JPH0918398A - Diversity equipment - Google Patents

Abstract

PURPOSE: To provide a diversity equipment capable of efficiently performing transmission by the power amplifier of low output. CONSTITUTION: This diversity equipment for performing diversity transmission and reception by at least two or more plural antennas 101, 102, 103 and 104 for both transmission and reception arranged spatially with a distance for performing the transmission and the reception by a single frequency is provided with irreversible passive circuits 105, 106, 107 and 108 for separating transmission and reception signals, the plural power amplifiers 119, 120, 121 and 122 respectively connected through the irreversible passive circuits 105 to 108 to the plural antennas and a transmission antenna selection switch means 118 for sending out the transmission signals to one of the plural power amplifiers 119-122 based on a reception level.

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. 7, 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.

[0005]

By the way, when the above-mentioned conventional technique is applied to, for example, a base station of a mobile phone, the switch circuit 17 is provided after the transmission signal is amplified by the transmission circuit 16 of one system. Since it is configured to be transmitted from either one of the antennas 1 and 2 via the power amplifier, in consideration of the loss of the switch circuit, a power amplifier with a considerably large output is required to obtain a predetermined output. Not only is such a high power amplifier very expensive,
There is a problem that power consumption and heat generation amount are large. Further, the switch circuit 17 needs to switch such a large power with good linearity, and there is a problem that such a switch circuit is also expensive. Further, there is a serious problem that transmission becomes impossible if the power amplifier fails.

[0006]

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 levels of the non-reciprocal passive circuit for separating the reception signal, the plurality of reception circuits respectively connected to the plurality of antennas through the non-reciprocal passive circuit, and the reception levels of the respective antennas detected by the plurality of reception circuits are compared. 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. And a transmitting antenna selection switch means for transmitting. Further, the present invention is characterized by having a reception antenna selection switch for selecting one of the plurality of reception circuits based on a comparison result of the comparison circuit.

Further, according to the present invention, a phase shifter for matching the phases of the respective received signals received by the plurality of receiving circuits, a weighting circuit for giving a predetermined weight to the respective received signals, and the respective received signals are combined. And a synthesizing circuit.

[0008]

According to the present invention, diversity reception is performed by post-detection selection or maximum ratio combining, and the transmission antenna switch is switched and controlled based on the reception level detected by the reception circuit, and a plurality of antennas are provided for each antenna. A transmission signal is amplified and transmitted by one of the power amplifiers.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment according to the present invention, which is based on a post-detection selection diversity system.

In the figure, 101, 102, 103, 1
Reference numeral 04 is a transmission / reception dual-purpose antenna, which is spatially spaced apart from each other, and is a nonreciprocal passive circuit 105, 106 such as a circulator, which is a circuit element that separates transmission / reception signals and has directivity. It is connected to 107 and 108. Reference numerals 109, 110, 111, and 112 denote receiving circuits connected to the antennas 101 to 104 via the irreversible passive circuits 105 to 108, and perform frequency conversion, band limitation, amplification, etc. of signals input from the antennas. 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. R
The SSI comparison circuit 114 compares the RSSIs from the respective reception circuits, sends a control signal for selecting the antenna with the highest reception level to the reception antenna selection switch 113, and controls the changeover switch 113. As a result, the antenna 1
Among 01 to 104, the signal received by the antenna having the highest reception level is sent to the demodulation circuit 115 and the digital signal is demodulated. In this way, 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, the power amplifiers 119 and 1 are provided to the antennas 101 to 104 via the non-reciprocal passive circuits 105 to 108, respectively.
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.

Further, the power amplifiers 119 to 122 are connected to the antennas 101 to 1 via the non-reciprocal passive circuits 105 to 108.
04, and the transmission antenna selection switch 118 is provided after the transmission antenna selection switch 118. Therefore, it is not necessary to consider the loss of the transmission antenna selection switch in the subsequent stage of the power amplifier, and the output is lower than that of the conventional technology. Can be composed of

Further, a high power switch such as a transmission antenna selection switch and a transmission / reception changeover switch is provided in the latter stage of the power amplifier.
Since no switch is required at all, distortion and switching noise of these transmitting switches do not occur.

Next, FIG. 2 shows a second embodiment according to the present invention, which realizes reception diversity by maximum ratio combining. The same components as those in the embodiment of FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. 123, 124, 1
Reference numerals 25 and 126 denote phase shifters connected to the receiving circuits 109 to 112, respectively. The phase of a received signal received by each receiving circuit is detected by a phase detecting means (not shown), and each of the phase shifters is detected based on the detection result. Control is performed so that the received signals have the same phase. 127, 128, 129 and 130 are phase shifters 1
It is a weighting circuit that weights the outputs of 23 to 126 based on the RSSI detected by the receiving circuits 109 to 112. Then, the phase-controlled and weighted received signals are combined by the combiner 131. In this way,
Maximum ratio combining reception diversity is performed. The transmission operation of this embodiment is similar to that of the first embodiment shown in FIG.

FIG. 3 is a block diagram showing an internal configuration example of the nonreciprocal passive circuit 105 of the present invention. In FIG. 3, 10
Reference numeral 5a is a directional passive element such as a circulator having three terminals, and terminals 101a, 109a and 119a are connected to the transmitting / receiving antenna 101, the receiving circuit 109 and the power amplifier 119, respectively.

The received signal inputted from the antenna 101 is transmitted from the terminal 101a through the circulator 105a to the terminal 10a.
The signal is supplied from the 9a terminal to the receiving circuit 109, and no signal is output to the 119a terminal.

On the other hand, the transmission signal input from the power amplifier 119 to the terminal 119a is sent from the antenna 101 through the terminal 101a via the circulator 105a,
It does not occur at terminal 109a. Furthermore, V of the antenna 101
Even if the SWR is deteriorated and the transmission signal is reflected at the end of the antenna 101, the signal is not returned to the transmission side of the power amplifier 119 due to the sufficient isolation characteristic of the circulator 105a, and the transmission intermodulation characteristic is deteriorated. High power amplifier 119
Will not be damaged. Also, the VSW of the antenna 101
Even if R changes, the VSWR of the terminal 109a on the receiving side via the circulator 105a is always stable. Therefore, the filters and rollers normally arranged inside the receiving circuit 109 are provided.
Since the input impedance of the noise amplifier is stable even if the input VSWR of the antenna 101 changes, it is possible to prevent the reception sensitivity characteristic from deteriorating and, in the worst case, the oscillation state.

FIG. 4 is a block diagram showing a second configuration example of the nonreciprocal passive circuit 105 of the present invention. At the time of transmission in the embodiment of FIG. 3, the 109a terminal is usually devised so as to have a circuit configuration in which it is terminated with an appropriate impedance (for example, 50Ω). However, if this termination condition is not achieved and impedance mismatch occurs at the terminal 109a, the isolation characteristic from 101a to 119a of the circulator 105a deteriorates. Further, at this time, when the transmission signal reflected at the end of the antenna 101 is returned to the transmission side due to the above-mentioned factors, deterioration of the transmission intermodulation characteristic and damage of the high power amplifier 119 are caused.

Therefore, in order to avoid this, in FIG. 4, an isolator (one terminal of the circulator with an absorption resistance added) 105b is connected to the 119a terminal and the circulator 10.
It is inserted between 5a.

With the configuration shown in FIG. 4, the security is improved during transmission.
Even if the isolation of the switch 105a deteriorates, the isolation
The reflected signal from the antenna 101 is absorbed by the absorption resistance inside the switch 105b and does not appear at the 119a terminal.
Sufficient isolation can be secured from the terminal to the 119a terminal.

FIG. 5 is a block diagram showing a third configuration example of the nonreciprocal passive circuit 105 of the present invention. An SPST changeover switch 105c is inserted between the terminals 105a and 109a of the circulators shown in FIG. This changeover switch 105
c is transmission / transmitted from a system control circuit (not shown)
The reception switching signal causes switching at a predetermined timing so that it is turned off during transmission and turned on during reception.

In FIG. 3, when the VSWR of the antenna 101 is deteriorated, 1 is output from the terminal 119a of the circulator 105a.
The isolation characteristic to the 09a terminal is deteriorated. Normally, a low-noise amplifier is arranged inside the receiving circuit 109, but if the isolation characteristic from the 119a terminal to the 109a terminal deteriorates during transmission, the high-power transmission signal will flow into the receiving system and damage the low-noise amplifier. I have something to do.

Therefore, the changeover switch 105c shown in FIG. 5 is provided so as to secure a sufficient isolation by turning off the switch at the time of transmission and prevent such damage of the low noise amplifier.

Further, a configuration in which FIG. 4 and FIG. 5 are used together,
That is, the isolator 105b is inserted between the terminals of the circulator 105a and 119a, and the circulator 10
It goes without saying that the circuit configuration may be such that the changeover switch 105c is inserted into the terminals 5a and 109a.

FIG. 6 is a block diagram showing a fourth configuration example of the nonreciprocal passive circuit 105 of the present invention. The SPDT changeover switch 105d is inserted between the terminals 105a and 109a of the circulators shown in FIG. This changeover switch 105
d is a transmission / transmission from a system control circuit (not shown)
The reception switching signal switches to the terminating resistor side during transmission and to the 109a terminal side during reception.

With such a structure, the circulator 105a can maintain a sufficient isolation characteristic.

The non-reciprocal passive circuits 106, 107 and 10
8 is also the non-reciprocal passive circuit 105 shown in FIGS.
The configuration is the same as the above and will be omitted.

[0029]

As described above, in the diversity device according to the present invention, the power amplifier for amplifying the transmission signal is provided in each of the plurality of transmitting / receiving antennas, and the transmitting antenna selection switch controlled based on the reception level is provided. Since the power amplifiers are provided in the subsequent stage, these power amplifiers can be configured with a relatively small output without loss of the transmission antenna selection switch in the subsequent stage of the power amplifier. Also, by providing non-reciprocal passive circuits in the respective stages after the power amplifier, high power switches such as a transmission antenna selection switch and a transmission / reception changeover switch are not required at all, so that the circuit scale is reduced and the distortion and switching of these transmission system switches are reduced. No noise is generated. As a result, heat generation by the power amplifier can be suppressed, and power saving and cost reduction of the device can be achieved. That is, since the power consumption is reduced, the heat dissipation structure can be simplified and the entire system can be downsized.

Further, even if one power amplifier system fails, in the worst case, the system operation can be continued with the power amplifiers of other systems, which causes a serious problem that the base station system fails. Can be prevented
High system reliability can be secured.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a first configuration example of a non-reciprocal passive circuit of the present invention.

FIG. 4 is a block diagram showing a second configuration example of the nonreciprocal passive circuit of the present invention.

FIG. 5 is a block diagram showing a third configuration example of the nonreciprocal passive circuit of the present invention.

FIG. 6 is a block diagram showing a fourth configuration example of the nonreciprocal passive circuit of the present invention.

FIG. 7 is a block diagram showing a conventional technique.

[Explanation of symbols]

101, 102, 103, 104 Transmission / reception antennas 105, 106, 107, 108 Non-reciprocal passive circuit 109, 110, 111, 112 Reception circuit 113 Reception antenna selection switch 114 RSSI comparison circuit 118 Transmission antenna selection switch 119, 120, 121, 122 power amplifier 123, 124, 125, 126 phase shifter 127, 128, 129, 130 weighting circuit 131 combining circuit

Claims (6)

[Claims] 1. 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 arranged at a distance, The receiving levels of the nonreciprocal passive circuit to be separated, the plurality of receiving circuits respectively connected to the plurality of antennas via the transmitting and nonreciprocal passive circuit, and the receiving levels of the respective antennas detected by the plurality of receiving circuits are compared. A comparison circuit, a plurality of power amplifiers respectively connected to the plurality of antennas via the transmission / reception switching means, and a transmission signal is sent to any one of the plurality of power amplifiers based on a comparison result of the comparison circuit. And a transmitting antenna selection switch means for performing the diversity device. 2. The diversity apparatus according to claim 1, further comprising an antenna selection switch that selects one of the plurality of reception circuits based on a comparison result of the comparison circuit. 3. A phase shifter for matching the phases of the respective received signals received by the plurality of receiving circuits, a weighting circuit for performing a predetermined weighting on the respective received signals, and a synthesizing circuit for synthesizing these respective received signals. The diversity device according to claim 1, further comprising: 4. The diversity apparatus according to claim 1, wherein the non-reciprocal passive circuit includes a circulator and an isolator. 5. The diversity device according to claim 1, wherein the non-reciprocal passive circuit includes a circulator and a switch controlled by a transmission / reception switching signal. 6. The non-reciprocal passive circuit includes a circulator and a switch controlled by a transmission / reception switching signal.
4. The diversity device according to claim 1, further comprising a terminating resistor connected by the switch during transmission.