JPH04236520A - Radio relay system - Google Patents

Abstract

PURPOSE:To realize the radio relay system able to improve the line quality in the radio relay system adopting the diversity switching system with respect to the radio relay system. CONSTITUTION:A frequency diversity synthesis means 6 is provided to an active channel receiver 4 and a standby channel receiver 5 of an intermediate relay station 3 inserted between both transmission reception terminal stations 1, 2 in the radio relay system in which the transmission terminal station 1 having a standby channel with respect to an active channel sends a radio signal through both the channels and the reception terminal station 2 selects and receives a signal of one channel, and the phase and amplitude of signals of both the channels are adjusted at a high and an intermediate frequency band and the result is synthesized and outputted.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a wireless relay system,
In particular, the present invention relates to a radio relay system in which diversity combining is performed for each relay section in a radio relay line that performs diversity switching between terminal stations based on a working channel and a protection channel.

[0002] In radio relay systems, line quality often deteriorates due to frequency selective fading. Therefore, a wireless relay method is used that prevents line quality deterioration by using a working channel and a protection channel and performing diversity switching between terminal stations.In this case, line quality deteriorates in different channels for each relay section. It is desired to be able to reduce line quality deterioration even when this occurs.

0003

[Prior Art] Adopted in a radio relay system of the N+1 route protection system, which has one protection channel for each N working channel, or the 1+1 twin path system, which has one protection channel for one working channel. Examples of methods used to improve line quality include the frequency diversity method and the space diversity method. Conventionally, when adopting a frequency diversity method to improve line quality, the status of each working channel and backup channel was monitored at the baseband at the end station, and switching was performed to select a channel with higher quality. A method is generally used that reduces deterioration of line quality during wireless transmission by doing so.

FIG. 5 shows a conventional wireless relay system in which intermediate relay stations B and C are placed between terminal stations A and D. ing. Station A and station D each have a changeover switch SW, and transmit the same signal from the transmitting terminal station to the working channel and protection channel using different radio frequencies, and the receiving terminal station converts the received signal into a baseband signal. By converting the signal into a digital signal and then selecting a channel with better line quality for reception, deterioration in line quality can be prevented even if frequency selective fading occurs in the wireless section.

[0005]

OBJECTS OF THE INVENTION The frequency diversity system is very effective as a method for reducing deterioration in line quality when frequency selective fading occurs. However, in the frequency diversity method in the conventional radio relay system, as shown in FIG. 5, switching between the working channel and the protection channel is performed in the baseband, and therefore it can only be performed on a terminal station basis.

[0006] Therefore, if there is deterioration in line quality in the working channel and the protection channel in different relay sections, there is a problem in that the improvement effect of the frequency diversity method cannot be expected. In Figure 5,
The × mark indicates a line quality deterioration section; on the working channel, there is a line quality deterioration section between stations B and C; on the protection channel, there is a line quality deterioration section between A and B stations; Even if channel switching is performed between the station and the D station for frequency diversity, deterioration in line quality cannot be prevented.

On the other hand, in order to obtain the effect of improving line quality in each relay section, it is necessary to turn all stations into terminal stations and convert the signals to baseband, but in this case, the terminal station equipment is Since it is expensive, there is a problem in that it is impossible to avoid a significant increase in line construction costs.

The present invention aims to solve the problems of the prior art, and provides a wireless relay system that can improve line quality in a diversity switching wireless relay system with minimum cost increase. is intended to provide.

[0009]

[Means for Solving the Problems] The present invention provides a protection channel for a working channel, transmits radio signals through both channels at a transmitting terminal station, and selects and receives signals from one channel at a receiving terminal station. In a wireless relay system, the phase and amplitude of the signals of both channels are transmitted to one or both of the working channel receiver and backup channel receiver of the intermediate relay station inserted between the two end stations in the high frequency band or intermediate frequency band. The present invention is characterized in that it is provided with a frequency diversity combining means for combining and outputting after adjustment.

The present invention also provides a radio relay system in which a protection channel is provided for a working channel, a transmitting terminal station transmits radio signals through both channels, and a receiving terminal station selects and receives the signal of one channel. Transmitting the radio signal of the working channel and the radio signal of the protection channel through different spatial paths, and transmitting the radio signal of the working channel and the radio signal of the protection channel to one or both of the receiver of the working channel and the receiver of the protection channel of an intermediate relay station inserted between both end stations, space diversity combining means that adjusts the phase and amplitude of signals transmitted through different spatial paths in a high frequency band or an intermediate frequency band, and then combines the signals; The present invention is characterized in that it is provided with frequency diversity synthesis means for adjusting the phase and amplitude in the band, and then synthesizing and outputting the result.

[0011]

[Operation] FIG. 1 shows the basic configuration of the present invention, in which (a) shows a working channel receiver 4 and a protection channel receiver 5 of an intermediate relay station 3 between both terminal stations 1 and 2. Toni,
A case in which a frequency diversity combining means 6 is provided is illustrated.

[0012] When line quality deterioration is detected at the terminal station 2 on the receiving side, a transmission parallel command is sent from the terminal station 2 to the terminal station 1 on the transmitting side, and the transmission switch TSW in the terminal station 1 is switched. , the same signal is transmitted as radio signals of different frequencies to the working channel and the protection channel. In the intermediate relay station 3, the signals are received by receivers 4 and 5, and after processing such as amplification, are transmitted to the terminal station 2 via transmitters 9 and 10, respectively. In the terminal station 2, the reception switch RSW selects and receives the signal of the working channel and the protection channel, whichever has better line quality, thereby obtaining the effect of improving line quality by frequency diversity switching.

At this time, the receivers 4 and 5 have frequency diversity combining means 6 in one or both of them, and combine the signals of the working channel and the protection channel after adjusting the phase and amplitude in the high frequency band or intermediate frequency band. and output it. Transmitters 9 and 10 transmit the outputs of receivers 4 and 5, respectively, as radio signals of different frequencies.

Therefore, according to the configuration (a), in a radio relay system in which a plurality of intermediate relay stations 3 having such a configuration are arranged between the terminal stations 1 and 2, the working channel and the working channel are connected in different relay sections. Even if there is line quality deterioration in each protection channel, it is possible to obtain the effect of improving line quality by frequency diversity combining.

In FIG. 1(b), space diversity combining means 7 and frequency diversity combining means 8 are installed in the working channel receiver 4 and the protection channel receiver 5 of the intermediate relay station 3 between the terminal stations 1 and 2. The example below shows the case where .

The configuration and operation of the terminal stations 1 and 2 in this case are the same as in the case (a). The receivers 4, 5 have a space diversity combining means 7 in one or both of them, and adjust the phase and amplitude of the signals of the working channel and the protection channel transmitted by different spatial paths in the high frequency band or intermediate frequency band. Then synthesize. Furthermore, it has a frequency diversity combining means 8, which adjusts the phase and amplitude of the output of the space diversity combining means 7 and the signal of the opposite channel in a high frequency band or an intermediate frequency band, and then combines and outputs the result. transmitter 9,
10 transmits the outputs of the receivers 4 and 5 as radio signals of different frequencies.

Therefore, according to the configuration (b), in a radio relay system in which a plurality of intermediate relay stations 3 having such a configuration are arranged between the terminal stations 1 and 2, the working channel and the working channel are connected in different relay sections. Even if there is line quality deterioration in the backup channel, it is possible to obtain the line quality improvement effect by space diversity combining and the line quality improvement effect by frequency diversity combining.

[0018]

[Embodiment] FIG. 2 shows an example of the configuration of a receiver of an intermediate relay station of a wireless relay system to which the present invention is applied, in which 11 is a receiving antenna, 12 is an embodiment of the present invention.
, 13 is a circulator that branches the input signal from the antenna 11; 14 and 15 are filters (FIL) that extract reception signals of different frequencies from the branched signals;
16 and 17 are receivers for the working channel and protection channel, respectively. Moreover, in the receivers 16 and 17,
RFA1, RFA2 are high frequency amplifiers, MIX1, MIX
2 is a mixer, LO1 and LO2 are local oscillators, IFA1,
IFA2 is an intermediate frequency amplifier, HYB1 and HYB2 are hybrids that separate and combine signals, DET is a detector for a received signal, and EPS is an infinite phase shifter that shifts the phase of an input signal.

The working channel signal and the protection channel signal, which are the same signals having different frequencies f1 and f2 inputted from the antenna 11, pass through circulators 12 and 13 and filters 14 and 15, and are converted into a signal of frequency f1. and a signal of frequency f2,
The signal is input to a receiver 16 for the working channel and a receiver 17 for the protection channel. The signals input to both receivers 16 and 17 have their amplitudes adjusted by high-frequency amplifiers RFA1 and RFA2, respectively, and are frequency-converted by mixers MIX1 and MIX2 using local oscillators LO1 and LO2 of different frequencies, so that the signals have the same frequency. IF (intermediate frequency) signals are generated, the amplitudes of which are adjusted by intermediate frequency amplifiers IFA1 and IFA2, respectively, and input to hybrids HYB1 and HYB2.

The IF signal of the protection channel receiver 17 is divided by the hybrid HYB2, and one of the signals is sent to the hybrid HYB1 of the receiver 16 for the working channel via an infinite phase shifter EPS. In the receiver 16 for the working channel, the IF signal of the working channel from the intermediate frequency amplifier IFA1 and the IF signal from the receiver 17 for the protection channel input via the infinite phase shifter EPS are combined by the hybrid HYB1. , an output is generated via the detector DET, but at this time, the infinite phase shifter EPS controls the phase of the output signal so that the combined signal is in the best condition according to the control signal from the detector DET. do.

The IF signal output of the working channel and the IF signal output of the protection channel are converted into signals with the original frequencies f1 and f2, or with signals of different frequencies, for example, f3 and f4, through a transmitter (not shown). and then sent to the next intermediate relay station or terminal station on the receiving side.

Therefore, according to the configuration shown in FIG. 2, frequency diversity synthesis is performed in the intermediate frequency band using the signal of the working channel and the signal of the protection channel.
Even if frequency selective fading occurs in the radio section before this intermediate relay station, in the working channel,
Deterioration of line quality due to this can be prevented. In this case, instead of performing frequency diversity synthesis in the intermediate frequency band, frequency conversion is performed in the high frequency band to make the signal of the working channel and the signal of the protection channel the same frequency signal, and the frequency is Diversity combining may also be performed.

FIG. 3 shows another embodiment of the present invention, and shows an example of a line configuration for three sections in a 1+1 twin path wireless relay system to which the configuration shown in FIG. 2 is applied. , A station, and D station are terminal stations, B station and C station are intermediate relay stations, and the signal flows from A station toward D station. Station A has a transmission switch TSW. Further, the D station has a reception switch RSW. In station B, 21 and 22 are a receiver for one working channel and a receiver for a protection channel, respectively. receiver 21,
22, AMP is an amplification unit, HYB is a hybrid that branches a signal, EPS is an infinite phase shifter that shifts the phase of a signal,
DET is a detector for the received signal, SW is a changeover switch for receiving the output of the infinite phase shifter EPS of the other receiver, and COMB is a switch for receiving the output of the infinite phase shifter EP of the other receiver.
This is a coupling unit that combines the signals of other channels from S and generates an output. Station C, which is another intermediate relay station, also has the same configuration as station B.

[0024] When station D detects deterioration in the line quality of the working channel 1, the transmission switch TS of station A is changed from station D to station A.
A sending parallel signal is sent to W. When the transmission switch TSW is switched at station A, the same signal is converted into two radio signals with different frequencies f1 and f2.
channel and a spare channel. At station B, which is an intermediate relay station, after confirming that the transmission switch TSW has been switched, the changeover switches SW of the receivers 21 and 22 are switched to switch between the working channel 1 and the backup channel, respectively. Combining with the signal is performed to perform frequency diversity reception. At station C, which is an intermediate relay station, combining is performed in the same manner, and frequency diversity reception is performed.

In this manner, in the configuration shown in FIG. 3, in each section, the signal of the working channel and the backup channel are combined with the signal of the opposite channel, and frequency diversity reception is performed for each section. Even if line deterioration due to selective fading occurs simultaneously in different sections and different channels, line quality can be improved.

FIG. 4 shows still another embodiment of the present invention, which is a triple diversity system that combines the frequency diversity method and the space diversity method by applying the configuration shown in FIG. 31 shows the configuration of the intermediate relay station in the main antenna (MA
INANT), 32 is a space diversity antenna (SDANT), 33 is a circulator, 34, 35
are filters (FIL) for extracting received signals of different frequencies, 36 is a working channel receiver, and 37 is a protection channel receiver. In the receiver 36 of the working channel, COMB1 is a combining unit for performing space diversity combining, and COMB2 is a combining unit for performing frequency diversity combining. Moreover, in the receiver 37 of the protection channel, HYB is a hybrid that branches signals.

The same two received signals having different frequencies f1 and f2 inputted from the main antenna 31 pass through a circulator 33 and filters 34 and 35, and are separated into a signal with a frequency f1 and a signal with a frequency f2. The information is input to machines 36 and 37. In the receiver 36 of the working channel, the received signal of the frequency f1 which is the output of the filter 34 and the signal of the frequency f1 received via the space diversity antenna 32 are combined in the combining unit COMB1, resulting in a normal signal. Space diversity synthesis is performed. On the other hand, the frequency f2 received at the receiver 37 of the backup channel
is split in the hybrid HYB and combined in the combination COMB2 with the output signal of frequency f1 from the combination COMB1 as explained in the embodiment of FIG. 2, thereby performing frequency diversity synthesis. It will be done.

According to the example shown in FIG. 4, since frequency diversity combining is performed after normal space diversity combining, triple diversity reception is performed in conjunction with frequency diversity switching at the receiving end station (not shown). be able to. Therefore, according to the configuration of FIG. 4, a triple diversity reception system can be realized at low cost with a simple configuration, and the effect of improving line quality is large. Note that such space diversity combining and frequency diversity combining can be performed in either or both of the working channel receiver 36 and the protection channel receiver 37.

[0029]

[Effects of the Invention] As explained above, according to the present invention, when line quality deteriorates, a radio signal is transmitted from a transmitting terminal station through a working channel and a protection channel, and the receiving terminal station performs diversity switching and receives the signal. In this wireless relay system, frequency diversity synthesis is performed in the high frequency band or intermediate frequency band in one or both of the working channel receiver and backup channel receiver of the intermediate relay station. Even if line quality deterioration occurs due to selective fading at different frequencies, the effect of line quality improvement can be achieved. In addition, in such a wireless relay system,
Space diversity combining is performed in the high frequency band or intermediate frequency band in one or both of the working channel receiver and backup channel receiver of the intermediate relay station, and then frequency diversity combining is performed, so that the relay line also has different Even if line quality deterioration occurs due to selective fading in sections and different frequencies, the effect of improving line quality can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of the present invention.

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

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing still another embodiment of the present invention.

FIG. 5 is a diagram showing a conventional wireless relay system.

[Explanation of symbols]

1, 2 Terminal 3 Intermediate relay station 4,5 Receiver

Claims (2)

[Claims] Claim 1: A wireless relay that has a backup channel for a working channel, transmits wireless signals through both channels at a transmitting terminal station (1), and selects and receives signals from one channel at a receiving terminal station (2). In the system, signals of both channels are sent to one or both of the working channel receiver (4) and the backup channel receiver (5) of the intermediate relay station (3) inserted between the end stations (1, 2). 1. A wireless relay system characterized in that a frequency diversity combining means (6) is provided which adjusts the phase and amplitude of the signals in a high frequency band or an intermediate frequency band, and then synthesizes and outputs the synthesized signal. Claim 2: A wireless relay that has a backup channel for the working channel, transmits wireless signals through both channels at a transmitting terminal station (1), and selects and receives signals from one channel at a receiving terminal station (2). In the system, a working channel radio signal and a protection channel radio signal are transmitted through different spatial paths, and the working channel receiver ( space diversity combining means (7) for adjusting the phase and amplitude of signals transmitted through different spatial paths in a high frequency band or an intermediate frequency band and then combining them in one or both of the receiver (5) of the spare channel and the receiver (5) of the spare channel; , frequency diversity combining means (7) for adjusting the phase and amplitude of the output of the space diversity combining means (7) and the signal of the opposite channel in a high frequency band or an intermediate frequency band, and then combining and outputting the resultant signal;
8) A wireless relay system characterized by providing.