Fuzzy-logic spread-spectrum adaptive power control

• US 5,963,583 A
• Filed: 01/14/1998
• Issued: 10/05/1999
• Est. Priority Date: 09/29/1995
• Status: Expired due to Fees

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Golden Bridge Technology Incorporated
• Inventors: Kanterakis, Emmanuel, Davidovici, Sorin
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): WEBSTER, BRYAN E
• Application Number:
  US09/007,026
• Time in Patent Office: 629 Days
• Field of Search: 375/200, 375/205, 375/207, 375/208, 375/219, 375/221, 375/227, 375/343, 375/344, 375/346, 370/319, 370/311, 370/332, 370/335, 455/38.3, 455/522, 455/68-70, 455/88, 364/148.05, 706/1
• US Class Current: 375/130
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04W 52/228 using past power values or information

Abstract

A fuzzy-logic spread-spectrum adaptive power control system comprising a base station and a plurality of remote units. The base station receives a spread-spectrum signal, and samples the despread spread-spectrum signal at a peak correlation time of the data channel, and at a non-peak correlation time of the data channel. This in turn generates a signal level and a noise level, respectively. A signal-to-noise ratio calculator generates a signal-to-noise ratio from the signal level and the noise level. A fuzzy-logic controller compares the signal-to-noise ratio to a set of predetermined thresholds, and using a state machine, generates a control signal which is thereby transmitted to the remote unit, indicating the amount by which to increase or decrease transmitted power. Each remote unit demodulates the control signal, and a transmitter controller adjusts a power level of the remote-unit spread-spectrum transmitter.

Claims

1. A fuzzy-logic spread-spectrum system for adaptive power control from a base station comprising:

a base antenna for receiving a first spread-spectrum signal having a pilot channel and a data channel;

a pilot-channel despreader operatively coupled to said base antenna for despreading a pilot channel signal embedded in the first spread-spectrum signal and for generating from the despread pilot channel signal a timing signal;

a sample-and-hold controller, coupled to said pilot-channel despreader, responsive to the timing signal for generating a first control signal and a second control signal;

a data-channel despreader, coupled to said base antenna, for despreading a data channel signal embedded in the first spread-spectrum signal as a despread signal;

a sample-and-hold circuit, operatively coupled to said data-channel despreader and to said sample-and-hold controller, responsive to the first control signal for sampling the despread signal at a peak correlation time of the data channel signal to generate from the despread signal a signal level, and responsive to the second control signal, for sampling the despread signal at a non-peak correlation time of the data channel signal to generate from the despread signal a noise level;

a first register coupled to said sample-and-hold circuit for storing the signal level;

a second register coupled to said sample-and-hold circuit for storing the noise level;

a signal-to-noise ratio calculator coupled to said first register and to second register, for generating a signal-to-noise ratio from the signal level and the noise level;

a fuzzy-logic controller coupled to said signal-to-noise ratio calculator for comparing the signal-to-noise ratio to a predetermined set of thresholds to generate a control signal; and

a base spread-spectrum transmitter, coupled to said fuzzy-logic controller, for transmitting the control signal to a remote unit for adjusting a transmitter power level of said remote unit.

2. A fuzzy-logic spread-spectrum system for adaptive power control from a base station comprising:

a base antenna for receiving a spread-spectrum signal;

a sample-and-hold controller for generating a first control signal and a second control signal;

a data-channel despreader, coupled to said base antenna, for despreading a data signal embedded in the spread-spectrum signal as a despread signal;

a sample-and-hold circuit, operatively coupled to said data-channel despreader and to said sample-and-hold controller, responsive to the first control signal, for sampling the despread signal at a peak correlation time of the data signal to generate from the despread signal a signal level and, responsive to the second control signal, for sampling the despread signal at a non-peak correlation time of the data signal to generate from the despread signal a noise level;

a signal-to-noise ratio calculator coupled to said first register and to said second register, for generating a signal-to-noise ratio from the signal level and the noise level;

a fuzzy-logic controller, coupled said signal-to-noise ratio calculator, for comparing the signal-to-noise ratio to a predetermined threshold to generate a control signal; and

a base spread-spectrum transmitter, coupled to said fuzzy-logic controller, for transmitting the control signal to remote unit for adjusting a transmitter power level of said remote unit.

3. The fuzzy-logic spread-spectrum system as set forth in claim 2, further comprising:

a first register, coupled between said sample-and-hold circuit and said signal-to-noise ratio calculator, for storing the signal level; and

a second register, coupled between said sample-and-hold circuit and said signal-to-noise ratio calculator, for storing the noise level.

4. The fuzzy-logic spread-spectrum system as set forth in claim 2, said remote unit comprising:

a remote-unit antenna;

a remote-unit spread-spectrum receiver coupled to said remote-unit antenna for receiving the control signal;

a remote-unit spread-spectrum transmitter coupled to said remote-unit antenna for transmitting the spread-spectrum signal; and

a transmitter controller coupled between said remote-unit spread-spectrum receiver and said remote-unit spread-spectrum transmitter, responsive to the control signal, for adjusting the transmitter power level of said remote-unit spread-spectrum transmitter.

5. The fuzzy-logic spread-spectrum system as set forth in claim 2, further comprising:

a pilot-channel despreader, coupled to said base antenna, for despreading a pilot signal embedded in the spread-spectrum signal and for generating, from the despread pilot signal, a timing signal;

said sample-and-hold controller generating, responsive to the timing signal, the first control signal and the second control signal.

6. A method for adaptive power control of a spread-spectrum signal using fuzzy-logic at a base station, comprising the steps of:

receiving, at the base station, a spread-spectrum signal;

generating a first control signal and a second control signal;

despreading a data signal embedded in the spread-spectrum signal as a despread signal;

sampling, in response to the first control signal, the despread signal at a peak correlation time of the data signal to generate from the despread signal a signal level;

sampling, in response to the second control signal, the despread signal at a non-peak correlation time of the data signal to generate from the despread signal a noise level;

generating a signal-to-noise ratio from the signal level and the noise level;

comparing the signal-to-noise ratio to a predetermined threshold;

generating, responsive to a relationship between the signal-to-noise ratio and the predetermined threshold, a control signal; and

transmitting the control signal to a remote unit for adjusting, at the remote unit and responsive to the control signal, a transmitter power level of said remote unit.

7. The method as set forth in claim 6, further comprising the steps of:

despreading a pilot signal embedded in the spread-spectrum signal to generate a timing signal; and

generating, using the timing signal, the first control signal and the second control signal.