Spread spectrum adaptive power control communications system and method

• US 6,226,316 B1
• Filed: 10/06/1998
• Issued: 05/01/2001
• Est. Priority Date: 11/16/1990
• Status: Expired due to Fees

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Moore, Timothy F. III, Garodnick, Joseph, Schilling, Donald L., Lomp, Gary
• Primary Examiner(s): LUTHER, WILLIAM A
• Application Number:
  US09/167,388
• Time in Patent Office: 938 Days
• Field of Search: 375/200, 375/206, 375/248, 375/201, 375/347, 375/346, 375/316, 375/223, 375/202, 375/222, 375/225, 375/208, 375/219, 375/224, 375/309, 375/295, 370/209, 370/342, 370/252, 370/441, 370/310, 370/208, 370/203, 370/319, 370/316, 370/315, 370/335, 370/468, 370/320, 370/465, 370/479, 370/464, 370/241, 370/431 , 370/347, 370/345, 380/34, 380/9, 380/33, 455/422, 455/522, 455/517, 455/507, 455/500, 455/39
• US Class Current: 375/142
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/709 Correlator structure
• CPC Class Codes: H04W 52/146 Uplink power control
• 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 52/245 taking into account received signal strength
• CPC Class Codes: H04W 52/246 where the output power of a terminal is based on a path parameter calculated in said terminal
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A system and method for adaptive-power control of a spread-spectrum transmitter of a mobile station operating in a cellular-communications network using spread-spectrum modulation. A mobile station transmits a first spread-spectrum signal. A base station has an automatic-gain-control circuit for generating an AGC-output signal, from a received signal. The received signal includes the first spread-spectrum signal and an interfering signal. The base station also has a correlator for despreading the AGC-output signal, a power-measurement circuit responsive to processing the received signal with the despread AGC-output signal for generating a received-power level, a comparator coupled to the power-measurement circuit for generating a comparison signal by comparing the received-power level to a threshold level, a transmitter for transmitting a second spread-spectrum signal, and an antenna. The mobile station has a variable-gain device responsive to the comparison signal for adjusting a transmitter-power level of the first spread-spectrum signal.

Claims

1. A communication station for use in a cellular-communications network using spread-spectrum modulation wherein a second station transmits a specific spread-spectrum signal at an adjustable power level, the communication station receives signals including the specific spread-spectrum signal and the communication station includes a transmitter and an associated antenna for transmitting spread-spectrum signals to the second station, the communication station comprising:

automatic gain control means for normalizing a power level associated with the received signals;

means for despreading said normalized received signals with a unique code to produce a despread signal corresponding to the specific spread-spectrum signal;

means for narrow band filtering said despread signal;

power measurement means for multiplying the received signals with said filtered despread signal and measuring a power level associated with a resultant multiplied signal to obtain a received power level associated with said specific spread-spectrum signal; and

means for generating a power command signal by comparing said received power level with a threshold level for controlling a variable-gain device in the second station for adjusting the transmit power level.

2. The communication station according to claim 1 wherein the multiplying is by logarithmically adding the received signals to said filtered despread signal and measuring a power level associated with a resultant logarithmically added signal.

3. The communication station according to claim 1 wherein said power command signal generating means further comprises:

a comparator to compare said received power level with a threshold level; and

a control word generator for generating said power command signal in response to the comparison.

4. The communication station according to claim 1 wherein the communication station is a base station communicating with a plurality of mobile stations and the second station is one of the plurality of mobile stations, each mobile station capable of transmitting a respective specific spread-spectrum signal at a respective adjustable power level, the communication station further comprising:

means for despreading said normalized received signals with a unique code associated with each of a plurality of respective specific spread-spectrum signals to produce a plurality of corresponding despread signals;

means for narrow band filtering each said despread signal;

power measurement means for multiplying the received signals with each of said filtered despread signals and measuring a power level associated with each resultant multiplied signal to obtain a plurality of received power levels associated with said plurality of respective specific spread-spectrum signals; and

means for generating a plurality of power command signals by comparing the respective received levels with a threshold level for controlling a variable-gain device in the respective mobile station for adjusting the respective transmit power level.

5. A system for adaptive power control in a cellular-communications network using spread-spectrum modulation, the system comprising:

a communication station for receiving signals including a specific spread-spectrum signal transmitted at an adjustable power level from a second communication station;

said communication station including;

automatic gain control means for normalizing a power level associated with the received signals;

means for despreading said normalized received signals with a unique code to produce a despread signal corresponding to the specific spread-spectrum signal;

means for narrow band filtering said despread signal;

power measurement means for multiplying the received signals with said filtered despread signal and measuring a power level associated with a resultant multiplied signal to obtain a received power level associated with the specific spread-spectrum signal; and

means for generating a power command signal by comparing said received power level with a threshold level for controlling a variable-gain device in said second station for adjusting the transmit power level; and

said second station including;

a transmitter and an associated antenna for transmitting spread-spectrum signals including said power command signal to said second station; and

said second station including;

a transmitter and an associated antenna for transmitting spread-spectrum signals including the specific spread-spectrum signal, the associated antenna also for receiving spread-spectrum signals including said power command signal; and

said variable gain device for adjusting the transmit power level.

6. The system according to claim 5 wherein the multiplying is by logarithmically adding the received signals to said filtered despread signal.

7. The system according to claim 5 wherein said power command signal generating means further comprises:

a comparator to compare said received power level with a threshold level; and

a control word generator for generating said power command signal in response to the comparison.

8. The system according to claim 5 wherein the communication station is a base station communicating with a plurality of mobile stations and said second station is one of said plurality of mobile stations, each mobile station capable of transmitting a respective spread-spectrum signal at a respective adjustable power level, the system further comprising:

said plurality of mobile stations, each comprising;

a transmitter and an associated antenna for transmitting spread-spectrum signals including the respective specific spread-spectrum signal, the associated antenna also for receiving spread-spectrum signals including a respective power command signal; and

a variable gain device for adjusting the transmit power level; and

the communication station further comprising;

means for despreading said normalized received signals with a unique code associated with each of a plurality of respective specific spread-spectrum signals to produce a plurality of corresponding despread signals;

means for narrow band filtering each said despread signal;

power measurement means for multiplying the received signals with each of said filtered despread signals and measuring a power level associated with each resultant multiplied signal to obtain a plurality of received power levels associated with said plurality of respective specific spread-spectrum signals; and

means for generating a plurality of power command signals by comparing the respective received power levels with a threshold level for controlling said variable-gain device in said respective mobile station for adjusting the respective transmit power level.

9. The system according to claim 5 wherein said variable gain device changes the transmitter power level by successively either geometrically increasing or decreasing the transmitter power level responsive to said power command signal until the power level passes a desired power level and subsequently alternating between geometrically increasing and decreasing the power level with diminishing margins of error with respect to said desired power level on each iteration until said desired power level is obtained.

10. The system according to claim 5 wherein said variable gain device changes the transmitter power level by successively either non-linearly increasing or decreasing the transmitter power level responsive to said power command signal until the power level passes a desired power level and subsequently alternating between non-linearly increasing and decreasing the power level with diminishing margins of error with respect to said desired power level on each iteration until said desired power level is obtained.

11. A method for adaptive-power control in a cellular-communications network using spread-spectrum modulation wherein a communication station receives signals including a specific spread-spectrum signal transmitted by a second communication station at an adjustable transmit power level, said method comprising the steps of:

receiving signals including said specific spread-spectrum signal by the communication station;

normalizing a power level associated with said received signals;

despreading said normalized received signals with a unique code to acquire a despread signal corresponding to the specific spread-spectrum signal;

narrow band filtering said despread signal;

multiplying said received signals with said filtered despread signal and measuring a power level associated with a resultant multiplied signal to obtain a received power level associated with the specific spread-spectrum signal;

generating a power command signal by comparing said received power level with a threshold level;

transmitting said power command signal to the second station; and

adjusting the second station transmit power level with said power command signal.

12. The method according to claim 11 wherein

the multiplying is by logarithmically adding said received signals to said filtered despread signal.

13. The method according to claim 11 wherein adjusting the second station transmit power level with said power command signal is by either geometrically increasing or decreasing the transmitter power level responsive to the power command signal until the power level passes a desired power level and subsequently alternating between geometrically increasing and decreasing the power level with diminishing margins of error with respect to said desired power level on each iteration until said desired power level is obtained.

14. The method according to claim 11 wherein adjusting the second station transmit power level with said power command signal is by either non-linearly increasing or decreasing the transmitter power level responsive to the power command signal until the power level passes a desired power level and subsequently alternating between non-linearly increasing and decreasing the power level with diminishing margins of error with respect to said desired lower level on each iteration until said desired power level is obtained.