device user data on a data channel and control information on a control channel, and a transmission arranged in a time slot comprises a user data field corresponding to a data channel and at least a first and a second control information field corresponding together to the control channel, said method comprising the steps of:

determining a first transmission power level, a second transmission power level and a third transmission power level; and

transmitting from the second device to the first device during a time slot by applying said first transmission power level to the transmission of the user data field, said second transmission power level to the transmission of the first control information field and said third transmission power level to the transmission of the second control information field, and also applying a first spreading code to the transmission of the user data field and a second spreading code, different than said first spreading code, to the transmission of at least one of the first control information field and the second control information field.

2. A method according to claim 1, wherein said second and third transmission power levels are equal and different from said first transmission power level, corresponding to the transmission of the data channel with one transmission power level and the control channel with another transmission power level.

3. A method according to claim 1, wherein said second and third transmission power levels are unequal, corresponding to the transmission of at least two control information fields of the data channel with mutually different transmission power levels.

4. A method according to claim 1, additionally comprising the steps of

sensing a quality factor of the connection between the first device and the second device and

adjusting at least one of said second and third transmission power levels in relation to said first transmission power level, on the basis of the sensed quality factor between the first and second device.

5. A method according to claim 4, wherein the step of adjusting at least one of said second and third transmission power levels comprises the substeps of adjusting said second transmission power level in a certain way and adjusting said third transmission power level in a different way on the basis of the same sensed quality factor.

6. A method according to claim 4, wherein, in a data transmission system comprising mobile stations as well as a number of base stations and a radio network controller controlling the operation thereof, it comprises the steps of

sensing a quality factor of a connection between a mobile station and a base station,

conveying a value representing the sensed quality factor to the radio network controller,

deciding in the radio network controller the adjustments to at least one of the second and third transmission power levels on the basis of said conveyed value,

conveying to at least one of said base station and said mobile station power control information representing the decided adjustments to the transmission power levels and

implementing in at least one of said base station and said mobile station the decided adjustments to the transmission power levels on the basis of said conveyed power control information.

7. A method according to claim 6, wherein during a given connection between said base station and said mobile station, the quality factor is sensed repeatedly, and that the radio network controller makes a new decision as regards the transmission power levels as a response to each occasion of sensing the quality factor.

8. A method according to claim 6, wherein at least one of the adjusted transmission power levels used by the base station is reported to the mobile station.

9. A method according to claim 6, wherein the radio network controller makes a decision as regards at least one of the second and third transmission power levels to be used by the base station on the basis of the sensed quality of a downlink connection between the base station and the mobile station.

10. A method according to claim 9, comprising the steps of

sensing at the mobile station the quality of the downlink connection between the base station and the mobile station,

reporting by the mobile station the sensed quality of the downlink connection to the radio network controller,

calculating at the radio network controller the initial adjusted transmission power levels to be used by said base station,

adding at the radio network controller a reliability margin to the initial adjusted transmission power levels to obtain final adjusted transmission power levels and

signalling the final adjusted transmission power levels to the base station.

11. A method according to claim 9, where additionally a macrodiversity connection is applied, where among the base stations controlled by the radio network controller there are a first and second base station, which are simultaneously in a data transmission connection with one and the same mobile station, said method comprising the steps of

sensing at the mobile station the quality of the downlink connection between the first base station and the mobile station and between the second base station and the mobile station,

reporting by the mobile station the sensed qualities of the downlink connections to the radio network controller,

selecting at the radio network controller the reported quality describing the better of the reported connection qualities as a reference value,

calculating at the radio network controller a distance attenuation factor for each base station by calculating the ratio between the reported quality regarding that base station and said reference value,

separately calculating at the radio network controller for each base station the relation of at least one of the second and third transmission power levels used by that base station to the first transmission power level used by that base station by multiplying said distance attenuation factor by a ratio of the unadjusted second or third transmission power level respectively and the first transmission power level,

adding at the radio network controller to the calculated second or third transmission power level for each base station a reliability margin and

signalling the so obtained final adjusted transmission power levels to the base stations.

12. A method according to claim 11, wherein the size of said reliability margin is separately determined for each base station.

13. A method according to claim 11, wherein the size of said reliability margin is selected on the basis of a data transmission rate applied in the connection in question.

14. A method according to claim 13, wherein the size of said reliability margin is an increasing function of the data transmission rate.

15. A method according to claim 6, wherein the radio network controller makes a decision as regards at least one of the second and third transmission power levels used by the base station on the basis of the sensed quality of an uplink connection between the base station and a mobile station.

16. A method according to claim 6, wherein the radio network controller first makes a decision of the first transmission power level to be used by the base station, and thereafter a decision of at least one of the second and third transmission power levels used by said base station in relation to the decided first transmission power level used by said base station.

17. A method according to claim 6, wherein the radio network controller makes a decision as regards at least one of the second and third transmission power levels to be used by the mobile station on the basis of the sensed quality of a uplink connection between the base station and the mobile station.

18. A method according to claim 4, wherein the sensed quality factor is one of the following:

SIR, S/N, S/(N+I), BER, FER, or an estimate of the reliability of a received value.

19. A method according to claim 1, wherein in a macrodiversity connection, where the first device is simultaneously in the data transmission connection with a primary second device and a secondary second device, the method comprises the steps of:

determining said first, second and third transmission power levels separately for said primary and said secondary second devices, and

transmitting from the primary second device to the first device during a time slot by applying the first, the second and the third transmission power levels determined for the primary second device, and from the secondary second device to the first device during a time slot by applying the first, the second and the third transmission power levels determined for the secondary second device.

20. A method according to claim 1, wherein the determination of the first, second and third transmission power levels is restricted so that each of them is always at least as high as a smallest allowed transmission power level predefined in the data transmission system, and at most as high as a highest allowed transmission power level predefined in the data transmission system.

21. A method according to claim 1, wherein the determination of the second and third transmission power levels is additionally restricted so that each of them is always at least as high as the first transmission power level multiplied by a given first factor, and at most as high as the first transmission power level multiplied by a given second factor.

22. A method according to claim 1, wherein the data transmission system comprises mobile stations and base stations so that first device is a mobile station and the second device is a base station, and the control information comprises power control commands sent by the base station to the mobile station, said method comprising the steps of

estimating at the mobile station the reliability of at least a majority of the power control commands received from the base station, and

when adjusting its own transmission power, observing at the mobile station only such power control commands, whose estimated reliability in reception surpasses a predetermined minimum reliability.

23. A method according to claim 22, wherein the mobile station estimates the reliability of the received power control commands by estimating the SIR value in the reception, in which case said predetermined minimum reliability corresponds to a predetermined SIR value.

24. An improved cellular radio system mobile station, comprising means for sending data to be transmitted and control data to a base station, and means for receiving data to be transmitted and control data from the base station, wherein the improvement lies in that it is provided to serve as the first or second device in the method described above in claim 1.

25. An improved cellular radio system base station, comprising means for sending data to be transmitted and control data to a mobile station and means or receiving data to be transmitted and control data from the mobile station, wherein the improvement lies in that it is provided to serve as the first or second device in the method described above in claim 1.