Transmission power controller for use in mobile communication terminal equipment

• US 6,330,455 B1
• Filed: 07/26/1999
• Issued: 12/11/2001
• Est. Priority Date: 07/27/1998
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ichihara, Masaki
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Milord, Marceau
• Application Number:
  US09/360,610
• Time in Patent Office: 869 Days
• Field of Search: 455/522, 455/126, 455/127, 455/69, 455/70
• US Class Current: 455/522
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

Disclosed is a transmission power controller to prevent a transmission power from being excessive in mobile communication terminal equipment that requires a precise transmission power control. Branching filter 11, detector 12 and smoothing circuit 13 in combination generate a detected voltage corresponding to an average transmission power from the mobile communication terminal equipment. Threshold setting circuit 14 generates a threshold voltage corresponding to an allowable maximum average transmission power. Voltage comparator 15 decides if the average transmission power from the mobile communication terminal equipment is higher or lower than the allowable maximum average transmission power by comparing the detected voltage with the threshold voltage. Controller 16 varies a control voltage so as to lower a gain of a variable gain amplifier 4 if the average transmission power is decided to be higher than the allowable maximum average transmission power.

Claims

1. A transmission power controller for use in mobile communication terminal equipment, comprising:

a variable gain amplifier that amplifies a communication signal to be transmitted from the mobile communication terminal equipment to a base station;

a detector circuit responsive to the transmission power level;

a smoothing circuit connected to the output of the detector circuit;

a transmitted power reference circuit that generates a threshold signal representing a maximum allowable average transmission power,

a decision circuit that determines whether average transmission power from the mobile communication terminal equipment is higher or lower than the allowable maximum average transmission power, the decision circuit being operative to compare the threshold signal and the output of the smoothing circuit and to generate a decision signal having a first value if the threshold signal exceeds the output of the smoothing circuit, and having a second value if the output of the smoothing circuit exceeds the threshold signal; and

a control circuit responsive to an open loop control signal and a closed loop control signal transmitted from the base station to adjust the transmission power as a function of the distance between the mobile communication terminal equipment and the base station, and further responsive to an output signal from the decision circuit that controls the gain of the variable gain amplifier to limit the transmission power if the average transmission power is greater than the allowable maximum average transmission power, the control circuit being operative in response to the first value of the decision signal to enable the gain of the variable gain amplifier to be raised and responsive to the second value of the decision signal to lower the gain of the variable gain amplifier.

2. The transmission power controller according to claim 1, wherein the decision circuit has an input-output characteristic with a hysteresis.

3. The transmission power controller according to claim 1, wherein the variable gain amplifier amplifies an intermediate frequency signal, the intermediate frequency signal being the communication signal.

4. The transmission power controller according to claim 1, further comprising a transmission circuit that transmits a signal representing the output of the decision circuit to the base station.

5. The transmission power controller according to claim 1, wherein the variable gain amplifier amplifies an intermediate frequency signal, the intermediate frequency signal being the communication signal.

6. The transmission power controller according to claim 1, further comprising a transmission circuit that transmits a signal representing the decision signal to the base station.

7. The transmission power controller according to claim 1, wherein:

the control circuit is operative to set a control signal at a value representing the open loop control signal, responsive to a first value of the closed loop control signal to increase the value of the control signal if the decision signal has the first value, and responsive to the second value of the decision signal to decrease the value of the control signal irrespective of the value of the closed loop control signal,

the gain of the variable gain amplifier being a function of the control signal.

8. The transmission power controller according to claim 1, wherein:

the control circuit is comprised of;

a counter;

a first input of the counter being connected to the open loop control signal;

a gate circuit having a first input connected to the closed loop control signal, a second input connected to the output of the decision circuit, and an output connected to a second input of the counter, the gate producing an output signal having a first value when the output of the decision circuit is at the first value and the closed loop control signal is at its first value, and a second value otherwise; and

a clock signal generator connected to a third input of the counter,

the counter being operative to load the value of the open loop control signal as a count value in response to a signal at a fourth input thereof,

responsive to the first value of the gate output signal and the clock signal to increase the count value, and

responsive to the second value of the gate output signal and the clock signal to decrease the count value; and

further including

a conversion circuit responsive to the count value to generate a signal for controlling the gain of the variable gain amplifier.

9. The transmission power controller according to claim 1, wherein:

the control circuit is operative to set a control signal at a value representing the open loop control signal, responsive to a first value of the closed loop control signal to increase the value of the control signal if the decision signal has the first value, and responsive to a second value of the decision signal to decrease the value of the control signal irrespective of the value of the closed loop control signal,

the gain of the variable gain amplifier being a function of the control signal.

10. A transmission power controller for use in mobile communication terminal equipment, comprising:

a variable gain amplifier that amplifies a communication signal to be transmitted from the mobile communication terminal equipment to a base station;

a decision circuit that determines whether average transmission power from the mobile communication terminal equipment is higher or lower than an allowable maximum average transmission power; and

a control circuit responsive to an open loop control signal and a closed loop control signal transmitted from the base station to adjust the transmission power as a function of the distance between the mobile communication terminal equipment and the base station, and further responsive to an output signal from the decision circuit that controls the gain of the variable gain amplifier to limit the transmission power if the average transmission power is greater than the allowable maximum average transmission power, wherein the control circuit is comprised of;

a counter;

a first input of the counter being connected to the open loop control signal;

a gate circuit having a first input connected to the closed loop control signal, a second input connected to the output of the decision circuit, and an output connected to a second input of the counter, the gate producing an output signal having a first value when the output of the decision circuit is at the first value and the closed loop control signal is at its first value, and a second value otherwise; and

a clock signal generator connected to a third input of the counter,

the counter being operative to load the value of the open loop control signal as a count value in response to a signal at a fourth input thereof,

the control circuit being responsive to the first value of the gate output signal and the clock signal to increase the count value, and

the control circuit being responsive to the second value of the gate output signal and the clock signal to decrease the count value; and

further including

a conversion circuit responsive to the count value to generate a signal for controlling the gain of the variable gain amplifier.

11. The transmission power controller according to claim 10, wherein the decision circuit has an input-output characteristic with a hysterestis.

12. A method for controlling transmission power of a mobile communication terminal, comprising the steps of:

detecting a transmission signal to be output to a base station;

smoothing the detected transmission signal to obtain an average transmission power;

determining whether average transmission power from the mobile communication terminal is higher or lower than an allowable maximum average transmission power at a given time to produce a decision signal having a first value if the average transmission power is lower than the allowable maximum average transmission power and having a second value if the average transmission power is higher than the allowable maximum average transmission power;

inputting an open loop control signal, a closed loop control signal transmitted from the base station, and the decision signal to a control circuit;

generating, by the control circuit, a control signal to adjust the transmission power of the mobile communication terminal in response to the open loop control signal and the closed loop control signal if the decision signal has the first value, and responsive to lower the transmission power if the decision signal has the second value.

13. A method according according to claim 12, wherein the step of generating the control signal comprises the steps of:

setting the control signal at a value representative of the open loop control singal;

increasing the value of the control signal in response to a first value of the closed loop control signal and a first value of the decision signal; and

reduction the value of the control signal in response to a second value of the decision signal, irrespective of the value of the closed loop control signal.