JP2007116340A - Communication repeater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform, with stable communication quality, bidirectional communication at a range of sub-millimeter wave band to milliwave band, a long range of cable or wireless communication, and bidirectional communication in case there exists a communication obstacle, by effectively using a standard TDD modem for wireless LAN as it is. <P>SOLUTION: The communication repeater repeats and transmits communication signals sent/received between one modem 1 of TDD system and the other modem. It comprises a trunk signal path R0 for transmitting communication signals on the side of one modem 1, first and second signal paths R1 and R2 provided on the other modem sides parallel to each other for transmitting transmission signals and reception signals of one modem 1, a transmission signal detecting circuit Z1 which detects whether a transmission signal is generated or not from one modem 1 based on the split signal from the trunk signal path R0, and a high frequency switch 31 for connecting the trunk signal path R0 either to a first signal path R1 or second signal path R2, based on the detection signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a communication relay device that relays and transmits a communication signal transmitted and received between one modem and another modem in a time division multiple overlap communication system.

In recent years, wireless LAN systems have become widespread for individuals, and communication devices used for them have been greatly reduced in cost as general-purpose products.
A typical example of a general-purpose communication device (spread product) used in a wireless LAN system that is currently in widespread use is connected to a communication entity such as a personal computer, and performs time-division multiple-duplex communication (TDD) communication. There are modems to be used (hereinafter referred to as TDD modems), frequency converters that mutually convert frequencies between wired communication signals and 2.4 GHz or 5 GHz band radio signals. It is preferable to configure a communication system using such communication apparatuses that are already widely used, because resource saving and cost reduction can be achieved.

By the way, although the frequency (radio frequency) of the radio wave that can be used for the radio communication is assigned based on the regulations of the Radio Law, the shortage of the frequency band at a frequency of about 10 GHz or less has become apparent.
For example, a 2.4 GHz band wireless LAN system uses 2.4 to 2.5 GHz (100 MHz band) of an ISM (Industrial, Science, and Medical) band. In this case, for example, in a wireless LAN system compliant with IEEE802.11g having a communication speed of 54 Mbps at the maximum, only four wireless channels can be used independently without radio wave interference. In addition, even in a 5 GHz band wireless LAN, there is no great difference in the situation, and only a few channels can be used independently without radio wave interference. If the number of users increases significantly in the near future, there is a concern that a sufficient communication speed cannot be obtained at each terminal due to the limitation of the number of radio channels.
In principle, it is possible to multiplex radio channels into a plurality of channels by paralleling a plurality of modems in order to increase the communication speed. For example, a maximum communication speed of 108 Mbps can be obtained by multiplexing two channels of the IEEE802.11g-compliant radio channel. However, in this case, since the limited frequency band of the wireless channel is occupied by more channels, it is considered that there are many problems in practical use.

On the other hand, a vast frequency band remains in the quasi-millimeter wave to millimeter wave band exceeding 10 GHz. As the radio communication frequency of the quasi-millimeter wave to millimeter wave band, frequencies of 22 GHz band, 26 GHz band, and 38 GHz band are already assigned as subscriber wireless access (FWA) for telecommunications business, Allocation of 18 GHz band is prepared for public works, and when these are combined, it becomes possible to use a wide band close to 4 GHz.
In addition, in quasi-millimeter-wave to millimeter-wave band wireless communication, depending on the system configuration, the communication speed can usually be several tens to 100 Mbps or higher, and high-speed communication comparable to communication using optical fibers is possible. It can be realized wirelessly.
Therefore, the problem of shortage of frequency bands can be solved by the widespread use of the broadband wireless communication system utilizing the quasi-millimeter wave to millimeter wave band for wireless data communication.
Therefore, if the wireless LAN system modem that has already been widely used is effectively used and the communication signal is converted to a frequency of quasi-millimeter wave to millimeter wave for wireless communication, resource saving and cost reduction can be achieved. It is considered that the spread of the wave to millimeter wave band FWA system can be promoted.

Conventionally, Patent Document 1 discloses that a TDD modem from a master station side (TDD modem) to a slave station side modem (TDD modem) is used to effectively use a TDD modem used in an existing wireless LAN. A millimeter wave wireless communication system (conventional example 1) is shown in which a transmission signal (2.4 GHz band, 5 GHz band) is converted into a frequency of 60 GHz and wirelessly transmitted.
FIG. 8 schematically shows a basic configuration of a wireless communication system A according to Conventional Example 1 shown in Patent Document 1. As shown in FIG.
As shown in FIG. 8, in the wireless communication system A of the conventional example 1, the master station modem 1 (TDD modem) has a transmission signal frequency from the modem frequency f0 (2.4 GHz band or 5 GHz band) to millimeter waves. A frequency up-converter device 81 for converting the frequency to the band frequency f1 is connected, and the slave station modem 2 (TDD modem) converts the frequency of the received signal from the antenna from the frequency f1 of the millimeter wave band to the frequency f0 of the modem. A frequency down-converter device 82 is connected. This makes it possible to effectively use the TDD modem for wireless LAN and perform wireless transmission in the millimeter wave band in a single direction from the master station to the slave station.

As another conventional example, Non-Patent Document 1 discloses a dual-band wireless LAN system that converts a frequency of a communication signal of a 5 GHz band wireless LAN to a 25 GHz band (Conventional Example 2).
FIG. 9 schematically shows a basic configuration of a wireless communication system B according to Conventional Example 2 shown in Non-Patent Document 1.
As shown in FIG. 9, the wireless communication system B of the conventional example 2 transmits the communication signal (baseband signal) to the TDD modems 1 and 2 on the master station side and the slave station side in the baseband for each direction of transmission / reception Frequency converter devices 91 and 92 that convert bidirectionally between a signal frequency f0 (5 GHz band) and a quasi-millimeter wave frequency f1 (25 GHz band) are connected. Furthermore, switches 93 and 94 are provided between the modems 1 and 2 and the frequency converter devices 91 and 92, and these switch the signal path between the transmission side and the reception side in synchronization with the transmission / reception timing of TDD communication. As a result, the basic function of the TDD modem for wireless LAN can be utilized to enable wireless communication in the quasi-millimeter wave band.
In addition, when the distance between the master station TDD modem and the slave station TDD modem is long or there is an obstacle in the communication path, the communication signal is amplified between the TDD modems to ensure stable communication. In some cases, it is desirable to arrange a relay device to be used.
JP 2003-168986 A 2003, IEICE "Communications Society Conference Proposal", B-5-173

However, in the configurations of the conventional example 1 and the conventional example 2, as shown below, when the signal attenuation is large due to a long distance between modems or an obstacle in the communication path, There is a problem that bidirectional communication cannot be performed while ensuring stable communication quality by effectively using the TDD modem.
For example, the configuration of the conventional example 1 has a problem that only wireless transmission in the downlink direction (from the master station to the slave station) is possible. Even if the communication signal of the TDD modems 1 and 2 is simply branched and a frequency up-converter device is provided on the slave station side and a down-converter device is provided on the master station side on the upstream side (slave station → master station), There is a problem that the transmission signal of the station wraps around to the reception side and interferes as noise, and stable communication quality cannot be obtained. In particular, the longer the communication distance, or the greater the signal attenuation due to obstacles in the communication path, the more the transmission wave (radio signal) must be amplified, but the more the power level of the transmission wave is amplified, There is a problem that noise due to the sneak in the transmission signal becomes significant.
In the configuration of Conventional Example 2, a transmission / reception timing switching signal for TDD communication is required. However, a conventional TDD modem for a wireless LAN does not have a function of outputting such a switching signal externally. The TDD modem cannot be effectively used as it is. Further, when the power level of the transmission wave is large (that is, when the communication distance is long or the signal attenuation due to an obstacle or the like is large), if the separation degree of the signal switching by the switches 93 and 94 is insufficient, the transmission of the own station Stable communication quality is achieved by saturating the signal on the receiving side and saturating the amplifiers on the receiving side of the frequency converter devices 91 and 92, or by causing the switches 93 and 94 to flow backward to deteriorate the SN ratio of the baseband signal. There was a problem that it could not be obtained.
Here, it is conceivable to use a circulator to perform path switching between the transmission signal and the reception signal (path switching between the downlink signal and the uplink signal), but the degree of signal separation by the circulator (the signal in the conduction direction and the signal in the cutoff direction). (Attenuation ratio with respect to signal) is about 20 dB (attenuation ratio is 1/100) at most, so that the degree of separation is not sufficient simply by providing a circulator, and a relatively expensive component such as a circulator is not used. Is more desirable.
Therefore, the present invention has been made in view of the above circumstances, and the object of the present invention is to provide a semi-priced configuration that effectively utilizes an existing popular TDD modem such as the 2.4 GHz band and the 5 GHz band as it is. For constructing a communication system capable of performing bi-directional communication in the millimeter-wave band to millimeter-wave band, and long-distance wired or wireless or bi-directional communication in the presence of communication obstacles with stable communication quality It is to provide a communication relay device.

In order to achieve the above object, the present invention relays and transmits a communication signal transmitted and received between one modem of a time division multiple-duplex system (TDD system) and another modem. A signal path for transmitting the communication signal on the side (hereinafter referred to as a first core signal path) and a transmission path of the one modem, which is provided in parallel with the other modem side than the first core signal path. Two signal paths for transmitting each of the signal and the received signal (hereinafter, the path of the transmission signal is referred to as a first signal path and the path of the reception signal is referred to as a second signal path), and the first basic signal path Transmission signal detection means for detecting whether or not a transmission signal is being generated from the one modem based on a branch signal, and based on the detection signal, the first backbone signal path is changed to the first signal path. Or any of the second signal paths Or connecting means for switching (hereinafter, referred to as first path switching means) to which is constituted as a communication relay apparatus for and a.
With such a configuration, the signal path is separated into the first signal path and the second signal path for each transmission direction of communication signals transmitted and received between modems (TDD modems). It is not necessary to take out a control signal for switching the signal path synchronized with TDD communication, and an existing TDD modem can be effectively used as it is.
For example, if a frequency conversion means for converting the frequency of a transmission signal is provided in each of the first signal path and the second signal path, the basic function of a 2.4 GHz band or 5 GHz band TDD modem for wireless LAN Can be used for wireless communication in a quasi-millimeter wave band to a millimeter wave band with a sufficient frequency band.
In addition, if each of the first signal path and the second signal path is provided with a transmission signal amplifying means for amplifying a transmission signal, it is possible to stabilize bidirectional communication when there is a long-distance or communication obstacle. It is possible to construct a communication system that can be performed with the communication quality. When the frequency conversion means is provided, the transmission signal amplifying means is generally provided together.

Here, when the communication relay device is provided on both sides of the TDD modem of the master station and the TDD modem of the slave station, that is, the communication relay device having the master station modem as the one modem, and the slave station modem When the communication relay device having the one modem is provided, the first signal path and the second signal path are extended to the partner station side, and a downstream signal (master station transmission signal) and upstream The signal (received signal of the master station) is relayed and transmitted while the signal path (wired) is separated. In addition, an antenna (transmission antenna and reception antenna) is individually provided for each of the first signal path and the second signal path, and relay transmission is performed using a radio signal through both antennas.
On the other hand, a signal path (hereinafter referred to as a second signal path) for transmitting the communication signal (transmission signal and reception signal) to the communication relay apparatus on the other modem side than the first signal path and the second signal path. And a means for switching whether the second backbone signal path is connected to the first signal path or the second signal path based on a detection signal of the transmission signal detection means. A configuration provided with (hereinafter referred to as second route switching means) is also conceivable.
In this case, when the communication signal is relay-transmitted by wire, the signal path (wired) can be made one except outside the configuration range of the communication relay device. In addition, when relay transmission is performed wirelessly, it is possible to use both a transmission antenna and a reception antenna with one antenna provided in the second backbone signal path.

Here, as a more specific configuration of the transmission signal detecting means, for example, a branch signal attenuating means for attenuating a branch signal from the first basic signal path and a signal after the attenuation are detected, and the detection result is obtained. A high frequency detector used as a detection signal can be considered.
As a result, when the signal level (voltage level) of the transmission signal (transmission burst signal) of the one modem is higher than that of the reception signal (reception burst signal), the transmission signal detection means is very simple and inexpensive. realizable.
On the other hand, when the signal level of the transmission signal of the one modem is lower than that of the reception signal, a specific configuration of the transmission signal detection means is, for example, a branch from the first basic signal path. A branch signal attenuating means for attenuating the signal, a high-frequency detector for detecting the attenuated signal (hereinafter referred to as a first high-frequency detector), a branch signal amplifying means for amplifying the branch signal, and a signal after the amplification A detection signal of the transmission signal is a high-frequency detector for detection (hereinafter referred to as a second high-frequency detector), and a signal obtained by performing an XOR operation on both detection signals of the first high-frequency detector and the second high-frequency detector. And an XOR operation means are considered.
In addition, if the transmission signal detection unit obtains the branch signal via a directional coupler with respect to the first backbone signal path, the transmission signal and the reception signal having different transmission directions can be more reliably obtained. This is preferable because it can be detected separately.

By the way, since the TDD modem switches between transmission and reception in a time division manner, the transmission signal in the second signal path is amplified while the transmission signal detection means detects the transmission signal from the one modem. There is no need to do signal amplification. Similarly, while the transmission signal from the one modem is not detected by the transmission signal detection means, it is not necessary to amplify the transmission signal in the first signal path, and rather the signal should not be amplified.
Therefore, if a means for switching the gain of the transmission signal amplifying means (hereinafter referred to as a first gain switching means) is provided based on the detection signal of the transmission signal detection means, the signal based on the sneak signal from the other signal path Interference can be prevented, the degree of separation between the transmission signal and the reception signal can be further increased, and good communication quality can be ensured. It also saves power.

In addition, based on a branch signal from the first backbone signal path, a reception signal detection means for detecting whether a reception signal to the one modem is being generated, and on the basis of the detection signal, the first signal If the means for switching the gain of the transmission signal amplifying means provided in the signal path 2 (hereinafter referred to as second gain switching means) is provided, the second signal is generated only during the generation of the received signal. It can be controlled to sufficiently amplify the signal of the path, and is still preferable in terms of signal interference and power saving.
Here, the transmission signal detection means includes a branch signal attenuation means for attenuating a branch signal from the first backbone signal path, and a high frequency detector that detects the attenuated signal and uses the detection result as a detection signal. In this case, as a specific configuration of the received signal detecting means, a branch signal amplifying means for amplifying a branch signal from the first basic signal path, a signal after the amplification, and a detection result are detected. A second high-frequency detector serving as a detection signal, and an XOR operation means using a signal obtained by performing an XOR operation on both detection signals of the first high-frequency detector and the second high-frequency detector as a detection signal of the received signal The thing comprised by these can be considered.
Thereby, when the signal level of the transmission signal of the one modem is higher than that of the reception signal, the generation of the reception signal can be detected.

  According to the present invention, the signal path is separated into the first signal path and the second signal path for each transmission direction of communication signals transmitted and received between modems (TDD modems). There is no need to take out a control signal for signal path switching in synchronization with TDD communication, and both existing wireless communication with quasi-millimeter wave and long distance or communication obstacles exist while effectively using the existing TDD modem as it is. Can be performed with stable communication quality. Moreover, it can be realized with a cheaper configuration without using expensive parts such as a circulator.

Embodiments and examples of the present invention will be described below with reference to the accompanying drawings for understanding of the present invention. The following embodiments and examples are examples embodying the present invention, and do not limit the technical scope of the present invention.
FIG. 1 is a schematic configuration diagram of the communication relay device X1 according to the first embodiment of the present invention, FIG. 2 is a time chart of various signals in the communication relay device X1, and FIG. 3 is a second embodiment of the present invention. 4 is a schematic configuration diagram of the communication relay device X2 according to the embodiment, FIG. 4 is a diagram illustrating a time chart of various signals in the communication relay device X2, and FIG. 5 is a schematic configuration diagram of the communication relay device X3 according to the third embodiment of the present invention. 6 is a schematic configuration diagram of a communication relay device X4 according to the fourth embodiment of the present invention, FIG. 7 is a time chart of various signals in the communication relay device X4, and FIG. 8 is a basic configuration of a conventional wireless communication system A. FIG. 9 is a diagram showing a basic configuration of a conventional wireless communication system B.

<First Embodiment>
First, the communication relay device X1 according to the first embodiment of the present invention will be described using the schematic configuration diagram of FIG.
In the communication system having the communication relay device X1 as a component, a master station TDD modem, which is a time division multiple-duplex (TDD) modem used for a so-called wireless LAN, is connected to a child, which is also a TDD modem. There is a station TDD modem, and the communication relay device X1 is connected to each of the modems of both TDD systems, and relays and transmits a communication signal transmitted and received between both modems by a radio signal. Hereinafter, a modem (one modem) on the local station side to which the communication relay device X1 is connected is referred to as a TDD modem 1. The local station modem may be either a master station TDD modem or a slave station TDD modem.
Although not shown in FIG. 1, an information processing apparatus such as a personal computer is connected directly or via a communication device such as a HUB to each of the TDD modem 1 on the local station side and the TDD modem on the partner station side. Then, the TDD modems of both stations modulate the transmission signal and demodulate the reception signal.

As shown in FIG. 1, the communication relay device X1 transmits a communication signal (transmission signal and reception signal) of the TDD modem 1 on the TDD modem 1 (one modem) side of the local station. A signal path (corresponding to the first core signal path) and the TDD modem of the partner station in parallel to the core signal path R0, and each of the transmission signal and the reception signal of the TDD modem 1 of the local station Are provided with two signal paths R1 and R2. Hereinafter, a path for transmitting a transmission signal is referred to as a first signal path R1, and a path for transmitting a reception signal is referred to as a second signal path R2.
Here, the first signal path R1 is provided with an up-converter 11a that raises the frequency of a signal transmitted through the path by a predetermined frequency width, and the second signal path R2 is transmitted through the path. A down converter 21a is provided for reducing the frequency of the signal by a predetermined frequency width. Here, the up-converter 11a and the down-converter 21a are examples of frequency conversion means.
The up-converter 11a and the down-converter 21a shown in FIG. 1 perform conversion for the same frequency width. For this reason, the up-converter 11a and the down-converter 21a are provided with the frequency mixers 11 and 21 (mixers) individually, but the reference signals (reference frequency signals) input to the frequency mixers 11 and 21 respectively. Is configured to be shared by both converters 11a and 21a. Thereby, the number of frequency oscillators is reduced, the configuration is simplified and miniaturized, and power is saved.
Each of the first signal path R1 and the second signal path R2 is provided with a transmission amplifier 12 and a reception amplifier 22 (an example of transmission signal amplification means) that amplify the transmission signal.
Further, a transmitting antenna 14 for wirelessly outputting a transmission signal of the TDD modem 1 is provided at the end of the first signal path R1 on the opposite station side, and a TDD modem 1 is provided at the end of the second signal path R2 on the opposite station side. The receiving antenna 24 for inputting the received signal by radio is provided.

For example, the up converter 11a is converted from the 2.4 GHz or 5 GHz band to the quasi-millimeter wave band or the millimeter wave band, and the down converter 21a is converted from the quasi-millimeter wave band or the millimeter wave band to the 2.4 GHz band or the 5 GHz band (same If the frequency is to be converted, the 2.4 GHz band or 5 GHz band wireless LAN TDD modem can be used effectively as the TDD modem on the local station side and the remote station side, and there is a margin in frequency band allocation. Wireless communication (wireless relay) can be performed in other frequency bands such as a certain quasi-millimeter wave band to millimeter wave band.
If the up-converter 11a is to be converted from the 2.4 GHz band to the 5 GHz band and the down-converter 21a is to be frequency-converted from the 5 GHz band to the 2.4 GHz band (for the same frequency width), A 2.4 GHz band wireless LAN TDD modem can be used as the TDD modem 1, and a 5 GHz band wireless LAN TDD modem can be used as the TDD modem on the partner station side.

Further, a transmission signal detection circuit Z1 for detecting whether or not a transmission burst signal is being generated from the TDD modem 1 based on a branch signal from the signal path is connected to the basic signal path R0.
The transmission signal detection circuit Z1 in the communication relay device X1 detects a variable attenuator 41 (an example of a branch signal attenuating means) that attenuates a branch signal from the trunk signal path R0 and a signal after the attenuation, and a detection result (detection) The signal Sd1) is constituted by a high-frequency detector 42 (high-frequency detector) that outputs the transmission burst signal as a detection signal Sa. The transmission signal detection circuit Z1 can be configured by a device that supports a relatively low frequency signal, and the circuit can be simplified, downsized, and reduced in cost.
A detection signal Sa of the transmission signal detection circuit Z1 is input as a control signal between the basic signal path R0, the first signal path R1, and the second signal path R2, and the state of the detection signal Sa (ON / OFF) is provided with a high-frequency switch 31 (an example of first path switching means) that switches whether the basic signal path R0 is connected to the first signal path R1 or the second signal path R2. . Specifically, the backbone signal path R0 is connected to the first signal path R1 while the transmission burst signal is being generated (when the detection signal Sa is ON), and in other cases, the backbone signal path R0 is set to the second signal path R0. Connect to signal path R2.
Further, for each of the transmission amplifier 12 and the reception amplifier 22, FET switches 13 and 23 (switching the gains of the amplifiers 12 and 22 according to the state of the detection signal Sa (transmission burst signal detection signal) of the transmission signal detection circuit Z1 ( An example of first gain switching means) is provided.

Hereinafter, the operation of the transmission signal detection circuit Z1 will be described with reference to a time chart of various signals shown in FIG.
In the communication relay device X1, the trunk signal path R0 is directly connected to the TDD modem 1, and the transmission burst signal S1 from the TDD modem 1 reaches the trunk signal path R0 with almost no attenuation, while receiving from the other station. The burst signal S2 is a signal transmitted as a radio signal (radio wave) is input via the reception antenna 24. Therefore, the burst signal S2 is amplified by the reception amplifier 22, but is transmitted from the transmission burst signal S1 in the basic signal path R0. The signal level is low.
Therefore, as shown in FIG. 2, the level (voltage level) between the level of the transmission burst signal S1 and the level of the reception burst signal S2 at the input end of the high-frequency detector 42 (that is, the output end of the variable attenuator 41). If the attenuation level of the variable attenuator 41 is adjusted in advance so that the detection threshold level Va of the high-frequency detector 42 is obtained, the output signal Sd1 of the high-frequency detector 42 is obtained from the transmission burst signal S1 as shown in FIG. It is ON (1) only during generation, and OFF (0) in other cases. That is, the output signal Sd1 of the high-frequency detector 42 becomes a detection signal Sa of the transmission burst signal output from the TDD modem 1 (detection signal of the transmission signal detection circuit Z1).
For example, the degree of coupling between the backbone signal path R0 and the transmission signal detection circuit Z1 is −6 dBm, the minimum detection sensitivity of the high frequency detector 42 is −60 dBm, the level of the transmission burst signal in the backbone signal path R0 is about +10 dBm, and the received burst signal Let us consider a case where the level is about -30 to -60 dBm.
In this case, if the attenuation amount (attenuation gain) of the variable attenuator 41 is set to about -40 dB (attenuation), the detection threshold level of the transmission signal detection circuit Z1 (high frequency detector 42) becomes -14 dBm, and only the transmission burst signal is detected. can do.

The detection signal Sa of the transmission burst signal as shown in FIG. 2 is input as a control signal to the high frequency switch 31 as shown in FIG. 1, so that the high frequency switch 31 receives the transmission burst signal from the TDD modem 1. Only during the occurrence, the basic signal path R0 is switched to the state where it is connected to the first signal path R1, and in other cases, the basic signal path R0 is switched to the state where it is connected to the second signal path R2. As a result, the signal path is separated into the first signal path R1 and the second signal path R2 for each transmission direction of the communication signal transmitted and received by the TDD modem, and a control signal for switching the signal path is transmitted from the TDD modem 1. There is no need to take out the existing TDD modem 1 as it is.
Further, in the communication relay device X1, as described above, the gains of the transmission amplifier 12 and the reception amplifier 22 are switched by the FET switches 13 and 23 based on the detection signal Sa of the transmission burst signal. Note that a signal obtained by inverting ON / OFF of the detection signal Sa of the transmission burst signal by the inverting element 32 is input to the FET switch 23 on the receiving side.
More specifically, while the transmission burst signal is detected (while the detection signal Sa is ON), the transmission amplifier 12 in the first signal path R1 is set to a high gain (a state in which the signal is amplified). In addition, the receiving amplifier 22 in the second signal path R2 is set to a low gain (a state in which the signal is attenuated or not amplified).
On the other hand, when the transmission burst signal is not detected, the transmission amplifier 12 is set to a low gain (a state in which the signal is attenuated or not amplified), and the reception amplifier 22 in the second signal path R2 is set to a high gain (signal). Is set to a state of amplifying. Here, “setting to a low gain” includes substantially blocking signal transmission.
In this way, by switching the gains of the amplifiers 12 and 22 based on the detection signal Sa of the transmission burst signal, signal interference due to the sneak signal from the other signal path is prevented, and the transmission signal and the reception signal are separated. The degree of communication can be further increased, and good communication quality can be ensured. It also saves power.
Further, with the configuration shown in FIG. 1, the degree of separation between the first signal path R1 and the second signal path R2 can be about 40 dB (= 1/10000) or more.

Second Embodiment
Next, the communication relay device X2 according to the second embodiment of the present invention will be described using the schematic configuration diagram shown in FIG. The same components as those of the communication relay device X1 and the communication system including the communication relay device X1 are represented by the same symbols.
Hereinafter, only the configuration of the communication relay device X2 that is different from the communication relay device X1 will be described.
The communication relay device X2 is further provided in the first signal path R1 with respect to the configuration of the communication relay device X1 described above, and a transmission-side variable gain amplifier 15 for adjusting the strength (voltage level) of the transmission signal, 2 is provided with a receiving side variable gain amplifier 25 for adjusting the intensity of the transmission signal and a reception signal detection circuit Z2 for detecting the reception burst signal of the TDD modem 1. .
Here, the gain of the transmission-side variable gain amplifier 15 is switched according to the detection signal Sa of the transmission signal detection circuit Z1. Specifically, the gain of the transmission side variable gain amplifier 15 is set to a high gain while the detection signal Sa is ON (when a transmission burst signal is being generated), and is set to a low gain while the detection signal Sa is OFF. Is set. That is, the high gain is set only during transmission burst signal generation.
Further, the gain of the reception side variable gain amplifier 25 is switched according to the detection signal Sb of the reception signal detection circuit Z2. Specifically, the gain of the reception-side variable gain amplifier 25 is set to a high gain while the detection signal Sb is ON (while the reception burst signal is being generated), and is set to a low gain while the detection signal Sb is OFF. Is set. That is, the high gain is set only during the generation of the reception burst signal. A gain switching circuit (not shown) included in the reception-side variable gain amplifier 25 is an example of a second gain switching unit.
Thereby, like the gain switching of the transmission amplifier 12 and the reception amplifier 22 by the FET switches 13 and 23, the degree of separation between the transmission signal and the reception signal can be further increased, and good communication quality can be ensured. It also saves power. In particular, since the reception-side variable gain amplifier 25 is set to a high gain only while the reception signal of the TDD modem 1 is generated, the degree of separation between the transmission signal and the reception signal can be further increased.
The reception-side variable gain amplifier 25 is for performing auxiliary level control on the reception burst signal.

  Further, as shown in FIG. 3, the reception signal detection circuit Z2 in the communication relay device X2 includes a variable gain amplifier 43 (a branch signal amplification unit) that amplifies a branch signal from the basic signal path R0 (first basic signal path). An example), a high-frequency detector 44 (an example of a second high-frequency detector) that detects the amplified signal and uses the detection result as a detection signal Sd2, and a high-frequency detector 42 (first) constituting the transmission signal detection circuit Z1. 1) and an XOR operator 45 that outputs a signal obtained by performing an XOR operation on both detection signals Sd1 and Sd2 of the high-frequency detector 44 constituting the reception signal detection circuit Z2 as a detection signal Sb of the reception burst signal It is comprised by.

Hereinafter, operations of the transmission signal detection circuit Z1 and the reception signal detection circuit Z2 will be described with reference to time charts of various signals shown in FIG.
Similarly to the communication relay device X1 described above, the communication relay device X2 is connected to the trunk signal path R0 directly to the TDD modem 1, and the received burst signal S2 is more signal than the transmission burst signal S1 in the trunk signal route R0. The level is low.
Here, the signal levels at the input / output terminals of the high-frequency detector 42 are the same as those shown in FIG.
On the other hand, as shown in FIG. 4, at the input terminal of the other high-frequency detector 44 (that is, the output terminal of the variable gain amplifier 43), the level between the received burst signal S2 and the signal level when there is no communication signal. If the amplification level of the variable gain amplifier 43 is adjusted in advance so that the level (voltage level) becomes the detection threshold level Vb of the high-frequency detector 44, the output signal Sd2 of the high-frequency detector 44 is as shown in FIG. In addition, it is ON (1) only during the generation of the transmission burst signal S1 and the reception burst signal S2, and is OFF (0) in other cases.
For this reason, the output signal of the XOR operator 45 that performs the XOR operation of the output signals Sd1 and Sd2 of both the high-frequency detectors 42 and 44 is ON (1) only during the generation of the reception burst signal S2, and is OFF (0) in other cases. )
That is, the output signal of the XOR operator 45 becomes the detection signal Sb of the reception burst signal (detection signal of the reception signal detection circuit Z2) input to the TDD modem 1.
With the configuration shown in FIG. 3, the transmission burst signal S1 and the reception burst signal S2 can be detected with a very simple circuit configuration.
For example, the degree of coupling between the backbone signal path R0 and the transmission signal detection circuit Z1 is −6 dBm, the minimum detection sensitivity of the high frequency detector 42 is −60 dBm, the level of the transmission burst signal in the backbone signal path R0 is about +10 dBm, and the received burst signal Let us consider a case where the level is about -30 to -60 dBm.
In this case, if the attenuation amount (attenuation gain) of the variable attenuator 41 is set to about −40 dB and the gain of the variable gain amplifier 43 is set to +20 dB (amplification), the transmission signal detection circuit Z1 (high-frequency detector 42) and the reception signal detection circuit. The detection threshold level of each of Z2 (high frequency detector 44) is −14 dBm and −74 dBm, and the high frequency detector 42 can detect only the transmission burst signal, and the high frequency detector 44 can detect both the transmission burst signal and the reception burst signal.

<Third Embodiment>
Next, a communication relay device X3 according to a third embodiment of the present invention will be described using the schematic configuration diagram shown in FIG. The same components as those of the communication relay devices X1 and X2 and the communication system including the same are represented by the same symbols.
Hereinafter, only the configuration of the communication relay device X3 that is different from the communication relay device X2 will be described.
In addition to the configuration of the communication relay device X2, the communication relay device X3 further includes a directional coupler connected between the first signal path R1 and the transmission signal detection circuit Z1 and the reception signal detection circuit Z2. 46 is added.
That is, in the communication relay device X3, each of the transmission signal detection circuit Z1 and the reception signal detection circuit Z2 is configured to obtain a branch signal from the basic signal path R0 (first basic signal path) via the directional coupler 46. The branch signal of the transmission burst signal from the TDD modem 1 flows to the transmission signal detection circuit Z1, and the branch signal of the reception burst signal having a transmission direction different from that flows to the reception signal detection circuit Z2.
Thereby, when the gain of each of the variable attenuator 41 and the variable gain amplifier 43 is adjusted, at what level the branch signal of the reception burst signal is input to the high frequency detector 42 of the transmission signal detection circuit Z1, or the transmission burst signal Therefore, it is not necessary to consider at what level the branch signal is input to the high-frequency detector 44 of the received signal detection circuit Z2, and the degree of freedom in gain adjustment is increased. For example, it is not necessary to consider that the high frequency detector 44 is destroyed by the branch signal of the amplified received burst signal by setting the gain of each variable gain amplifier 43 too high.
As a result, the gains of the variable attenuator 41 and the variable gain amplifier 43 can be set so that the transmission burst signal and the reception burst signal having different transmission directions can be separated and detected more reliably.

<Fourth embodiment>
Next, a communication relay device X4 according to a fourth embodiment of the present invention will be described using the schematic configuration diagram shown in FIG. In addition, about the same component as the said communication relay apparatus X1-X3 and the communication system containing it, it represents with the same symbol.
Hereinafter, only the configuration of the communication relay device X4 different from the communication relay device X1 will be described.
The communication relay device X4 is different from the configuration of the communication relay device X1 described above except that the up converter 11a and the down converter 21a are removed, the second backbone signal path R3, the second high frequency switch 33, and the communication relay device X2 are the same. A transmission-side variable gain amplifier 15 having the same function as that provided is added, and the transmission signal detection circuit Z1 is replaced with a transmission signal detection circuit Z1 ′ having the same transmission burst signal detection function. is there. For convenience, each of the basic signal path R0 and the high frequency switch 31 in the communication relay device X4 is hereinafter referred to as a first basic signal path and a first high frequency switch.
Here, the second backbone signal path R3 is a transmission signal and reception signal of the TDD modem 1 on the side of the TDD modem 2 that is the counterpart station of the TDD modem 1 relative to the first signal path R1 and the second signal path R2. This is a signal path for transmitting (communication signal).
The second high-frequency switch 33 receives the detection signal Sa of the transmission signal detection circuit Z1 ′, and the first high-frequency signal path R3 is set to the first in accordance with the state (ON / OFF) of the detection signal Sa. This is a switch for switching between the signal path R1 and the second signal path R2 (an example of the second path switching means).

This communication relay device X4 is arranged in the communication path of the TDD modems 1 and 2 that communicate with each other, and separates the communication signal for each transmission direction and amplifies and relays the signal. 6 shows an example in which the TDD modem on the master station side is the TDD modem 1 on the local station side and the TDD modem on the slave station side is the TDD modem 2 on the partner station side, but the reverse connection relationship A communication system is also conceivable.
Here, as a signal transmission form with the TDD modem 1 of the local station, an antenna 35 is provided in the first basic signal path R0, and a communication signal is transmitted by radio signal through the antenna 35 to and from the antenna 1a of the TDD modem 1. And a mode in which a communication signal is transmitted by wired connection to the TDD modem 1 can be considered.
Similarly, a signal transmission form with the TDD modem 2 of the counterpart station is a form in which an antenna 34 is provided in the second basic signal path R3, and a communication signal is transmitted by a radio signal through the antenna 34 and the antenna 2a of the TDD modem 2. In addition, it is conceivable that the communication signal is transmitted by wired connection with the TDD modem 2.

In this communication relay device X4, the transmission burst signal S1 from the TDD modem 1 reaches the first backbone signal path R0 in a state of being greatly attenuated through the state of the radio signal, while the reception burst signal S2 from the partner station is Since the signal is amplified by the reception amplifier 22 and reaches the first basic signal path R0, the signal level of the reception burst signal S2 is higher than that of the transmission burst signal S1 in the first basic signal path R0.
Therefore, as shown in FIG. 6, the transmission signal detection circuit Z1 ′ in the communication relay device X4 includes a variable attenuator 41 ′ (an example of a branch signal attenuation unit) that attenuates a branch signal from the first backbone signal path R0. A first high-frequency detector 42 ′ for detecting the attenuated signal, a variable gain amplifier 43 ′ (an example of a branch signal amplification means) for amplifying a branch signal from the first basic signal path R0, Detection of a transmission burst signal using a second high-frequency detector 44 ′ for detecting the signal and a signal obtained by performing an XOR operation on both detection signals Sd1 ′ and Sd2 ′ of the first high-frequency detector 42 ′ and the second high-frequency detector 44 ′ An XOR operator 45 ′ for a signal Sa is used.

Hereinafter, the operation of the transmission signal detection circuit Z1 ′ will be described with reference to a time chart of various signals shown in FIG.
As described above, in the communication relay device X4, the signal level of the reception burst signal S2 is higher than that of the transmission burst signal S1 in the first backbone signal path R0.
Here, when the signal level at the input end of the high-frequency detector 42 'is compared with the signal level at the input end of the high-frequency detector 42 shown in FIG. 4, the level relationship between the transmission burst signal and the reception burst signal is reversed. Therefore, as shown in FIG. 7, at the input end of the high-frequency detector 42 ′ (that is, the output end of the variable attenuator 41 ′), a level (voltage) between the level of the reception burst signal S2 and the level of the transmission burst signal S1. If the attenuation of the variable attenuator 41 ′ is adjusted in advance so that the level becomes the detection threshold level Va of the first high-frequency detector 42 ′, the output signal Sd1 ′ of the high-frequency detector 42 ′ It is ON (1) only during generation of the signal S2, and is OFF (0) in other cases.

On the other hand, as shown in FIG. 7, at the input end of the other high-frequency detector 44 '(ie, the output end of the variable gain amplifier 43'), the level of the transmission burst signal S1 and the signal level when there is no communication signal If the amplification level of the variable gain amplifier 43 ′ is adjusted in advance so that the level (voltage level) between them becomes the detection threshold level Vb of the high frequency detector 44 ′, the output signal Sd2 ′ of the high frequency detector 44 ′ is , ON (1) only during generation of the transmission burst signal S1 and reception burst signal S2, and OFF (0) in other cases.
For this reason, the output signal of the XOR operator 45 ′ that performs the XOR operation of the output signals Sd1 ′ and Sd2 ′ of both the high-frequency detectors 42 ′ and 44 ′ is ON (1) only during the generation of the transmission burst signal S1, and the other In this case, it is OFF (0).
That is, the output signal of the XOR calculator 45 ′ becomes the detection signal Sa of the transmission burst signal output from the TDD modem 1 (the detection signal of the transmission signal detection circuit Z1 ′).
With the configuration shown in FIG. 6, the transmission burst signal S1 can be detected with a very simple circuit configuration.

In 1st-3rd embodiment shown above, although it showed about communication relay apparatus X1-X3 which performs conversion for the same frequency width by the up converter 11a and the down converter 21a, it does not restrict to this.
When the up-converter 11a and the down-converter 21a perform conversion for different frequency widths, frequency oscillators having different oscillation frequencies may be provided individually. In this case, wireless communication can be performed at a different frequency for each signal transmission direction.
Moreover, in the said communication relay apparatus X1-X3, although the up converter 11a and the down converter 21a are made into 1 step | paragraph conversion for convenience, the structure which superimposes and converts two or more steps (serially) may be sufficient.
Further, a configuration in which each of the up-converter 11a and the down-converter 21a is provided in each of the first signal path R1 and the second signal path R2 in the communication relay device X4 of the fourth embodiment described above is also conceivable.
In the above-described embodiment, the variable attenuator (attenuator) is used as means for attenuating the branch signal from the basic signal path R0. In addition, the gain is set to the attenuation side using a variable gain amplifier. Also possible is the configuration.

  The present invention can be used for a communication relay device.

1 is a schematic configuration diagram of a communication relay device X1 according to a first embodiment of the present invention. The figure showing the time chart of the various signals in the communication relay apparatus X1. The schematic block diagram of the communication relay apparatus X2 which concerns on 2nd Embodiment of this invention. The figure showing the time chart of the various signals in the communication relay apparatus X2. The schematic block diagram of the communication relay apparatus X3 which concerns on 3rd Embodiment of this invention. The schematic block diagram of the communication relay apparatus X4 which concerns on 4th Embodiment of this invention. The figure showing the time chart of the various signals in the communication relay apparatus X4. The figure showing the basic composition of the conventional radio | wireless communications system A. The figure showing the basic composition of the conventional radio | wireless communications system B. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... TDD modem 11a ... Up converter 12 ... Transmission amplifier 13, 23 ... FET switch 14 ... Transmission antenna 15 ... Transmission side variable gain amplifier 21a ... Down converter 22 ... Reception amplifier 24 ... Reception antenna 25 ... Reception side variable gain amplifier 34, 35 ... Antennas 41, 41 '... Variable attenuators 42, 44, 42', 44 '... High frequency detectors 43, 43' ... Variable gain amplifiers 45, 45 '... XOR computing units X1-X4 ... Communication relay devices Z1, Z1 '... Transmission signal detection circuit Z2 ... Reception signal detection circuits R0, R3 ... Core signal path R1 ... First signal path R2 ... Second signal path Sa ... Transmission burst signal detection signal Sb ... Reception burst signal detection signal

Claims (10)

A communication relay device that relays and transmits a communication signal transmitted and received between one modem and another modem in a time division multiple-duplex system,
A first backbone signal path for transmitting the communication signal on the one modem side;
A first signal path and a second signal path which are provided in parallel to the other modem side than the first basic signal path and transmit each of the transmission signal and the reception signal of the one modem;
Transmission signal detection means for detecting whether or not a transmission signal is being generated from the one modem based on a branch signal from the first backbone signal path;
First path switching means for switching whether to connect the first backbone signal path to the first signal path or the second signal path based on a detection signal of the transmission signal detection means;
A communication relay device comprising: A second backbone signal path for transmitting the communication signal on the other modem side than the first signal path and the second signal path;
Second path switching means for switching whether to connect the second backbone signal path to the first signal path or the second signal path based on the detection signal of the transmission signal detection means;
The communication relay device according to claim 1, comprising:   The transmission signal detecting means is constituted by a branch signal attenuating means for attenuating a branch signal from the first basic signal path and a high frequency detector for detecting the attenuated signal and using the detection result as a detection signal. The communication relay device according to claim 1.   The transmission signal detection means is a branch signal attenuation means for attenuating a branch signal from the first backbone signal path, a first high-frequency detector for detecting the attenuated signal, and a branch signal for amplifying the branch signal. Amplifying means and a second high frequency detector for detecting the amplified signal, and a signal obtained by performing an XOR operation on both detection signals of the first high frequency detector and the second high frequency detector The communication relay device according to claim 1, further comprising: an XOR operation unit that serves as a detection signal.   5. The communication relay device according to claim 1, wherein the transmission signal detection unit obtains the branch signal through a directional coupler with respect to the first backbone signal path.   The communication relay device according to any one of claims 1 to 4, wherein frequency conversion means for converting a frequency of a transmission signal is provided in each of the first signal path and the second signal path.   The communication relay device according to any one of claims 1 to 6, wherein transmission signal amplification means for amplifying a transmission signal is provided in each of the first signal path and the second signal path.   The communication relay device according to claim 7, further comprising a first gain switching unit that switches a gain of the transmission signal amplification unit based on a detection signal of the transmission signal detection unit. Received signal detection means for detecting whether a received signal to the one modem is being generated based on a branch signal from the first backbone signal path;
9. The device according to claim 7, further comprising a second gain switching unit that switches a gain of the transmission signal amplifying unit provided in the second signal path based on a detection signal of the reception signal detection unit. The communication relay device described. The transmission signal detecting means includes a branch signal attenuating means for attenuating a branch signal from the first basic signal path, and a first high-frequency detector that detects the attenuated signal and uses the detection result as a detection signal. If
A branch signal amplifier for amplifying a branch signal from the first backbone signal path; a second high frequency detector for detecting the amplified signal and using the detection result as a detection signal; 10. An XOR operation means comprising: a signal obtained by performing an XOR operation on both detection signals of the first high-frequency detector and the second high-frequency detector, and using a detection signal of the received signal as a detection signal. The communication relay device described.

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