JP2015056744A - Mobile communication terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately reduce power consumption of a mobile communication terminal.SOLUTION: A mobile communication terminal 1 comprises: power-saving means (switch SW1, switch SW2, first voltage control unit 12a, second voltage control unit 12b and power-saving control unit 23) which refers to a result of determination by a cell determination unit 24 that determines coverage areas of base stations with which radio transmission units 13 and 14 are performing radio communication, and controls voltage to be applied to amplifiers PA1 and PA2 in order to reduce power consumption.

Description

  The present invention relates to a technique for reducing power consumption of a mobile communication terminal.

  In recent years, mobile communication terminals typified by smartphones tend to increase power consumption as their processing speed increases and display panels increase in size. On the other hand, in a mobile communication terminal, extending the continuous use time is a great user's need. In order to satisfy this need, techniques for reducing power consumption of mobile communication terminals have been actively studied.

  In Patent Document 1, in a transmission power control method of a transmission power control apparatus having a semiconductor amplification element whose source is grounded in a high-frequency power amplification circuit, (i) only the drain voltage and gate voltage of the semiconductor amplification element, or the drain voltage is obtained. Controlling the transmission power by linearly changing the gain of the high-frequency power amplifier circuit; and (ii) the transmission output level of the high-frequency power amplifier circuit is equal to or higher than a threshold level lower than a maximum output level and the battery When the voltage is lower than the reference level, the battery voltage is supplied to the drain terminal of the semiconductor amplifying element, and when the transmission output level is higher than the threshold level and the battery voltage exceeds the reference level, the battery It is described that a voltage is dropped to the reference level and supplied to the drain terminal.

JP 2002-94392 A (published March 29, 2002)

  The inventors of the present invention have been studying effective low power consumption technology in mobile communication terminals. Here, in the technique described in Patent Document 1, the power consumption control is performed based on the maximum output of the communication signal. However, it is useful to provide a power consumption reduction technique more suitable for mobile communication terminals. It is.

  The present invention has been made in view of the above problems, and a main object of the present invention is to provide a technique for suitably reducing power consumption in a mobile communication terminal.

  In order to solve the above problems, a mobile communication terminal according to an aspect of the present invention includes an amplifier, a wireless transmission unit that performs wireless communication with a base station, and a voltage applied to the amplifier, the transmission output of the amplifier Power saving means for controlling the power consumption of the amplifier to be reduced, and cell discrimination means for discriminating the coverage of a base station with which the radio transmission unit performs radio communication. The means includes a plurality of voltage control units that control the voltages by mutually different voltage control methods, and switches the voltage control unit that controls the voltage applied to the amplifier with reference to the determination result of the cell determination unit. It is characterized by.

  According to one aspect of the present invention, it is possible to appropriately reduce power consumption by determining a cell coverage in which a mobile communication terminal is located and switching a voltage control method of a voltage applied to an amplifier according to the coverage. it can.

It is a functional block diagram which shows schematic structure of the mobile communication terminal which concerns on Embodiment 1 of this invention. (A) shows an example of the voltage output by the voltage control unit in the APT (Average Power Tracking) method, and (b) shows an example of the voltage output by the voltage control unit in the ET (Envelope Tracking) method. is there. It is a figure which shows an example of a heterogeneous network. It is a figure explaining control of the transmission power of the mobile communication terminal by a base station. It is a figure which shows the amplitude density function for every reception level of the electromagnetic wave which a mobile communication terminal receives. It is a figure which shows the amplitude density function for every transmission power of the electromagnetic wave which a mobile communication terminal transmits. It is a flowchart which shows an example of the power saving control of the mobile communication terminal which concerns on Embodiment 1 of this invention. It is a figure explaining switching of the gain mode of an amplifier. It is a figure explaining switching of the gain mode of an amplifier. It is a figure which shows the amplitude density function for every transmission power of the electromagnetic wave which a mobile communication terminal transmits. It is a flowchart which shows an example of the power saving control of the mobile communication terminal which concerns on Embodiment 2 of this invention.

  A mobile communication terminal according to an embodiment of the present invention is a mobile communication terminal that performs wireless communication for voice communication or data communication with a base station. The communication method is not particularly limited as long as it is a communication method for performing wireless communication with a base station. For example, UMTS, LTE, CDMA2000 1x, LTE, especially LTE-Advanced that is expected to be developed in the future. The mobile communication system can be used.

Embodiment 1
(Mobile communication terminal)
FIG. 1 is a functional block diagram illustrating a schematic configuration of a mobile communication terminal 1 according to the first embodiment. In addition, although this embodiment demonstrates the case of FDD (Frequency Division Duplex) as an example, this invention is not limited to this. In the case of TDD (Time Division Duplex), it can be configured by replacing DUP1 and DUP2 with a Switch device and a band limiting filter (not shown). As shown in FIG. 1, the mobile communication terminal 1 includes a battery (power source) 10, a power management unit 11, a first voltage control unit (power saving unit) 12a, and a second voltage control unit (power saving unit). ) 12b, first wireless transmission / reception unit (wireless transmission unit) 13, second wireless transmission / reception unit (wireless transmission unit) 14, switch SW1, switch SW2, input / output device 15, USIM 16, flash memory 17, memory 18, communication A processing unit 20 and an application processing unit 30 are provided.

  The first wireless transmission / reception unit 13 includes an antenna ANT1, a duplexer DUP1, an amplifier PA1, a band limiting filter Tx1_BPF, a band limiting filter Rx1_BPF, and a low noise amplifier LNA1. The second radio transmission / reception unit 14 includes an antenna ANT2, a duplexer DUP2, an amplifier PA2, a band limiting filter Tx2_BPF, a band limiting filter Rx2_BPF, and a low noise amplifier LNA2. The communication processing unit 20 includes a transmission processing unit 21, a reception processing unit 22, a power saving control unit (power saving unit) 23, a cell determination unit (cell determination unit) 24, a transmission processing unit 25, a reception processing unit 26, and a communication unit. A CPU 27 is provided. The application processing unit 30 includes an input / output device control unit 31, an authentication unit 32, and an application CPU 33. The transmission processing unit 21 and the reception processing unit 22 correspond to the first wireless transmission / reception unit 13. The signal Tx1_OUT modulated, frame processed, amplified, and the like in the transmission processing unit 21 is band-limited by the band-limiting filter Tx1_BPF, and is input to the amplifier PA1 as the signal Tx1_PA_in. The amplifier PA1 has a characteristic according to the voltage Vcc1 applied via the switch SW1, and amplifies the signal Tx1_PA_in and outputs it as a Tx1 signal. The Tx1 signal is radiated as a radio wave from the antenna ANT1 through the duplexer DUP1.

  Further, the radio wave received by the antenna ANT1 is band-limited by the signal band limiting filter Rx1_BPF as the signal Rx1 via the duplexer DUP1, and is input to the low noise amplifier LNA1 as the signal Rx1_LNA1. The low noise amplifier LNA1 amplifies the signal Rx1_LNA1 and outputs it as a signal Rx1_IN. The signal Rx1_IN1 is input to the reception processing unit 22, and is amplified and demodulated. Note that the duplexer DUP1 is a frequency filter composed of a dielectric, a SAW device, or the like, and distributes the signal TX1 and the signal RX1 having different frequencies. Similarly, the transmission processing unit 25 and the reception processing unit 26 correspond to the second wireless transmission / reception unit 14. The details of the operation of the second wireless transmission / reception unit 14 are the same as those of the first wireless transmission / reception unit 13, and the description thereof is omitted. And the 1st radio | wireless transmission / reception part 13 and the 2nd radio | wireless transmission / reception part 14 are mutually independent, and can operate | move simultaneously.

  The battery 10 supplies the voltage Battery_V to the power management unit 11. The power management unit 11 performs operations such as generation of a voltage necessary for each circuit, charge control, and detection of power reduction from the voltage Battery_V. Then, the switch SW1, the switch SW2, the first voltage control unit 12a and the second voltage control unit 12b supplied with the battery voltage VBat corresponding to the voltage Battery_V from the power management unit 11, and the power saving control for controlling them. Power saving is realized by the unit 23. Therefore, the switch SW1, the switch SW2, the first voltage control unit 12a, the second voltage control unit 12b, and the power saving control unit 23 are also referred to as power saving means. Details will be described later.

  A communication CPU (C-CPU) 27 is a processor that controls all operations of the communication processing unit 20. The operation program of the communication CPU 27 is stored in advance in the flash memory 17, for example. The operation program stored in advance in the flash memory 17 may be copied to a memory 18 constituted by DRAM, SRAM, etc., which can be accessed at a higher speed than the flash memory 17. Note that a DSP may be used in addition to or instead of the communication CPU 27 for high-speed signal processing. An application CPU 33 (Application CPU: A-CPU) 33 is a processor that performs all the processes of the application except the communication process. The input / output device 15 is, for example, a device such as a speaker, a microphone, a display, a key, a sensor, GPS, or IrDA, and is controlled by the input / output device control unit 31. The authentication unit 32 uses the information of the USIM 16 to perform authentication processing with the network service.

(Voltage control unit)
As shown in FIG. 1, the first voltage control unit 12 a is controlled by the control signal A from the power saving control unit 23, and the battery voltage Vbat supplied from the power management unit 11 is converted by the first voltage control method. The conversion voltage Vcnt_A is converted within an allowable range. Further, the second voltage control unit 12b is controlled by the control signal B from the power saving control unit 23, and the battery voltage Vbat supplied from the power management unit 11 is allowed in the second voltage control method. The conversion voltage Vcnt_B is converted. The conversion voltages Vcnt_A and Vcnt_B are applied to the amplifier PA1 or PA2 via the switch SW1 or SW2.

  Here, even if the voltage applied to the amplifier PA1 or PA2 is changed, the relationship between the amplified signal and the consumed current value is usually not greatly changed. Since power = current × voltage, the voltage applied to the amplifier PA1 or PA2 by the first voltage control unit 12a or the second voltage control unit 12b is reduced within an allowable distortion characteristic range, thereby the amplifier PA1. Alternatively, the power consumption of PA2 can be reduced.

  In general, amplifiers (amplifiers PA1 and PA2) that amplify transmission signals consume much more power than amplifiers (low-noise amplifiers LNA1 and LNA2) that amplify reception signals. Low power consumption in the mobile communication terminal 1 by reducing the power consumption in the amplifier PA1 or PA2 that amplifies the transmission signal by the voltage conversion operation of the first voltage control unit 12a or the second voltage control unit 12b. Electricity can be effectively achieved.

  The first voltage control unit 12a that converts the battery voltage Vbat to the conversion voltage Vcnt_A and the second voltage control unit 12b that converts the battery voltage Vbat to the conversion voltage Vcnt_B usually output a conversion voltage that satisfies the desired characteristics. In order to achieve this, a DC-DC converter is used. The DC-DC converter is also called SMPS (Switch-mode Power Supplies).

  Further, the voltage control method by which the power saving control unit 23 controls the first voltage control unit 12a and the second voltage control unit 12b is not particularly limited, and a known low power consumption method may be adopted. Examples of typical low power consumption methods include an APT (Average Power Tracking) method and an ET (Envelope Tracking) method. In the present embodiment, the first voltage control method is the ET method, and the second voltage control method is the APT method. Both voltage control systems have the following characteristics.

  The first voltage control unit 12a controlled by the power saving control unit 23 using the ET method converts the conversion voltage Vcnt_A so as to follow the envelope of the transmission signal (see FIG. 2B). In order to follow a high-speed output change of the transmission signal, the first voltage control unit 12a requires a high-speed operation. Therefore, in the ET method, the power consumption of the first voltage control unit 12a itself tends to be high, but is sufficiently low compared to the large current consumption of the amplifier (PA1) in the region near the maximum transmission power. The current reduction effect can be demonstrated. Furthermore, in order to ensure distortion characteristics in a region close to the maximum transmission power, a peak voltage close to the VBat voltage or the VBat voltage may be required, but the signal changes even near the maximum transmission output. Since control according to the envelope of the transmission signal by the ET method is performed, current consumption can be reduced, and a large current flow effect can be obtained at a portion that becomes a valley of the envelope. On the contrary, since the current consumption of the amplifier (PA1) is originally low in the region where the transmission power is low, the comparison with the current consumed by the first voltage control unit 12a itself is small. Therefore, the ET method exhibits excellent low power consumption characteristics when amplifying signals distributed in a region where the output of the transmission signal is relatively high.

  On the other hand, the second voltage control unit 12b controlled by the power saving control unit 23 using the APT method outputs a converted voltage Vcnt corresponding to an average value in a certain region (for example, frame unit) in the time axis direction of the transmission signal ( (See (a) of FIG. 2). For example, since the conversion voltage Vcnt is controlled on a frame basis, a high-speed operation is not necessary as compared with the ET method. Therefore, the power consumption of the second voltage control unit 12b itself is lower than that of the ET system, and is sufficiently lower than the low current consumption in the region where the output of the transmission signal is relatively low. I can do it. On the other hand, in a region where the output of the transmission signal is relatively high, a relatively high voltage may be required to ensure satisfactory distortion characteristics. Therefore, the control voltage in the region where the output of the transmission signal is relatively high, particularly in the region close to the maximum transmission power, requires the Vbat voltage or a voltage close to the Vbat voltage, so that the current consumption reduction effect cannot be exhibited. From the above characteristics, the APT system exhibits excellent low power consumption characteristics when amplifying signals distributed in a region where the output of the transmission signal is relatively low.

  As described above, it is understood that it is desirable to select a voltage control method that exhibits excellent low power consumption characteristics according to the output region of the transmission signal. Furthermore, since the transmission power of the mobile communication terminal changes from moment to moment, a transmission power probability distribution as described later must be considered in order to effectively reduce current. That is, when the transmission power probability distribution is distributed in a high area, it is advantageous to use a voltage control method such as the ET control described above, and the transmission power probability distribution is large in a low area. If distributed, the APT control described above is advantageous.

  In this specification, in this specification, the transmission output region optimal for power saving of the first voltage control unit 12a controlled by the ET method (a transmission signal whose amount of reduction in power consumption is larger than that of other voltage control units). The output region) may be expressed as being higher than the transmission output region optimal for power saving of the second voltage control unit 12b controlled by the APT method.

  In the present embodiment, the first voltage control unit 12a and the second voltage control unit 12b are assigned to either the first radio transmission / reception unit 13 or the second radio transmission / reception unit 14, respectively. The voltage applied to the amplifier (PA1 or PA2) provided in the assigned wireless transmission / reception unit is controlled. That is, when the first voltage control unit 12a is assigned to the first wireless transmission / reception unit 13, the terminal A-B of the switch SW1 is turned on, and the voltage Vcc1 applied to the amplifier PA1 becomes the conversion voltage Vcnt_A. The power saving control (voltage control) is performed by the ET method. When the first voltage control unit 12a is assigned to the second radio transmission / reception unit 14, the terminal EF of the switch SW2 is turned on, and the voltage Vcc2 applied to the amplifier PA2 becomes the conversion voltage Vcnt_A. The power saving control (voltage control) is performed by the ET method. When the second voltage control unit 12b is assigned to the first wireless transmission / reception unit 13, the terminal AC of the switch SW1 is turned on, and the voltage Vcc1 applied to the amplifier PA1 becomes the converted voltage Vcnt_B. , Power saving control (voltage control) is performed by the APT method. When the second voltage control unit 12b is assigned to the second radio transmission / reception unit 14, the terminal EG of the switch SW2 is turned on, and the voltage Vcc2 applied to the amplifier PA2 becomes the conversion voltage Vcnt_B. , Power saving control (voltage control) is performed by the APT method. The switch SW1 is controlled by the power saving control unit 23 via the signal SW1_CTRL, and the switch SW2 is controlled by the signal SW2_CTRL. Note that the Vbat voltage can be applied by turning on the terminals A and D of the switch SW1 or the terminals E and H of the switch SW2 at the time of starting the entire system or before performing a cell search.

(Cell coverage)
The cell discriminating unit 24 discriminates the cell coverage of the base station with which the first radio transmitting / receiving unit 13 and the second radio transmitting / receiving unit 14 perform radio communication, and sends a cell discrimination signal to the power saving control unit 23. Here, cell coverage will be described. A range (cell) capable of wireless communication with the mobile communication terminal is set in the base station that performs wireless communication with the mobile communication terminal. Each cell has a corresponding name defined for each vendor or operator depending on its coverage (size). For example, a macro cell (the maximum distance from the base station is several hundred meters to several kilometers, the transmission power of the base station is about 5 to 10 W), and a pico cell narrower than the macro cell (the maximum distance from the base station is 500 meters to 1). .5 km, base station transmission power of about 1 to 5 W), femtocell narrower than picocell (maximum distance from base station from 100 meters to 200 meters, base station transmission power of about 10 to 100 mW), etc. In general, from the radio wave propagation characteristics, the coverage of a high frequency band (for example, 2 GHz) is smaller than the coverage of a low frequency band (for example, 800 MHz).

  A network in which a plurality of cells having different coverages are mixed is referred to as a heterogeneous network. FIG. 3 is a diagram illustrating an example of a heterogeneous network. Wide-area BSs and narrow-area BS_A to BS_C represent base stations, and MS1 to MS4 represent mobile communication terminals. In the example shown in FIG. 3, a heterogeneous network is formed at the positions of MS2 and MS3.

  In the present specification, among the cells where the mobile communication terminal 1 according to the present embodiment is located, a relatively wide cell is referred to as a wide area cell, and a relatively narrow cell is referred to as a narrow area cell. In particular, as shown in FIG. 3, a heterogeneous network is assumed in which the narrow area cell is sufficiently smaller than the wide area cell. For example, when the mobile communication terminal 1 is located in a macro cell and a pico cell, the macro cell is referred to as a wide area cell and the pico cell is referred to as a narrow area cell. When the mobile communication terminal 1 is located in a macro cell and a femto cell, the macro cell is referred to as a wide area cell and the femto cell is referred to as a narrow area cell. When the mobile communication terminal 1 is located in a pico cell and a femto cell, the pico cell is referred to as a wide area cell, and the femto cell is referred to as a narrow area cell. Note that the narrow cell may be placed at a position (cell edge) where the coverage of the wide cell is expanded and interpolated.

  Here, since the base station receives radio waves from a plurality of mobile communication terminals, the base station controls the transmission output at each mobile communication terminal in order to prevent interference of radio waves, that is, strong radio waves cancel out weak radio waves. Thus, the reception levels from the respective mobile communication terminals are made uniform. This will be described with reference to FIG. In FIG. 4, BS is a base station, MSn, MSm and MSf are mobile communication terminals, Tx_n, Tx_m and Tx_f are transmission outputs of MSn, MSm and MSf, Rx_n, Rx_m and Rx_f are MSn, MSm and Each reception level in MSf is shown. The length of the arrow line indicating the radio wave propagation path is correlated with the attenuation amount of the radio wave. Note that this attenuation amount includes not only the distance but also the influence of reflection and diffraction caused by the weather or obstacles. When the transmission output is the same, the signal level received by the BS decreases as the radio wave propagation distance increases.

  4B to 4D are flowcharts for explaining the control of the BS with respect to MSn, MSm, and MSf. The BS receives the propagated UL_n, UL_n, and UL_n signals transmitted from MSn, MSm, and MSf, and measures the reception level (step Sn1, step Sm1, and step Sf1). Then, the measured reception level is compared with a reference value (Step Sn2, Step Sm2, Step Sf2), and if the reception level is larger than the reference value, a command is issued to decrease the transmission output (Step Sn3, Step Sm3). Step Sf3) If the reception level is smaller than the reference value, a command is issued to increase the transmission output (Step Sn4, Step Sm4, Step Sf4). As a result, the reception levels of the MSn, MSm, and MSf at the BS become uniform. In addition, a mobile communication terminal located farther from the BS requires a larger transmission output.

  Also on the mobile communication terminal side, if the received signal level from the base station is low, it is far from the base station, the transmission output is increased, and if the received signal level from the base station is high, it is close to the base station As a result, the transmission output is reduced. The amplitude density function (PDF: Probability Density Function) of a radio wave received by a mobile terminal that cannot be seen by the base station has a Rayleigh distribution as shown in FIG. Further, the amplitude density function of the radio wave received by the terminal moving where the base station can be seen becomes a Rice distribution as shown in FIG. 5B when a direct wave from the base station is added. That is, the transmission output of the mobile communication terminal is also correlated with this distribution.

  As can be seen from these figures, the probability density of the maximum output is very small, and it is clear that the effect is small even if the power is saved by focusing on the maximum output as in the prior art. An example of an amplitude density function of radio waves transmitted from terminals located in a wide area cell is described in DG. Assuming the 09 model, as shown in (a) of FIG. 10, the appearance probability is distributed with a peak in the vicinity of transmission power = −5 dBm, and the effect of the conventional power saving control focusing on the maximum output region is small. I understand that.

  Furthermore, in a signal using a wide band and a more complicated modulation method for realizing high throughput, the current consumption of the amplifier increases, but distortion characteristics become severe, so MPR (Maximum Power Reduction) is defined. In general, the maximum transmission power is reduced. Therefore, just because the maximum transmission power is large does not necessarily mean that the maximum power saving effect is obtained.

  Also, the amplitude density function of the radio wave transmitted by the terminal located in the narrow cell shifts to a direction with less transmission power as compared to the case where the terminal is located in the wide area cell, as shown in FIG. Yes. Therefore, since the average current also decreases, it is desirable to perform power saving control that can exhibit a reduction effect with respect to a small current consumption.

  Furthermore, when the wide area cell and the narrow area cell use the same frequency, it is necessary to perform interference prevention control in which the wide area BS is the primary and the narrow area BS is the secondary. In the LTE scheme, signals Tx_n, Tx_m, and Tx_f transmitted from the mobile communication terminal to the base station employ SC-FDMA (Single Carrier Frequency Division Multiple Access), and are orthogonal in the frequency domain. Therefore, fractional TPC (Transmission Power Control) that controls the target value of transmission power control for each mobile communication terminal can be applied. Therefore, the mobile communication terminal that wants to increase the throughput can also improve the throughput by increasing the target value of the transmission power according to the control from the base station.

  Note that the method by which the cell determining unit 24 determines cell coverage is not particularly limited, and various methods can be used. As an example, the case of LTE Home eNB (femtocell) will be described (see Chapter 8 of 3GPP TS 22.011). Note that the coverage of LTE Home eNB (femtocell) is sufficiently small for wide area cells.

  In general, in the wide area cell, the wide area BS becomes the primary and the secondary narrow area BS is controlled. As an example of a narrow band BS, system information broadcast by an eNB (evolved Node B) of LTE is transmitted on a BCCH (Broadcast Control Channel). BCCH is allocated to BCH (Broadcast Channel) and DL-SCH (Downlink Shared Channel). What is assigned to the BCH is an MIB (Master Information Block), which includes information on the physical layer necessary for receiving system information. System information blocks (SIBs) allocated to the DL-SCH are classified into a plurality of types such as SIB types 1 to 16, and information on the home eNB is written in SIB Type 9 among them. As information about the HOME eNB, an ID as a CSG (Closed Subscriber Group) is used. The SIB may be expanded in the future.

  Those pieces of information are transmitted in a period set for each. By receiving the information, the mobile communication terminal can determine that it is within the coverage of the HOME eNB, which is a narrow cell with a narrow coverage.

  In addition, when the mobile communication terminal stores a list of information on eNBs that have been stored in advance or have connected in the past, the mobile communication terminal can check the cell by checking the list with the received eNB information. It can be handled as a candidate for selection. Cell selection can be performed with support from the network, and the mobile communication terminal can also perform selection.

  Furthermore, a home eNB (femtocell) is installed in a general home, a small office, or the like, and is connected to a mobile carrier network (CN: core network) via a general broadband line such as an optical line or ADSL. There are also things. For this reason, the mobile telecommunications carrier network (CN: core network) side authenticates that the femtocell is a valid device from the viewpoint of security. For example, the femtocell holds a USIM card including authentication data, and uses this information to authenticate to the authentication server of the mobile carrier network when connecting to the line. Therefore, the server of the mobile carrier network holds a list of femtocell base stations that can communicate. A femto cell is assigned a unique number (FemtoID) and is managed in a database on the network. The CN holds a FemtoID list corresponding to a femto cell that is permitted to be used on the subscriber profile, and is used to determine whether or not the user can be in the location at the time of location registration.

  The cell discriminating unit 24 of the mobile communication terminal 1 refers to the list of femtocell base stations via the mobile communication carrier network, and thereby the first radio transmission / reception unit 13 and the second radio transmission / reception unit 14. It is possible to determine whether or not the base station that performs wireless communication is a femtocell.

  As described above, since the cell determination unit 24 can determine a narrow-area cell, it can also be determined exclusively as a wide-area cell.

  Note that the mobile communication terminal 1 stores the ID, frequency, scrambling code, etc. of the narrow cell once in the cell as a candidate list, periodically performs a cell search of the candidate list, and is spontaneous Alternatively, it may be located in a narrow cell. In this case, the cell determination unit 24 also determines whether the cell of the base station with which the first wireless transmission / reception unit 13 and the second wireless transmission / reception unit 14 perform wireless communication is included in the candidate list. The cell coverage of the station can be determined.

(Amplifier gain mode)
FIG. 8A shows how the gain mode of the amplifier PA1 is switched. The gain mode of the amplifier PA1 is switched by a signal PA1_HL from the power saving control unit 23. Specifically, the amplifier PA1 has an H-mode that is a setting such as a bias that optimizes efficiency and distortion characteristics in a high output region, and a L that is a setting such as a bias that optimizes efficiency and distortion characteristics in a low output region. -The gain mode is switched between the modes. In switching between the H-mode and the L-mode, as shown in FIG. 8A, the output level of the amplifier PA1 exceeds or falls below a predetermined switching point with hysteresis for each amplifier. Is controlled by. Note that the value of Tx_Out at the switching point is an example. The gain mode is not limited to two, and may be three or more.

  Similarly to the amplifier PA1, the amplifier PA2 is controlled by a signal PA2_HL from the power saving control unit 23, as shown in FIG. 8B. Note that the value of Tx_Out at the switching point is an example. In addition, the setting of each switching point is a setting value that matches the characteristics of the amplifier.

  By switching the gain mode in this way, the transmission power Tx_Out and Vcc1 (or Vcc2) have a relationship as shown in FIG. 9A, for example.

  Furthermore, as shown in FIGS. 9B and 9C, the gain switching and the voltage control method can be switched synchronously. In the example shown in FIG. 9B, the gain mode in the region where Tx_Out is large is H-Mode, and the voltage control is the ET method. Specifically, Vcc1 or Vcc2 controlled by the ET method has a waveform along the envelope of the transmission signal as shown in FIG. 2B, but shows a waveform of an average value simplified for the sake of explanation. . On the other hand, the gain mode in the region where Tx_Out is small is L-Mode, and the voltage control is the APT method. This is advantageous for power saving when the transmission power probability is distributed in a large amount in the high output area as in the wide area cell. In the example shown in FIG. 9C, the gain mode in the region where Tx_Out is large is H-Mode, and the voltage control is the APT method. On the other hand, the gain mode in the region where Tx_Out is small is L-Mode, and the voltage control is the APT method. This is advantageous for power saving when the transmission power probability is widely distributed in the low output area as in the narrow area cell. Of course, other combinations of gain mode and voltage control method are also possible. Further, the switching between the gain mode and the voltage control method may be asynchronous. Furthermore, if the voltage control of the ET method with low power consumption can be realized, the ET method may be used even when the transmission power probability is distributed in the low output region.

(Power saving control)
As described above, the transmission output of the first wireless transmission / reception unit 13 or the second wireless transmission / reception unit 14 of the mobile communication terminal 1 is equal to the radio wave propagation distance between these wireless transmission / reception units and the base station with which the wireless communication is performed. Will change accordingly. Therefore, the transmission power in the mobile communication terminal 1 changes from moment to moment. Therefore, when evaluating the duration of the battery, that is, the degree of achievement of power saving, it is necessary to evaluate the distribution of the appearance frequency of the transmission output. Here, as shown in FIG. 6, the distribution of the appearance frequency of the transmission output is different between the wide cell having a wide cell range and the narrow cell having a narrow cell range. This is because, when wirelessly communicating with a narrow cell base station, the possibility that the base station is relatively close to the wireless cell base station is higher than when communicating wirelessly with a wide area cell base station. Therefore, when wirelessly communicating with a narrow cell base station, the probability distribution is shifted toward a lower transmission power than when wirelessly communicating with a wide area cell base station. Therefore, in wireless communication with a narrow cell base station, a voltage control method having a low transmission output area that is optimal for power saving is applied (effective in a low transmission power area). The power consumption can be suitably reduced by applying a voltage control method having a high transmission output region that is optimal for power saving (effective in a high transmission power region). Such power saving control is included in SV-LTE (Simultaneous Voice and LTE) that simultaneously supports LTE and 3G communication functions and CA (Carrier Aggregation) that is being studied in LTE-Advanced as a next-generation communication technology. This is particularly effective in a technology for bundling communication resources between a macro cell in a wide area and a small cell in a narrow area.

  FIG. 7 is a flowchart showing an example of power saving control in the mobile communication terminal 1. For convenience of explanation, a heterogeneous network composed of macro cells and small cells is taken as an example of explanation. In the following example, the cell discriminating unit 24 discriminates a macro cell as a wide-area cell and a cell having a smaller coverage than the macro cell (a pico cell in the following example) as a narrow-area cell.

  First, the power saving control unit 23 initializes the registers RF1 and RF2 (step S1). Subsequently, the communication processing unit 20 performs a search (cell search) for a base station with which the first wireless transmission / reception unit 13 and the second wireless transmission / reception unit 14 perform wireless communication (step S2). When the communication processing unit 20 finds a base station with which the first wireless transmission / reception unit 13 performs wireless communication (YES in step S3), the cell determination unit 24 determines whether the base station is a wide area cell or a narrow area cell. Is determined (step S4). For example, when the cell determination unit 24 determines that the base station is a pico cell and a narrow area cell (pico cell in step S4), the power saving control unit 23 stores information indicating “narrow area” in the register RF1. Save (step S5). When the cell determination unit 24 determines that the base station is a macro cell and a wide area cell (macro cell in step S4), the power saving control unit 23 stores information indicating “wide area” in the register RF1. (Step S6). When the communication processing unit 20 does not find a base station with which the first wireless transmission / reception unit 13 performs wireless communication (NO in step S3), the power saving control unit 23 stores information indicating “out of service” in the register RF1. Save (step S7).

  Subsequently, when the communication processing unit 20 finds a base station with which the second wireless transmission / reception unit 14 performs wireless communication (YES in step S8), the cell determination unit 24 determines whether the base station is a wide area cell or a narrow area. It is determined whether it is a cell (step S9). For example, when the cell determination unit 24 determines that the base station is a pico cell and a narrow cell (pico cell in step S9), the power saving control unit 23 stores information indicating “narrow region” in the register RF2. Save (step S10). When the cell determination unit 24 determines that the base station is a macro cell and a wide area cell (macro cell in step S9), the power saving control unit 23 stores information indicating “wide area” in the register RF2. (Step S11). When the communication processing unit 20 does not find a base station with which the second wireless transmission / reception unit 14 performs wireless communication (NO in step S9), the power saving control unit 23 stores information indicating “out of service” in the register RF2. Save (step S12). In addition, the 1st radio | wireless transmission / reception part 13 and the 2nd radio | wireless transmission / reception part 14 may assist the cell search of the other, if the direction which detected the base station previously acquires the information of the cell which adjoins.

  Then, the power saving control unit 23 performs power saving control with reference to the registers RF1 and RF2 (step S13). Table 1 shows an example of power saving control. For example, the power saving control unit 23 controls the switches SW1 and SW2 according to the registers RF1 and RF2, and controls the voltages Vcc1 and Vcc2 applied to the amplifiers PA1 and PA2, as shown in Table 1. Thereby, when the coverage of the base station with which the wireless transceiver (the first wireless transceiver 13 or the second wireless transceiver 14) communicates is wider, the voltage control of the amplifier of the wireless transceiver is higher. The transmission output area can be switched so as to be performed by the voltage control unit whose transmission output area is optimal for power saving.

  In particular, when any one of the radio transmission / reception units performs radio communication alone, as shown in FIG. 9B, the voltage control unit is switched in synchronization with the switching of the gain mode of the amplifier, thereby simplifying the operation. The power consumption can be further reduced by this method (“gain mode synchronization” in Table 1). Further, as shown in FIG. 9C, it is not necessary to synchronize.

  In addition, when the first wireless transmission / reception unit 13 and the second wireless transmission / reception unit 14 are performing wireless communication with different base stations in parallel, the wireless transmission / reception unit wirelessly communicates with a base station having a wider coverage. On the other hand, it is possible to assign a voltage control unit in which a higher transmission output area is an optimal transmission output area for power saving. In the case of “adaptive” in Table 1, it is not possible to determine which cell is a wide area, so power saving can be achieved according to other criteria (for example, signal type, bit rate, bandwidth, etc.). What is necessary is just to select the radio | wireless transmission / reception part which controls.

[Modification]
For example, in step S4 or step S9 in FIG. 7, the cell determination unit 24 may determine the cell coverage from the user authentication result information of the communication carrier. In LTE, a CSG (Closed Subscriber Group) function that allows only a specific user access to a cell is provided. The telecommunications carrier knows what kind of cell it is based on the ID, but the mobile communication terminal stores in advance a CSG ID list with access rights, and the CGS ID broadcasted as the CGS cell The list may be collated to be a connection destination candidate, and when it is not found in the list, it may be handled as a normal macro cell.

  Further, in the above description, the radio transmission unit that performs radio communication with a base station having a wider coverage has been described as allocating a voltage control unit in which a higher transmission output region is an optimal transmission output region for power saving. On the other hand, a voltage control unit in which a lower transmission output area is an optimal transmission output area for power saving may be assigned to a wireless transmission section that performs wireless communication with a base station having a narrower coverage.

  In the above-described embodiment, the antennas ANT1 and ANT2 have been described as independent antennas for convenience of explanation. However, the present embodiment is not limited to this, and a single antenna is provided to provide the first wireless communication. The transmission / reception unit 13 and the second wireless transmission / reception unit 14 may be configured to match each of the antennas. The antennas ANT1 and ANT2 may be used as a primary antenna and a secondary antenna in MIMO transmission / reception or diversity transmission / reception. In the embodiment described above, the case where there are two transmission / reception systems has been described for convenience of explanation, but the transmission / reception system may be one system or three or more systems. In that case, the mobile communication terminal may include the same number of voltage control units as the number of transmission / reception systems, and in order to save the mounting area and cost of the voltage control units, the number of voltage control units is smaller than that of the transmission / reception systems. And using the present invention, an optimum voltage control unit may be selected according to the coverage in which a plurality of transmission / reception systems operate.

[Embodiment 2]
FIG. 11 is a flowchart showing another example of power saving control in the mobile communication terminal 1. In the example shown in FIG. 11 as well, for convenience of explanation, a heterogeneous network composed of macro cells and small cells is taken as an example of explanation. A macro cell is referred to as a wide area cell, and a cell having a smaller coverage than the macro cell is referred to as a narrow area cell. Furthermore, it is assumed that the wireless transmission / reception unit 1 is set to perform cell search first. In addition, since the control from the wide area BS becomes the primary, the wide area search is performed first.

  First, the power saving control unit 23 initializes the registers RF1 and RF2 (step S101). Subsequently, the communication processing unit 20 searches for a wide area base station (cell search) in which the first wireless transmission / reception unit 13 performs wireless communication (step S102).

  Then, as a result of the search in step S102, when a wide area base station with which the first wireless transmission / reception unit 13 performs wireless communication is found (YES in step S103), the communication processing unit 20 receives a signal from the wide area base station. Information (MIB, SIB, etc.) acquired by doing so is stored in the register RF1 (step S104). Subsequently, the communication processing unit 20 performs a search (cell search) for a base station with which the second wireless transmission / reception unit 14 performs wireless communication with reference to the acquired information (step S105). At this time, the communication processing unit 20 may read information on a connectable base station or a base station with connection experience stored in advance in the flash memory 17 of the mobile communication terminal 1 and may assist the search.

  If the base station is not found as a result of the search in step S105 (NO in step S106), the communication processing unit 20 stores information indicating “out of service” in the register RF2 (step S107). Further, the cell determination unit 24 stores information indicating “wide area” in the register RF1 (step S108). In step S109, the power saving control unit 23 performs power saving control. If the base station is found as a result of the search in step S105 (YES in step S106), the communication processing unit 20 uses the information (MIB, SIB, etc.) acquired by receiving the signal from the base station. And stored in the register RF2 (step S110). In step S111, the cell determination unit 24 refers to the base station information stored in the register RF1 and the register RF2, and compares cell coverage.

  On the other hand, as a result of the search in step S102, when the base station with which the first wireless transmission / reception unit 13 performs wireless communication is not found (NO in step S103), the communication processing unit 20 indicates “out of service” to the register RF1. Information is stored (step S112). Subsequently, the communication processing unit 20 searches for a base station (cell search) with which the second wireless transmission / reception unit 14 performs wireless communication (step S113).

  Then, as a result of the search in step S113, if the base station with which the second wireless transmission / reception unit 14 performs wireless communication is not found (NO in step S114), the communication processing unit 20 indicates “out of service” to the register RF2. The information is stored (step S115), and the process returns to step S102, and the first wireless transmission / reception unit 13 searches for a base station (cell search) for wireless communication again. As a result of the search in step S113, if a base station with which the second radio transceiver unit 14 communicates wirelessly is found (YES in step S114), the communication processing unit 20 sends a register RF2 from the wide area base station. Information (MIB, SIB, etc.) acquired by receiving the signal is stored (step S116). Subsequently, the communication processing unit 20 performs a search (cell search) for a base station with which the first wireless transmission / reception unit 13 performs wireless communication with reference to the acquired information (step S117). At this time, the communication processing unit 20 may read information on a connectable base station or a base station with connection experience stored in advance in the flash memory 17 of the mobile communication terminal 1 and may assist the search.

  If the base station is not found as a result of the search in step S117 (NO in step S118), the communication processing unit 20 stores information indicating “out of service” in the register RF1 (step S119). Further, the cell determination unit 24 stores information indicating “wide area” in the register RF1 (step S120). In step S109, the power saving control unit 23 performs power saving control. If the base station is found as a result of the search in step S117 (YES in step S118), the communication processing unit 20 uses information (MIB, SIB, etc.) acquired by receiving a signal from the base station. The data is stored in the register RF1 (step S121). In step S111, the cell determination unit 24 refers to the base station information stored in the register RF1 and the register RF2, and compares cell coverage.

  In step S111, the cell determination unit 24 refers to the base station information stored in the register RF1 and the register RF2, and the cell coverage of the base station with which the first wireless transmission / reception unit 13 performs wireless communication and the second wireless transmission / reception. The unit 14 discriminates cell coverages of base stations with which radio communication is performed, and compares them with each other. As a result of the comparison, when it is determined that the coverage of the base station related to the information stored in the register RF2 is narrower than that of the register RF1 (RF1> RF2 in step S111), the cell determination unit 24 uses the register RF1. Is stored in the register RF2 and information indicating "narrow area" is stored in the register RF2 (step S122). Further, as a result of the comparison, when it is determined that the coverage of the base station related to the information stored in the register RF1 is narrower than that of the register RF2 (RF1 <RF2 in step S111), the cell determination unit 24 Information indicating “narrow area” is stored in the register RF1, and information indicating “wide area” is stored in the register RF2 (step S124). As a result of the comparison, when it is determined that the base stations related to the information stored in the register RF1 and the register RF2 have the same coverage (RF1 = RF2 in step S111), both the register RF1 and the register RF2 have “ Information indicating “wide area” is stored, or information indicating “narrow area” is stored in both the register RF1 and the register RF2 (step S123).

  As in the first embodiment, the power saving control unit 23 performs power saving control with reference to the registers RF1 and RF2 (step S109). Table 1 shows an example of power saving control. For example, the power saving control unit 23 controls the switches SW1 and SW2 according to the registers RF1 and RF2, and controls the voltages Vcc1 and Vcc2 applied to the amplifiers PA1 and PA2, as shown in Table 1. As a result, the voltage control of the amplifier of the wireless transmission / reception unit with the wider coverage of the base station with which the wireless transmission / reception unit (the first wireless transmission / reception unit 13 or the second wireless transmission / reception unit 14) communicates wirelessly has a high transmission power. Switching can be performed by a voltage control unit that is advantageous for saving power in the region. Furthermore, it is possible to switch so that the voltage control of the amplifier of the wireless transmission / reception unit with the narrower coverage is performed by a voltage control unit of a method advantageous for power saving in a region with low transmission power.

  In addition, the modification shown in Embodiment 1 can be applied to the present invention as far as possible.

[Summary]
The mobile radio communication terminal 1 according to the first aspect of the present invention includes amplifiers (PA1, PA2), and radio transmission units (first radio transmission / reception unit 13, second radio transmission / reception unit 14) that perform radio communication with a base station. And power-saving means (switch SW1, switch SW2, first voltage control unit 12a, second voltage control unit 12b, and the like) that control the voltage applied to the amplifier so that the power consumption of the amplifier is reduced. A power saving control unit 23) and a cell discriminating unit (cell discriminating unit 24) for discriminating the coverage of a base station with which the radio transmitting unit performs radio communication. The power saving unit includes different voltage controls. A plurality of voltage control units (first voltage control unit 12a, second voltage control unit 12b) for controlling the voltage in a manner, and applying to the amplifier with reference to the discrimination result of the cell discrimination means Voltage control to control voltage Switch the part.

  In a mobile communication terminal, the mobile communication system or mode with the highest maximum output power does not necessarily have higher power consumption. The transmission power of the mobile communication terminal changes from moment to moment, and power control is performed such that it is small when the distance to the base station is short and large when the distance to the base station is far. Therefore, appropriate power saving control cannot be executed by the control according to the maximum output power as in the prior art. On the other hand, according to the above configuration, the power consumption is suitably reduced by determining the cell coverage in which the mobile communication terminal is located and switching the voltage control method of the voltage applied to the amplifier according to the coverage. be able to.

  In the mobile radio communication terminal 1 according to aspect 2 of the present invention, in the aspect 1, the plurality of voltage control units correspond to different transmission output regions optimum for power saving with respect to the transmission output of the amplifier. In the optimal transmission output area, the amount of power consumption reduction is larger than that of other voltage control units, and the power saving means is the same as the cell discrimination means. When the determined coverage is wider, it is preferable to switch so that the voltage control unit in which the higher transmission output region is the optimum transmission output region for power saving controls the voltage applied to the amplifier. According to the above configuration, in wireless communication with a narrow cell base station, since the transmission power distribution is distributed on the low output side, a voltage control method effective for power saving in the low transmission power region is applied. In wireless communication with cell base stations, the transmission power distribution is distributed on the high output side, so the power consumption can be suitably reduced by applying a voltage control method effective for power saving in the high transmission power region. Can do. In other words, power consumption can be suitably reduced by allocating a voltage control unit having a higher transmission output region optimum for power saving to a radio transmission unit with a wider coverage.

  The mobile radio communication terminal 1 according to aspect 3 of the present invention further includes gain mode switching means (power saving control unit 23) for switching the gain mode of the amplifier in the aspect 2, wherein the power saving means is When the gain mode switching means switches the gain mode of the amplifier, the voltage control unit that controls the voltage applied to the amplifier may be switched. Since the gain mode of the amplifier is switched according to the output region of the amplifier, the power consumption can be reduced by a simple method by switching the voltage control unit in synchronization with the switching of the gain mode.

  A mobile radio communication terminal 1 according to aspect 4 of the present invention includes the above-described plurality of radio transmission units in the above-described aspect 2 or 3, and each radio transmission unit and radio Communication is possible, and each of the plurality of voltage control units controls a voltage applied to an amplifier of an assigned wireless transmission unit, and the power saving unit is determined by the cell determination unit. A voltage control unit in which a higher transmission output area is an optimal transmission output area for power saving may be assigned to a wireless transmission section that performs wireless communication with a base station having a wider coverage. According to the above configuration, when the mobile communication terminal includes a plurality of radio transmission units capable of performing radio communication with different base stations in parallel, the voltage control unit is assigned to each radio transmission unit. Can be suitably performed.

  A mobile radio communication terminal 1 according to aspect 5 of the present invention includes the above-described plurality of radio transmission units in the above-described aspect 2 or 3, and each radio transmission unit and radio Communication is possible, and each of the plurality of voltage control units controls a voltage applied to an amplifier of an assigned wireless transmission unit, and the power saving unit is determined by the cell determination unit. A voltage control unit in which a lower transmission output area is an optimal transmission output area for power saving may be assigned to a wireless transmission section that performs wireless communication with a base station having a narrower coverage. According to the above configuration, when the mobile communication terminal includes a plurality of radio transmission units capable of performing radio communication with different base stations in parallel, the voltage control unit is assigned to each radio transmission unit. Can be suitably performed.

  In the mobile radio communication terminal 1 according to aspect 6 of the present invention, in the above aspect 4 or 5, the base station with which the plurality of radio transmission units perform radio communication preferably constitutes a heterogeneous network. According to the above configuration, since the mobile communication terminal performs wireless communication with a plurality of base stations having different coverages, the mobile communication terminal determines cell coverage and performs wireless transmission corresponding to a wide area cell. By prioritizing voltage control for power saving, power consumption can be suitably reduced.

  The mobile radio communication terminal 1 according to Aspect 7 of the present invention is the mobile radio communication terminal 1 according to Aspects 1 to 6, wherein the cell discrimination means is configured such that a base station with which each of the plurality of radio transmission units performs radio communication is a macro cell base station or a pico cell base. It may be determined whether it is a station or a femtocell base station. According to the above configuration, the cell determination unit determines whether the base station with which each of the plurality of wireless transmission units performs wireless communication is a macro cell base station, a pico cell base station, or a femto cell base station, The coverage of each base station can be easily determined.

  In the mobile radio communication terminal 1 according to aspect 8 of the present invention, in the above aspects 1 to 7, the voltage control unit (the first voltage control unit 12a and the second voltage control unit 12b) is an APT (Average Power Tracking). The voltage may be controlled according to a system or an ET (Envelope Tracking) system. According to said structure, the voltage control part can reduce the power consumption of the said amplifier suitably by controlling the voltage applied to an amplifier according to an APT system or an ET system.

  The mobile radio communication terminal control method according to aspect 9 of the present invention is different from each other in radio transmission units (first radio transmission / reception unit 13 and second radio transmission / reception unit 14) including amplifiers (PA1, PA2). A control method for mobile communication terminal 1 comprising a plurality of voltage control units (first voltage control unit 12a, second voltage control unit 12b) for controlling voltage in a mode, wherein the radio transmission unit is a base A wireless communication step of wirelessly communicating with a station, a power saving step of controlling a voltage applied to the amplifier so that power consumption of the amplifier is reduced, and a base on which each of the plurality of wireless transmission units performs wireless communication A cell discriminating step for discriminating the coverage of the station, and in the power saving step, referring to the discrimination result of the cell discriminating step, the voltage control unit for controlling the voltage applied to the amplifier is switched. . According to said structure, there exists an effect equivalent to the mobile radio | wireless communication terminal 1 which concerns on aspect 1 of this invention.

  The present invention can be used in the field of manufacturing mobile communication terminals.

    DESCRIPTION OF SYMBOLS 1 Mobile communication terminal 12a 1st voltage control part (power saving control means, voltage control part) 12b 2nd voltage control part (power saving control means, voltage control part) 13 1st radio | wireless transmission / reception part (wireless transmission part) 14 Second wireless transmission / reception unit (radio transmission unit) 23 Power saving control unit (power saving control unit, gain mode switching unit) 24 Cell discrimination unit (cell discrimination unit) PA1, PA2 Amplifier SW1, SW2 Switch (power saving control) means)

Claims (5)

A wireless transmitter having an amplifier and wirelessly communicating with the base station;
Power saving means for controlling the voltage applied to the amplifier so that the power consumption of the amplifier is reduced; and
Cell discriminating means for discriminating the coverage of the base station with which the radio transmitting unit communicates by radio, and
The power saving unit includes a plurality of voltage control units that control voltages by mutually different voltage control methods, and refers to a determination result of the cell determination unit to control a voltage applied to the amplifier. A mobile communication terminal characterized by switching a part. The plurality of voltage control units have voltage control methods corresponding to different transmission output regions that are optimal for power saving with respect to the transmission output of the amplifier, and power consumption is reduced in the optimal transmission output region. The amount is larger than the voltage control method of other voltage control units,
The power saving unit controls a voltage applied to the amplifier by a voltage control unit in which a higher transmission output region is the optimum transmission output region for power saving when the coverage determined by the cell determination unit is wider. The mobile communication terminal according to claim 1, wherein the mobile communication terminal is switched so as to. Further comprising gain mode switching means for switching the gain mode of the amplifier,
The movement according to claim 2, wherein the power saving unit switches a voltage control unit that controls a voltage applied to the amplifier when the gain mode switching unit switches the gain mode of the amplifier. Body communication terminal. A plurality of the above-described wireless transmission units, each wireless transmission unit is capable of wireless communication with different base stations in parallel with each other,
Each of the plurality of voltage control units is adapted to control the voltage applied to the amplifier of the assigned radio transmission unit,
The power saving unit is configured to perform voltage control such that a higher transmission output region is an optimum transmission output region for power saving with respect to a wireless transmission unit that performs wireless communication with a base station having a wider coverage determined by the cell determination unit. The mobile communication terminal according to claim 2 or 3, wherein the mobile communication terminal is assigned. A plurality of the above-described wireless transmission units, each wireless transmission unit is capable of wireless communication with different base stations in parallel with each other,
Each of the plurality of voltage control units is adapted to control the voltage applied to the amplifier of the assigned radio transmission unit,
The power saving unit is configured to perform voltage control such that a lower transmission output region is an optimum transmission output region for power saving with respect to a wireless transmission unit that performs wireless communication with a base station with a narrower coverage determined by the cell determination unit. The mobile communication terminal according to claim 2 or 3, wherein the mobile communication terminal is assigned.

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