Spread spectrum adaptive power control system and method

• US 5,835,527 A
• Filed: 11/04/1996
• Issued: 11/10/1998
• Est. Priority Date: 01/04/1995
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Lomp, Gary R.
• Primary Examiner(s): Ghebretinsae, Temesghen
• Application Number:
  US08/743,379
• Time in Patent Office: 736 Days
• Field of Search: 375/200, 375/349, 455/33.1, 455/59, 455/61, 455/103, 379/59, 379/63
• US Class Current: 375/142
• 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 buy a base correlator and then processed as a received-power level. The received-power level is then compared to a threshold level level to generate a power command signal. The power command signal is transmitted to the mobile stations as a spread-spectrum signal. The mobile station despreads the second-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 operating in a cellular-communication network using spread-spectrum modulation, comprising:

a mobile station having a mobile transmitter coupled to a mobile antenna for transmitting a 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;

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 power-command circuit coupled to said power measurement circuit for generating, responsive to a relationship between the received-power level and a threshold power level, a power-command signal;

an antenna;

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

said mobile station further including

a mobile correlator coupled to said mobile antenna for despreading the power-command signal as a power-adjust signal; and

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

2. The system as set forth in claim 1 wherein an AGC-control signal is combined with said received power level of the despread AGC-output signal to create an adjusted power level which is compared to said threshold power level to generate the power-command signal.

3. The system as set forth in claim 40 or 41 with said first variable-gain device adjusting the transmitter-power level using nonlinear steps in power level.

4. 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 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 spread-spectrum signal, for generating an AGC-output signal;

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

comparator means for comparing the received-power level to a threshold level to generate a comparison signal; and

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

said mobile station having,

means for receiving the power-command signal as a power-adjust signal; and

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

5. The system as set forth in claim 4 with said power means for processing the received signal with the AGC-output signal to generate the received-power level.

6. The system as set forth in claim 4 with said variable-gain means adjusting the transmitter-power level using nonlinear steps in power level.

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

8. The system as set forth in claim 4, 5, 6 or 7 wherein said AGC means includes an automatic-gain-control circuit.

9. The system as set forth in claim 4, 5, 6 or 7 wherein said variable-gain means includes a variable-gain attenuator for adjusting the transmitter-power level.

10. The system as set forth in claim 4, 5, 6 or 7 wherein said variable-gain means includes a variable-gain amplifier for adjusting the transmitter-power level.

11. The system as set forth in claim 4, 5, 6 or 7 wherein an AGC-control signal is combined with said received power level of the despread AGC-output signal to create an adjusted power level which is compared to said threshold power level to generate the power-command signal.

12. The system as set forth in claim 11 wherein said AGC-control signal is logarithmically added to said received power level.

13. 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;

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

comparing the received-power level to a threshold;

generating, responsive to the comparison between the received-power level and the threshold, a power-command signal;

receiving, at said mobile station, the power-command signal as a power-adjust signal; and

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

14. The method as set forth in claim 13 wherein the step of processing, at said base station, includes the step of despreading the AGC-output signal and processing the received signal with the despread AGC-output signal, for generating the received-power level.

15. The method as set forth in claim 13 or 14 wherein the step of adjusting includes the step of adjusting the transmitter-power level using nonlinear steps in power level.

16. A system for adaptive-power control of a spread-spectrum transmitter operating in a cellular-communication 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 and an AGC-control signal, with the received signal including the first spread-spectrum signal and an interfering signal;

a first weighting device, coupled to said automatic-gain-control circuit, for weighting the AGC-control 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 second weighting device, coupled to said power measurement circuit, for weighting the received-power level;

a combiner, coupled to said second weighting device and to said first weighting device, for combining the weighted-received-power level and the weighted-AGC-control signal as an adjusted-received-power level; and

a power-command circuit coupled to said combiner for generating, responsive to a relationship between the adjusted-received-power level and a threshold level, a power-command signal;

said mobile station further including

a despreader for despreading the power-command signal as a power-adjust signal; and

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

17. The system as set forth in claim 16 further comprising:

a plurality of base correlators coupled to said AGC circuit for despreading a plurality of channels, respectively, as a plurality of despread data; and

a plurality of power-measurement circuits coupled to said plurality of base correlators, respectively.

18. The system as set forth in claim 16 or 17 with said variable-gain device adjusting the transmitter-power level using nonlinear steps in power level.

19. A system for adaptive-power control of a spread-spectrum transmitter of a motile 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;

first weighting means for weighting the AGC-control signal;

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

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

second weighting means for weighting the received-power level;

combining means for combining the weighted-received-power level and the weighted-AGC-control signal as an adjusted-received-power level;

comparator means for comparing the adjusted-received-power level to a threshold level and for outputting a power-control signal; and

delta modulating means for converting the power-control signal to a power-command signal;

said mobile station having,

correlator means for despreading the power-command signal as a power-adjust signal; and

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

20. The system as set forth in claim 19 further comprising:

a plurality of base correlator means for despreading a plurality of channels, respectively, as a plurality of despread AGC-output signals; and

a plurality of power measurement means for processing the plurality of despread-AGC-output signals, respectively;

said combining means for combining the plurality of processed-despread-AGC-output signals prior to transmission to the mobile station.

23. The system as set forth in claim 19, or 20 wherein said AGC means includes an automatic-gain-control circuit.

24. The system as set forth in claim 19 or 20 wherein said variable-gain means includes a variable-gain attenuator for adjusting the transmitter-power level.

25. The system as set forth in claim 19 or 20 wherein said variable-gain means includes a variable-gain amplifier for adjusting the transmitter-power level.

21. The system as set forth in claim 61 or 62 with said I variable-gain means adjusting the transmitter-power level using nonlinear steps in power level.

22. The system as set forth in claim 61 or 62 with said variable-gain means adjusting the transmitter-power level using linear steps in power level.

26. 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, an AGC-output signal and an AGC-control signal;

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

weighting the AGC-control signal;

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

weighting the received-power level;

combining the weighted-received-power level and the weighted-AGC-control signal as an adjusted-received power control signal;

comparing the adjusted-received-power control signal to a threshold;

generating, at said base station, a power-command signal from the comparison;

despreading, at said mobile station, the power-command signal as a power-adjust signal;

tracking previous power levels; and

adjusting, at said mobile station, responsive to the power-adjust signal and tracked previous power levels, a transmitter-power level of the first spread-spectrum signal.

27. The method as set forth in claim 72 wherein the step af adjusting includes the step of adjusting the transmitter-power level using nonlinear steps in power level.