Received power calculating method and mobile station

• US 6,628,732 B1
• Filed: 07/14/1999
• Issued: 09/30/2003
• Est. Priority Date: 07/17/1998
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Takaki, Tetsuya
• Primary Examiner(s): Liu, Shuwang
• Application Number:
  US09/353,750
• Time in Patent Office: 1,539 Days
• Field of Search: 375/345, 375/340, 375/227, 375/146, 370/342, 370/335, 455/522
• US Class Current: 375/345
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• 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 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A radio portion controlling means of a receiver of a mobile station has an average time setting means. A controlling means supervises an average received power. When the average received power approaches a power at which the gain of a gain changing means should be changed, the controlling means causes a received power calculating means to increase the time period for the calculation of the average received power so as to decrease the error of the average received power at which the gain of the gain selecting means is changed.

Claims

1. A method by which a mobile station controls a transmission power of a base station, the method comprising:

setting a threshold value for the mobile station that represents a signal power level at which a frequency converter at the mobile station to which a signal is applied would operate in a saturation region;

calculating an average power of a signal received by the mobile station'"'"'s antenna;

attenuating a power level of the received signal, when the calculated average power of the received signal is lower than the threshold value, and amplifying the power level of the received signal by the mobile station if the calculated average power of the received signal is higher than the threshold value;

increasing the time period for calculating an average received power of the received signal when the calculated average received power approaches the threshold value;

calculating a power level of a received channel based on the calculated average received power and despread received signals; and

generating and transmitting a first control signal based on the power level of the received channel, such that when the power level of the received channel is lower than the threshold level the first control signal causes the base station to increase its transmission power, and when the power level of the received channel is higher than the threshold level the first control signal causes the base station to decrease its transmission power.

2. The method as set forth in claim 1, comprising comparing the calculated average received power of the received signal with the threshold value and generating a second control signal that causes a gain changing circuit to change a gain of the received signal by switching between an attenuator and an amplifier.

3. The method as set forth in claim 2, comprising:

changing the gain when the gain changing circuit receives the second control signal;

controlling the gain of a variable gain circuit when the gain changing circuit receives the second control signal;

monitoring the average received power; and

increasing the time period for the calculation of the received power when the average received power is within a predetermined range of the threshold value.

4. A mobile station that calculates an average received power of a signal received by the mobile station, and controls a transmission power of a base station based on the calculated average received power, the mobile station comprising:

a gain changing circuit that selects either a radio frequency amplifier or an attenuator, the selection preventing a first frequency converter from operating in a saturation region, wherein the first frequency converter converts a radio frequency signal into an intermediate frequency signal;

a variable gain circuit disposed upstream of a second frequency converter, the second frequency converter converting the intermediate frequency signal into a base band signal and quadrature demodulating the base band signal, the variable gain circuit keeping the power of the quadrature demodulated signal constant, the quadrature demodulated signal being supplied to an A/D converter that converts the quadrature demodulated signal from an analog signal into a digital signal;

a radio portion controller including;

a received power calculator that calculates the average received power so as to control a gain of the variable gain circuit;

a gain changing circuit controller that controls the gain changing circuit;

a transmission power controller that generates a first control signal that (i) causes the base station to increase transmission power when a power of a received channel is lower than a predetermined threshold value, and that (ii) causes the base station to decrease the transmission power when the power of the received channel is higher than the predetermined threshold value;

a transmission signal generator that transmits the first control signal to the base station; and

an average time setting circuit that sets an average time period for a calculation of the received power to the received power calculator; and

a time setting controller that receives the average received power from the received power calculator, compares the average received power with the predetermined threshold value of the received power, and causes the average time setting circuit to change the average time period for the calculation of the received power when the average received power approaches a value within a predetermined range of the threshold value.

5. The mobile station as set forth in claim 4, wherein:

the threshold value is a value at which the first frequency converter operates in the saturation region; and

the gain changing circuit controller compares the threshold value with the average received power received from the received power calculator, generates a second control signal when the average received power exceeds the threshold value, and supplies the second control signal to the gain changing circuit.

6. The mobile station as set forth in claim 5, wherein:

the gain changing circuit changes the gain when the gain changing circuit receives the second control signal; and

the received power calculator generates a third control signal that it sends to the variable gain circuit so as to control the gain of the variable gain circuit when the gain changing circuit receives the second control signal.

7. The mobile station as set forth in claim 6, wherein the time setting controller monitors the average received power, the time setting controller comparing the average received power received from the received power calculator with the threshold value, and when the average received power reaches a value within a predetermined range of the threshold value, the time setting controller causes the received power calculator to increase the time period for the calculation of the received power.

8. The mobile station as set forth in claim 7, wherein the time setting-controller causes the average time setting circuit to restore the time period for the calculation of the received power to an initial value so that the received power calculator operates in an initial operation state when the average received power received from the received power calculator deviates from a value within the predetermined range of the threshold value.