JPH1098430A - Radio communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly execute communication with a base station while suprressing average power consumption by controlling output power to a high level within the allowable error range of prescribed power when received electric field strength gets lower than a prescribed value. SOLUTION: A power amplifier 1 outputs the output power to be controlled by a control signal S8 from a comparison control means 21 to an antenna 4. The comparison control means 21 generates a control signal S8 so that an output power signal S5 of the power amplifier 1 detected by a power detecting means 20 matches the reference signal S11 from a reference signal generating means 22. In a speaking mode, the output power of the power amplifier 1 is kept at 28.5dbm within 29.8dbm of FCC standard. In this case, the reference signal generating means 22 always monitors a received radio wave state signal Sr outputted from an intermediate frequency amplifier 14 and when the strength of an electric field received at the antenna 4 gets lower than -100dmb, for example, the reference signal S11 is changed so that the output power of the power amplifier 1 can be increased to 29.0dbm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication device such as an automobile telephone and a portable telephone, and more particularly, to a configuration for controlling transmission power thereof.

[0002]

2. Description of the Related Art Conventionally, a high-frequency radio communication device such as a cellular phone amplifies a modulated transmission signal with a power amplifier and radiates the amplified transmission signal via an antenna.

An output control circuit is connected between the output terminal of the power amplifier and the control terminal of the power amplifier by feedback. The output control circuit has a function of outputting a control signal for controlling the gain of the power amplifier. Have. When the power (output power) of the transmission signal output from the power amplifier fluctuates, the level of the control signal fluctuates in accordance with the fluctuation, and the control signal is input to the control terminal of the power amplifier. . That is, when the output power of the power amplifier fluctuates, the power amplifier is controlled by the control signal in such a direction as to cancel the fluctuation, whereby the power amplifier transmits a transmission signal of constant power.

[0004] On the other hand, in the call connection, the portable telephone communicates with the base station using a control channel, an access channel and a voice channel for system access. Through this communication, the mobile phone is connected for call. Also in this call connection, the output power of the power amplifier is controlled to be constant in each channel, and a transmission signal of this constant power is radiated to the base station via the antenna, and the system access of the mobile phone is performed. It is supposed to be.

[0005]

By the way, in the above-mentioned conventional portable telephone, since the output power (power of the transmission signal) during the call connection is a constant value determined by the channel, the portable telephone has a weak electric field. When moving to or existing in an area, the output power is constant but the received power is weak, so it becomes difficult to communicate with the base station using the voice channel and the like, and the call connection is reduced. Was.

In the communication mode, the transmission power is controlled so as to be the power instructed by the base station. However, in consideration of power consumption, the transmission power is reduced to a small transmission power within an allowable error range with respect to the command power. If you try to control so that the call is interrupted in the weak electric field area,
On the other hand, if the transmission power is controlled so as to be large within the allowable error range with respect to the command power, the power consumption increases.

[0007] In a portable telephone complying with the CDMA system, the above-mentioned problem does not occur because the transmission power is controlled so as to have a linear relationship with the received electric field strength during a call.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is intended to perform appropriate call connection and communication even in a weak electric field area, even if the transmission power is specified to be a constant value. It is an object of the present invention to provide a wireless communication device that can perform power consumption.

[0009]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention relates to a radio communication apparatus for amplifying a transmission signal by a power amplifier so as to have a predetermined power, (1) a power amplifier. Power detection means for detecting the output power, (2) generating a reference signal corresponding to the predetermined power, and when the received electric field strength becomes equal to or less than a predetermined value, a value larger than the allowable error range of the predetermined power. Reference signal generating means for generating a reference signal of (3) according to a level difference between the output power detected by the power detecting means and the reference signal, so that the output power is the one indicated by the reference signal. And a comparison control means for controlling the power amplifier.

[0010] According to such a configuration, when the received electric field strength becomes equal to or less than a predetermined value (for example, a level at which a call connection with a base station cannot be properly performed), the reference signal generating means sets an allowable error range of the predetermined power. A reference signal indicating a higher level is generated, and the comparison control means controls the output power of the power amplifier according to the level difference between the reference signal and the output power. Even though the control is performed, communication with the base station can be properly performed even when the received electric field strength is low, and the average power consumption can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a wireless communication apparatus according to the present invention will be described with reference to the drawings. Here, FIG. 1 is a circuit diagram of a transmission unit and a reception unit of the wireless communication device according to the present embodiment.

This wireless communication device is a portable telephone, and has a power amplifier 1 for amplifying a transmission signal Si modulated by a modulation circuit of a transmission unit (not shown). The output side of the power amplifier 1 is connected to a transmission / reception splitter 3 via a directional coupler 2. An antenna 4 is connected to the transmission / reception branching filter 3.

The power amplifier 1 is formed of a GaAs-FET (field effect transistor) or the like capable of obtaining high efficiency at a low voltage, and is constituted by a multi-stage amplifier circuit. By the control signal S8 supplied to the power control terminal, the output power of the power amplifier 1 can be varied from several hundred mw to several mw.

The directional coupler 2 has a function of detecting the output power of the power amplifier 1. Examples of the directional coupler 2 include a path difference type directional coupler, a series-parallel type directional coupler, a cross-type directional coupler, a multi-element coupling type directional coupler, and a slot coupling type directional coupler. Applicable.

The transmission / reception splitter 3 transmits the output power of the power amplifier 1, that is, the transmission signal to the antenna 4, and separates the reception radio wave received by the antenna 4 from the transmission signal and inputs it to the reception unit. And includes a transmission filter, a reception filter, and a demultiplexer (not shown). The branching circuit is constituted by a strip line or the like. In the transmission / reception branching filter 3, a transmission filter is connected to the output side of the power amplifier 1, a reception filter is connected to the reception unit side, and a branching circuit is connected to the antenna 4.

The directional coupler 2 is connected to a detection diode 5 for converting the output power into a DC voltage (detection signal S5). The directional coupler 2 and the detection diode 5 constitute a power detection unit 20 that detects the output power of the power amplifier 1 and outputs a detection signal S5.

The output side of the detection diode 5 is connected to the (−) side input terminal (inverted input terminal) of the operational amplifier 6. A reference signal S1 output from the D / A converter 11 is supplied to the (+) side input terminal (non-inverting input terminal) of the operational amplifier 6.
1 is input.

The operational amplifier 6 compares the detection signal S5 supplied from the detection diode 5 with the reference signal S11 so that the level difference between the two signals becomes zero.
The output terminal is connected to the base of a PNP control transistor 8 via a resistor 7. The emitter of the control transistor 8 is a voltage power supply Vcc.
, And the collector is connected to the power control terminal of the power amplifier 1.

The control transistor 8 includes an operational amplifier 6
The collector voltage (control signal S8) changes according to the magnitude of the base current supplied from the output terminal of the power amplifier 1
Has the function of changing the output power of the The operational amplifier 6, the resistor 7, the control transistor 8 and the like constitute a comparison control means 21.

The mixer 12 receives a radio signal from the antenna 4 and receives a signal output from the transmission / reception splitter 3.
The received signal is dropped to the intermediate frequency band by mixing with the local oscillation signal (local signal) output from the first local oscillation circuit (first local circuit) 13. The signal mixed in the intermediate frequency band is input to the intermediate frequency amplifier 14.

The first local circuit 13 includes a VCO (not shown)
/ PLL / LPF to generate a certain set reference frequency. An intermediate frequency amplifier (including a detection function) 14 amplifies and detects the received signal down-converted to the intermediate frequency band by the mixer 12 and outputs the amplified signal as an audio signal, and also checks the communication state of the received radio wave received by the antenna 4. It monitors and outputs a signal (signal representing a channel, a received electric field strength, etc.) Sr indicating the communication state obtained by the monitor.

The portable telephone is provided with a memory 9 for storing data for setting a power level to be output from an antenna output terminal in accordance with a transmission channel. A CPU 10 is connected to the memory 9.
A signal Sr indicating a communication state output from the intermediate frequency amplifier 14 on the receiving side is input to 10. CPU1
The D / A converter 11 is connected to 0.

The CPU 10 has a function of controlling data access to the memory 9 and outputting data read from the memory 9 as a control signal S10.

The D / A converter 11 converts a digital control signal S10 output from the CPU 10 into an analog reference signal S11 and outputs the analog control signal S11 to the (+) input terminal of the operational amplifier 6. These memory 9, CPU
10 and reference signal generating means 2 by D / A converter 11
2 are configured.

Hereinafter, the operation of the wireless communication apparatus according to the embodiment including the above components will be described with reference to FIG.

First, the CPU 10 reads data corresponding to the used channel stored in the memory 9 in advance, and outputs a control signal S10 corresponding to the read data. The control signal S10 is converted into an analog reference signal S11 by the D / A converter 11, and is sent to the (+) input terminal of the operational amplifier 6.

On the other hand, the output power of the power amplifier 1 is detected by the directional coupler 2, and the detection signal S5 of the DC voltage is detected by the detection diode 5, and the detection signal S5
Is sent to the (−) side input terminal of the operational amplifier 6.

In the operational amplifier 6, the reference signal S11
Is compared with the level of the detection signal S5, and the two level difference voltages obtained as a result of the comparison are supplied to the base of the control transistor 8 via the resistor 7.

In response to this supply, a control signal S8, which is the collector voltage of the control transistor 8, is supplied to the power control terminal of the power amplifier 1. In response to this supply, the level of the output power of the power amplifier 1 changes to the level of the reference signal S11. Is controlled to be equivalent to

By this control, a stable output power corresponding to the reference signal S11 output from the D / A converter 11 is output from the power amplifier 1. This stable output power is split by the transmitter / receiver 3 via the directional coupler 2 and radiated from the antenna 4 as a transmission radio wave.

FIG. 2 is a diagram for explaining an example of a sequence in which the high-frequency radio communication apparatus shown in FIG. 1 is call-connected.

FIG. 2 shows the state of communication between the base station 20 and the mobile station 30 which is the portable telephone shown in FIG.
And the electric field intensity from the base station 20 to the mobile device 30 (the received electric field intensity as viewed from the mobile device 30).

When the mobile station 30 is in the standby state, the mobile station 30 receives the signal a from the base station 20 and is in the standby state (standby state) as indicated by reference numeral 40.

At this time, the mobile device 30 is grasping a certain designated control channel. In order to establish communication, incoming data b is provided from the base station 20 to the mobile device 30 through a control channel.

The mobile station 30 receiving the incoming data b accesses the channel again. That is, an access channel scan is performed as indicated by reference numeral 41. After the access channel scan, the mobile device 30 confirms whether the electric field intensity at the location where the mobile device exists is the strongest or the semi-strongest.

Then, the mobile station 30 sends a signal c indicating the result of the confirmation to the base station 20 via the access channel. As a result, the base station 20 and the device 30 communicate. When the communication is completed, the mobile station 30 scans the voice channel indicated by the signal d from the base station 20 as indicated by reference numeral 42 and shifts to the voice channel.

Here, when shifting to the voice channel,
The mobile device 30 transmits, for example, a wireless continuity test signal e to the base station 20 via a voice channel. After receiving the uplink radio continuity test signal e or the like, the base station 20 sends a call signal f to the mobile station 30. That is, even in this voice channel, the base station 20 and the mobile station 30 communicate signals e and f.

When transmitting the signals c and e from the mobile station 30, the transmission is performed with the full power transmission power uniquely determined by the access channel and the voice channel. In this case, the allowable error range of the full power is used. At a level of 28.5 dbm. Even at the time of such transmission, although not shown in FIG. 2, transmission power control according to the received electric field strength (refer to transmission power control in the call mode) is executed.

When the mode is shifted to the talk mode 43 through the above-described communication, the output power of the power amplifier 1 of the mobile device 30 becomes 28.5 dbm, which is the normal talk mode 43 indicated by F.
Is set to The mobile device 30 and the base station 20 regularly exchange data. The base station 20 appropriately designates transmission power.

During the call mode, the mobile station 30 constantly monitors the state Sr of the received radio wave output from the intermediate frequency amplifier 14. When the state of the received radio wave received from the antenna 4 is good (the electric field is strong), the received radio wave state signal Sr
(High DC voltage) is a strong state.

This DC voltage is applied to the A / D inside the CPU 10.
Input to the converter. When the state of the received radio wave Sr falls below the electric field indicated by Y, that is, -100 dbm, the CPU 1
By 0, data for increasing the output power of the power amplifier 1 is read from the memory 9. Note that, even when the output power is increased, the transmission power does not exceed the predetermined upper limit of the allowable error range of the transmission power.

The control signal S10 corresponding to the read data is converted by the D / A converter 11 into an analog reference signal S11.
And supplied to the (+) side input terminal of the operational amplifier 6, and the level of the supplied reference signal S11 and the level of the output power of the power amplifier 1 supplied to the (−) side input terminal at this time. Is compared with the detection signal S5, and the level difference voltage between the two is supplied to the base of the control transistor 8 via the resistor 7.

In response to this supply, the control signal S8 of the control transistor 8 is supplied to the power control terminal of the power amplifier 1,
In response to this supply, the level of the output power of the power amplifier 1 is increased, and as a result, the transmission power radiated from the antenna 4 is increased, and a state of 29.0 dbm indicated by G is reached.

Thereafter, after the time indicated by τ1 has elapsed and the state of the received radio wave Sr has returned to the electric field Y or higher, the power amplifier 1
Is set to the normal mode indicated by H equivalent to F. That is, the following relationship exists between the output power level G and the output power level H of the power amplifier 1.

G = H + I I; increase in output power Generally, the higher the output power G of the power amplifier 1 is, the more the call connection rate to the base station 20 is improved. However, on the other hand, the power consumption of the power amplifier 1 increases. In a mobile phone (mobile device 30) that operates on a battery power source or the like, an increase in power consumption affects the actual use time, which is a problem in actual use.
Also, according to the FCC standard, etc., each level G of the output power is
It is specified as 0.6W + 2db (29.8dbm) or less.

In this embodiment, the output power which does not exceed the predetermined upper limit of the allowable error range of the transmission power is set to about 29.0 dbm so as not to affect the actual use time.

As described above, in this embodiment, the electric field of the received radio wave is monitored during the system call connection, and the output power level of the power amplifier 1 is increased only when the electric field is equal to or less than a certain electric field (Y = −100 dbm). ing. For this reason, despite low power consumption, before the call mode is reached, and
The call connection efficiency during a call can be increased. Therefore, there is an effect that the telephone can be easily connected without interruption.

Although the wireless communication apparatus of the above-described embodiment is premised on being used for a mobile phone, the present invention can be applied to any mobile device such as an automobile phone regardless of the analog or digital system. In addition, for the transmission power,
Basically, it is necessary to adopt constant value control.

Further, in the above-described embodiment, the case where the level is increased by one step according to the received electric field strength is described. However, the level may be gradually increased to any one of a plurality of levels according to the received electric field strength. good. For example, if the reception electric field strength is -10
0 dBm or less, the output power is increased to 29.0 bdm, and when the reception electric field strength is -105 dbm or less,
The output power may be increased to 29.5 bdm.

[0050]

As described above, according to the wireless communication apparatus of the present invention, the level of amplification in a power amplifier is controlled, and the power of a transmission signal radiated from an antenna is increased only below a certain reception electric field. Since communication with the base station is performed during call connection control and call connection, high call quality such as low noise and the like can be ensured while maintaining low power consumption without call interruption in a weak electric field. it can.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a transmission unit and a reception unit of a wireless communication device according to an embodiment.

FIG. 2 is a diagram illustrating a sequence in which the wireless communication device shown in FIG. 1 is call-connected.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 power amplifier 20 power detection means 21 comparison control means 22 reference signal generation means S5 detected output power S11 reference signal or specific reference signal

Claims (2)

[Claims] 1. A wireless communication apparatus for amplifying a transmission signal with a power amplifier so as to have a predetermined power, comprising: power detection means for detecting an output power of the power amplifier; and a reference according to the predetermined power. A signal is generated, and when the received electric field strength becomes equal to or less than a predetermined value, the signal is detected by the reference signal generation means for generating a reference signal having a further larger value within an allowable error range of the predetermined power, and the power detection means. And a comparison control means for controlling the power amplifier so that the output power is indicated by the reference signal in accordance with the level difference between the output power and the reference signal. 2. The wireless communication apparatus according to claim 1, wherein a predetermined value for determination for increasing the level of the reference signal is two or more.