JPH11239077A - Digital radio - Google Patents

Abstract

(57) [Summary] (Modified) [PROBLEMS] To provide a receiving path with a switching circuit as a circuit configuration of a multiple branch diversity system, and to provide a transmitting path with wireless communication via a wireless base station or a wireless terminal station without providing a switching circuit. Wireless communication is performed directly between the transmission lines to remove nonlinear distortion in the transmission path. A transmission unit for a first frequency band, first and second frequency bands are provided.
In a digital radio having a receiving unit in a frequency band, a branch connecting a first receiver in a second frequency band to a first antenna 101 connected to a transmitting unit, a signal in the first frequency band and a signal in the second frequency band. And the switching circuits 122 and 12
And a control unit 157 for switching the switching circuit, the receiving unit having a receiving diversity configuration of at least two branches. The switching circuit of the device is controlled to switch between a diversity receiving function for receiving a signal in the second frequency band and a non-diversity receiving function for receiving a signal in the first frequency band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention combines the function of a wireless terminal station that performs wireless communication via a wireless base station with the function of a wireless terminal station that performs direct wireless communication between wireless terminal stations without involving a wireless base station. The present invention relates to a digital wireless device having the same.

[0002]

2. Description of the Related Art Conventionally, as a radio communication system which has been put into practical use, a control station for controlling a radio communication line, relay of radio communication between radio terminal stations and control of a service area under the control of the control station. There is a digital wireless communication system including one or more wireless base stations for maintaining and a plurality of wireless terminal stations for performing wireless communication via the wireless base stations. In such a digital wireless communication system (similarly in an analog wireless communication system), when a certain wireless terminal station performs wireless communication with another wireless terminal station, the certain wireless terminal station sets the wireless base station to have a wireless communication range. In the service area to be maintained, wireless communication is performed with another wireless terminal station via the wireless base station using a wireless communication line controlled by the control station. On the other hand, a wireless terminal station used in such a digital wireless communication system is separated from control by a control station in a service area of the wireless base station, and a certain wireless terminal station is not connected to the wireless base station but is connected to another wireless terminal station. A direct communication function between wireless terminal stations capable of performing direct wireless communication with wireless terminal stations is provided.

In the digital radio communication system as described above, duplex communication is used in radio communication via a radio base station, and simplex communication is used in direct communication between radio terminals without passing through a radio base station. . As described above, there are two wireless communications. Generally, in the duplex communication, the frequencies used for transmission and reception are allocated by tens or tens of MHz apart. Therefore, since the frequency interval between transmission and reception is so far apart, in digital direct communication between wireless terminal stations, the transmission frequency of the wireless terminal station is generally widely used for communication.

FIG. 2 shows a part of the configuration of a digital radio used as a radio terminal station in a conventional digital mobile radio communication system. Hereinafter, the operation in the high-frequency section of the digital wireless device in the case where communication is performed via the wireless base station using the digital wireless device of the wireless terminal station shown in FIG. 2 and in the case where direct wireless communication is performed between wireless terminal stations. Give an explanation. First, the receiving operation will be described. The wireless terminal station must have a function of receiving signals in two frequency bands: an assigned channel frequency of the transmission frequency fk from the wireless base station and an assigned channel frequency of the transmission frequency fi from the wireless terminal station. For this reason, the digital wireless device of the wireless terminal station receives the transmission signal of the wireless base station and receives the signal from the reception amplifier 207 for amplifying the received signal at high frequency.
And a reception amplifier 209 for receiving a transmission signal of a wireless terminal station for direct wireless communication between wireless terminal stations and amplifying the received signal at a high frequency, in addition to a reception filter 208 for selecting and band limiting the received signal. Is generally provided with a reception filter 210 for selecting and band limiting. Therefore, the switches 205 and 20 for receiving the transmission signal of the radio base station and the transmission signal of the radio terminal station with one antenna 201, switching between the two reception signals, and amplifying the high frequency with the reception amplifier 207 or the reception amplifier 209.
6, 211.

A transmission signal from a radio base station is transmitted to an antenna 2
01, becomes a reception signal, is selected by the reception filter 204 for the radio base station of the duplexer 202, passes therethrough, and
06 is output. At this time, the switch 206 has been switched to the contact b side, and the received signal is
7, the signal is subjected to high-frequency amplification by the reception amplifier 207, further selected by the reception filter 208, band-limited, and output to the switch 211. Similarly, switch 2
Reference numeral 11 is switched to the contact b side, and outputs a reception signal whose band is limited by the reception filter 208 to the mixer 212. The mixer 212 receives a local frequency signal from the reception synthesizer unit 234 in addition to the band-limited reception signal input from the switch 211.
The frequency of the received signal is converted to a first IF (intermediate frequency) signal, and the frequency-converted first IF signal is converted to a first IF filter 2.
13 is output.

[0006] The first IF filter 213 limits the band of the input first IF signal and outputs the band-limited first IF signal to the reception IF unit 214. The reception IF unit 214 receives the band-limited first signal input from the first IF filter 213.
In addition to the IF signal, a local frequency signal is separately input from the reception synthesizer unit 234, and the first IF signal is amplified to a required level, frequency-converted to the second IF signal, and the frequency-converted second IF signal is converted to the second IF signal. Output to the filter 215. The second IF filter 215 limits the band of the input second IF signal, and performs the band-limited second IF
The signal is output to demodulation section 216. Demodulation section 216 demodulates the input band-limited second IF signal by a required demodulation method, and outputs demodulated reception information to demodulation section output terminal 217. The demodulated reception information output to the demodulation unit output terminal 217 is output to another circuit and subjected to required reception processing. For example, if the demodulated reception information is audio information, reception processing is performed. The received voice is output.

[0007] In such a digital mobile radio communication system, the radio terminal station is required to follow the transmission frequency of the radio base station, and the demodulation section 216 of the digital radio sets the transmission frequency of the radio base station. And detects frequency deviation information from a predetermined frequency based on a reference frequency oscillated by a reference signal source of the digital radio, and outputs the detected frequency deviation information to the D / A converter 235. D
The / A converter 235 performs digital / analog conversion of the input frequency deviation information, and outputs a frequency deviation signal obtained by the conversion to the reference signal source 231. The reference signal source 231 corrects the oscillating reference frequency according to the input frequency deviation signal, operates so as to follow the transmission frequency of the radio base station, and transmits the frequency-corrected reference frequency reference signal to the transmission synthesizer unit. 232 and the reception synthesizer section 234.

Next, the transmission operation will be described. For example, an audio signal to be transmitted from a digital radio is
The necessary transmission processing is performed by another circuit, which becomes transmission information, and is input to the modulation unit 226 from the modulation unit input terminal 227. Modulation section 226 digitally modulates the input transmission information and outputs a digitally modulated signal to linearizer section 225. There are various digital modulation schemes used in the modulation section 226, and a required modulation scheme suitable for a digital radio communication system is used.
The 4-shift QPSK modulation scheme and the like are commonly used modulation schemes.

[0009] The linearizer 225 outputs the input digital modulation signal to the quadrature modulator 224. The quadrature modulation section 224 performs quadrature modulation on the carrier wave separately input from the transmission synthesizer section 232 with the input digital modulation signal, and outputs a modulated wave signal to the transmission power amplification section 223. The transmission power amplification unit 223 power-amplifies the input modulated wave signal to a predetermined power, and outputs the power-amplified modulated wave signal to the switch 205 via the isolator 221 (also output to the switch 206, but also to the switch 206). Indicates that the contact b side is selected). The switch 205 has been switched to the contact a side, and the power-amplified modulated wave signal is transmitted to the wireless base station transmission filter 203 of the duplexer 202.
After the band is limited by, the signal is output from the antenna 201 as a transmission signal.

On the other hand, a part of the modulated wave signal output from the transmission power amplifier 223 is extracted by the directional coupler 222 disposed on the output side of the transmission power amplifier 223 and output to the feedback circuit 233. I have. The feedback circuit 233 separately converts the input extracted modulated wave signal into a transmission synthesizer unit 232.
, And outputs the demodulated digital modulated signal to the linearizer unit 225. The linearizer 225 performs an addition process on the digital modulation signal input from the modulation unit 226 and the digital modulation signal obtained by demodulating the feedback output input from the feedback circuit 233 using a predetermined algorithm to compensate for nonlinear distortion. It operates so as to suppress the spread of the spectrum that interferes with the nearby communication channel due to the nonlinear distortion generated in the transmission power amplifier 223. Although various methods are known as a method for compensating for nonlinear distortion, the above example is generally called a Cartesian method.

The switching from the wireless communication via the wireless base station in the service area of the wireless base station to the direct wireless communication between the wireless terminal stations is performed by a manual switch or an automatic switch. The operation of the digital wireless device when direct wireless communication is performed between wireless terminal stations after setting the changeover switch is as follows. A transmission signal transmitted directly from a certain wireless terminal station is received by antenna 201 to become a reception signal and output to duplexer 202, as in the case of receiving a transmission signal transmitted from a wireless base station. Since the transmission signal uses the same band frequency as the transmission signal from the wireless terminal station as described above, the transmission signal passes through the transmission filter 203 for the wireless base station, which is originally for transmission, of the duplexer 202, and is transmitted to the switch 205. Is output. In this case, the switch 205 is switched to the contact “b” side, and the received signal is input to the receiving amplifier 209, amplified at high frequency by the receiving amplifier 209, and further received by the receiving filter 2.
10 and a predetermined band limitation is performed.
1 is output. The switch 211 has been switched to the contact a side, and outputs the reception signal band-limited by the reception filter 210 to the mixer 212. The subsequent receiving operation from the mixer 212 is the same as that in the case of the wireless communication via the wireless base station described above, and the description is omitted.

Since direct wireless communication between wireless terminal stations is simplex communication, a frequency in the same band as that used for communication from a wireless terminal station to a wireless base station is used. The transmission information is input to the modulation unit input terminal 227 and becomes a digital modulation signal. The carrier is orthogonally modulated by the orthogonal modulation unit 224 and the modulated wave signal is output to the transmission power amplification unit 223 via the above-described radio base station. Since it is the same as the case of all wireless communication, the description is omitted. The transmission power amplification unit 223 power-amplifies the input modulated wave signal to a predetermined power and outputs the power-amplified modulated wave signal to the switch 206 via the isolator 221 (also output to the switch 205. The contact b side is selected). The switch 206 is switched to the contact a side, and the power-amplified modulated wave signal is transmitted to the reception filter 204 for the radio base station of the duplexer 202.
, Is output from the antenna 201 as a transmission signal. The direct wireless communication between the wireless terminal stations is usually a simplex communication of the press talk system, and the direct wireless communication between the wireless terminal stations is performed as described above.

[0013]

According to the prior art, the function of a wireless terminal station performing wireless communication via a wireless base station and the function of a wireless terminal station performing direct wireless communication between wireless terminal stations without passing through a wireless base station are described. Digital radios with
It has the following disadvantages. 1. In either case of wireless communication via a wireless base station or direct wireless communication between wireless terminal stations, since a signal is transmitted through the switch 205 or 206, the transmission spectrum is expanded due to nonlinear distortion generated in the switch, It has the disadvantage of interfering with other nearby communication channels. In particular, in a digital radio communication system for public business, adjacent channel leakage power is, for example, −45.
Due to the demand for strict performance from dB to -60 dB, improvement of nonlinear distortion is an important performance and cost improvement item in digital radio device manufacturing. 2. When the switch is constituted by a diode switch or the like, the non-linear distortion is a problem. On the other hand, when the switch is constituted by a coaxial switch, there is a disadvantage that it is disadvantageous for downsizing the device. 3. Since a switch is provided in the transmission power path, it is necessary to increase the transmission power by the insertion loss of the switch in order to obtain a predetermined output, which is disadvantageous in terms of both low power consumption and realization of linear compensation performance of the transmission unit. have. 4. As another disadvantage, when the wireless terminal station is attached to a moving object, the communication characteristics of the propagation path fluctuate instantaneously, and communication deterioration is likely to occur.

According to the present invention, in order to solve the above-mentioned drawbacks, a receiving path is provided with a switching circuit as a circuit configuration of a plurality of branch diversity systems, and a transmitting path is provided with a wireless communication or wireless communication via a wireless base station without providing a switching circuit. It is an object of the present invention to provide a digital wireless device that performs direct wireless communication between terminal stations and eliminates a defect caused by nonlinear distortion of a switching circuit of a transmission path. Further, as a second object of the present invention, when setting direct wireless communication between wireless terminal stations, by switching from the diversity receiving method to the non-diversity receiving method, the redundancy of the circuit configuration of the device is reduced and the size is reduced. It is an object of the present invention to provide a digital radio with reduced power consumption and reduced cost.

[0015]

In order to achieve the above object, a digital radio according to the present invention comprises a transmitter for transmitting a signal in a first frequency band, a first frequency band and a second frequency band. And a receiving unit for receiving the signal of the first frequency band, wherein the first antenna connected to the transmitting unit for transmitting the signal of the first frequency band receives the signal of the second frequency band. The branch connecting the receiver and the first
A branch that connects a second receiver that receives a signal of the frequency band and a signal of the second frequency band by switching the switching circuit to a second antenna, and a control unit that switches the switching circuit, A signal having a second frequency band is received by controlling the switching circuit of the second receiver connected to the second antenna from the control section, the signal having the receiving section having a 2-branch reception diversity configuration. And a non-diversity receiving function for receiving a signal in the first frequency band.

Also, the digital radio of the present invention is a communication between radio terminal stations, and a first frequency used for radio communication via a radio base station and direct radio communication between radio terminal stations. A transmitting unit for transmitting a signal in a band, a signal in a first frequency band used for wireless communication via a wireless base station and direct wireless communication between wireless terminal stations, and wireless communication via a wireless base station. And a receiving unit for receiving a signal of a second frequency band to be used. In a digital wireless device used as a wireless terminal station, the digital wireless device performs wireless communication via a wireless base station and direct wireless communication between wireless terminal stations. A first antenna for receiving a signal in a second frequency band used for wireless communication via a wireless base station to a first antenna connected to the transmitting unit for transmitting a signal in a first frequency band to be used; Branch connected machines,
A signal in a first frequency band used for wireless communication via a wireless base station and a direct wireless communication between wireless terminal stations, and a signal in a second frequency band used for wireless communication via a wireless base station And a control unit for switching the switching circuit, the control unit including a branch connected to a second antenna for receiving a second receiver by switching the switching circuit, and a control unit for switching the switching circuit.
Having a plurality of reception diversity configurations including a branch of the branch, by controlling a switching circuit of the second receiver connected to the second antenna from the control unit, through the radio base station A diversity receiving function of receiving a signal of a second frequency band used for wireless communication of the first type, and a signal of a first frequency band used for wireless communication via a wireless base station and direct wireless communication between wireless terminal stations Is switched to a non-diversity receiving function for receiving the data.

Further, the digital radio of the present invention digitally modulates frame-processed transmission information and outputs a digitally modulated signal, and a quadrature modulation which orthogonally modulates a carrier with the digitally modulated signal and outputs a modulated wave signal. Department and
A power amplification unit that power-amplifies and outputs the modulated wave signal, a transmission unit that has a first antenna that receives the power-amplified modulated wave signal via a duplexer and transmits the signal as a signal in a first frequency band, A first antenna for receiving a signal of the second frequency band and outputting the signal via the duplexer; a receiving amplifier for amplifying and outputting an output signal input from the first antenna; A first receiver having a mixer that mixes the received reception signal and the local frequency signal to output an intermediate frequency reception signal, and a demodulation unit that demodulates the intermediate frequency reception signal and outputs a demodulation signal; A second antenna that receives a signal of the first frequency band or a signal of the second frequency band and outputs a received signal; a switch that switches and outputs an output signal input from the second antenna;
A receiving amplifier that amplifies the received signal of the switched first frequency band at a high frequency, a receiving amplifier that amplifies the received signal of the switched second frequency band at a high frequency, and a first amplifier that is amplified at a high frequency. And a switch for switching and outputting the received signal of the second frequency band or the received signal of the first frequency band or the second frequency band. And a local frequency signal, and a mixer for outputting an intermediate frequency received signal, and a demodulator for demodulating the intermediate frequency received signal to output a demodulated signal and outputting frequency deviation information. And a diver that performs diversity processing on a demodulated signal output from the first receiver and a demodulated signal output from the second receiver, and switches and outputs the processed signal. And a control unit that controls switching between a diversity receiving function for receiving a signal in the second frequency band and a non-diversity receiving function for receiving a signal in the first frequency band, and stores frequency deviation information. A diversity reception function having a memory circuit and a reference signal source for correcting a reference frequency oscillated by frequency deviation information, receiving a signal in a second frequency band, and a non-diversity receiving a signal in a first frequency band This is to switch between the reception function. When switching to the non-diversity receiving function of receiving a signal of the first frequency band, the frequency deviation information stored in the memory circuit is read at the time of diversity reception, and the operation is performed so as to correct the reference frequency oscillated by the reference signal source. It is like that.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an embodiment of a digital radio according to the present invention, basic matters according to the present invention will be described. 2. Description of the Related Art In a digital radio communication system using a digital radio, it is widely known that the effectiveness of using a reception diversity system as a system for improving the bit error rate of digitally coded communication contents and improving the quality of a communication line. Have been. Various systems, such as a selection system after demodulation or a synthesis system, are disclosed as a diversity processing system of a digital wireless device using a reception diversity system. Also, a system combining a delay equalizer and a two-branch diversity system is known, and measures for improving the quality of a communication line against fading and delay spread have been studied. In particular, in a business digital wireless communication system employing a so-called large zone or middle zone system having a large service area of a wireless base station, the use of the reception diversity system has a great effect of improving the quality of the communication line. There is. Therefore, in a radio communication using a service area of a radio base station in a digital radio communication system, it is very necessary to adopt a reception diversity system of two branches or a plurality of branches in a radio terminal station. From the above, a circuit that configures a reception diversity system by adopting a reception diversity system in a wireless terminal station having a function of performing wireless communication via a wireless base station and a function of performing direct wireless communication between wireless terminal stations. Constructing a circuit for direct wireless communication between wireless terminal stations by utilizing a switching circuit is extremely effective for reducing the production cost and reducing the size and power consumption in addition to improving the quality of the communication line. . In general, direct wireless communication between wireless terminal stations has a relatively high reception electric field level because the wireless terminal station is located at a short distance compared to a case where the wireless terminal station performs wireless communication using the service area of the wireless base station. Since the frequency of requiring the reception diversity system is low, it is considered that there is no practical problem.

The digital radio according to the present invention is not connected to an antenna duplexer in order to improve the quality of a communication line by using a reception diversity system and to utilize a circuit constituting the reception diversity system by a switching circuit. A receiving high-frequency unit and a switching circuit for direct wireless communication between wireless terminal stations are provided on the receiving-only antenna side, and a switching operation with a receiving high-frequency unit for wireless communication via a wireless base station is performed. . Further, the digital wireless device of the present invention performs a non-diversity operation in conjunction with a switching operation of a setting switch of direct wireless communication between wireless terminal stations, and performs a receiving operation and a demodulating operation for direct wireless communication between wireless terminal stations. It is intended to be controlled. Also, in conjunction with the switching operation of the direct wireless communication setting switch between wireless terminal stations, the operation of setting the non-diversity operation and outputting the frequency correction data from the memory circuit storing the frequency correction data to perform the frequency control operation may be linked. It was made. Here, a frequency correction method in the case of direct wireless communication between wireless terminal stations will be described. For example, in the case of direct wireless communication between wireless terminal stations in an FDMA digital wireless communication system with a communication channel interval of several kHz,
In order to remove mutual interference between communication channels, a method of correcting a frequency deviation of a reference signal source by reading out frequency correction data stored during wireless communication via a wireless base station from a memory circuit is known. ing. In the method of correcting the frequency deviation, even when the frequency stability including the aging of the wireless terminal station, the deviation due to the temperature change, and the like is several times to one digit larger than the frequency stability of the wireless base station, A reference signal source (for example, VC-
It is possible to obtain the frequency accuracy of the order added with the aging of TCXO). As a result, the wireless terminal station does not require a reference signal source having high frequency stability, which is advantageous for reducing the production cost of devices and reducing the size and power consumption.

An embodiment of the digital radio according to the present invention will be described with reference to FIG.
A digital wireless device according to the present invention has a function of a wireless terminal station performing wireless communication via a wireless base station and a function of a wireless terminal station performing direct wireless communication between wireless terminal stations without passing through a wireless base station. Machine. Hereinafter, using the block diagram of the digital wireless device of the wireless terminal station shown in FIG. 1, the digital wireless device for performing wireless communication via the wireless base station and the digital wireless device for performing direct wireless communication between wireless terminal stations will be described. The operation will be described. First, the receiving operation when performing wireless communication via a wireless base station will be described. The wireless terminal station must have a function of receiving signals in two frequency bands, a transmission frequency in a predetermined frequency band transmitted from the wireless base station and a transmission frequency in the predetermined frequency band transmitted from the wireless terminal station. . Therefore, when communication is performed via a wireless base station, the digital wireless device of the present invention performs a diversity operation. In the embodiment, the digital wireless device has a two-branch configuration.

The signal from the radio base station is transmitted to the antenna 101
The signal received by the antenna 121 and the signal received by the antenna 101 becomes a reception signal, and is transmitted to the reception filter 104 of the duplexer 102.
The received signal is output to the switch 122. When wireless communication is performed via the wireless base station, the switch 122 is switched to the contact b side, and the reception signal is transmitted to the reception filter 1.
32. The reception filter 132 limits the band of the input reception signal and outputs the band-limited reception signal to the reception amplifier 133. The reception amplifier 133 high-frequency-amplifies the input reception signal to a required level, and outputs the high-frequency amplified reception signal to the reception filter 134. The receiving filter 134 limits the band of the received high-frequency amplified received signal, and outputs the band-limited received signal to the switch 126. The switch 126 has been switched to the contact b side, and outputs the reception signal band-limited by the reception filter 134 to the mixer 127.

The mixer 127 receives a local frequency signal from the reception synthesizer section 136 in addition to the band-limited received signal input from the switch 126 and converts the received signal into a first IF (intermediate frequency) signal. The converted and frequency-converted first IF signal is output to the first IF filter 128. The first IF filter 128 limits the band of the input first IF signal, and limits the band of the first IF signal.
The signal is output to the reception IF unit 129. Receive IF unit 129
Represents the reception synthesizer unit 13 separately from the band-limited first IF signal input from the first IF filter 128.
6, the local IF signal is amplified, the first IF signal is amplified to a required level, the frequency is converted to a second IF signal, and the frequency-converted second IF signal is output to the second IF filter 130. The second IF filter 130 is
The band of the input second IF signal is limited, and the band-limited second IF signal is output to the demodulation unit (2) 131. The demodulation unit (2) 131 demodulates the input band-limited second IF signal by a predetermined demodulation method. The demodulation unit (2) 13
The demodulation in 1 may be any demodulation method according to the configuration of the device.

On the other hand, the reception filter 104 of the duplexer 102
Selects the received signal input from the antenna 101, limits the band, and transmits the band-limited received signal to the receiving amplifier 105.
Output to The receiving amplifier 105 high-frequency-amplifies the input band-limited reception signal to a required level, and outputs the high-frequency amplified reception signal to the reception filter 106. The reception filter 106 limits the band of the input high-frequency amplified received signal, and outputs the band-limited received signal to the mixer 107. The mixer 107 receives a local frequency signal from the reception synthesizer unit 136 in addition to the band-limited reception signal input from the reception filter 106, performs frequency conversion on the reception signal into a first IF signal, and performs frequency conversion. The first IF signal is output to first IF filter 108. The first IF filter 108 limits the band of the input first IF signal, and receives the band-limited first IF signal
Output to the unit 109. The receiving IF unit 109 receives a local frequency signal from the receiving synthesizer unit 136 in addition to the band-limited first IF signal input from the first IF filter 108, and amplifies the first IF signal to a required level. , To the second IF signal, and outputs the frequency-converted second IF signal to the second IF filter 110. The second IF filter 110 receives the input second
The IF signal is band-limited, and the band-limited second IF signal is output to demodulation section (1) 111. The demodulation unit (1) 111
The input band-limited second IF signal is demodulated by a predetermined demodulation method.

In the digital radio according to the present invention, diversity communication is performed when communication is performed via a radio base station. In this state, demodulation sections (1) 111 and (2) 131 perform predetermined reception. Diversity processing and switching section 135 for each demodulated signal demodulated by the demodulation method.
Output to The diversity processing and switching unit 135 includes:
Diversity processing is performed on the respective demodulated signals input from the demodulation units (1) 111 and (2) 131 according to a predetermined algorithm, the diversity processing is performed, and the switched demodulation information is sent to the frame processing unit 147. Is output. The algorithm for performing the diversity processing includes, for example, various methods such as a synthesis method and a selection method, and any of these methods may be used. The frame processing unit 147 decomposes the demodulation information input from the diversity processing and switching unit 135 into a transmission frame according to a predetermined procedure, and extracts specified information.

Since the digital radio needs to follow the transmission frequency of the radio base station, the demodulation section (2) 131 oscillates the transmission frequency of the radio base station and the reference signal source of the digital radio. Frequency deviation information from a predetermined frequency based on the detected reference frequency is detected, and the detected frequency deviation information is stored in the D / A converter 159 and the memory circuit 1.
58. The D / A converter 159 performs digital / analog conversion of the input frequency deviation information, and outputs a frequency deviation signal obtained by the conversion to the reference signal source 148. The reference signal source 148 corrects the oscillating reference frequency based on the input frequency deviation signal, operates so as to follow the transmission frequency of the radio base station, and transmits the frequency-corrected reference frequency reference signal to the transmission synthesizer unit. 149 and the reception synthesizer section 136.
On the other hand, the memory circuit 158 stores the data value of the latest detected frequency deviation information, and the data value is written at predetermined intervals. Note that a series of processes relating to the frequency correction may be performed by the demodulation unit (1) 111 instead of the demodulation unit (2) 131.

The frame processing section 147 outputs the processed coded signal to the voice coding / decoding section 156. The audio encoding / decoding unit 156 decodes the encoded signal input from the frame processing unit 147 and converts the digital audio signal into a PCM signal.
Output to the codec 155. PCM codec 155
Converts the input digital audio signal into an analog audio signal and outputs the analog audio signal to the speaker 153. Speaker 153
Outputs the voice transmitted from the digital radio of another radio terminal station transmitted via the radio base station.

Next, the transmission operation will be described.
(The transmission operation is the same for both wireless communication via a wireless base station and direct wireless communication between wireless terminal stations.) The microphone 154 receives a voice to be transmitted to another wireless terminal station, and converts an analog voice signal. PCM codec 1
Output to 55. The PCM codec 155 converts the input analog audio signal into a digital audio signal, and converts the converted digital audio signal into an audio encoding / decoding unit 156.
Output to Audio encoding / decoding section 156 encodes the input digital audio signal, and outputs the encoded audio signal to frame processing section 147. Frame processing unit 14
7 assembles the input coded audio signal into a frame in a transmission format, and outputs the frame-processed transmission information to the modulation unit 146. Modulating section 146 digitally modulates the input transmission information and outputs a digitally modulated signal to linearizer section 145. The modulation unit 14
There are various types of digital modulation schemes used in 6 and a required modulation scheme suitable for a digital radio communication system is used. For example, a π / 4 shift QPSK modulation scheme is a commonly used modulation scheme. It is a method.

The linearizer 145 outputs the input digital modulation signal to the quadrature modulator 144. The quadrature modulation section 144 is a digital modulation signal input from the linearizer section 145, and is separately provided with a transmission synthesizer section 149.
, And quadrature-modulates the carrier input from, and outputs a modulated wave signal to the transmission power amplifier 143. Transmission power amplifier 143
Power-amplifies the input modulated wave signal to a predetermined power,
The power-amplified modulated wave signal is output to transmission filter 103 of duplexer 102 via isolator 141. The transmission filter 103 of the duplexer 102 band-limits the input power-amplified modulated wave signal, and outputs the band-limited modulated wave signal to the antenna 101. Antenna 101 outputs a modulated wave signal as a transmission signal.

On the other hand, a part of the modulated wave signal output from transmission power amplification section 143 is extracted by directional coupler 142 arranged on the output side of transmission power amplification section 143 and output to feedback circuit 150. I have. The feedback circuit 150 separately converts the input extracted modulated wave signal into a transmission synthesizer section 149.
, And outputs the demodulated digital modulation output to the linearizer unit 145. The linearizer 145 performs an addition process on the digital modulation signal input from the modulation unit 146 and the demodulated digital modulation signal of the feedback output input from the feedback circuit 150 by a predetermined algorithm to compensate for nonlinear distortion. It operates so as to suppress the spread of the spectrum that interferes with the nearby communication channel due to the nonlinear distortion generated in the transmission power amplifier 143. Although various methods are known as a method for compensating for nonlinear distortion, any method may be used.

The operation of the digital wireless device when switching from wireless communication via the wireless base station in the service area of the wireless base station to direct wireless communication between wireless terminal stations is as follows. The mode for direct wireless communication between wireless terminal stations is set by the switch 152 for direct wireless communication between wireless terminal stations. The direct wireless communication setting switch 152 is
The set signal of the set mode is output to the man-machine interface 151. Man Machine Interface 15
1 outputs the input setting signal to the control unit 157. The control unit 157 includes the direct wireless communication setting switch 15.
In order to perform switching control from wireless communication via a wireless base station to direct wireless communication between wireless terminal stations in accordance with the setting signal input from 2, the diversity processing and switching unit 135 is controlled via a control line 161. The diversity processing performed in accordance with the algorithm is referred to as non-diversity processing, and the demodulated signal is output to the frame processing unit 147 in a non-diversity processing state. In addition to the control of the non-diversity processing, the switches 122 and 126 are controlled via control lines 163 and 164 to control the switching of the receiving high-frequency section to a circuit for direct wireless communication between wireless terminal stations.

The states of the switches 122 and 126 shown in FIG. 1 indicate circuit states in which the switches are switched to the contact a side, respectively, and the mode is switched to the direct wireless communication mode between wireless terminal stations. A signal directly transmitted from a digital wireless device of a certain wireless terminal station is received by an antenna 121, and a received signal is output to a switch 122. As described above, the switch 1 switched to the direct wireless communication mode between wireless terminal stations.
Reference numeral 22 is switched to the contact a side, and the reception signal is output to the reception filter 123. The reception filter 123
The input reception signal is band-limited, and the band-limited reception signal is output to reception amplifier 124. Receiver amplifier 124
, Amplifies the input received signal to a required level at a high frequency, and outputs the received signal subjected to the high frequency amplification to the reception filter 125. The reception filter 125 band-limits the received high-frequency amplified reception signal, and outputs the band-limited reception signal to the switch 126. The switch 126 has been switched to the contact a side, and outputs the reception signal band-limited by the reception filter 125 to the mixer 127. Mixer 1
Since the receiving operation from 27 is the same as that in the case of the wireless communication via the wireless base station described above, the description is omitted.

At this time, control unit 157 controls memory circuit 158 via control line 162 in conjunction with the control of the non-diversity processing performed according to the above-described algorithm and the switching control of switches 122 and 126.
In the case of wireless communication via the wireless base station, the data value of the stored frequency deviation information is read, and the read frequency deviation information is output to the D / A converter 159. D /
The A converter 159 performs digital / analog conversion of the input frequency deviation information, and outputs the frequency deviation signal obtained by the conversion to the reference signal source 148, as in the case of wireless communication via the wireless base station. Then, the reference frequency oscillated by the reference signal source 148 is corrected. The setting from the direct wireless communication between the wireless terminal stations to the wireless communication via the wireless base station is performed by the direct wireless communication setting switch 152 between the wireless terminal stations.
Is turned off, and the control from the control unit 157 is switched to operate in reverse.

As described above, the digital radio of the present invention has the following features. (1) In switching between wireless communication via a wireless base station and direct wireless communication between wireless terminal stations, there is no switching circuit in the transmission circuit, and no nonlinear distortion is generated by the switching circuit.
There is no interference to the proximity communication channel. (2) In switching between wireless communication via a wireless base station and direct wireless communication between wireless terminal stations, since there is no switching circuit in the transmitting circuit, there is no insertion loss due to the switching circuit and transmission power loss due to the switching circuit. Since there is no such device, it is advantageous for reducing the power consumption of the device. (3) In switching between wireless communication via a wireless base station and direct wireless communication between wireless terminal stations, only the receiving circuit performs a switching operation.
Since the power withstand performance of the switching circuit can be kept low, it is advantageous for downsizing the equipment. (4) In the case of direct wireless communication between wireless terminal stations that performs wireless communication at a short distance as compared with wireless communication via a wireless base station, reception diversity is not used and a reception high-frequency unit is added to a circuit of reception diversity. , The number of circuits is reduced, the size and power consumption are reduced, and the production cost is reduced. (5) In the case of direct wireless communication between wireless terminal stations, since the frequency deviation correction control is performed by controlling the memory circuit for frequency deviation correction in conjunction with the control of the non-diversity processing, the control including the demodulation unit is performed. Can be simplified.

[0034]

According to the present invention, the receiving path is provided with a switching circuit as a circuit configuration of a plurality of branch diversity systems, and the transmitting path is provided with a wireless communication via a wireless base station or directly between wireless terminal stations without providing a switching circuit. It is possible to provide a digital wireless device that performs wireless communication and eliminates a defect caused by nonlinear distortion caused by a switching circuit. Furthermore, when direct wireless communication between wireless terminal stations is set, by switching from the diversity reception method to the non-diversity reception method, the redundancy of the circuit configuration of the device has been reduced to reduce the size and power consumption and reduce the cost. A digital radio can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital wireless device according to the present invention.

FIG. 2 is a block diagram showing a high-frequency section of a conventional digital radio.

[Explanation of symbols]

101, 121, 201 ... antenna, 102, 202 ...
Duplexer, 103, 203 ... duplexer transmission filter, 10
4, 204: duplexer receiving filter, 105, 124, 1
33, 207, 209 ... receiving amplifiers, 106, 123,
125, 132, 134, 208, 210 ... receive filters, 107, 127, 212 ... mixers, 108, 12
8, 213: first IF filter, 109, 129, 21
4: Receive IF unit, 110, 130, 215: Second IF filter, 111: Demodulator (1), 122, 126, 20
5, 206, 211 ... switch, 131 ... demodulation unit (2), 135 ... diversity processing unit and switching unit, 1
36, 234 ... reception synthesizer section, 141, 221 ...
Isolator, 142, 222 ... directional coupler, 14
3, 223: transmission power amplifying unit, 144, 224: quadrature modulation unit, 145, 225: linearizer unit, 146, 22
6 Modulation section, 147 Frame processing section, 148, 231
... Reference signal sources, 149, 232...
150, 233: feedback circuit, 151: man-machine interface, 152: setting switch, 153: speaker,
154: microphone, 155: PCM codec, 1
56: voice encoding / decoding unit, 157: control unit, 158 ...
Memory circuits, 159, 235 ... D / A converters, 216 ...
Demodulation unit.

Claims (4)

[Claims] 1. A digital radio having a transmitting unit for transmitting a signal in a first frequency band and a receiving unit for receiving a signal in a first frequency band and a signal in a second frequency band. A first antenna connected to the transmitting unit for transmitting the signal of the second frequency band, a first receiver for receiving a signal of the second frequency band, a signal of the first frequency band and a second frequency A second antenna connected to a second antenna for receiving a band signal by switching a switching circuit; and a control unit for switching the switching circuit, wherein the reception has a reception diversity configuration of at least two branches. A diversity receiving function of receiving a signal in a second frequency band by controlling a switching circuit of the second receiver connected to the second antenna from the control unit, the first receiving unit comprising: Week A digital wireless device characterized by switching between a non-diversity receiving function for receiving a signal in a wavenumber band. 2. A transmitter for transmitting a signal in a first frequency band used for wireless communication via a wireless base station and direct wireless communication between wireless terminal stations for communication between wireless terminal stations. A signal in a first frequency band used for wireless communication via a wireless base station and a direct wireless communication between wireless terminal stations, and a signal in a second frequency band used for wireless communication via a wireless base station A digital radio used as a radio terminal station, wherein a signal in a first frequency band used for radio communication via a radio base station and direct radio communication between radio terminal stations is provided. A branch in which a first receiver for receiving a signal in a second frequency band used for wireless communication via a wireless base station is connected to a first antenna connected to the transmitting unit for transmitting a signal, Direct communication between wireless terminals via wireless stations and wireless terminal stations A second receiver for receiving a signal of a first frequency band used for line communication and a signal of a second frequency band used for wireless communication via a wireless base station by switching a switching circuit; And a control unit that switches the switching circuit. The control unit includes a plurality of reception diversity units including at least the first and second branches. The second antenna A diversity receiving function of receiving a signal of a second frequency band used for wireless communication via a wireless base station by controlling a switching circuit of the second receiver connected to the wireless base station from a control unit; The first is used for wireless communication via a station and direct wireless communication between wireless terminal stations.
And a non-diversity receiving function for receiving a signal of a frequency band of the digital radio device. 3. A modulating section for digitally modulating frame-processed transmission information and outputting a digitally modulated signal, an orthogonally modulating section for orthogonally modulating a carrier with the digitally modulated signal and outputting a modulated wave signal; A power amplifying unit for amplifying and outputting, a transmitting unit having a first antenna for inputting a power-amplified modulated wave signal via a duplexer and transmitting the signal as a signal in a first frequency band; A first antenna for receiving a signal and outputting the signal through the duplexer, a receiving amplifier for amplifying and outputting the output signal input from the first antenna at a high frequency, A first receiver having a mixer for mixing a frequency signal and outputting an intermediate frequency reception signal; a first receiver having a demodulation unit for demodulating the intermediate frequency reception signal and outputting a demodulated signal; A second antenna that receives signals in several bands or a signal in a second frequency band and outputs a received signal; a switch that switches and outputs an output signal input from the second antenna; A receiving amplifier for amplifying a received signal of a first frequency band at a high frequency, a receiving amplifier for amplifying a switched received signal of a second frequency band at a high frequency, and a receiving signal of a first frequency band amplified at a high frequency Alternatively, a switch for switching and outputting a received signal in the second frequency band, and a switch between the switched and output high frequency amplified received signal in the first frequency band or the received signal in the second frequency band and the local frequency signal. A mixer that mixes and outputs an intermediate frequency reception signal, and a demodulation unit that demodulates the intermediate frequency reception signal and outputs a demodulated signal and outputs frequency deviation information. A second receiver having a said diversity processing and switching unit for outputting the demodulated signal is switched to diversity processing the demodulated signal output from the first receiver is output from the second receiver,
A control unit for controlling switching between a diversity receiving function for receiving a signal in the second frequency band and a non-diversity receiving function for receiving a signal in the first frequency band, a memory circuit for storing frequency deviation information, and frequency deviation information And a reference signal source that corrects a reference frequency oscillated by the control unit, and switches between a diversity receiving function of receiving a signal of the second frequency band and a non-diversity receiving function of receiving a signal of the first frequency band. A digital radio characterized by the following. 4. The apparatus according to claim 3, wherein when switching to a non-diversity receiving function for receiving a signal in the first frequency band, frequency deviation information stored in a memory circuit at the time of diversity reception is read out, and a reference signal source is used. A digital wireless device operable to correct an oscillating reference frequency.