JP2965821B2 - Wireless relay device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is used for relaying radio signals. In particular, the present invention relates to detection of radio wave wraparound between a transmitting antenna and a receiving antenna. Further, the present invention relates to the prevention of oscillation caused by the radio wave wraparound.

[0002]

2. Description of the Related Art In a radio relay apparatus, in order to prevent oscillation caused by a radio wave wraparound between a transmitting antenna and a receiving antenna, when amplifying and retransmitting a radio frequency reception signal, the frequency of the transmission signal is changed to the reception signal. In this case, the signal is transmitted with a slight offset from the frequency of the received signal, and an offset frequency component included in the received signal is detected to measure the amount of radio wave wraparound between the transmitting antenna and the receiving antenna. Such a technique is disclosed, for example, in
No. 2-141826 (Japanese Patent Application No. 60-28121)
9), Japanese Patent Application Laid-Open No. 62-266930 (Japanese Patent Application No. 61-266930).
1111088) and JP-A-63-79429 (Japanese Patent Application No. 61-223496). FIG. 2 shows a basic configuration disclosed in these publications.

FIG. 2 shows a block diagram of a conventional radio relay apparatus, FIG. 3 shows an example of a waveform of a radio signal to be relayed, FIG. 4 shows an example of an actual received signal waveform, and FIG. 5 shows an example of a TDMA signal waveform. Here, a configuration example in which the relay direction is one direction is shown, but when used for two-way communication, an equivalent configuration is provided in the opposite direction.

This prior art device comprises a receiving antenna 1, a coupler 2, an attenuator 3, a frequency offset circuit 4, an amplifier 5,
It includes a detector 6, a controller 7, and a transmission antenna 8. The basic operation of the wireless relay device is to receive the wireless signal 11 to be relayed by the receiving antenna 1, amplify the signal by the amplifier 5, and then transmit the signal as the transmission signal 12 from the transmitting antenna 8. In a communication system in which a plurality of wireless channels are transmitted from a wireless base station such as an automobile telephone, the wireless relay device relays the plurality of wireless channels simultaneously.

In such an operation, the transmitting antenna 8
A part of the transmission signal 12 from is transmitted to the reception antenna 1 as a loop signal 13. Assuming that the relay gain of the wireless relay apparatus is G and the coupling attenuation between the transmitting antenna 8 and the receiving antenna 1 is L, the total gain of the loop signal 13 is positive when L <G, and the system is unstable. As a result, oscillation occurs, which adversely affects the communication system.

Therefore, the frequency offset circuit 4
The frequency of the transmission signal 12 is offset from the radio signal 11 to be relayed. However, the radio channel of the transmission signal 12 is the same as the radio signal 11. The frequency offset amount is an amount that does not affect communication, for example, 800 MHz
It is about 100 Hz for the band signal. Here, it is assumed that the signal level of the radio signal 11 to be relayed is constant as shown in FIG. Since the wraparound signal 13 from the transmitting antenna 8 is superimposed on this radio signal 11, the receiving antenna 1
As shown in FIG. 4, a beat having a frequency equal to the amount of offset by the frequency offset circuit 4 is generated in the envelope received by. The magnitude of this beat accurately represents the level difference between the radio signal 11 to be relayed and the transmission signal 12. The relay gain is controlled by measuring the beat amount.

That is, the signal received by the receiving antenna 1 is split by the coupler 2, and the beat amount of the split signal is measured by the detector 6. Thereby, the amount of the wraparound signal 13 from the transmitting antenna 8 to the receiving antenna 1 can be accurately detected. If this amount increases and the danger of oscillation occurs,
The relay gain is reduced by the controller 7 to prevent oscillation.
In the example shown in FIG. 2, the attenuator 3 is provided in a stage preceding the frequency offset circuit 4, and the level of the attenuator 3 is adjusted to control the relay gain. In a communication method in which a plurality of wireless channels are transmitted from a wireless base station such as an automobile telephone, the detector 6 performs measurement for each wireless channel and performs control so as to correspond to the channel having the largest wraparound amount.

[0008]

However, the conventional wireless relay device is not suitable for relaying a wireless signal whose signal level fluctuates in a burst manner. For example, TDMA (time division multiplex communication) used in digital mobile communication systems
In the signal, a plurality of signals (for example, three channels) are multiplexed, and depending on a communication state such as whether each channel is communicating or not,
The signal level of each channel slot is different. That is, as shown in FIG. 5, the envelope of the wireless signal periodically fluctuates like a burst. In such a case, in the above-described conventional wireless relay device, even when the wraparound signal is minute, a large envelope variation is measured when a burst-like fluctuating wave is received, and erroneously detected as occurrence of a beat caused by the wraparound signal. Resulting in. For this reason, the gain of the relay device is reduced, which adversely affects communication.

SUMMARY OF THE INVENTION It is an object of the present invention to solve such a problem and to provide a radio relay apparatus capable of preventing a malfunction of the loop detection / oscillation prevention control even when a signal fluctuates in a burst manner.

[0010]

According to the present invention, there is provided a radio relay apparatus comprising: a receiving means for receiving a radio frequency signal; an amplifying means for amplifying a reception output of the receiving means; and a radio signal using the output of the amplifying means as a relay signal. A transmitting means for transmitting to the section, a frequency offset means for giving a minute frequency offset to a radio frequency of a signal transmitted from the transmitting means in the same radio channel, and an interference component generated in a reception output of the receiving means by the frequency offset. In a wireless relay device including a detection unit that detects a signal transmitted from a transmission unit to a reception unit, a sampling measurement unit that samples a reception output at regular intervals and measures a signal level thereof, The level difference between two consecutive signal levels measured by the measuring means is predetermined When exceeded is characterized by comprising determination means for determining that it has received the bursty fluctuation wave.

When the level adjusting means for adjusting the transmission level of the transmitting means, that is, the relay gain, with respect to the receiving level of the receiving means in accordance with the output of the detecting means, and when the judging means judges that a burst-like fluctuating wave has been received, this level is determined. And means for interrupting the level adjustment by the adjusting means.

[0012]

The received signal is measured for each radio channel, and if the level of the received signal fluctuates rapidly, it is regarded that the level of the received signal fluctuates in a burst. Then, the measurement of the wraparound signal detection is interrupted or transferred to another channel to prevent malfunction of the wraparound detection control.

[0013]

FIG. 1 is a block diagram showing a wireless relay apparatus according to an embodiment of the present invention.

This radio relay apparatus includes a receiving antenna 1 as a receiving means for receiving a radio frequency signal, an amplifier 5 as an amplifying means for amplifying the reception output of the receiving antenna 1, and outputs the output of the amplifier 5 to a relay signal. A transmission antenna 8 is provided as a transmission means for transmitting to a wireless section.
Further, a frequency offset circuit 4 is provided in front of the amplifier 5 as frequency offset means for giving a small frequency offset to the radio frequency of the signal transmitted from the transmission antenna 8 within the same radio channel. A coupler 2 and a detector 6 are provided as detection means for detecting a signal transmitted from the transmission antenna 8 to enter the reception antenna 1 due to an interference component generated in the reception output. Further, the transmission antenna 8 with respect to the reception level of the reception antenna 1 according to the output of the detector 6.
A controller 7 and an attenuator 3 are provided as level adjusting means for adjusting the transmission level of the signal.

The present embodiment is characterized in that a sampling circuit 9 is provided as sampling measuring means for sampling the reception output of the reception antenna 1 at regular intervals and measuring its signal level.
When the level difference between two consecutive signal levels measured by the above exceeds a predetermined value, a judging means for judging that a burst-like fluctuating wave has been received is provided in the controller 7. . The controller 7 further includes control means for interrupting the level adjustment by the attenuator 3 when it is determined that a burst-like fluctuating wave has been received.

The basic operation of this radio relay device is to receive a radio signal 11 to be relayed by a receiving antenna 1, amplify the reception output by an amplifier 5, and transmit the amplified signal as a transmission signal 12 from a transmission antenna 8. is there.

The reception output of the reception antenna 1 is branched by a coupler 2, one of which is input to an amplifier 5 via an attenuator 3 and a frequency offset circuit 4. The attenuator 3 adjusts the relay gain of the wireless relay device as a whole.
The frequency offset circuit 4 applies a frequency offset to the input signal of the amplifier 5 so that the frequency of the transmission signal 12 has a minute frequency offset that does not change the wireless channel.

The other reception output branched by the coupler 2 is input to a detector 6 and a sampling circuit 9. The detector 6 measures the amount of beat included in the reception output, and detects the amount of the sneak signal 13 from the transmission antenna 8 to the reception antenna 1. The controller 7 controls the amount of attenuation of the attenuator 3 according to the output of the detector 6, and controls the relay gain. As a result, oscillation caused by the radio wave wraparound is prevented.

The sampling circuit 9 samples the input signal from the coupler 2 at regular time intervals, and outputs it to the level detection circuit 10. The sampling speed is, for example, 1000 samples per second. The level detection circuit 10 detects a signal level for each sampling. The controller 7 compares the level with the previous sample for each sample. If the level difference in the comparison exceeds a predetermined value, the controller 7 determines that the change is a burst-like level change and reduces the relay gain. Control so that you do not.

This operation will be described in more detail with reference to FIGS.

As shown in FIG. 4, due to the radio signal 11 to be relayed and the wraparound signal 13 from the transmitting antenna 8, a beat of a frequency equal to the offset by the frequency offset circuit 4 is included in the signal received by the receiving antenna 1. Occur. At this time, the beat fluctuates like a sine wave,
The level difference between two consecutive samples by the sampling circuit 9 is as small as, for example, 3 dB or less. On the other hand, when the signal fluctuates in bursts as in the TDMA system, as shown in FIG. 5, when the envelope of the received signal fluctuates, two samples between two consecutive samples at the burst change point are obtained. The level greatly varies, for example, 5 dB or more.

Therefore, a prescribed value of, for example, 3 dB is provided in advance in the controller 7, and when the level difference between consecutive samples is within the prescribed value, a beat is detected to measure the amount of the sneak signal, and the sneak signal is used. If there is a risk of oscillation, gain adjustment control is performed. On the other hand, if the level difference between successive samples is equal to or greater than the specified value, it is assumed that the input signal has fluctuated in a burst manner, and the gain adjustment control is stopped until the received signal no longer fluctuates in a burst manner. In mobile communication and other multi-carrier communication systems, when a burst-like variation in a received signal is detected during beat measurement, the beat measurement of that channel is stopped, and the beat is transferred to another channel and measured.

In the above embodiment, the relay gain is adjusted using the attenuator 3 different from the amplifier 5. However, the present invention can be similarly implemented by directly adjusting the gain of the amplifier 5. Further, a different arrangement of the attenuator 3 and the frequency offset circuit 4 from the above-described embodiment is possible.

[0024]

As described above, the radio relay apparatus of the present invention provides a frequency offset to the radio frequency of a transmission signal and measures the amount of beat generated in the reception signal due to the wraparound of the transmission signal. If there is a sudden change in the level, it is considered that the signal fluctuates in a burst. This prevents erroneous detection of a wraparound when a burst signal is received, thereby preventing erroneous adjustment of relay gain. Therefore, there is an effect that a radio signal that fluctuates in a burst, such as a TDMA signal, can be relayed while preventing oscillation caused by a radio wave wraparound.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a wireless relay apparatus according to an embodiment of the present invention.

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

FIG. 3 is a diagram showing a waveform example of a wireless signal to be relayed.

FIG. 4 is a diagram showing a waveform example of a reception signal on which a wraparound signal is superimposed.

FIG. 5 is a diagram showing a waveform example of a TDMA signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiving antenna 2 Coupler 3 Attenuator 4 Frequency offset circuit 5 Amplifier 6 Detector 7 Controller 8 Transmission antenna 9 Sampling circuit 10 Level detection circuit 11 Radio signal to be relayed 12 Transmission signal 13 Sneak signal

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 7/14-7/195 H04B 7/22

Claims (2)

(57) [Claims] A receiving means for receiving a radio frequency signal; an amplifying means for amplifying a reception output of the receiving means; a transmitting means for transmitting an output of the amplifying means as a relay signal to a wireless section; Frequency offset means for giving a small frequency offset to the radio frequency of the signal to be transmitted within the same radio channel; and reception of the signal transmitted from the transmission means by an interference component generated in the reception output of the reception means due to the frequency offset. A wireless relay device provided with a detecting means for detecting a wraparound to the means; a sampling measuring means for sampling a reception output of the receiving means at regular intervals and measuring a signal level thereof; Level difference between two consecutive signal levels exceeds a predetermined value A wireless relay device comprising: a determination unit for determining that a fluctuating wave is sometimes received. 2. A level adjusting means for adjusting a transmission level of the transmitting means with respect to a receiving level of the receiving means in accordance with an output of the detecting means, and when the judging means judges that a burst-like fluctuating wave has been received. 2. The wireless relay apparatus according to claim 1, further comprising: means for interrupting level adjustment by said level adjusting means.