Power control scheme for maximizing carrier signal-to-noise ratio in multicarrier transmitters

• US 6,570,929 B1
• Filed: 07/08/1999
• Issued: 05/27/2003
• Est. Priority Date: 07/08/1999
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Eriksson, Patrik
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Tran, Khai
• Application Number:
  US09/349,717
• Time in Patent Office: 1,419 Days
• Field of Search: 375/260, 375/295, 375/345, 455/127, 455/522, 455/103, 455/232.1, 455/234.1, 455/245.1, 455/250.1, 330/254, 330/278, 330/129, 330/130
• US Class Current: 375/260
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/2637 with direct modulation of individual subcarriers
• CPC Class Codes: H04L 5/06 the signals being represented by different frequencies combined with time-division multiplexing H04L5/26
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 distributing total power among users or channels

Abstract

A method and apparatus for maximizing the signal-to-noise ratio of an output signal from a digital-to-analog converter. In a multicarrier transmitter the power of a plurality of modulated digital data streams are individually adjusted so that the peak power of the sum of the signals of the modulated data streams is equal to a full scale level of a digital-to-analog converter. The power adjusted signals are upconverted to their respective carrier frequencies and combined into a single digital data stream by an adder. The single digital data stream is converted into an analog data stream by the digital-to-analog converter. The power of the analog data stream is adjusted so that the power of each carrier frequency is at a level which provides a corresponding mobile station with a signal of acceptable quality.

Claims

1. In a multicarrier transmitter, a method for maximizing a signal-to-noise ratio of each of a plurality of individual carriers, the method comprising the steps of:

modulating a plurality of baseband data streams;

adjusting the power level of each of said plurality of modulated baseband data streams;

upconverting, to a respective carrier frequency, each of said plurality of power modulated, baseband data streams to form the plurality of individual carriers;

combining said plurality of individual carriers into a single data stream with a power level which is a function of the power levels associated with said plurality of individual carriers;

converting, in a digital to analog converter, said single data steam into an analog waveform; and

variably adjusting the power level of said analog waveform.

2. The method of claim 1, wherein the step of adjusting the power level of the plurality of modulated baseband data streams comprises the step of:

individually setting a gain of said plurality of modulated baseband data streams so that the power level of said plurality of individual carriers is equal to a full scale range of a digital-to-analog converter.

3. The method of claim 1, wherein said step of variably adjusting the power level of said analog waveform comprises the step of:

setting a gain for said analog waveform so that an absolute output power level of each of the carriers is equal to an amount of power required to provide a mobile station with an acceptable signal.

4. The method of claim 1, wherein said power level of the single data stream is equal to the square of the sum of the square root of each individual carrier.

5. A radiocommunication transmitter comprising:

a digital power control module;

a digital-to-analog converter;

an analog power control module; and

a radio control unit for adjusting the gain of said digital power control module and for adjusting the gain of said analog power control module, wherein the gain of said digital power control module is set such the output of said power control module is equal to a full scale range of said digital-to-analog converter.

6. A radiocommunication transmitter comprising:

a digital power control module;

a digital-to-analog converter;

an analog power control module;

a radio control unit for adjusting the gain of said digital power control module and for adjusting the gain of said analog power control module;

a modulator for modulating a baseband data stream and providing said modulated data stream to said digital control module; and

a multiplier for upconverting signals from said digital power control module to a corresponding carrier frequency and for providing said signals to said digital-to-analog converter.

7. A multicarrier transmitter comprising:

a plurality of digital power control modules;

a digital-to-analog converter; and

a radio control unit for individually adjusting the gain of each of said plurality of digital power control modules;

wherein the gain of each of said plurality of digital power control modules is set such that the square of the sum of the square root of power levels associated with the output of each of said power control modules is equal to a full scale range of said digital to analog converter.

8. The multicarrier transmitter of claim 7 further comprising:

an analog power control module; and

wherein a gain of said analog power control module is set such that power levels of individual carrier signals at an output of said analog power module are equal to a predetermined power level.

9. The multicarrier transmitter of claim 8, wherein said predetermined power level is a power level which a mobile station corresponding to one of said carrier signals receives a signal of acceptable quality.

10. The multicarrier transmitter of claim 7, further comprising:

a plurality of modulators for modulating a plurality of baseband data streams and providing said modulated data streams to said plurality of digital control modules;

a plurality of multipliers for upconverting signals from said digital power control modules to a plurality of corresponding carrier frequencies; and

an adder for summing said plurality of upconverted signals and providing said summed signals to said digital-to-analog converter.

11. A multicarrier transmitter comprising:

means for individually adjusting a power level of a plurality of modulated data streams;

means for upconverting said modulated data streams to form a plurality of carrier signals;

means for combining said plurality of carrier signals into a single data stream;

means for converting said single data stream from a digital waveform into an analog waveform; and

means for adjusting the power level of said analog waveform;

wherein said means for adjusting the power level of said analog waveform is controlled by a radio control unit.

12. In a multicarrier transmitter, a method for maximizing a signal-to-noise ratio of each individual carrier, the method comprising the steps of:

modulating a plurality of baseband data streams;

adjusting the power level of each of said plurality of modulated data streams;

upconverting, to a respective carrier frequency, each of said plurality of power adjusted data streams to form the plurality of carriers;

combining said plurality of carriers into a single data stream; and

converting, in a digital-to-analog converter, said combined data steam into an analog waveform;

wherein a peak power level of said plurality of modulated data streams is adjusted so that the power level of said single data stream is equal to a full scale range of a digital-to-analog converter.

13. The method of claim 12, further comprising the step of:

variably adjusting the power level of said analog waveform.

14. The method of claim 13, wherein said step of variably adjusting the power level of said analog waveform comprises the step of:

setting a gain for said analog waveform so that an absolute output power level of each of the carriers is equal to an amount of power required to provide a mobile station with an acceptable signal.

15. In a multicarrier transmitter, a method for maximizing a signal-to-noise ratio of each of a plurality of individual carriers and of a sum of said plurality of individual carriers, the method comprising the steps of:

modulating a plurality of baseband data streams;

adjusting the power level of each of said plurality of modulated baseband data streams;

applying a respective spreading code on each of said plurality of power modulated, baseband data streams to form the plurality of individual carriers;

combining said plurality of individual carriers into a single data stream;

converting, in a digital to analog converter, said single data steam into an analog waveform; and

variably adjusting the power level of said transmission signal.

16. The method of claim 15, wherein the step of adjusting the power level of the plurality of modulated baseband data streams comprises the step of:

individually setting a gain of said plurality of modulated baseband data streams so that the power level of said single data stream is equal to a full scale range of a digital-to-analog converter.

17. The method of claim 15, wherein said step of variably adjusting the power level of said analog waveform comprises the step of:

setting a gain for said analog waveform so that an absolute output power level of each of the carriers is equal to an amount of power required to provide a mobile station with an acceptable signal.