Spread spectrum adaptive power control

• US 6,671,308 B2
• Filed: 02/07/2002
• Issued: 12/30/2003
• Est. Priority Date: 01/04/1995
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Lomp, Gary R.
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US10/071,964
• Publication Number:
  US 20020122460A1
• Time in Patent Office: 691 Days
• Field of Search: 375/140, 375/345, 370/320, 370/335, 370/342, 370/441, 455/522
• US Class Current: 375/130
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H03G 3/3047 for intermittent signals, e.g. burst signals
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/709 Correlator structure
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 1/712 Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
• CPC Class Codes: H04B 2201/70707 Efficiency-related aspects
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04J 13/0003 Code application, i.e. aspects relating to how codes are applied to form multiplexed channels
• CPC Class Codes: H04J 13/10 Code generation
• CPC Class Codes: H04J 13/16 Code allocation
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/22 taking into account previous information or commands
• CPC Class Codes: H04W 52/221 using past power control commands
• 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 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/362 Aspects of the step size
• CPC Class Codes: H04W 52/367 : Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/52 : using AGC [Automatic Gain Control] circuits or amplifiers
• CPC Class Codes: H04W 52/54 : Signalisation aspects of the TPC commands, e.g. frame structure

Abstract

A system and method for adaptive power control of a spread spectrum transmitter of a mobile unit operating in a cellular-communications network having a plurality of mobile units in communication with a base station. In response to a received signal from the mobile unit, the received signal having a first spread-spectrum signal and an interfering signal, an automatic gain control (AGC) circuit within the base station generates an AGC-output signal which is despread by a base despreader and then processed as a received-power level. A power command signal is generated using a threshold test and the received-power level. The power command signal is transmitted to the mobile station as a second spread-spectrum signal. The mobile station despreader despreads the second spread-spectrum signal as a power adjust signal and, responsive to the power adjust signal, increases or decreases the power level of the first spread spectrum signal.

Claims

1. A system for adaptive-power control of a spread-spectrum transmitter of a mobile station operating in a cellular-communications network using spread-spectrum modulation, comprising:

a mobile station having a mobile transmitter coupled to a mobile antenna for transmitting a first spread-spectrum signal using radio waves;

a base station having an automatic-gain-control (AGC) circuit, responsive to a received signal, for generating an AGC-output signal, with the received signal including the first spread-spectrum signal and an interfering signal;

a base correlator coupled to said AGC circuit for despreading the AGC-output signal;

a power-measurement circuit coupled to said base-correlator, for processing the despread AGC-output signal as a received-power level;

a comparator coupled to said power-measurement circuit for generating a comparison signal using a threshold test and the received-power level;

a power-command circuit coupled to said comparator and responsive to the comparison signal for generating a power-command signal;

an antenna;

a transmitter coupled to said antenna and to said power-command circuit for transmitting the power-command signal as a second spread-spectrum signal; and

said mobile station further including a mobile correlator coupled to said mobile antenna for despreading the power-command signal from the second spread-spectrum signal as a power-adjust signal;

a decision device coupled to said mobile correlator for responding to the power-adjust signal;

an accumulator coupled to said decision device;

a step-size algorithm device coupled to said decision device and to said accumulator for storing an algorithm for adjusting a power level; and

a first variable-gain device coupled to said accumulator, responsive to the power-adjust signal, for adjusting a transmitter-power level of the first spread-spectrum signal transmitted from said mobile-transmitter.

2. The system of claim 1 with said power-measurement circuit coupled to said AGC circuit and to said base-correlator, responsive to processing the received signal with the despread AGC-output signal, for generating the received-power level.

3. The system of claim 1 with said first variable-gain device adjusting the transmitter-power level using nonlinear steps in power level.

4. The system of claim 1 wherein a power control scheme of the system is based on a signal to noise ratio of the first spread-spectrum signal.

5. A system for adaptive-power control of a spread-spectrum transmitter of a mobile station operating in a cellular-communications network using spread-spectrum modulation, with the mobile station transmitting a first spread-spectrum signal, said system comprising:

a base station having,

automatic gain control (AGC) means, responsive to a received signal, with the received signal including the first spread-spectrum signal and an interfering signal, for generating an AGC-output signal and an AGC-control signal;

base-correlator means for despreading the AGC-output signal as a despread AGC-output signal;

power means for processing the despread AGC-output signal as a received-power level;

comparator means for generating a comparison signal using a threshold test and the received-power level;

modulator means for converting the comparison signal to a power command signal; and

transmitter means for transmitting the power-command signal as a second spread-spectrum signal;

a mobile station having,

despreader means for despreading the power-command signal from the second spread-spectrum signal as a power-adjust signal;

decision means, responsive to the power-adjust signal, for increasing or decreasing a power level; and

variable-gain means, responsive to said decision means, for adjusting a transmitter-power level of the first spread-spectrum signal.

6. The system of claim 5 with said power means responsive to processing the received signal with the despread AGC-output signal, for generating the received-power level.

7. The system of claim 5 with said variable-gain means adjusting the transmitter-power level using nonlinear steps in power level.

8. The system of claim 5 wherein said AGC means includes an automatic-gain-control circuit.

9. The system of claim 5 wherein said variable-gain means includes a variable-gain attenuator for adjusting the transmitter-power level.

10. The system of claim 5 wherein said variable-gain means includes a variable-gain amplifier for adjusting the transmitter-power level.

11. The system of claim 5 wherein a power control scheme of the system is based on a signal to noise ratio of the first spread-spectrum signal.

12. A method for adaptive-power control, from a base station, of a spread-spectrum transmitter of a mobile station operating in a cellular-communications network using spread-spectrum modulation, with the mobile station transmitting a first spread-spectrum signal, said method comprising the steps of:

generating at said base station, from a received signal, with the received signal including the first spread-spectrum signal and an interfering signal, an AGC-output signal;

despreading, at said base station, the AGC-output signal as a despread AGC-output signal;

processing, at said base station, the despread AGC-output signal to generate a received-power level;

generating, at said base station, a comparison signal using a threshold test and the received power level and generating a power command signal responsive to said comparison signal;

transmitting, from said base station, the power-command signal as a second spread-spectrum signal;

despreading, at said mobile station, the power-command signal from the second spread-spectrum signal as a power-adjust signal; and

adjusting, at said base station, responsive to the power-adjust signal, a transmitter-power level of the first spread-spectrum signal.

13. The method of claim 12 wherein the step of adjusting includes the step of adjusting the transmitter-power level using nonlinear steps in power level.

14. The method of claim 12 wherein a power control scheme of the method is based on a signal to noise ratio of the first spread-spectrum signal.