JP2014087016A - Radio communication terminal, radio communication method and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication terminal, a radio communication method and a control program, capable of easily and appropriately controlling antenna impedance according to the use state of the radio communication terminal.SOLUTION: A radio communication terminal 100 for performing communication with a frequency-division duplex method includes: a call processing unit 130 for switching a present call connection state of the self-terminal and for reporting the present call connection state; a use state detection unit 140 for detecting a present use state of the self-terminal; a storage unit 150 for storing an impedance set value according to the use state and the call connection state; and based on the stored set value, an impedance control unit 160 for controlling a variable impedance circuit connected to the antenna, according to the reported call connection state and the detected use state. With this, power consumption and reception sensitivity of the radio communication terminal 100 can be improved.

Description

  The present invention relates to a radio communication terminal, a radio communication method, and a control program that are compatible with frequency division duplex (FDD) and are equipped with a technique for adaptively controlling the impedance of an antenna.

  In a small wireless communication terminal typified by a mobile phone, it is known that the input impedance of the antenna changes depending on the usage state of the user, and impedance mismatching occurs and transmission / reception characteristics deteriorate. In contrast, many control methods and circuit configurations have been devised in which a matching circuit capable of dynamically changing the impedance is inserted between the antenna of the terminal and the transmission / reception RF circuit, and matching is adaptively adapted to changes in the surroundings. ing.

  In a wireless device represented by Patent Document 1, reflected power due to mismatch is detected by a directional coupler inserted between an antenna matching circuit and a transmission / reception circuit, and the impedance of the antenna matching circuit is adapted so as to minimize reflection loss. Control. In such a method, since the matching circuit constant is determined so that the best communication state can be obtained while switching the impedance in a specific frequency band, it takes time until the determination, and the communication state during that time becomes unstable. Can happen. On the other hand, in the wireless communication terminal represented by Patent Document 2, the state in which the user is using the terminal is detected as a posture state in order to easily control while solving the above problem, and corresponding to the state The constant of the matching circuit determined in advance is selected.

Japanese Patent Laid-Open No. 7-7357 JP 2010-56944 A

  FIG. 6 is a graph showing an example of the radiation efficiency characteristics of the antenna when the small antenna is in free space and close to a human body. As shown in FIG. 6, a small antenna with a narrow band may not be able to obtain the best characteristics in both transmission and reception bands at the same time.

  FIG. 7 is a sequence chart showing call connection processing between a terminal and a base station when FDD (Frequency Division Duplex) is applied. The FDD scheme is a scheme that uses different frequencies for uplink and downlink, and is employed in wireless communication systems represented by LTE (Long Term Evolution), which is a standard of 3GPP (Third Generation Partnership Project).

  As shown in FIG. 7, there are a state in which only transmission is performed as a terminal, a state in which reception is performed, and a state in which transmission / reception is performed. In this case, even if the impedance variable circuit set in advance corresponding to each of the free space state and the human body proximity state is controlled by the method disclosed in the above patent document, the antenna is always optimal in all call connection states. It cannot be a special characteristic. As a result, when the circuit constant is selected so that the best characteristic can be obtained in the reception band, the transmission characteristic of the antenna deteriorates in the transmission state and the transmission / reception state. In addition to the need for excessive transmission power, problems such as an increase in the number of random access and RRC connection request transmissions occur.

  On the other hand, when the circuit constant is selected so that the best characteristic can be obtained in the transmission band, the reception sensitivity of the antenna deteriorates. As a result, problems such as a decrease in throughput during data reception, a cell search failure, a random access response, and an RRC connection setting information reception error may occur. Further, even when a constant is set so that resonance is obtained at a frequency between transmission and reception bands in consideration of the balance of transmission and reception characteristics, the best characteristics cannot be obtained in each call connection state.

  The present invention has been made in view of such circumstances, and provides a wireless communication terminal, a wireless communication method, and a control program capable of easily and appropriately controlling the impedance of an antenna according to the use state of the wireless communication terminal. The purpose is to provide.

  (1) In order to achieve the above object, a wireless communication terminal of the present invention is a wireless communication terminal that performs communication using a frequency division duplex method, and switches the current call connection state of the terminal itself and calls the current call. A call processing unit for notifying a connection state; a utilization state detection unit for detecting a current utilization state of the terminal; a storage unit for storing a call connection state and an impedance setting value according to the utilization state; And an impedance control unit that controls an impedance variable circuit connected to the antenna according to the notified call connection state and the detected use state based on a set value.

  In this way, the wireless communication terminal of the present invention simplifies the antenna impedance according to the use state of the terminal and the call connection state with the base station on the communication system using the frequency division duplex method (FDD method). And it can be controlled appropriately. As a result, the power consumption and reception sensitivity of the wireless communication terminal can be improved.

  (2) Further, the wireless communication terminal of the present invention is characterized in that the usage state detection unit detects a state of whether or not a human body is close to the antenna. Thereby, even if an appropriate impedance changes due to the proximity of the human body, the impedance value can be changed accordingly.

  (3) In addition, in the wireless communication terminal of the present invention, when the usage state detection unit detects a state where a human body is close to the antenna, the wireless communication terminal further determines whether the terminal is in a plurality of states. It is characterized by detecting. Thereby, the control according to the state of the own terminal becomes possible. Note that the state of the terminal itself is not necessarily limited to a specific number of types.

  (4) Further, in the wireless communication terminal according to the present invention, when the use state detection unit detects a state in which a human body is close to the antenna, whether the own terminal is in a browsing state or a call state It is characterized by detecting. Thereby, detailed control according to the browsing state or the call state is possible.

  (5) Also, in the wireless communication terminal of the present invention, whether the call processing unit is in a transmission, reception or simultaneous transmission / reception state when the call processing unit triggers switching of the current call connection state It is characterized by notifying.

  As a result, the characteristics in the transmission band when performing only transmission, the characteristics of the reception band when performing only reception, and the balanced characteristics when performing transmission and reception according to the usage state of the wireless communication terminal. Can be improved.

  (6) In the wireless communication terminal of the present invention, the usage state detection unit acquires the wireless quality state of the terminal itself, and detects the current usage state based on the acquired wireless quality state. It is said. Thereby, even if it does not have devices, such as a sensor, a utilization state can be detected.

  (7) Further, in the wireless communication terminal of the present invention, the usage state detection unit switches the impedance to a setting value corresponding to each usage state and acquires the received signal sensitivity for all states as the wireless quality state, and the acquisition The use state in which the received signal sensitivity is maximized is detected as the current use state. As a result, the current usage state can be easily detected.

  (8) In the wireless communication terminal of the present invention, a plurality of the antennas are installed, each of which corresponds to the same frequency band, and the storage unit has an impedance corresponding to a call connection state and a use state for each antenna. The impedance control unit controls an impedance variable circuit for each antenna, a plurality of impedance variable circuits are installed, each connected to each of the plurality of antennas, and the impedance control unit The setting value of the impedance for each antenna is changed. Thereby, even when the wireless communication terminal has a plurality of antennas, the impedance of the antenna can be controlled easily and appropriately according to the usage state of the wireless communication terminal.

  (9) Further, in the wireless communication terminal of the present invention, the storage unit has the best transmission characteristics or reception characteristics for at least one of the plurality of antennas according to a call connection state and a use state. The impedance setting value is stored, and for other antennas, the impedance setting value with the best reception characteristics is stored according to the use state. As a result, even in a wireless communication terminal corresponding to a communication method in which the number of reception antennas used in the downlink is larger than the number of transmission antennas used in the uplink, as represented by LTE, the use state of the own terminal is maintained. Accordingly, the impedance of the antenna can be easily controlled, and the storage area can be reduced.

  (10) Further, in the wireless communication terminal of the present invention, the usage state detection unit acquires reception signal sensitivities for each of the plurality of antennas arranged, and determines a usage state of the terminal based on the acquired reception signal sensitivities. It is characterized by identification. Thereby, the usage state can be detected with high accuracy.

  (11) The wireless communication method of the present invention is a wireless communication method for performing communication using a frequency division duplex method, and switches the current call connection state of the wireless communication terminal and notifies the current call connection state. A step of detecting a current use state of the wireless communication terminal, and a call connection state and a detected use detected based on a call connection state stored in advance and an impedance setting value corresponding to the use state And a step of controlling an impedance variable circuit connected to an antenna of the wireless communication terminal according to a state. Thereby, the power consumption and reception sensitivity of the wireless communication terminal can be improved.

  (12) A control program according to the present invention is a control program for performing communication using a frequency division duplex method, and is a process of switching a current call connection state of a wireless communication terminal and notifying the current call connection state. , Based on the process of detecting the current usage state of the wireless communication terminal, and the call connection state and the impedance setting value corresponding to the usage state stored in advance, the notified call connection state and the detected usage state Accordingly, a process for controlling an impedance variable circuit connected to an antenna of the wireless communication terminal is executed by a computer mounted on the wireless communication terminal. Thereby, the power consumption and reception sensitivity of the wireless communication terminal can be improved.

  According to the present invention, it is possible to easily and appropriately control the impedance of an antenna according to a use state of a wireless communication terminal and a call connection state with a base station on a communication system using a frequency division duplex method (FDD method). Can do. As a result, the power consumption and reception sensitivity of the wireless communication terminal can be improved.

It is a block diagram which shows the structure of the radio | wireless communication terminal which concerns on 1st Embodiment. It is a flowchart which shows operation | movement of the radio | wireless communication terminal which concerns on 1st Embodiment. It is a block diagram which shows the structure of the radio | wireless communication terminal which concerns on 2nd Embodiment. It is a flowchart which shows a use state detection process. It is a block diagram which shows the structure of the radio | wireless communication terminal which concerns on 3rd Embodiment. It is a graph which shows an example of the radiation efficiency characteristic of the free space of a small antenna, and the antenna at the time of human body proximity | contact. It is a sequence chart which shows the call connection process between a radio | wireless communication terminal and a base station at the time of applying FDD.

  Next, embodiments of the present invention will be described with reference to the drawings. In order to facilitate understanding of the description, the same reference numerals are given to the same components in the respective drawings, and duplicate descriptions are omitted.

[First Embodiment]
(Configuration of wireless communication terminal)
FIG. 1 is a block diagram illustrating a configuration of the wireless communication terminal 100. The wireless communication terminal 100 performs communication using a frequency division duplex method. As shown in FIG. 1, the radio communication terminal 100 includes an antenna A0, a variable capacitance circuit 112 (impedance variable unit), a frequency duplexer 113, a transmission RF circuit 114, a reception RF circuit 115, a baseband signal processing circuit 120, a call processing. Unit 130, usage state detection unit 140, storage unit 150, and impedance control unit 160.

  The antenna A0 is connected to the variable capacitance circuit 112 for transmission and reception. The variable capacitance circuit 112 (impedance variable circuit) switches the capacitance setting value (impedance) according to an instruction from the impedance control unit 160.

  The frequency duplexer 113 is a duplexer corresponding to the frequency division duplex method. The transmission RF circuit 114 is an RF circuit for transmitting information to the base station. The reception RF circuit 115 is an RF circuit for receiving information from the base station. The baseband signal processing circuit 120 performs signal processing corresponding to the frequency division duplex method.

  The call processing unit 130 is compatible with the frequency division duplex method, and switches the current call connection state of the terminal itself. At the same time, as the current call connection state at the timing when the call connection processing state between the own terminal and the base station is switched, whether the state after the switching is a state in which the own terminal only performs transmission or only reception, or simultaneously transmits and receives The impedance control unit 160 is notified of the state to be performed.

  That is, notification of whether the current call connection state is a state of transmission, reception or simultaneous transmission / reception is triggered by switching of the call connection state. By switching the capacity setting value accordingly, the characteristics in the transmission band are improved when only transmission is performed, the characteristics of the reception band are improved when only reception is performed, and the balance between the two is balanced when performing transmission and reception. Improved characteristics can be improved.

  The usage state detection unit 140 detects the current usage state of the terminal itself. The usage state detection unit 140 detects the presence / absence of the proximity of the human body to the antenna and notifies the impedance control unit 160 of it. Thereby, the value of impedance can be appropriately changed corresponding to the proximity of the human body. For example, a sensor device such as a capacitance sensor is used for the use state detection unit 140, and the proximity of the human body can be determined based on whether or not the obtained capacitance value exceeds a threshold value. A detection method that does not use a sensor device will be described later.

  When the use state detection unit 140 detects a state in which a human body is close to the antenna, it is preferable that the use state detection unit 140 further detects whether the terminal is in a browsing state or a call state. Thereby, further detailed control according to the browsing state or the call state is possible.

  The storage unit 150 stores a variable capacitance circuit setting value (impedance setting value) corresponding to the call connection state and usage state as a capacitance setting value table. The variable capacity circuit setting value is determined according to the call connection state and the use state by the capacity setting value table.

  For example, the above table determines the variable capacitance value that is best in each of the transmission and reception bands in the free space state and when the human body is in proximity. In addition, when the transmission / reception band is used at the same time, a variable capacitance value is determined so that both transmission and reception characteristics are favorable. These values are acquired in advance and stored in the storage unit 150.

  Note that the state when the human body is close to the antenna A0 detected by the usage state detection unit 140 may be a more fragmented state such as browsing and a conversation state, and the capacity values corresponding to each state are detected. A configuration using a setting table may be used.

  The impedance control unit 160 controls the impedance variable circuit connected to the antenna based on the stored setting value. Thereby, impedance control according to the notified call connection state and the detected use state is enabled.

Table 1 shows an example of notification bit information generated by the usage state detection unit 140, and Table 2 shows an example of notification bit information generated by the call processing unit 130. The use state and the call connection state can be notified by such a notification bit.

The impedance control unit 160 determines the capacitance setting value of the variable capacitance circuit based on the capacitance value setting table of the storage unit 150 from the bits notified from the usage state detection unit 140 and the call processing unit 130, and determines the capacitance value of the variable capacitance circuit. To control. Table 3 shows a capacity setting value table.

  In this way, the radio communication terminal 100 simply and appropriately sets the antenna impedance according to the call connection state and the use state of the terminal with the base station on the communication system using the frequency division duplex method (FDD method). To control. As a result, the power consumption and reception sensitivity of the wireless communication terminal 100 can be improved.

(Operation of wireless communication terminal)
An operation of the wireless communication terminal 100 configured as described above will be described. FIG. 2 is a flowchart showing the operation of the wireless communication terminal 100. First, a usage state such as whether or not a human body is in proximity to the wireless communication terminal 100 is detected (step S1). Next, the current call connection state notified from the call processing unit 130 is referred to (step S2).

  Then, it is identified as the current individual connection state whether the terminal is in a transmission state, a reception state, or a transmission / reception state with respect to the base station. With reference to the stored table, the capacity setting value is specified from the call connection state and the use state (step S3), and the impedance is controlled based on the capacity setting value (step S4). In this way, impedance corresponding to the usage state and individual connection state of the wireless communication terminal 100 can be realized, and the power consumption and reception sensitivity of the terminal itself can be improved.

[Second Embodiment]
(Configuration of wireless communication terminal)
In the above embodiment, the usage state is detected by a device such as a sensor. However, the usage state may be detected using wireless quality information that can be acquired by a wireless communication terminal. FIG. 3 is a block diagram illustrating a configuration of the wireless communication terminal 200 that detects the usage state using the wireless quality information. The wireless communication terminal 200 has the same configuration as the wireless communication terminal 100 except for the usage state detection unit 240 and the impedance control unit 260.

  The use state detection unit 240 and the impedance control unit 260 switch the set capacitance value (impedance) to the set value corresponding to each use state, and acquire the received signal sensitivity (RSSI) for all states. In this way, the usage state detection unit 240 acquires the received signal sensitivity (RSSI) for all states as the wireless quality state, and detects the usage state where the acquired received signal sensitivity is maximized as the current usage state. As a result, the current usage state can be easily detected.

  The wireless quality state of the terminal itself is acquired, and the current usage state is detected based on the acquired wireless quality state. Thereby, even if it does not have devices, such as a sensor, a utilization state can be detected.

(Usage status detection process)
In the present embodiment, the variable capacity setting value T (i, j) is represented by a setting capacity value table, and is specified corresponding to the usage state i and the call processing connection state j. The usage state is detected by generating a trigger at power-on and periodically thereafter at a predetermined time interval.

  FIG. 4 is a flowchart showing the usage state detection process. First, when a trigger is detected, j = 0 is initialized (step T1). Then, the variable capacitance circuit is set to a set value m = T (0, j) (step T2).

  Next, the received signal strength (RSSI) for the set value j is measured (step T3). Then, it is determined whether j = N-1 (step T4). When j is not N-1, j is incremented by 1 (step T5), and the process returns to step T2. When j = N−1, the usage state corresponding to the capacity value at which the measured value is maximized is detected as the current usage state (step T6). In this manner, three states are detected: a state where no human body is in proximity, a human body proximity browsing state, and a human body proximity call state.

Table 4 shows an example of the capacity setting value when the usage state is detected.

  In the example shown in Table 4, the capacity setting value used at the time of detection is sequentially changed from j = 0 to 2, and the RSSI for the capacity value T (0, j) is acquired. The usage state corresponding to j to be maximized is detected as the current usage state, and the detection result is notified to the impedance control unit.

[Third Embodiment]
In the above embodiment, the wireless communication terminal 200 has one antenna, but may have a plurality of antennas. FIG. 5 is a block diagram illustrating a configuration of a wireless communication terminal 300 having a plurality of antennas. The wireless communication terminal 300 is an example of a typical wireless communication terminal compatible with LTE.

  The wireless communication terminal 300 is basically configured in the same manner as the wireless communication terminal 200, but the wireless communication terminal 300 is provided with a plurality of antennas A0 and A1, each corresponding to the same frequency band. The configuration related to is different. Radio communication terminal 300 receives MIMO transmission with two-element antennas A0 and A1 in the downlink, and transmits from one-element antenna A0 in the uplink. Thus, the antenna A0 performs both transmission and reception, and the antenna A1 is configured to receive only.

  The antenna A0 is connected to the transmission RF circuit 114 and the reception RF circuit 115 via the variable capacitance circuit 112 and the frequency duplexer 113. The antenna A1 is connected to the reception RF circuit 314 via the variable capacitance circuit 312.

  The call processing unit 330 notifies the impedance control unit 360 of the switched call connection state at the timing when the call connection processing state between the wireless communication terminal 300 and the base station is switched. The call connection state includes a state where radio communication terminal 300 performs only reception, a state where only transmission is performed, and a state where transmission and reception are performed.

  The usage state detection unit 340 detects the usage state of the wireless communication terminal 300. Specifically, the reception signal sensitivity (RSSI) for each antenna is acquired, and the use state of the own terminal is specified based on the acquired reception signal sensitivity. Thereby, the usage state can be detected with high accuracy.

When performing detection, it is possible to detect a usage state that maximizes RSSI while switching the capacitance values of both antenna A0 and antenna A1. The usage state that maximizes the RSSI may be detected while switching the capacity value of only the antenna A1, and the detection may be easily performed while ensuring the stability of the communication quality at the time of detection. Table 5 shows an example of notification bit information generated by the usage state detection unit 340. Table 6 shows an example of the capacity setting value when the usage state is detected.

  The storage unit 350 stores a variable capacitance value (impedance setting value) corresponding to a call connection state and a use state for each antenna. In particular, in the case of a wireless communication terminal compatible with LTE, as shown in Table 6, the storage unit 350 has set values C0, C1, and an antenna A0 that have the best characteristics according to the call connection state and the use state. C3 and C4 are stored, and it is preferable that the antennas A1 store setting values C2 and C5 that provide the best characteristics in the reception frequency band according to the usage state.

  In antenna A0, the set capacity value at the time of performing data transmission and transmission at the same time as that at the time of performing only transmission can be made the same, and the capacity set value according to the transmission band can be used. Since the antenna A1 is an antenna that performs only reception, the antenna A1 does not switch the capacity value according to the call processing, but switches the set capacity value according to only the usage state.

  Since the antenna A1 has a capacity setting value that matches the reception band regardless of the call processing state, a balance of transmission and reception quality can be easily achieved by using the capacity setting value that matches the transmission band when transmitting and receiving with the antenna A0. Can be taken. In this way, in the radio communication terminal 300 corresponding to LTE, the impedance of the antenna can be controlled easily and appropriately according to the usage state of the terminal itself.

  As described above, the storage unit 350 stores the capacity setting value that provides the best transmission characteristics or reception characteristics according to the call connection state and the use state for at least one of the plurality of antennas. For the antenna, it is preferable to store a capacity setting value that provides the best reception characteristics according to the usage state.

  The impedance control unit 360 refers to the stored set capacity value, determines the set capacity value of both antennas A0 and A1 from the call connection state and the use state, and the variable capacity circuit connected to each antenna A0 and A1. By controlling 112 and 312, the impedance is controlled for each antenna. The impedance control unit 360 can send an instruction signal and control both capacitance values independently.

  A plurality of variable capacitance circuits 112 and 312 (impedance variable circuits) are installed, each connected to each of a plurality of antennas, and subjected to impedance control to change the impedance of each antenna. Thereby, also in the radio communication terminal 300 having a plurality of antennas, the impedance of the antenna can be controlled easily and appropriately according to the call connection state and the use state. The operation of the wireless communication terminal of the present invention is performed by executing a program installed in the wireless communication terminal.

100 wireless communication terminal A0 antenna 112 variable capacitance circuit 113 frequency duplexer 114 transmission RF circuit 115 reception RF circuit 120 baseband signal processing circuit 130 call processing unit 140 usage state detection unit 150 storage unit 160 impedance control unit 200 wireless communication terminal 240 usage State detection unit 260 Impedance control unit 300 Wireless communication terminal A1 Antenna 312 Variable capacitance circuit 314 Reception RF circuit 330 Call processing unit 340 Usage state detection unit 350 Storage unit 360 Impedance control unit

Claims (12)

A wireless communication terminal that performs communication using a frequency division duplex method,
A call processing unit for switching a current call connection state of the terminal and notifying the current call connection state;
A usage status detector that detects the current usage status of the terminal;
A storage unit for storing a set value of impedance according to a call connection state and a use state;
And an impedance control unit that controls an impedance variable circuit connected to an antenna according to the notified call connection state and the detected use state based on the stored setting value. Terminal.   The wireless communication terminal according to claim 1, wherein the usage state detection unit detects a state of whether or not a human body is close to the antenna.   3. The radio according to claim 2, wherein when the use state detection unit detects a state in which a human body is close to the antenna, the use state detection unit further detects which of the plurality of states the terminal itself is. Communication terminal.   The said use state detection part detects further whether a self-terminal is a browsing state or a telephone call state, when the state which a human body adjoins with respect to the said antenna is detected. Wireless communication terminal.   2. The call processing unit according to claim 1, wherein the call processing unit notifies whether the current call connection state is a transmission state, a reception state, or a simultaneous transmission / reception state by using the switching of the current call connection state as a trigger. Item 5. The wireless communication terminal according to any one of Items 4 to 6.   The said usage status detection part acquires the radio | wireless quality state of an own terminal, and detects the said present usage status based on the acquired radio | wireless quality state, The said in any one of Claim 1-5 characterized by the above-mentioned. The wireless communication terminal described.   The usage state detection unit acquires the reception signal sensitivity for all states as the wireless quality state by switching the impedance to a setting value corresponding to each usage state, and the usage state in which the acquired reception signal sensitivity is maximized. The wireless communication terminal according to claim 6, wherein the wireless communication terminal is detected as a current use state. A plurality of the antennas are installed, each corresponding to the same frequency band,
The storage unit stores a set value of impedance according to a call connection state and a use state for each antenna,
The impedance control unit controls an impedance variable circuit for each antenna,
8. The impedance variable circuit is provided in a plurality, each connected to each of the plurality of antennas, and the impedance control unit changes a set value of impedance for each of the antennas. A wireless communication terminal according to any one of the above.   The storage unit stores, for at least one of the plurality of antennas, an impedance setting value that provides the best transmission characteristics or reception characteristics according to a call connection state and a use state, and for other antennas 9. The wireless communication terminal according to claim 8, wherein a set value of an impedance with which reception characteristics are best according to a use state is stored.   9. The usage status detection unit acquires reception signal sensitivities for each of the plurality of antennas arranged, and specifies a usage status of the terminal based on the acquired reception signal sensitivities. 9. A wireless communication terminal according to 9. A wireless communication method for performing communication using a frequency division duplex method,
Switching the current call connection state of the wireless communication terminal and notifying the current call connection state;
Detecting a current usage state of the wireless communication terminal;
An impedance variable circuit connected to the antenna of the wireless communication terminal according to the notified call connection state and the detected use state based on the preset value of the impedance according to the call connection state and the use state stored in advance And a step of controlling the wireless communication method. A control program for performing communication by frequency division duplex,
Switching the current call connection state of the wireless communication terminal and notifying the current call connection state;
A process of detecting a current usage state of the wireless communication terminal;
An impedance variable circuit connected to the antenna of the wireless communication terminal according to the notified call connection state and the detected use state based on the preset value of the impedance according to the call connection state and the use state stored in advance And a control program for causing a computer mounted on the wireless communication terminal to execute the process.

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