JPH0923177A - Diversity device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and price of this diversity device by selecting the monitor output of each coupler prepared in each two power amplifier outputs for plural transitting/receiving antennas and controlling the output of a transmitting circuit by a single control circuit. SOLUTION: A transmitting antenna selecting switch(SW) 118 selects one of power amplifiers 119 to 112 based upon control signals 114a to 114c to transmit a signal obtained by frequency-converting a modulated transmitting signal through a transmitting circuit 117. Each of the signals 114a to 114c indicates the system of an antenna having a maximum receiving level and allows the SW 118 and the circuit 117 to select one of respective power amplifiers and one of couplers 129, 130 connected in parallel correspondingly to each two power amplifiers. An automatic power control circuit 128 controls the transmitting output of the circuit 117 based upon an output from a SW A27 and controls the transmitting output of a specified antenna at a prescribed value. Since a transmitting output is controlled by two couplers and the single circuit 128, the size and price of the device can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity apparatus for improving the reception level deterioration at the base station side due to fading caused by the movement of a mobile unit in mobile communication for time division communication.

[0002]

2. Description of the Related Art In mobile communication, there is a drawback in that the reception level is deteriorated due to fading caused by the movement of a mobile station and the communication quality is deteriorated. As means for solving this drawback, for example, Japanese Patent Laid-Open No. 19223/1990
A diversity technique as described in Japanese Patent Publication No. 0 (H04B7 / 04) has been conventionally known. In this conventional technique, transmission and reception are performed by the same radio frequency,
Switching between transmission and reception is performed by dividing the time, and at the time of reception, an antenna selected by diversity after detection is used as a transmission antenna, and is configured as shown in FIG.

In FIG. 4, signals received by antennas 1 and 2 which are spatially separated are input to receiving circuits 5 and 6 via circulators 3 and 4, respectively. The outputs of the reception circuits 5 and 6 are input to the demodulation circuits 7 and 8, respectively, and part of them are input to the control circuit 9. The control circuit 9 measures the output signal levels of the receiving circuits 5 and 6 and compares them. As a result of the comparison, a control signal for selecting the demodulation circuit connected to the signal branch having the higher signal level is output to the switch circuit 10. The output of the selected demodulation circuit is input to the digital-analog conversion circuit 11, and the received analog signal is output to the output terminal 12.

On the other hand, the analog signal input to the input terminal 13 is converted into a digital signal by the analog-digital conversion circuit 14. This digital signal is modulated by the modulator 15. The modulated signal is input to the transmission circuit 16 that performs frequency conversion, amplification, etc., and is input to the switch circuit 17. At this time, as described above, the control circuit 9 stores the selection branch selected in the immediately preceding reception, and outputs the control signal for selecting the antenna belonging to this selection branch to the switch circuit 17. Therefore, the transmission signal is transmitted from the antenna selected by the switch circuit 10.

By the way, when the above-mentioned conventional technique is applied to, for example, a base station of a mobile phone, the transmission signal is amplified by the transmission circuit 16 of one system, and then the antenna 1 is transmitted via the switch circuit 17. Since it is configured to be transmitted from any one of the two, in consideration of the loss of the switch circuit, a power amplifier with a considerably large output is required to obtain a predetermined output. Such a large output power amplifier is not only very expensive, but also has a problem in that it consumes a large amount of power and generates a large amount of heat. In addition, the switch circuit 17
However, there is a problem that it is necessary to switch such a large power with good linearity, and such a switch circuit is also expensive. Further, there is a serious problem that transmission becomes impossible if the power amplifier fails.

[0006] Therefore, in order to improve the problems of the prior art, the applicant of the present application has filed Japanese Patent Application No. 7-125249. This application transmits / receives at the same radio frequency, switches transmission / reception by dividing time, and uses an antenna selected by diversity after detection at reception as a transmitting antenna, as shown in FIG. Is composed of.

FIG. 2 is based on a 4-branch post-detection selective diversity system having four antennas.

In FIG. 2, 101, 102, 103,
Reference numerals 104 denote transmission / reception dual-purpose antennas, which are spatially spaced apart from each other, and a transmission / reception changeover switch 105 as transmission / reception changeover means which is switched at a predetermined timing by a transmission / reception changeover signal transmitted from a system control circuit (not shown). , 106, 107, 108. 109, 110, 111, and 112 are antennas 101 to 104 via transmission / reception changeover switches 105 to 108.
Is a receiver circuit connected to, and performs frequency conversion, band limitation, amplification, etc. of the signal input from each antenna. The signals received by each of the receiving circuits 109 to 112 are sent to the receiving antenna selection switch 113 for diversity reception, the receiving level (RSSI) is measured, and the measurement result is sent to the RSSI comparing circuit 114. To be done. In the RSSI comparison circuit 114, the RS from each reception circuit
The SI is compared, a control signal for selecting the antenna with the highest reception level is sent to the reception antenna selection switch 113, and the changeover switch 113 is controlled. As a result, of the antennas 101 to 104, the signal received by the antenna with the highest reception level is sent to the demodulation circuit 115,
Demodulation of the digital signal is performed, and in this manner, post-detection selection diversity is performed.

On the other hand, the transmission signal is subjected to predetermined modulation in the modulation circuit 116, frequency conversion is performed in the transmission circuit 117, and then sent to the transmission antenna selection switch 118. By the way, a power amplifier 119 is provided to each of the antennas 101 to 104 via the transmission / reception changeover switches 105 to 108.
The power amplifiers 119 to 122 are connected to the transmission antenna selection switch 118. The transmitting antenna selection switch 118 is the receiving antenna selection switch 11
Similar to 3, the switching control is performed by the control signal output from the RSSI comparison circuit, and therefore the transmission signal output from the transmission circuit 117 is connected to the antenna of the power amplifiers 119 to 122 having the maximum reception level. It is amplified and transmitted depending on what is present.

The power amplifiers that are not selected by the transmission antenna selection switch 118 during the transmission period are controlled to be inoperative.

FIG. 3 is a block diagram of a conventional example in which the transmitting section of FIG. 2 is further described in detail.

In FIG. 3, power amplifiers 119 and 12 are provided.
Outputs 0, 121 and 122 are couplers 123 and 12 respectively.
4, 125, 126.

The couplers 123 to 126 are inserted to monitor the output of each power amplifier and control the transmission output, and the transmission system operating in each output of the power amplifier monitor is switched via the changeover switch 127. Select and switch the 1-system monitor output.

Such couplers 123 to 126 are usually formed on the dielectric substrate by microstrip lines,
It is composed of a main line inserted in each transmission system in series, a sub line arranged in parallel with the main line with a certain gap and coupled at high frequencies, and a terminating resistor. The coupling degree of this coupler is usually selected to be about 15 to 20 dB.

After that, the auto power control circuit 12
8, the control signal from the system control circuit (not shown) is used to generate a control signal to the variable attenuator disposed inside the transmission circuit 117, and a feedback loop of the transmission unit is formed to transmit the signal. Stable output control or stepwise output control.

[0016]

The above-described FIG.
In the prior art, as many monitor couplers as power amplifiers are required.

Further, the selector switch 127 for each coupler monitor output has the same S as the selector switch 118.
A P4T switch is required. This changeover switch 11
8 and 127 are configured by combining three SPDT switches indicated by broken lines. SPDT switches are more general in the field of consumer communication than SP4T switches.
It is used more often than the P4T switch. Also, three SPDT switches are generally less expensive than one SP4T switch. However, in such a configuration of the changeover switch, the switch changeover control signal supplied from the RSSI comparison circuit 114 is required for each switch.

Therefore, in the above-mentioned conventional technique, the number of parts and the number of signal wirings such as control signals are increased, and the circuit scale is large and complicated.

[0019]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art by transmitting on a single frequency,
In a diversity device that performs reception and reception, and performs diversity transmission and reception with at least two or more transmission and reception antennas that are spatially separated,
The reception level of each antenna detected by the plurality of reception circuits is compared with the transmission / reception switching means switched by the reception switching signal, the plurality of reception circuits respectively connected to the plurality of antennas via the transmission / reception switching means. Comparing circuit, a plurality of power amplifiers respectively connected to the plurality of antennas via the transmission / reception switching means, and a transmission signal to any one of the plurality of power amplifiers based on a comparison result of the comparing circuit. It is characterized in that it has transmission antenna selection switch means for transmitting and a coupler for symmetrically arranged between two line outputs of the plurality of power amplifier output lines to monitor the output.

Further, the present invention is characterized by having a changeover switch for inputting the coupler monitor output, selecting any one of the monitor outputs and outputting the changeover output.

[0021]

According to the present invention, diversity reception is performed, and the transmission antenna switch is switched and controlled based on the reception level detected by the reception circuit.
The transmission signal is amplified and transmitted by one of the plurality of power amplifiers provided in each antenna.

Since the coupler for monitoring the transmission output is also used, the number of couplers to be arranged can be reduced.

Further, the number of changeover switches for changing over the coupler monitor output can be reduced, and the number of switch changeover control signals can be reduced.

Therefore, the circuit scale such as the number of parts and the number of signal wirings can be reduced, and the size and cost can be reduced.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment according to the present invention. It should be noted that the same configurations as those of the related art shown in FIGS. 2 and 3 are denoted by the same reference numerals and the description thereof is omitted.

In FIG. 1, the modulated transmission signal input from the terminal 116a is frequency-converted by the transmission circuit 117 and then transmitted to the transmission antenna selection switch 118.

The internal circuit of the SP4T changeover switch 116 for selecting the transmitting antenna is composed of, for example, three SPDT changeover switches.

The control signal 1 output from the RSSI comparison circuit 114 is sent to the transmission antenna selection changeover switch 118.
The transmission signals output from the transmission circuit are switched and controlled by the power amplifiers 119 to 114c.
Of the 122, the one that is connected to the antenna having the maximum reception level is amplified and transmitted for transmission diversity.

The power amplifiers that are not selected by the transmission antenna selection switch 118 during the transmission period are controlled to be inoperative.

Power amplifiers 119-120 and 121-
122 is a coupler 129 for monitoring the output.
And 130 are provided.

In the couplers 129 and 130, a power amplifier 119 or 120, and a power amplifier 119 or 120, and a coupler line which are arranged in parallel with the main lines of the two transmission lines and have the same gap and are symmetrically arranged, are provided. The transmission signal output from the power amplifier 121 or 122 is monitored.

By inserting a coupler line having such a symmetrical structure, one coupler can also serve as a transmission signal monitor-output from either one of both main lines.

The monitor outputs of the couplers 129 and 130 are input to one SPDT changeover switch 127. Changeover control signal 1 supplied to this changeover switch
14a is supplied from the RSSI comparison circuit 114, and the monitor output from the transmission system of any one power amplifier currently operating is selected.

Thereafter, using this monitor output, the automatic power control circuit 128 stably controls the transmission output level sent from the antenna to a predetermined value, or in some cases, an instruction from a system control circuit (not shown). Generates a control signal for changing the transmission output stepwise.

Further, the automatic power control circuit 12
The eight outputs are input to the transmission circuit 117, and a feedback loop of the transmission unit is formed by a method such as controlling the attenuator amount of the internal variable attenuator, and the above transmission output control is performed.

[0036]

As described above, in the diversity device according to the present invention, two power amplifier output lines of two systems are provided for a plurality of power amplifier outputs for amplifying a transmission signal provided in each of a plurality of transmitting / receiving antennas. The number of couplers can be reduced by arranging coupler lines so as to be symmetrical between them and sharing the monitor output.

Further, since the monitor output of each coupler line is selectively switched by the selector switch, the number of circuit components such as switches and the number of signal wirings such as control signals can be reduced and the circuit scale can be reduced.

Therefore, downsizing and cost reduction of the entire system can be realized.

[Brief description of drawings]

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

FIG. 2 is a block diagram illustrating a conventional technique.

FIG. 3 is a block diagram showing a conventional technique.

FIG. 4 is a block diagram showing a conventional technique.

[Explanation of symbols]

101, 102, 103, 104 Transmitting / receiving antennas 105, 106, 107, 108 Transmission / reception switching means (selection switch) 109, 110, 111, 112 Reception circuit 113 Reception antenna selection switch 114 RSSI comparison circuit 115 Demodulation circuit 116 Modulation circuit 117 Transmission Circuit 118 Transmission antenna selection switch 119, 120, 121, 122 Power amplifier 123, 124, 125, 126 Coupler 127 Monitor output selection switch 128 Auto power control circuit 129, 130 Coupler

Claims (2)

[Claims] 1. A transmission / reception switching signal in a diversity apparatus for transmitting / receiving at a single frequency and performing diversity transmission / reception with at least two or more transmitting / receiving antennas spatially separated from each other. Transmission / reception switching means, a plurality of reception circuits respectively connected to the plurality of antennas via the transmission / reception switching means, and a comparison circuit for comparing reception levels of the respective antennas detected by the plurality of reception circuits. A plurality of power amplifiers respectively connected to the plurality of antennas via the transmission / reception switching means, and a transmission for transmitting a transmission signal to any one of the plurality of power amplifiers based on a comparison result of the comparison circuit. The antenna selection switch means and the output of two lines of the plurality of output lines of the power amplifier are symmetrically arranged to monitor the output. A diversity device having a coupler. 2. The diversity apparatus according to claim 1, further comprising a changeover switch for inputting the coupler monitor output and selectively changing and outputting any one of the monitor outputs.