JPH0759136A - Inter-station phase compensation method in wide area radio calling system - Google Patents

Abstract

PURPOSE:To reduce the number of times of start and stop in the operation on a transmitter of each station and to improve the reliability of phase synchronization operation when the phase synchronization is executed among plural radio base stations forming the wide area radio calling system. CONSTITUTION:Reception stations 31-3m are installed to points at which radio call signals from plural peripheral stations 21-2n are receptible. The reception stations always monitor a specific call signal sent from a central station 1 or the peripheral station and send a phase correction start instruction to the central station 1 when the specific call signal cannot be detected. Furthermore, a delay in the peripheral station being a phase synchronization object is detected by using a synchronizing signal and a phase correction signal simultaneously. The central station sets the reception station to a state that the reception station is receptible of the phase correction signal from the radio base station being a reference of phase synchronization based on the phase correction start instruction and sets a delay in a signal transmission line 5 tying the peripheral radio base stations being an object of phase synchronization based on the delay from the reception station.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a central radio base station (hereinafter, referred to as
In a wide area wireless paging system in which a plurality of wireless paging stations composed of a central station) and a plurality of peripheral wireless base stations (hereinafter, peripheral stations) wirelessly transmit the same paging signal at the same time, the paging signal timings between the paging stations are in phase with each other. The present invention relates to an inter-station phase compensation method for controlling digitalization.

[0002]

2. Description of the Related Art In a mobile communication system, when a wide service area is covered by using a plurality of small wireless zones, radio waves are simultaneously transmitted from a plurality of wireless base stations installed in each small wireless zone for the purpose of effectively using frequencies. The sending method is used. For example, “Basics of Mobile Communication” published by The Institute of Electronics, Information and Communication Engineers, Section 7.4. At this time, it is necessary to synchronize the phases of the signals transmitted from the respective radio base stations in order to secure the required transmission quality in an area where the intensities of radio waves from the plurality of radio base stations are almost equal. In order to perform the phase synchronization of the signals transmitted from the two base stations, the signal transmission path between the station that sends out the signal that is the basis of the phase, that is, the central station, and each radio base station, that is, the peripheral station, is used. It is necessary to measure the delay time and delay the signal so that the delay time is the same for the central station at each peripheral station. As a method of measuring this delay time, there is a method of receiving the phases of the radio waves of the central station at the peripheral stations and comparing them with each other, and generally uses a wireless line.
For example, "Car Phone" published by The Institute of Electronics, Information and Communication Engineers, 7.5
Term. In this case, the phase of the signal transmitted from the central station needs to be delayed so as to be longer than the delay time of the signal transmission path between the central station and other peripheral stations.

FIG. 8 is an overall system diagram of a conventional system adopting such a system, which is a central station 1 and a plurality of peripheral stations 2.
1 to 2n are signal transmission lines 5 via a modem (modulator / demodulator) 4.
Are connected to each other. As shown in FIG. 9, the peripheral station 2
Each of 1 to 2n includes a transmitter 211 and a receiver 212, and transmits a signal transmitted by the transmitter 211 to the receiver 212 of its own station.
But it is configured so that it can be received. With this receiver,
A signal is received by the phase synchronization receiving antenna 213, and RF is received.
The code decoding unit 215 detects the phase correction signal included in the signal from the signal received by the reception unit 214, and at the same time, the clock synchronization generation unit 216 detects the synchronization signal. And
The phase comparison measurement unit 217 measures the phase difference between the two signals, and the measured phase difference controls the variable delay unit 218 provided in the signal transmission line 5 connected to the central office 1 to set the delay amount of the signal transmission line. , The phase is synchronized with the central station. 219 is a transmitting antenna.

For example, an example of the phase synchronization operation when the phase of the peripheral station 21 deviates from the central station 1 will be shown. The phase synchronization operation at that time is as shown in FIG.
Then, the synchronization signal S0 transmitted from the local station at a certain interval
Is received by the receiver of its own station, and a predetermined fixed length a up to the phase correction signal S1 is measured with reference to it. Next, after stopping the transmitter 211 of its own station for a short period t before and after including a certain length a measured from the synchronization signal S0, the radio wave from the central station 1 serving as a reference for phase correction is generated. Is received and the phase correction signal S included in this is received.
Receive 1 The delay time of the signal transmission path can be equivalently measured by measuring the length b from the synchronization signal S0 to the phase correction signal S1 and comparing the difference between the a and b. During this period, the transmitters of other peripheral stations 22 and the like are stopped in synchronization with the peripheral station 21 based on the length a measured by the peripheral station 21. Hereinafter, as shown in FIG. 6B, the phase of the peripheral station 22 is similarly synchronized with the phase of the peripheral station 21 as a reference. When synchronizing the phases of this peripheral station 22 and below,
The central station 1 transmitter is also stopped together with other peripheral stations. In this way, by sequentially synchronizing the phases up to the peripheral station 2n, the entire phase can be synchronized.

[0005]

As described above, in the conventional phase synchronization system, since the frequencies of the radio waves of the peripheral stations and the central station which are received in the phase synchronization operation are the same, the stations performing the phase synchronization operation are When receiving the radio wave of the reference station, it is necessary to temporarily stop the radio wave of the own station to receive the radio wave.
When the own station and another station perform the phase synchronization operation, only the reference station activates the transmission operation of the transmitter, and the transmitters of the other stations stop. Conventionally, since such a phase synchronization operation is performed at regular intervals of sending a ringing signal, the number of times of starting and stopping the transmission operation of the transmitter at each station becomes extremely large, which causes stress and adverse effects on circuit components and the like. And caused a failure.

Further, since the peripheral station performing the phase synchronization operation needs to receive the signal from the reference station, the reception electric field is weak due to the arrangement of the stations and the phase synchronization operation cannot be performed with high reliability. was there. An object of the present invention is to suppress the occurrence of a failure by reducing the number of times of starting and stopping the operation of a transmitter in a radio base station that performs a phase synchronization operation, and to prevent the reliability of the phase synchronization operation from decreasing due to a received electric field. To provide the inter-station phase compensation method.

[0007]

According to the present invention, a receiving station is installed at a point where wireless calling signals from a plurality of wireless base stations can be received. Means for constantly monitoring the specified ringing signal, means for sending a phase correction start command to the central station when the specified ringing signal cannot be detected, and the synchronization signal and phase transmitted by the peripheral station to be phase-synchronized. Based on the phase correction signal transmitted by the radio base station that serves as the synchronization reference, the delay amount in the peripheral radio base station that is the target of the phase synchronization is detected, and this delay amount is sent to the central station via the uplink. Means are provided. In addition, the central station sends a synchronization signal to the downlink to the peripheral stations subject to phase synchronization based on the phase correction start command input from the uplink, and then the radio base station to be the reference for phase synchronization. A means for sending a phase correction signal to the transmitter of, and a signal for stopping the operation of the transmitter of the peripheral station that is the target of phase synchronization with a predetermined time difference from this, and the phase based on the delay amount from the receiving station. There is provided variable delay means for setting the delay amount in the signal transmission line connecting the peripheral wireless base stations to be synchronized. The receiving station receives the synchronization signal transmitted from the peripheral station that is the target of phase synchronization, measures the first length at which the phase correction signal should be received from this synchronization signal, and then from the radio base station that serves as the phase synchronization reference. The phase correction signal to be transmitted is received, the second length between the synchronization signal and the phase correction signal is measured, and the measured first and second lengths are compared to be a phase synchronization target. Detect the amount of delay in peripheral stations. In addition, the central station can receive at the receiving station with a time difference around the first length at which the phase correction signal measured by the receiving station is received after transmitting the synchronization signal to the wireless base station that is the reference for wireless synchronization. Send a signal to stop the operation of the transmitter of the peripheral station.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a service area diagram including a plurality of small wireless zones, which includes a central station area A0 and a plurality of peripheral station areas A1 to An. The central station area A0 has a central station 1 installed therein. Peripheral stations 21 to 2n are installed in the areas A1 to An, respectively. In addition, a receiving station 31 capable of receiving signals from the central station 1 and signals from a plurality of peripheral stations
.About.3 m is installed in an area where these peripheral station areas overlap, for example. FIG. 2 is a system diagram of the entire system, in which the central station 1, a plurality of peripheral stations 21 to 2n and receiving stations 31 to 3m are connected to each other via a modem 4 and a signal transmission line 5, respectively. The signal transmission line 5 includes an up line and a down line.

FIG. 3 is a system diagram of the peripheral stations 21 to 2n,
Based on the signal sent from the central office 1 in the downlink of the signal transmission line 5, the clock synchronization generation unit 201 detects the synchronization signal, and the code decoding unit 202 detects the specific calling signal, and these synchronization signals and the specific calling are detected. The signal is superimposed on the transmission signal and transmitted from the transmission antenna 204 by the transmitter 203.
Also, the phase correction signal sent from the central office 1 can be detected and sent by the code decoding unit 202.

FIG. 4 is a system diagram of the receiving stations 31 to 3m,
RF receiving unit 302 via phase synchronization receiving antenna 301
Signal is received by the clock synchronization generating unit 303 based on the received signal, and the code decoding unit 30 detects the synchronization signal.
At 4, the specific call signal is detected. When the specific call signal cannot be detected by the code decoding unit 304, the phase correction start command generation unit 305 generates a phase correction start command, which is coded by the coding unit 307 and centralized on the upstream line of the signal transmission line. Send to the station. Further, the code decoding unit 304 can detect the phase correction signal from the received signal, the phase comparison and measurement unit 306 obtains the phase difference between the synchronization signal and the phase correction signal, and measures the delay time difference based on this phase difference. Equivalently measure the delay time of the signal transmission line from the delay time difference.
This delay amount is encoded by the encoding unit 307 in synchronization with the synchronization signal detected by the clock synchronization generation unit 308 based on the signal from the central office through the downlink, and is transmitted to the central office via the uplink.

FIG. 5 is a system diagram of the central station 1. The signal transmission path 5 between each of the peripheral stations 21 to 2n has a variable delay section 101 to 10n for each peripheral station collectively. Further, the signal transmission path connecting the receiving stations 21 to 2m has a code decoding section 110 and a clock synchronization generating section 111, and each of the signal transmissions is performed based on the encoded delay amount included in the signal from the receiving station. Variable delay units 101-provided on the road
It is configured to control a delay amount of 10n. It is needless to say that the central station can also transmit a signal in which the synchronization signal, the specific calling signal and the phase correction signal are superimposed, from its own transmitter, similarly to each peripheral station.

Next, the phase correction operation in the system having the above configuration will be described. For example, as shown in FIG. 6A, it is assumed that the reception station 31 receives the reception signals from the three stations, that is, the central station 1, the peripheral station 21, and the peripheral station 22. At this time, if the demodulated waveforms from each station are synchronized, the receiving station 31 receives the signal at the RF receiving section 302, and then the code decoding section 30.
In 4, the specific call signal included in the received signal at a constant interval is detected at the timing based on the synchronization signal, and it is confirmed that the phase of the signal from each wireless station is synchronized. However, when the demodulated waveforms of the received signals from the three stations are not synchronized, the demodulated waveforms of the received signals from the three stations include jitter as shown in FIG. It becomes impossible to detect the sync signal or the specific ringing signal. Therefore, the receiving station 31 determines that the signals of the respective radio base stations are out of phase, and sends the phase correction start command generated by the phase correction start command generation unit 305 to the central office 1 through the uplink.

Then, in the central station 1 that receives the phase correction start command, the peripheral stations 21 and 2 and the receiving station 3 through the downlink.
The phase correction operation command is sent to 1 to start the phase correction operation. For example, here, it is assumed that the peripheral station 21 in the peripheral station area A1 is phase-synchronized. At this time, as shown in FIG. 7A, in the receiving station 31, the peripheral station 2
It receives a synchronization signal transmitted from one transmitter, measures a fixed length a up to the phase correction signal S1 with reference to it, and sends it to the central office 1. Then, the central station 1 performs the radio transmission operation of the transmitter of the peripheral station 21 for a short period t including before and after the measured length a from its own synchronization signal S0 and other peripheral stations that can be received by the receiving station 31. In this example, the wireless transmission operation of the transmitter of the peripheral station 22 is stopped.
As a result, the receiving station 31 receives only the radio wave from the central office 1, and the phase correction signal S included in the signal from the central office 1 is received.
1 is detected by the code decoding unit 304, and the length b from the synchronization signal S0 to the phase correction signal S1 is measured. Then, the phase comparison measurement unit 306 compares the difference between the lengths a and b to measure the delay time difference Δ, and the peripheral station 2 is equivalently measured.
1 measures the delay time in the signal transmission path 5 between the central office 1 and the central office 1. The measured delay amount is encoded and sent to the central office 1 through the uplink.

The central station 1 detects the coding delay amount from the receiving station 31 sent through the upstream line, and the peripheral station 2
The variable delay circuit 101 installed in the downlink to 1 adjusts the delay amount for the peripheral station 21 and executes the phase synchronization for the central station 1. Similarly, the signal phase of the peripheral station 22 in the area A2 is synchronized with the signal phase of the peripheral station 21 in the area A1 as a reference during the period G2 as shown in FIG. Hereinafter, by sequentially synchronizing the phases up to the peripheral stations 2n in the area An in the period of G3 to Gn, the phases of the entire area of the system can be synchronized. In this case, needless to say, the wireless transmission operations of the transmitters of other peripheral stations and the central station are stopped.

As in this example, the receiving station 31 can receive the specific calling signal transmitted from each of the transmitters of the central station 1, the peripheral station 21 and the peripheral station 22, and the receiving station 31 can detect the specific calling signal. Only when it does not exist, it is determined that the phase of the signal between the radio base stations is not synchronized, and the operation of synchronizing the phase of the entire system is performed. Therefore, when the phase of each station is not deviated and the specific call signal is correctly received by the receiving station, the phase correction start signal is not generated and the phase correction operation is not performed. For this reason, the number of times the transmitter of each station stops and starts up during the phase correction operation is reduced, and the occurrence of a failure can be suppressed. In addition, each peripheral station does not need to receive signals from the central station and other reference stations, eliminating the need for a receiver that was installed in each peripheral station, reducing the number of peripheral station equipment, and enabling multiple stations. Since the receiving station is installed at the point where the electric field received from the station is the same and the phase synchronization operation is performed, malfunction of the phase correction operation due to the weak electric field can be prevented.

[0016]

As described above, according to the present invention, a wide area radio paging system having a central station and peripheral stations is provided with a receiving station,
This receiving station detects the phase non-synchronization of the specific ringing signal from each peripheral station, and only when this phase non-synchronization is detected, the central station controls each radio station and each of the radio signals detected by the receiving station. Since the phase synchronization operation is performed based on the delay amount of the peripheral station, periodic phase synchronization operation is unnecessary, and the number of times of stopping and starting the transmission operation of the transmitter of each wireless station can be reduced. This has the effect of reducing the stress and adverse effects on the line parts of the transmitter, etc. Also, since the receiving station detects the amount of delay at each peripheral station,
Since it is not necessary to provide a receiver in each peripheral station, there is an effect that the facilities of the peripheral stations can be reduced. In particular, when a receiving station capable of receiving radio waves from a large number of peripheral stations is installed, the system can be constructed with a smaller number of receiving stations, and the effect of reducing the equipment of the peripheral stations becomes great. Further, since the receiving station is installed at a point where the electric fields received from several radio base stations are equal, it is possible to prevent malfunction of the phase correction operation due to a weak reception electric field and reduce the number of receivers for each radio station. There is.

[Brief description of drawings]

FIG. 1 is a service area diagram composed of small wireless zones of a wide area wireless calling system to which the present invention is applied.

FIG. 2 is an overall system diagram of a wide area wireless calling system to which the present invention is applied.

FIG. 3 is a system diagram of a peripheral station.

FIG. 4 is a system diagram of a receiving station.

FIG. 5 is a system diagram of a central office.

FIG. 6 is a diagram showing states of signals received by a receiving station when the phases of the signals are synchronized and when the phases are not synchronized.

FIG. 7 is a timing diagram for explaining a phase synchronization operation.

FIG. 8 is a system diagram of a conventional wide area radio calling system.

FIG. 9 is a system diagram of a conventional peripheral station.

[Explanation of symbols]

 1 Central Station 21-2n Peripheral Station 31-3m Receiving Station 4 Modem 5 Signal Transmission Line S0 Synchronization Signal S1 Phase Correction Signal A0-An Peripheral Station Area

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical indication H04Q 7/36

Claims (3)

[Claims] 1. A wide area wireless paging system in which a large number of wireless base stations including a central wireless base station and a plurality of peripheral wireless base stations simultaneously wirelessly transmit the same wireless paging signal in their respective service areas. A receiving station is installed at a location where the wireless call signal from the station can be received, and the receiving station cannot constantly detect the specific call signal transmitted from each wireless base station and cannot detect the specific call signal. A means for sending a phase correction start command to the central radio base station at the time, a synchronization signal transmitted by a peripheral radio base station that is a phase synchronization target, and a phase correction signal transmitted by a radio base station that is a reference for phase synchronization. Based on the phase synchronization target, the delay amount in the peripheral radio base station is detected, and the delay amount is transmitted to the central radio base station via the uplink. The line base station transmits a synchronization signal to the downlink to the peripheral radio base station subject to phase synchronization based on the phase correction start command input from the uplink, and then the radio base station to be the reference for phase synchronization. Means for sending a phase correction signal to the transmitter of the above, and a signal for stopping the operation of the transmitter of the peripheral wireless base station subject to the phase synchronization with a predetermined time difference from this, and the delay amount from the receiving station. And a variable delay means for setting a delay amount in a signal transmission line connecting peripheral wireless base stations to be subject to phase synchronization based on the inter-station phase compensation method of a wide area wireless paging system. 2. A receiving station receives a synchronization signal transmitted from a peripheral radio base station to be phase-synchronized, measures a first length from which the phase correction signal should be received, and performs phase synchronization. A second signal between the synchronization signal and the phase correction signal is received by receiving a phase correction signal transmitted from a reference wireless base station.
2. The inter-station phase of the wide area wireless paging system according to claim 1, wherein the delay amount in the peripheral wireless base station that is the target of phase synchronization is detected by measuring the length of each of the first and second measured lengths. Compensation method. 3. The central radio base station transmits a synchronization signal to a radio base station serving as a reference for radio synchronization, and then a time difference before and after a first length at which a phase correction signal measured by the reception station is received. 3. The inter-station phase compensation method of the wide area wireless paging system according to claim 2, wherein a signal for stopping the operation of the transmitter of the peripheral wireless base station receivable at the receiving station is transmitted.