JPH09326724A - Radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reception wave interference of a distance problem by ensuring a required adjacent channel leakage power ratio in the radio equipment of the digital linear modulation system making communication between a base station and a mobile station or inter-mobile-station communication via the base station and having a control function of a transmission output level based on a command of the base station or a reception electric field strength of the mobile station. SOLUTION: Changeover circuits 21, 22 switched to provide an output of a preamplifier 6 to a power amplifier 4 on one hand and to an output stage of the power amplifier 4 and a loop interruption circuit 23 to interrupt or connect a feedback loop selectively are added to the radio equipment. Thus, the output of the preamplifier 6 is inputted to a post-stage after a directional coupler 3 to conduct output power control equivalently without nonlinear distortion compensation thereby ensuring a specified required adjacent channel leakage power ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital linear modulation type radio for performing communication between a base station and a mobile station or between mobile stations via the base station, the radio having a power amplifier having a feedback compensation circuit. The present invention relates to the configuration of the non-linear distortion compensation circuit of the transmitter of the machine.

[0002]

2. Description of the Related Art As a wireless communication system used for general business, a communication system for performing simplex and duplex communication between a base station and a mobile station or between mobile stations via the base station is widely used. For example, according to the standard for digital mobile communication systems for public affairs (RCR STD-39), when adjacent frequencies are used in the same base station, the reception wave from the far-end mobile station is In order to reduce the interference due to the adjacent channel leakage power that accompanies the transmission wave from the near-end mobile station, the mobile station has two functions: autonomous transmission output control and forced transmission output control based on a base station instruction. Regarding the adjacent channel leakage power of the transmitter, the mobile station has a function of lowering the transmission output when the reception input from the base station exceeds a certain value.
There is an item to decrease -10 dB when inputting 0 dBμ and -20 dB when inputting 50 dBμ.

A conventional example of this transmission output control will be described below with reference to FIG. In FIG. 2, 1 is an antenna duplexer, 2 is an isolator, 3 is a directional coupler, 4 is a power amplifier, 5 is a bandpass filter, 6 is a preamplifier, and 7
Is a variable attenuator, 8 is a quadrature modulator, 9 is a compensation circuit, 10 is a digital modulator, 11 is a variable attenuator, 12 is a feedback circuit, 13 is a high frequency receiving section, 14 is a mixer section, 15 is an intermediate frequency section, 16 is a demodulation unit, 17 is a synthesizer unit, 18
Is a CPU control unit, 19 is a reception signal output terminal, and 20 is a transmission signal input terminal.

In the figure, a transmission signal input from a transmission signal input terminal 20 is modulated into a digital signal of an I component and a Q component by a digital modulating section 10, and passes through a compensating circuit 9 for compensating the non-linear distortion of the power amplifying section. The quadrature modulator 8 quadrature-modulates the local frequency signal from the synthesizer unit 17, the bandpass filter 5 limits the band through the variable attenuator 7 and the preamplifier 6, and the power amplifier 4 performs power amplification.
The signal is output from the antenna via the directional coupler 3, the isolator 2, and the antenna duplexer 1. A part of the output of the power amplifier 4 is extracted by the directional coupler 3 and is output to the variable attenuator 1
1 through the loop feedback circuit 12 to synthesizer unit 1
Is quadrature modulated using the local frequency signal from
It is generated as a component and a Q component. The I component and the Q component are fed back to the compensating circuit 9 of the power amplifying unit to perform non-linear distortion compensation. In this way, the preamplifier 6 and the power amplifier 4
The non-linear distortion generated in 1 is compensated by the compensating circuit 9 through the loop feedback circuit 12. At this time, when the variable attenuator 7 and the variable attenuator 11 in the main circuit and the feedback path set the attenuation amount of 10 dB in the variable attenuator 7 so as to keep the loop gain of the negative feedback loop constant, The negative feedback loop is configured to control so that the set value of the variable attenuator 11 is reduced by 10 dB.

Here, the control for reducing the transmission output by 10 dB is performed by setting the variable attenuator 7 and the variable attenuator 11 as described above. Further, the reception signal input from the antenna is frequency-converted into an intermediate frequency by the local frequency signal from the synthesizer unit 17 in the mixer unit 14 via the reception filter of the antenna duplexer 1 and the reception high frequency unit 13, and the intermediate frequency unit 15 , Is output as a reception demodulation signal from the reception signal output terminal 19 via the demodulation unit 16. Also,
The RSSI output circuit built in the intermediate frequency unit 15 A / D-converts the received electric field strength signal (RSSI signal) and then C
It is input to the PU control unit 18.

The CPU controller 18 controls the transmission output according to the received electric field strength. That is, as described above, 0 dB, -10 dB, -20 dB with respect to the rated transmission output.
The attenuation control is such that when the variable attenuator 7 is set to 10 dB, the set value of the variable attenuator 11 is adjusted to be reduced by 10 dB, and the feedback loop gain is held constant, whereby the signal output level of the power amplifier 4 is reduced. Is used. This is because, for example, non-linear distortion compensation control of −55 dBc or less is not easy, so power control for attenuating transmission is performed for a required value above this value, and the required adjacent channel leakage power ratio is equivalently set. The structure to secure is adopted.

[0007]

Generally, as described above, when the interference of the near-far problem of the mobile station is considered, the received wave from the distant mobile station is in a critical reception state in the base station, and the mobile station in the vicinity is in the base station. When the distance is extremely short, the required adjacent channel leakage power ratio is -80 to -90 dBc.
The value of the degree is required. However, in the non-linear distortion compensation control that suppresses the output power to -55 dBc or less, which is shown as the conventional example, it is not easy to reduce the specified output by 20 dB or more from the viewpoint of stability, as described later, and it is necessary to sufficiently reduce the interference of received waves. It is difficult to secure the adjacent channel leakage power ratio. In order to obtain the adjacent channel leakage power ratio by using the conventional technique for the above problem, a method of further attenuating the input level to the power amplification unit and lowering the adjacent channel leakage power ratio can be considered. Normally, the power amplification unit is designed with a rated transmission output, so that it is difficult to obtain a stable low transmission output of the power amplification unit at a low input level, and the power efficiency is significantly deteriorated. FIG. 3 shows an example of input / output characteristics and power efficiency of the linear power amplifier. As described above, it is difficult to control the transmission output power of −30 dB or the like using the conventional technique in terms of stability.

An object of the present invention is to reduce the interference in the above-mentioned near-far problem, in a radio device in which a mobile station self-determines a received electric field strength of a base station and controls a transmission output level, for example, a required value- Attenuation level of 30 dB or more is stably realized, and transmission power control is equivalently performed without burdening the non-linear distortion compensation circuit, thereby obtaining the required adjacent channel leakage power and taking measures against reception wave interference. is there.

[0009]

In order to achieve the above object, the present invention has the following circuit configuration. As a transmission system circuit configuration, a transmission signal input from a transmission signal input terminal 20 is modulated into a digital signal of an I component and a Q component by a digital modulation unit 10, and passes through a compensation circuit 9, a quadrature modulator 8 and a variable attenuator 7. The preamplifier 6, bandpass filter 5, switching circuit 21, power amplifier 4, switching circuit 2
After being amplified to a predetermined power at 2, the signal is output from the antenna via the directional coupler 3, the isolator 2, and the antenna duplexer 1. At this time, the local frequency signal from the synthesizer unit 17 is input to the feedback circuit 12 including the quadrature modulator 8 and the quadrature demodulator, and quadrature modulation and quadrature demodulation are performed, respectively. A part of the output of the power amplifier 4 is extracted by the directional coupler 3, passed through the loop disconnecting circuit 23 and the variable attenuator 11, and then converted into the I component and the Q component by the feedback circuit 12 and fed back to the compensating circuit 9. To be done. That is, the feedback loop has a configuration in which the non-linear distortion generated in the preamplifier 6 and the power amplifier 4 is compensated and controlled by the feedback circuit 12 and the compensation circuit 9 and input to the preamplifier 6 and the power amplifier 4.

On the other hand, in the circuit configuration of the receiving system, the received signal input from the antenna is passed through the receiving filter of the antenna duplexer 1 and the receiving high frequency section 13 to the intermediate frequency by the local frequency signal from the synthesizer section 17 in the mixer section 14. To the demodulation unit 16 via the intermediate frequency unit 15 and output from the reception signal output terminal 19 as a reception demodulation signal. Further, the RSSI output circuit built in the intermediate frequency unit 15 is input to the CPU control unit 18 after A / D conversion of the received electric field strength signal (RSSI signal).

In the CPU control unit 18, in order to control the transmission output according to the received electric field strength as in the conventional technique,
For example, as shown in the above example, when the variable attenuator 7 is set to 10 dB by attenuating the rated transmission output by 0 dB, -10 dB, and -20 dB, the variable attenuator 1 is set.
The feedback loop gain is held constant by controlling the addition and subtraction so that the set value of 1 is reduced by 10 dB, thereby attenuating the signal input level to the preamplifier 6 and the power amplifier 4. Furthermore, at the maximum attenuation for making the adjacent channel leakage power less than or equal to the required value, that is, when the rated transmission output is attenuated by −30 dB, the transmission signal to the power amplifier 4 is switched by the switching circuit 21. By making a detour via the circuit 22, the output of the preamplifier 6 is directly input to the circuit subsequent to the directional coupler 3 without passing through the power amplifier 4. At this time, the loop disconnection circuit 16 of the feedback loop section disconnects the inputs to the feedback circuit 11 and the compensation circuit 8 to open the feedback loop. In general,
In the preamplifier output stage, the specified adjacent channel leakage power ratio as shown in the above example can be secured without performing non-linear distortion compensation.
The feedback circuit 12 and the compensation circuit 9 may be separated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 1 is an antenna duplexer, 2 is an isolator, 3 is a directional coupler, 4 is a power amplifier, 5 is a bandpass filter, 6 is a preamplifier, 7 is a variable attenuator, 8 is a quadrature modulator, 9 is a compensation circuit, 10 is a digital modulator, 11 is a variable attenuator, 12 is a feedback circuit,
13 is a reception high frequency part, 14 is a mixer part, 15 is an intermediate frequency part, 16 is a demodulation part, 17 is a synthesizer part, 18 is C
PU control unit, 19 is a reception signal output terminal, 20 is a transmission signal input terminal, 21 is a switching circuit, 22 is a switching circuit, and 23 is a loop disconnection circuit. In the figure, a transmission signal input from a transmission signal input terminal 20 is modulated into a digital signal of an I component and a Q component by a digital modulation unit 10, and a quadrature modulation is performed via a compensation circuit 9 that compensates for nonlinear distortion of a power amplification unit. Bowl 8
Is quadrature-modulated with the local frequency signal from the synthesizer unit 17, and band-limited by the bandpass filter 5 via the variable attenuator 7 and the preamplifier 6, and the power amplification is performed by the switching circuit 21, the power amplifier 4, and the switching circuit 22. After that, it is output from the antenna via the directional coupler 3, the isolator 2, and the antenna duplexer 1. At this time, the local frequency signal from the synthesizer unit 17 is input to the feedback circuit 12 including the quadrature modulator 8 and the quadrature demodulator to perform quadrature modulation and quadrature demodulation, respectively.

A part of the output of the power amplifier 4 is extracted by the directional coupler 3, and the local frequency signal from the synthesizer section 17 is used by the feedback circuit 12 through the loop disconnecting circuit 23 and the variable attenuator 11. Quadrature demodulation,
It is generated as an I component and a Q component. This I component and Q
The component is fed back to the compensating circuit 9 of the power amplifying unit to perform non-linear distortion compensation. That is, the feedback loop compensates and controls the non-linear distortion generated in the preamplifier 6 and the power amplifier 4 by the compensation circuit 9 via the feedback circuit 12. At this time, the variable attenuator 7 and the variable attenuator 11 in the main circuit and the feedback path are, for example, so as to keep the loop gain of the negative feedback loop constant.
When the attenuation amount of 10 dB is set in the variable attenuator 7, the negative feedback loop is configured to perform control to reduce the set value of the variable attenuator 11 by 10 dB. Here, the control for reducing the transmission output by 10 dB is performed by setting the variable attenuator 7 and the variable attenuator 11 as described above. On the other hand, the reception signal input from the antenna is frequency-converted into an intermediate frequency by the mixer 14 via the reception filter of the antenna duplexer 1 and the reception high frequency unit 13 by the local frequency signal from the synthesizer unit 17, and the intermediate frequency unit 15 The signal is input to the demodulation unit 16 via and is output from the reception signal output terminal 19 as a reception demodulation signal. Further, the RSSI output circuit built in the intermediate frequency unit 15 is input to the CPU control unit 18 after A / D conversion of the received electric field strength signal (RSSI signal).

In the CPU control unit 18, in order to control the transmission output according to the received electric field strength in the same manner as the conventional technique, for example, as shown in the above example, the rated transmission output is
In the control for attenuating 0 dB, -10 dB, and -20 dB, when the variable attenuator 7 is set to 10 dB, the feedback loop gain is kept constant by controlling the setting value of the variable attenuator 11 to be reduced by 10 dB. The method of attenuating the signal output level of the power amplifier 4 is used. Furthermore, at the maximum attenuation to keep the adjacent channel leakage power below the required value, that is, for example, for the rated transmission output,
In the case of attenuating −30 dB, the variable attenuator 7 is set to 0 dB and the transmission signal to the power amplifier 4 is diverted via the switching circuit 14 and the switching circuit 15, so that the power amplifier 4 is directly bypassed. The output of the preamplifier 6 is input to the subsequent circuit after the directional coupler.

At this time, the loop disconnection circuit 1 of the feedback loop section
6 cuts off the inputs to the feedback circuit 11 and the compensation circuit 8,
Make the feedback loop open loop. As described above, in this embodiment, the switching circuit for bypassing the transmission signal is provided between the stages of the power amplification unit, and the feedback loop circuit is provided with the feedback loop disconnection circuit for making an open loop. The switching circuit, the feedback loop disconnection circuit, the main circuit, and the means for controlling the variable attenuators in the feedback path are provided. As a result, generally, in the preamplifier output stage, the prescribed required adjacent channel leakage power ratio as shown in the above example can be secured without performing non-linear distortion compensation.

[0016]

As described above, according to the present invention, in a wireless device in which the mobile station self-determines the received electric field strength of the base station and controls the transmission output level, for example, a required value of 30d
The transmission output attenuation level of B or more is stably realized, and the transmission output control is equivalently performed without burdening the non-linear compensation distortion compensating circuit to obtain the required adjacent channel leakage power. The problem of received wave interference can be solved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional wireless device.

FIG. 3 is a diagram showing an example of input / output characteristics and power efficiency of a linear power amplifier.

[Explanation of symbols]

1 ... Antenna duplexer, 2 ... Isolator, 3 ... Directional coupler, 4 ... Power amplifier, 5 ... Bandpass filter, 6 ... Preamplifier, 7 ... Variable attenuator, 8 ... Quadrature modulator, 9 ... Compensation circuit , 10 ... Digital modulator, 11 ... Variable attenuator, 12
... Feedback circuit, 13 ... Reception high frequency section, 14
… Mixer part, 15… Intermediate frequency part, 16
… Demodulator, 17… Synthesizer, 18…
CPU control unit, 19 ... Received signal output terminal, 2
0 ... Transmission signal input terminals 21, 22 ... Switching circuit,
23 ... Loop breaking circuit.

Claims (1)

[Claims] 1. Communication between a base station and a mobile station, or between mobile stations via the base station, and controlling the transmission output level of the mobile station according to a command from the base station or a received electric field strength of the mobile station. In a digital linear modulation type wireless device having means, a directional coupler, an isolator, an antenna duplexer connected to the output side of a power amplifier and a feedback loop for supplying to a compensation circuit via the directional coupler are configured. A feedback circuit, a compensation circuit for compensating for the non-linear distortion of the power amplification section, a transmission section composed of a main circuit forming a feedback loop and a variable attenuator in each feedback path, and one of the antenna duplexers. It has a receiving high frequency section, an intermediate frequency section having an RSSI output circuit, and a control section for judging the RSSI level. One of the outputs of the preamplifier is input to the power amplifier, and the other is the power amplifier. A switching circuit for switching to output to the output stage, a loop disconnecting circuit for selectively connecting or disconnecting the feedback loop, and means for selectively controlling the variable attenuator, the switching circuit, and the loop disconnecting circuit. A digital linear modulation type radio characterized by the following.