JPH03210837A - Phase synchronization device - Google Patents

Abstract

PURPOSE:To continue the operation even in the case of a fault of a device or test by feeding back an output signal of a variable delay circuit to a changeover circuit provided before a phase comparator circuit so as to switch the operating system and the standby system. CONSTITUTION:A signal from a receiver is outputted at all times to a phase comparator circuit in an operating system 10, a signal of a radio wave of a reference station and a signal of a radio wave of a station around its own station are compared and a delay of a variable delay circuit 16 is adjusted so as to eliminate a phase difference. An output signal of a variable delay circuit 26 in the standby system 20 is fed back to a changeover circuit 28 provided before a phase comparator circuit 24 and a signal from the variable delay circuit 26 of the standby system 20 is outputted in place of an output signal of a receiver 22 in the timing when a signal of a radio wave of the station around its own station by means of the changeover circuit 28 to allow the phase comparator circuit 24 to compare the signal of the radio wave of the reference station with an output signal of the standby system 20 and the delay of the variable delay circuit 26 is adjusted to eliminate the phase difference.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a phase synchronization device necessary for simultaneous multi-station transmission in a mobile communication system.

(Prior art) In mobile communication systems, when covering a wide area using multiple small wireless zones, there is a method in which radio waves of the same frequency are simultaneously transmitted from multiple wireless base stations installed in each small wireless zone. be. This is called simultaneous multi-station transmission, and is used in radio paging systems, car telephone systems, etc. This is reference 1 (Fundamentals of Mobile Communications, published by the Institute of Electronics, Information and Communication Engineers)
Section 7.4, pages 180 to 185).

In this case, transmission quality improves due to the diversity effect in places where the distance from multiple wireless base stations, that is, the strength of the received radio waves is almost equal, but if the phase shift of the signals sent from each wireless base station becomes large, the Transmission quality deteriorates. Therefore, when performing multi-station simultaneous transmission, it is essential to achieve phase synchronization of signals transmitted from each base station. For example, in the radio paging system, transmission signals are transmitted from each radio base station via a switching center that transmits signals (hereinafter referred to as the "central station"), but in order to achieve phase synchronization, this central station and each It is necessary to measure the delay time of the transmission path between base stations and adjust the signal delay so that the delay time is the same for all wireless base stations. This situation is shown in FIGS. 3 and 4. FIG. 3 shows the line configuration of the radio paging system, and FIG. 4 shows the configuration of the base station.

As shown in Figure 3, the delay adjustment method involves sending out the same signal from a central station to multiple base stations, and transmitting the same signal to a reference radio base station (hereinafter referred to as the "reference station") that is modulated by that signal. ) is received by other wireless base stations (hereinafter referred to as "peripheral stations"), the phase is compared with the signal sent from the central station via the wired transmission path, and the base station A common method is to adjust the variable delay circuit of the station. In Figure 3, in the case of peripheral stations that cannot directly receive the radio waves of the reference station, the phase of many base stations can be adjusted by repeatedly adjusting the variable delay circuit using the peripheral station with the same phase as the reference station as the reference station. Can be matched. The details are described in Document 2 ("Car Telephone", Section 7.5, pages 150 to 152, published by the Institute of Electronics, Information and Communication Engineers).

In this case, since the delay can be adjusted using the delay circuit in the peripheral station, the delay time between the central station and the reference station is wider than the delay time between the central station and other peripheral stations. , it is necessary to insert a fixed delay circuit between the central station and the reference station.The configuration of the base station required for this is shown in Figure 4(a).However, in this case, the variable delay circuit is inserted in front of the transmitter. Since the transmission phase error due to variations in the delay time of the base station's transmitter cannot be removed. Adjust the delay to synchronize with.

This is shown in Figure 4(b), and details are given in the above-mentioned document 2.
It is described in.

In this case, the frequencies of the received radio waves are the same, so when receiving the radio waves from the reference station, as shown in Figure 5, the radio waves from the surrounding stations are stopped and the special signal inserted into the signal is By measuring the time difference between the signals (the time difference between receiving the special signal A and receiving the special signal B), the delay time difference of the transmission path can be measured isometrically. In addition, as a method to stop the radio waves of the peripheral station, by setting the time difference between special signal A and special signal B as a fixed time interval, the peripheral station demodulates and decodes the radio waves sent from its own peripheral station and transmits the special signal. This can be easily realized by stopping the radio waves of stations surrounding the station within α sand diameter when signal A is detected, and starting radio wave transmission after receiving special signal B. Also, the time difference β and α between receiving special signal A and receiving special signal B (α−β)
is the phase error.

Time can be measured by methods such as obtaining a signal at constant time intervals by frequency-dividing the lock required for decoding the signal, or counting the number of periodic pulses in the decoded signal.

FIG. 6 shows an example of a conventional configuration of a peripheral station, which consists of two systems, an active system IO and a standby system 20, in order to ensure reliability.
Operate while switching.

(Problem to be solved by the invention) In such a configuration, the operating system measures the phase difference between the radio wave signal of the reference station and the radio wave signal of the own peripheral station, and adjusts the delay amount of the variable delay circuit so that the difference disappears. However, in the standby system, even if the delay amount of the variable delay circuit is changed, the phase of the signal of the local station does not change, and due to the operation of the active system, the phase of the signal of the reference station and the local station Since the phase difference between the station radio signals is negligible, the delay amount of the variable delay circuit will maintain its initial value.

Therefore, in such a system, even if there is an abnormality in the equipment, the abnormality cannot be detected, so when a failure occurs in the active system, the failure of the standby system does not occur for the first time when switching to the standby system and attempting to continue operation. As a result, it became impossible to continue operation, and there was no point in trying to ensure reliability by creating two systems.

In addition, in the standby system, it is not possible to compare the signal whose phase has been changed by the variable delay circuit with the signal from the reference station, so unless you switch to the standby system, it is difficult to determine whether the standby system will operate normally. The drawback was that it could not be tested.

An object of the present invention is to provide a phase synchronization device that solves these problems.

(Means for Solving the Problems) A feature of the present invention is that it is composed of two systems of phase-locked circuits and a switch for selecting one of them, and each phase-locked circuit has a radio receiver and a switch for switching to the receiver. a phase comparison circuit that compares the phase of the reference station radio wave with the radio wave phase of its own wireless base station by coupling through a circuit and detecting a signal for phase synchronization from the output of the switching circuit; a variable delay circuit that delays a signal transmitted from the central office in accordance with an output control signal, and the switching circuit switches the input to the phase comparison circuit between the output of the receiver and the output of the variable delay circuit. There is a phase synchronizer to switch between.

(Function) In the present invention, the output signal of the variable delay circuit is fed back to the switching circuit provided before the phase comparison circuit. This differs from the conventional technology in that in the standby system, the output signal of this variable delay circuit is used instead of the radio wave signal of the own peripheral station.

When the phase synchronization circuit is in operation, the output of the receiver is input to the phase comparison circuit via the switching circuit. The operation in this case is the same as the conventional technique.

When the phase synchronization circuit is in standby mode, the output of the variable delay circuit is input to the phase comparator circuit via the switching circuit, and therefore the delay amount of the variable delay circuit is constantly updated. Therefore, by switching between the active system and the standby system, operation can be continued even in the event of equipment failure or testing.

(Example) FIG. 1 is a diagram for explaining the present invention in detail. Hereinafter, the present invention will be explained in detail based on the drawings.

In FIG. 1, 10 is a first phase-locked circuit, 20 is a second phase-locked circuit, and 30 is a switch for selecting their outputs and inputting them to a transmitter 40. 12 and 22 are receivers, 14 and 24 are phase comparison circuits, 16 and 26 are variable delay circuits, 18
and 28 are switching circuits for switching the input to the phase comparison circuit to the output of the receiver or the output of the variable delay circuit, and 19 and 20 are modems.

In Figure 1, in the operating system IO, the signal from the receiver is always output to the phase comparator circuit, and the radio wave signal of the reference station is compared with the radio wave signal of the own peripheral station, so that the phase difference between them is eliminated. Then, the delay amount of the variable delay circuit 16 is adjusted. In the standby system 20, the output signal of the variable delay circuit 26 is fed back to the switching circuit 28 provided before the phase comparison circuit 24, and at the timing when the switching circuit 28 receives the radio wave signal of the own peripheral station, the receiver By outputting the signal of the variable delay circuit 26 of the standby system 20 instead of the output signal of the standby system 22, the phase comparator circuit 24 compares the radio wave signal of the reference station and the output signal of the standby system 20, and calculates the phase difference between them. It operates to adjust the amount of delay of the variable delay circuit 26 so that the delay amount disappears.

As the signal for driving the switching circuit, the signal for stopping the transmission of radio waves from the own peripheral station explained in FIG. 5 can be used as is.

Furthermore, as shown in FIG. 2, when a delay circuit 50 is inserted into the transmission path and its delay amount is changed to create a state in which the delay time of the transmission path is changed isometrically, the delay of the variable delay circuit is It is also possible to check the operation of the circuit by checking whether the amount changes by the amount of delay of the delay circuit inserted in the transmission path.

(Effects of the Invention) As explained above, in the present invention, the output signal of the variable delay circuit is fed back to the switching circuit provided before the phase comparator circuit, so in the standby system, the radio waves of the own peripheral station are The output signal of this variable delay circuit can be used instead of the signal, and if the delay time of the transmission path between the central station and the relevant peripheral station changes, that change is detected and the amount of delay of the variable delay circuit is changed. It will be necessary to do so. Therefore, if there is any abnormality in the circuit, it will become impossible to detect the special signals A and B shown in Figure 5, there will be a large difference in the amount of delay added by the variable delay circuit between the active system and the standby system, and the transmission line It is possible to detect an abnormality based on an event such as a change in the amount of delay added by the standby variable delay circuit even though the delay time has not changed.

[Brief explanation of drawings]

FIG. 1 is a configuration example of an embodiment of the present invention, FIG. 2 is a configuration example of another embodiment of the present invention, FIGS. 3, 4, and 5 are diagrams for explaining phase synchronization. FIG. 6 is a configuration diagram of a conventional phase synchronization device. 10.20. Phase-locked circuit, 12.22. Receiver, 14, 24・Phase comparison circuit, 16, 26; Variable delay circuit, 18, 28; Switching circuit, 19. 29; Modem, 30: Switch, 40; Transmitter, 50; Delay circuit. Diagram

Claims (1)

[Claims] Consisting of two systems of phase-locked circuits and a switch for selecting one of them, each phase-locked circuit is coupled to a radio receiver via a switching circuit, and is connected to the receiver via a switching circuit. A phase comparison circuit that compares the phase of the reference station radio wave with that of its own wireless base station by detecting a phase synchronization signal from the output of the circuit; and a variable delay circuit that delays the signal, wherein the switching circuit switches the input to the phase comparison circuit between the output of the receiver and the output of the variable delay circuit. Phase synchronizer.