JPH053465A - Multiplex radio equipment by hot standby communication system - Google Patents

Abstract

PURPOSE:To change over the system without causing phase deviation at all times by synchronizing a carrier phase, a clock and a frame of signals between systems at all times and switching the signal through the use of a high speed switch. CONSTITUTION:An absolute delay time correction circuit DADE is inserted to either of a sender side and a receiver side so that absolute delay times DAD1, DAD2 between a modulator NOD and a demodulator DEM for a main signal S1 of a V polarized wave system and a main signal S2 of an II polarized wave system are made coincident and absolute delay times DAD1' and DAD2' of leaked signals are respectively coincident with the times DAD2 and DAD1. Moreover, when a disturbing wave ratio D/U is deteriorated due to fading or the like between different polarized wave signals, the phase of the sender side of two systems is to be maintained so that a signal wave of the different polarized wave received in addition to the DADE is not at least in opposite phase. Thus, an active channel receiving the effect of frequency selective fading is advantageous to receive positively a different polarized wave signal of a standby system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital multiplex radio apparatus, and in particular, has two communication systems,
For both systems, always turn on the power, select one of the systems as the active system, and make the other system stand by as a standby system.
The present invention relates to a hot standby communication multiplex wireless communication device that dynamically switches between a working system and a standby system when a failure occurs in the working system.

[0002]

2. Description of the Related Art In a multiplex radio system in which a transmission frequency is assigned to one frequency, there are two transmitters and receivers for the purpose of relieving a device failure at a transmitting end station, and the two systems are in a standby state with a power supply always on. The hot standby communication method is generally adopted.

FIG. 21 is an explanatory diagram of such a conventional hot standby communication system. In the figure, 1 and 1'are transmitters (represented by TX1 and TX2), 2 is a changeover switch, 3 is a transmitting antenna, 4 is a receiving antenna, 5 and 5'are hybrid, and 6 and 6'are receivers ( RX1, R
X2), 7 is a changeover switch, and 7a is a changeover control unit.

A signal transmitted from one of the transmitters (TX1 in the illustrated example) selected by one of the changeover switches 2 is received by two receivers (RX1, RX2) and selected by the changeover switch 7. The output of the receiver of the system (RX1 in the illustrated example) is output as a reception signal.

The changeover control section 7a performs hitless changeover of the receiving end, monitors the bit error rate of the received signal, and when the bit error rate exceeds a predetermined constant value, the changeover switch 7 operates at high speed. And the output of the receiver of another system (RX2 in the illustrated example) is selected so that the communication operation is always performed on the communication path with good line quality.

In such hitless switching at the receiving end station, since high-speed synchronous switching can be performed by using an electronic logic switch as the changeover switch 7, synchronization of the carrying end does not occur and an arbitrary system can be operated. Since the receiver can be switched and selected at any time, it has the feature that it can be used even during maintenance of receiving equipment.

However, in the case of switching the transmission system at the transmitting end station, as shown in the figure, the changeover switch 2 is provided so as to switch the output of the final stage of the transmitter (high frequency power amplifier), and normally a mechanical switch is provided. Since it is used, high-speed switching cannot be performed, which causes loss of synchronization of the carrier recovery circuit in the wireless section, loss of synchronization of the clock recovery circuit, loss of synchronization of the frame synchronization circuit, etc., resulting in loss of synchronization at the carrying end. For this reason, maintenance performed by switching the changeover switch on the sending end side has a drawback that it cannot be easily executed, such as performing maintenance at night because it adversely affects normal operation.

[0008]

SUMMARY OF THE INVENTION The present invention makes it possible to perform hitless switching of a transmitter and a receiver without losing synchronization in a multiplex communication apparatus of a hot standby communication system and facilitate maintenance during communication operation. Is intended.

[0009]

In order to solve the above problems, the present invention provides two independent communication systems each including a transmitter, a transmitting antenna, a receiving antenna, and a receiver in parallel, and each has a single frequency. It is used for the V polarized wave and the H polarized wave, so that one system can be arbitrarily selected on the receiving end side and the received signals are synchronized with each other between the two systems. .

Therefore, in order to make the signal arrival times of the paths from the transmitters to the receivers of the respective systems coincide with each other and to avoid the adverse effect of the cross polarization interference between the systems which occurs when the level of any one system is lowered, At the same time, make sure that the signals of different polarization from the transmitting antennas of other systems that are input to the receiving antennas of each system do not have opposite phases, and when the signal frequency characteristics deteriorate due to frequency selective fading, the signals of different polarization from other systems are generated. If the leak signal is not affected by this fading, it is rather controlled to actively use it. As a result, hitless switching between the transmitter and the receiver at the receiving end can be easily performed without causing phase shift.

FIG. 1 is a diagram for explaining the principle of the present invention. In the figure, 1 and 1'are transmitters (TX1, TX2), 3 and 3'are transmitter antennas, 4 and 4'are receiver antennas, 5 is hybrid, and 6 and 6'are receivers (RX1, RX2), 7 Is a changeover switch, and 8, 8 ′, 9, 9 ′ are synchronization adjusting means.

In FIG. 1, the transmitter 1 (T
The transmission signal output from X1) is transmitted from the transmission antenna 3 as a V-polarized radio wave, received by the reception antenna 4, and received by the reception unit 6 (RX1). Similarly, in the second system, the transmission signal output from the transmission unit 1 '(TX2) is transmitted from the transmission antenna 3'in H-polarized radio waves, received by the reception antenna 4', and received by the receiver 6 '( R
Reception processing is performed in X2).

The synchronization adjusting means 8 and 8'on the transmitter side and the synchronization adjusting means 9 and 9'on the receiver side are such that the carrier phase and clock or frame of the reception signals of both systems are synchronized on the receiver side. In addition, it is provided in the necessary place. For example, in Figure 2
As shown in (a), where the absolute delay times DAD1 and DAD2 of the paths from the transmitter to the receiver of each system are equal and the arrival times of the received signals are the same, the delay time is short. An absolute delay time correction circuit is inserted in the form of adjusting to a long place.

As a measure against interference between different polarization reception signals when the signal level is lowered due to fading or the like, as shown in FIG. 2 (b), there are four paths existing between the transmitter and the receiver of each system. Of the signals S ₁ , Si ′, S ₂ , Sβ ′ of S
_A method of controlling the sending end phase is adopted so that the relative phase differences Φ ₁ and Φ ₂ between ₁ and Sβ ′ and between S ₂ and Si ′ do not become opposite phases. And a phase detection means on the receiver side for phase control.

Further, in the case where the frequency characteristic of the signal is deteriorated by the frequency selective fading, the frequency characteristic of the signal is detected on the receiver side and the power level on the transmitter side is detected as shown in FIG. 2 (c). Control so that a received signal with different polarization can be used depending on the situation. Therefore, the signal level varying means is provided on the transmitter side, and the amplitude frequency characteristic detecting means is provided on the receiver side.

[0016]

In the multiplex radio apparatus of the hot standby communication system of the present invention shown in FIG. 1, the changeover switch 7 is controlled to perform hitless switching in units of a system including a transmitter and a receiver. Since the carrier phase of the signal between the systems, the clock, and the frame are always synchronized, it is possible to perform hitless switching without loss of synchronization by using a high-speed switch as the changeover switch 7.

Further, when it is desired to maintain a transmitter or receiver of an arbitrary system for the same reason, it is possible to disconnect the transmitter or the receiver independently, and even if the system including the maintenance target device is in communication operation. You can always safely switch to the non-selected side, which enables maintenance.

Further, even if the signal level of the working system is lowered due to the deterioration of the line condition, the interference of the different polarization signal from the other system is small, and the polarization signal of the better quality is adopted so that there is no loss of synchronization. It is possible to maintain good communication quality.

[0019]

EXAMPLES Next, examples of the present invention will be described. The symbols in the figures used in the description of the examples below are as follows (shown in alphabetical order).

ATT: Attenuator B / U: Bipolar / unipolar conversion circuit CONT: Control circuit EPS: Infinite phase shifter F characteristic DET: Frequency characteristic detector H: Hybrid IFLo: IF local signal MIX: Mixer MOD: Modulator OSC : Oscillator PDET: Phase detection circuit RFLo: RF local signal RX: Receiver SW: Changeover switch SYS1: System 1 SYS2: System 2 TX: Transmitter U / B: Unipolar / bipolar conversion circuit Vco: Regenerated carrier wave (1) receiver Delay time to make the signal arrival time to the same
Example of Correction In a transmitter and a receiver of two systems having different polarizations, the signal arrival time to the receiver of each system, that is, the absolute delay time, is calculated between the signals of the main polarization and the polarization of the main and leakage polarizations. In order to make the signals equal to each other, as shown in FIG. 3, the modulator MO of the main signal S ₁ of the V polarization system and the main signal S ₂ of the H polarization system is used.
Each absolute delay time DAD1 and D between D and the demodulator DEM
As AD2 and matches, also 'absolute delay time DAD1' and H leakage signals S ₁ from the series of V-polarized wave of the system of the H-polarized wave
In order to match the absolute delay time DAD2 ′ of the leakage signal Sβ ′ from the polarized wave system to the V polarized wave system with DAD2 and DAD1, respectively, in either of the transmitting side and the receiving side, An absolute delay time correction circuit DADE is inserted.

In FIG. 3, the DADE is the IF on the transmitting side and the IF on the receiving side.
Although the example is inserted in the band section, it may be inserted in the RF section as shown in FIG. Sender's DADE and receiver's DADE
Has the following functions. Sender-side DADE FIG. 5 shows reception in the V-polarized system.
Is the path of the main signal S ₁ of the V polarization system, and path 2 is H
This is the path of the leakage signal Sβ ′ from the polarization system to the V polarization system. Normally, the reception level of the signal Sβ ′ on the path 2 side is a level lower by the cross polarization discrimination degree XPD of the reception antenna,
Effect of cross polarization interference is increased if the path 1 side of the signals S ₁ level is lowered due to the influence of such fading. To avoid this, DAD is set to the shorter of the absolute delay times DAD1 and DAD1 ′ of path 1 and path 2, whichever is shorter.
E is inserted (FIGS. 3 and 4 are examples when DAD1 is short). Similarly, for reception of the H-polarized wave system, DADE is inserted on the transmission side. For the same reason as the transmitting side DADE, as shown in FIG. 6, for example, in order to avoid interference when the signal level is lowered on the receiving side of the H-polarized system, DAD1 and DAD2 'become the same. The DAD on the receiving side with the shorter absolute delay time.
Insert E. FIG. 3 shows an example in which DADE is inserted in the RF section, and FIG. 4 shows an example in which it is inserted in the IF section. (2) Example of transmission end phase control Between the signals of different polarizations, the interference wave ratio D /
When U decreases, in addition to the above DADE, at the receiving input, the phase on the transmitter side of the two systems is set so that the received two signal waves having the different polarization relationship do not become at least opposite phases. Must be maintained.

7 to 14 are for minimizing the phase difference between the two receivers by detecting the phase difference between the two receivers on the receiving side and controlling the signal phase on the transmitter side.
7 to 14 show a method of controlling the signal phase on the transmission side by introducing the IF signals of the two receivers into the phase detection circuit PDET including a multiplier, transferring the phase information through the service channel of the reverse link, etc. Is.

FIG. 7 shows the IF local signal IF in the transmission system of SYS1 as means for varying the phase of the transmission signal.
An embodiment in which the phase of Lo is changed by using the infinite phase shifter EPS will be described.

FIG. 8 shows the IF local signal IFLo of FIG.
An example in which the RF local signal RFLo is changed instead of FIG. 9 shows an embodiment in which the IF signal is introduced into the EPS and its phase is directly changed.

FIG. 10 shows that an RF signal is introduced into the EPS,
An example in which the phase is directly changed will be shown. 11 to 1
4 is a means for obtaining phase error information in the receiver,
In this embodiment, a method for detecting the phase difference of the reproduced carrier wave Vco of the DEM by PDET is used. A logic circuit or an analog multiplier is used for PDET, and other configurations are similar to those of the embodiments of FIGS. (3) Embodiment of transmission power control Although the embodiments described above are effective for fading that acts uniformly on frequency characteristics, in the case of frequency selective fading, the amplitude frequency characteristics deteriorate. Therefore, it is advantageous to discard the normal reception polarization signal and actively receive the standby polarization signal in the active channel affected by the frequency selective fading. 15 and 16 show an embodiment that adopts the method.

In the embodiment shown in FIG. 15, the attenuator ATT is inserted in the IF section (MOD output) of the transmitter.
In this embodiment, the ATT is inserted in the RF section (TX output) of the transmitter. The frequency characteristic is detected for the IF signal (RX output) of the receiver in both embodiments, and the frequency characteristic of the IF signal of each system is detected using the F characteristic DET, and both are detected by the CONT on the receiver side. The frequency characteristics of the system are checked for deterioration, the system suitable for reception is determined, and the information is notified to the CONT on the transmitter side using the reverse link.
The CONT on the transmitter side is AT based on the notified information.
Control T. That is, when the frequency characteristics of the polarization signal on the side that is normally received deteriorates, the transmission level is forcibly lowered so that the signal on the different polarization side is mainly received. In this case, the extent to which the transmission level is lowered depends on the F special DET.
Must be within the range that can be identified by the level detection ability of. It is also effective because it is possible to raise the level on the different polarization side at the same time. A variable gain amplifier may be used instead of the ATT.

The embodiments (1), (2) and (3) described above can be arbitrarily combined. For example, FIG. 17 is an embodiment in which the embodiment of FIG. 3 of absolute delay time correction and the embodiment of FIG. 7 of sending end phase control are combined, and FIG. 18 is the embodiment of FIG. 3 and FIG.
FIG. 19 is a combination of the embodiments of FIGS. 3, 7, and 15, and FIG. 20 is a combination of the embodiments of FIGS. 3, 10, and 14. This is an example.

[0028]

According to the present invention, since there is no phase difference between the received signals of the V and H polarized wave systems, the system switching can always be performed without causing a phase shift, so that the communication quality is improved. In addition, the system can be switched at any time for the purpose of maintaining the transmitter or receiver, so that it is possible to avoid maintenance during communication as in the past and perform maintenance only at night. No restrictions are required, and maintainability is significantly improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of the configuration of the present invention.

FIG. 3 is a configuration diagram of an embodiment in which DADE is inserted in an IF section.

FIG. 4 is a configuration diagram of an embodiment in which DADE is inserted in an RF section.

FIG. 5 is an explanatory diagram of a transmitting DADE.

FIG. 6 is an explanatory diagram of a receiving DADE.

FIG. 7 IF signal phase detection-IFL. It is a block diagram of the Example of phase control.

FIG. 8 IF signal phase detection-RFL. It is a block diagram of the Example of phase control.

FIG. 9 is a configuration diagram of an embodiment of IF signal phase detection-IF signal phase control.

FIG. 10 is a configuration diagram of an embodiment of IF signal phase detection-RF signal phase control.

FIG. 11 is a configuration diagram of an embodiment of phase detection-IFLo phase control by a reproduced carrier wave Vco.

FIG. 12 is a configuration diagram of an embodiment of phase detection-RFLo phase control by a reproduced carrier wave Vco.

FIG. 13 is a configuration diagram of an embodiment of phase detection-IF signal phase control by a reproduced carrier wave Vco.

FIG. 14 is a configuration diagram of an embodiment of phase detection-RF signal phase control by a reproduced carrier wave Vco.

FIG. 15 is a configuration diagram of an embodiment of transmission power control by an IF stage.

FIG. 16 is a configuration diagram of an embodiment of transmission power control by the RF stage.

FIG. 17 is a configuration diagram of an embodiment (part 1) by combination.

FIG. 18 is a configuration diagram of an embodiment (part 2) by combination.

FIG. 19 is a configuration diagram of a combination example (part 3).

FIG. 20 is a configuration diagram of a combination example (Part 4).

FIG. 21 is an explanatory diagram of a conventional hot standby communication system.

[Explanation of symbols]

1, 1 ': transmitter (TX1, TX2) 3, 3 ': transmitting antenna 4,4 ': receiving antenna 6,6 ': receiver (RX1, RX2) 8, 8 ', 9, 9': synchronization adjusting means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takayuki Ozaki             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited

Claims (4)

[Claims] 1. A communication system comprising a transmitter, a transmitting antenna, a receiving antenna and a receiver is provided in two systems, and each system has one of a single frequency orthogonal V polarization and one H polarization. In a multiplex radio apparatus by a hot standby communication system in which radio waves are used and one of the reception signal outputs of the receivers of the respective systems is switched and selected at any time, in the receivers of each of the two communication systems A multiplex radio apparatus according to a hot standby communication system, characterized by comprising synchronization adjusting means for synchronizing received signals. 2. The synchronization adjusting means for synchronizing the reception signals of the receivers of the respective systems according to claim 1, wherein the signal arrival times are equal for all paths from the transmitters of the respective systems to the receivers of the respective systems. A multiplex radio apparatus according to a hot standby communication system, which is an absolute delay time correction circuit provided as follows. 3. The synchronization adjusting means for synchronizing the reception signals of the receivers of the respective systems according to claim 1, the phase varying means provided in at least one of the transmitters of the respective systems, and the receivers of the respective systems. A multiplex radio apparatus according to a hot standby communication system, comprising: phase detecting means for detecting a phase between received signals, and controlling the phase varying means so that the phases between the received signals do not become opposite phases. 4. The signal level varying means provided in the transmitter of each system and the amplitude frequency characteristic detecting means provided in the receiver of each system according to claim 1, A hot standby communication system characterized by detecting frequency selective fading from the amplitude frequency characteristic, lowering the transmission power level of the system in which the fading is occurring, and receiving by the different polarization signal of another system Multiple wireless devices by.