JPH08321798A - Diversity device - Google Patents

Abstract

PURPOSE: To provide the diversity device capable of conducting efficient transmission by the use of a low output power amplifier. CONSTITUTION: The diversity device uses plural (at least two) transmission reception common use antennas 101 to 104 each making transmission/reception at a single frequency and arranged at a distance spatially to conduct diversity transmission reception and is provided with transmission reception changeover means 105 to 108 switched by a transmission/reception switching signal and plural power amplifiers 119 to 122 connecting respectively to the antennas 101 to 104 via the transmission reception changeover means 105-108. Furthermore, a transmission antenna switch means 118 sends a transmission signal selectively to any of the power amplifiers 119 to 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. 3, signals received by antennas 1 and 2 spatially separated from each other 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 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. And transmitting antenna 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 denotes a transmission / reception dual-purpose antenna arranged spatially at a distance, and a transmission / reception changeover switch 105 as a transmission / reception changeover unit which is changed over at a predetermined timing by a transmission / reception changeover signal transmitted from a system control circuit (not shown). , 106, 107, 108. Reference numerals 109, 110, 111, and 112 denote receiving circuits connected to the antennas 101 to 104 via the transmission / reception changeover switches 105 to 108, and perform frequency conversion, band limitation, amplification, etc. of signals input from the antennas. The signal received by each of the receiving circuits 109 to 112 is sent to the receiving antenna selection switch 113 for diversity reception, and its receiving level (RSSI) is measured,
This measurement result is sent to the RSSI comparison circuit 114.
In the RSSI comparison circuit 114, the RSSI from each reception circuit
And the control signal for selecting the antenna with the highest reception level is sent to the reception antenna selection switch 113 to control the changeover switch 113. As a result, of the antennas 101 to 104, the signal received by the antenna having the highest reception level is sent to the demodulation circuit 115, the digital signal is demodulated, and the post-detection selection diversity is performed in this manner.

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.

The power amplifiers 119 to 122 are connected to the antennas 101 to 101 via transmission / reception changeover switches 105 to 108.
Since each of the antennas is provided in each of the 104 and further after the transmitting antenna selection switch 118, it is not necessary to consider the loss of the transmitting antenna selection switch in the latter stage of the power amplifier, and the output is lower than that of the conventional technology. Can be composed of

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.

[0015]

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 they are installed in the latter stage, these power amplifiers have no loss due to the transmitting antenna selection switch in the latter stage of the power amplifier,
It can be configured with a relatively small output. 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 will not function. Can be prevented
High system reliability can be secured.

[Brief description of 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 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 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 (3)

[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 transmission / reception 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. A diversity device comprising: an antenna selection switch means. 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: