JP3351373B2 - Hot standby line switching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot standby line switching system used in digital radio communication, and more particularly to a terminal station capable of judging deterioration of line quality due to a natural phenomenon and stopping unnecessary line switching. It relates to a hot standby line switching system that can be used.

[0002]

2. Description of the Related Art In general, in order to improve the reliability of a digital radio line, there are provided two radio transmission / reception devices, an active system used for actual communication and a standby system used for backup. A hot standby line switching method is known in which, when one of the devices fails, the device is switched to a standby device to operate.

[0003] However, in the conventional hot standby line switching method, deterioration of line quality due to a natural phenomenon is a failure common to both systems even if line switching is performed, so that the line is not restored. In addition, the reason for determining the line switching based on the decrease in the reception level is that monitoring of the reception level alone indicates a failure of a common device such as a switching device or a duplexer, or that the device is normal and the quality is deteriorated due to a natural phenomenon. Cannot be determined.

Therefore, for example, Japanese Patent Application Laid-Open No. 9-8706 proposes a hot standby line switching system in which line switching is not performed when line quality is deteriorated due to natural phenomena, and line switching is performed only in the event of equipment failure. I have. This conventional hot standby line switching system detects a failure in the receiving system of each of the working and standby systems, and switches the receiving system of its own station based on the detection result, or switches the transmission system of the opposite station. A switching control circuit that outputs a control signal,
A degradation cause determination circuit that determines a line degradation state based on a state of a reception signal in a reception system and outputs a control signal to the switching control circuit based on the determination result,
The deterioration cause determination circuit compares the time difference between two different line deterioration information, and outputs a control signal to the switching control circuit when the time difference is equal to or longer than a predetermined time, and the switching control circuit detects a fault in both systems. When the control signal is input from the deterioration cause determination circuit, the output of the switching control signal to the opposite station is stopped.

[0005] According to the conventional hot standby line switching method, when there is an interval of a certain time or more between the two occurrence times due to the difference between the occurrence times of two line deterioration alarms having different detection criteria in the same received signal, a natural phenomenon occurs. If both occur within a certain period of time, it is determined that the equipment has failed, and if the former is the case, it is necessary to wait for recovery without performing line switching, thereby fading or causing natural phenomena such as rainfall. Unnecessary line switching when line quality is degraded due to the above can be stopped.

[0006]

However, this conventional technique has the following problems. As shown in FIG. 6, one or more regenerative relay stations 602 (two in the drawing) are provided between an upper terminal station 600 and a lower terminal station 601, and the same system is used for all sections. In the case of the hot standby line switching system in which the selected line is switched, for example, when the signal is out of frame synchronization in section 2 of FIG. 6, the upper terminal 600 does not synchronize the frame of the received signal and extracts signal information. Since it cannot be performed, only the loss of frame synchronization is confirmed, and line switching is performed.

If the cause of the frame synchronization loss in section 2 is a failure of one of the systems, the line is restored and there is no problem. However, in the case of deterioration due to natural phenomena in section 2, whether the switching information itself reaches the lower terminal station. The line is not restored without switching the line. That is, when all switching control is performed by the upper terminal station, deterioration due to natural phenomena occurring in sections other than section 1 cannot be detected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. In a circuit having one or more regenerative relay stations, a section other than the most recent section (one or more regenerative relay stations) is viewed from a terminal station. A hot standby line in which a terminal station can determine that the cause of frame loss is due to a natural phenomenon, even if the frame loss has occurred due to the deterioration of the line quality due to the natural phenomenon that occurred in the sandwiched section). An object is to provide a switching method.

[0009]

SUMMARY OF THE INVENTION The present invention has a terminal station and one or more regenerative relay stations provided between the terminal stations. In the hot standby line switching method for switching from the active system to the standby system, the regenerative relay station is configured such that the reception level alarm signal generated when the reception input level of the reception signal falls below a predetermined reference and the reception signal are out of word synchronization. When the time difference between the occurrence of the word out-of-synchronization signal and the occurrence of the out-of-synchronization signal is equal to or longer than a predetermined time, a deterioration cause determination circuit that determines that the deterioration cause of the received signal is due to a natural phenomenon, A frame synchronization detection circuit for detecting, a pseudo frame generation circuit for generating a pseudo frame signal including determination information by the degradation cause determination circuit, and a degradation cause determination circuit. If it is determined that the cause of the deterioration of the received signal is due to a natural phenomenon, and the received signal is out of frame synchronization, the signal is generated by the pseudo frame generating circuit instead of the signal to be transmitted to the opposite station. And a selection circuit for transmitting the pseudo frame signal to the opposite station.

[0010] It is preferable that the pseudo frame signal includes own station number information.

The selection circuit is provided in the modulation signal processing section or the demodulation signal processing section.

[0012]

Uplink and downlink may be controlled by the upper terminal or lower terminal, the downlink may be controlled by the upper terminal, and the uplink may be controlled by the lower terminal. May control the uplink and the lower terminal may control the downlink.

According to the present invention, a pseudo-frame signal can be transmitted in place of a signal that has become out of synchronization in the regenerative relay station. The terminal station can also determine the line degradation due to a natural phenomenon that occurs thereafter.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the hot standby line switching system of the present invention. In the embodiment shown in FIG. 1, only the upper terminal station and the next regenerative relay station are shown in the line configuration having a plurality of regenerative relay stations. There is a lower terminal (not shown).

The upper terminal station 100 includes a transmitting device 120, a receiving device 130, and a switching control unit 105. Each transmitting device 1
20 and the receiving apparatus 130 are composed of two systems, an active system used for actual communication and a standby system used for standby (hereinafter, -1 is added after the reference numeral of a component of the active system, −0 is added after the reference number of the constituent part of the standby system).

The transmitting apparatus 120 includes a distributing section 109 for distributing a transmission signal to an active system and a standby system, and a modulation signal processing section 101-1 for performing signal processing such as insertion of information and modulating the signal into an intermediate frequency band signal. , 101-0 and the modulation signal processing unit 101-
It has transmission units 102-1 and 102-0 for converting signals from the signals 101 and 101-0 into signals in the carrier frequency band and transmitting the signals, and a changeover switch 107 for selecting between the active system and the standby system. The transmission signal is transmitted to the regenerative relay station 2 via the antenna 111.
Sent to 00.

Receiving apparatus 130 has a distribution section 110 for distributing the received signal received via antenna 111 to the working system and the standby system, and a receiving section 104-for receiving the received signal and converting it to an intermediate frequency band signal. 1, 104-0, and a demodulated signal processing unit 103-1 that demodulates a signal converted into an intermediate frequency band by the receiving units 104-1, 104-0 into a baseband digital signal and performs signal processing. 103-0
Switch 108 for selecting between the active system and the standby system
Receiving level alarm signals S20 and S22 from the receiving units 104-1, 104-0, and the demodulated signal processing units 103-1 and 103-1.
Deterioration cause determination circuit 106 that determines a line degradation state based on word out-of-sync signals S21 and S23 from 03-0.
And

The switching control unit 105 receives a switch switching signal S
18 to the changeover switch 107 and the changeover switch 10
7 and the switch switching signal S
19 to the changeover switch 108 and the changeover switch 10
8 is controlled.

The switching control section 105 also outputs a deterioration alarm signal S24 based on the judgment result of the deterioration cause judgment circuit 106.
, The switching operation of the changeover switches 107 and 108 is stopped.

The regenerative relay station 200 has a transmission / reception apparatus 220 for the downlink, a transmission / reception apparatus 230 for the uplink, and a switching control unit 205. Each transmission / reception device is composed of two systems, an active system used for actual communication and a standby system used for protection (hereinafter,-after a reference numeral of a component of the active system).
1 is added, and −0 is added after the reference numeral of the component of the standby system).

Downlink transmission / reception apparatus 220 includes distribution section 209 for distributing the received signal to the working system and the standby system via antenna 211, and receiving section 204 for receiving the received signal and converting it to an intermediate frequency band signal. -1, 204-0, and a demodulated signal processing unit 203-1 for demodulating a signal converted into an intermediate frequency band by the receiving units 204-1 and 204-0 into a baseband digital signal and performing signal processing. , 203
−0, and modulated signal processing units 201-1 and 201-0 that modulate into a signal in an intermediate frequency band after signal processing such as insertion of information.
And a transmission unit 202 that converts signals from the modulation signal processing units 201-1 and 201-0 into signals in a carrier frequency band and transmits the signals.
-1, 202-0, and a changeover switch 207 for selecting between the active system and the standby system. The signal transmitted from the changeover switch 207 is transmitted to the next regenerative relay station or lower terminal station (not shown) via the antenna 212.

An uplink transmission / reception apparatus 230 includes a distribution section 210 for distributing a reception signal to a working system and a protection system via an antenna 212, and a reception section 214 for receiving the reception signal and converting the reception signal into an intermediate frequency band signal. -1, 214-0, and a demodulated signal processing unit 213-1 for demodulating a signal converted into an intermediate frequency band by the receiving units 214-1, 214-0 into a baseband digital signal and performing signal processing. 213
−0, and modulated signal processing units 211-1 and 211-0 that modulate into a signal of an intermediate frequency band after signal processing such as insertion of information.
And a transmission unit 212 that converts signals from the modulation signal processing units 211-1 and 211-0 into signals in a carrier frequency band and transmits the signals.
-1, 212-0, a changeover switch 208 for selecting between the working system and the standby system, the reception level warning signals S5 and S6 from the receiving units 214-1, 214-0, and the demodulation signal processing unit 2.
13-1, 213-0, the word out-of-sync signal S7,
And a deterioration cause determination circuit 206 for determining a line deterioration state based on S8.

The deterioration cause judging circuit 206 outputs the deterioration alarm signal S11 based on the judgment result to the modulation signal processing section 211-.
1, 211-0. Demodulated signal processing unit 213
1, 213-0 are out-of-frame signals S9, S10
Is transmitted to the modulation signal processing units 211-1 and 211-0.

The switching control unit 205 includes a demodulation signal processing unit 20
A switch switching signal S3 is transmitted to the switch 207 based on the switching control signals S1 and S2 from 3-1 and 203-0, and the switching operation of the switch 207 is controlled. The switching control unit 205 also transmits a switch switching signal S4 to the switch 208, and controls the switching operation of the switch 208.

In FIG. 1, signals S12 and S13 are switching information signals output from the switching control section 105. These signals are transmitted to the modulation signal processing sections 101-1 and 101-0, and The demodulated signal processing sections 203-1 and 203-0 of the regenerative relay station 200 become the switching control signals S1 and S2 via the relay relay station 200. The signals S14 and S16 are transmitted to the regenerative relay station 200.
Signals S15 and S
Reference numeral 17 denotes a frame out-of-synchronization signal transmitted from the reproduction relay station 200.

FIG. 2 shows a demodulated signal processing section 21 of the regenerative relay station.
FIG. 3 is a block diagram showing a configuration of 3-1 and a modulation signal processing unit 211-1.

As shown in FIG. 2, the demodulated signal processing unit 213
-1 indicates a demodulation circuit 301 and an error correction decoding circuit 302
And a signal processing circuit (reception unit) 303 and a frame synchronization detection circuit 304. The received signal is converted into a baseband signal, an error correction code is decoded, frame synchronization is established, and signal processing is performed. Do. The error correction decoding circuit 302 detects a word out-of-synchronization state in which an error correction code cannot be found. If the frame synchronization is not established, the frame synchronization detection circuit 304 sends the out-of-frame signal S9 to the modulation signal processing unit 211-1.

The modulation signal processing section 211-1 includes a signal processing circuit (transmission section) 305 and a pseudo frame generation circuit 306.
, A selection circuit 307, an error correction coding circuit 308,
The signal processing circuit (transmission unit) 305 performs signal processing, and then sends out the signal A to the selection circuit 307. Pseudo frame generation circuit 30
6 generates a predetermined frame configuration irrespective of the received signal and sends it to the selection circuit 307 as a signal B.

The out-of-frame signal S9 output from the demodulation signal processing section 213-1 and the deterioration cause determination circuit 2
The deterioration warning signal S11 output from 06 is input to the AND gate 310, and the selection signal S30 is output. The selection circuit 307 selects the signal A and the signal B according to the selection signal S30. The selected signal is subjected to error correction coding by an error correction coding circuit 308 and modulated by a modulation circuit 309 to a signal in an intermediate frequency band.

FIG. 3 is an explanatory diagram showing a frame structure of the signal A and the signal B. FIG. 3A shows a signal A in which some frame bits are crushed. FIG. 3B shows a signal B generated by the pseudo frame generation circuit 306 in the modulation signal processing unit 211-1. The frame of the signal B includes information such as a RAIN ALM (alarm due to space, that is, an alarm of deterioration of line quality due to natural phenomena such as fading and rainfall) and own station number in advance.

FIG. 4 is a circuit diagram showing a deterioration cause judging circuit. As shown in FIG. 4, the deterioration cause determination circuit 206 (1
06) includes a delay unit 504, a flip-flop 505, an AND gate 506, and the like. The deterioration cause determination circuit 206 includes a reception level warning signal S5 generated when the reception input level of the reception signal is lower than a predetermined reference, and a word synchronization signal S7 generated when the reception signal is out of word synchronization. At a timing delayed by a predetermined time t (for example, 10 ms) from the signal S5.
7 and waits longer than the predetermined time t, it is determined that the line has deteriorated due to a natural phenomenon such as fading or rainfall, and the deterioration alarm signal S11 and the switching control signal S24.
Is output.

Next, the operation of the hot standby line switching system of the present invention will be described. In FIG. 1, the case where the channel quality is degraded due to a natural phenomenon in section 2 will be described in the working system. The receiving section 214-1 of the regenerative relay station 200 via the antenna 212 and the distribution section 210 on the section 2 side
Is converted into a signal in the intermediate frequency band. The reception unit 214-1 monitors the reception input level, and when the level decreases with time, a reception level warning signal S5 is transmitted from the reception unit 214-1 to the deterioration cause determination circuit 206.

The signal converted into the intermediate frequency band is demodulated into a baseband digital signal by a demodulation signal processing unit 213-1, and necessary information is extracted, line quality is monitored, and the like. In addition, as a result of monitoring the line quality, the demodulation signal processing unit 213-1 sends the out-of-synchronization signal S7 to the deterioration cause determination circuit 206, and transmits the out-of-frame signal S9 to the modulation signal processing unit 211-1.

When the deterioration cause judging circuit 206 judges that the deterioration is caused by a natural phenomenon, the deterioration warning signal S11 is transmitted to the modulation signal processing section 211-1.

The output of the demodulated signal processing section 213-1 is subjected to signal processing such as insertion of information in the modulated signal processing section 211-1, and then the digital signal is again modulated into an intermediate frequency band signal. The signal is converted into a carrier frequency band by 1 and transmitted to the upper terminal station 100 from the antenna 211 via the switch 208.

The pseudo frame generation circuit 306 in the modulation signal processing section 211-1 has a frame bit, RA
A pseudo frame (see signal B in FIG. 3) composed of information to be transmitted to the upper terminal station 100 even when frame synchronization is lost, such as IN ALM and own station number. Selection circuit 307
Now, for the signals A and B, which are the original received signals,
A normal signal is generated by a selection signal S30 generated by taking the logical product of the out-of-frame signal S9 and the degradation warning signal S11.
The signal A is selected, and the signal B is selected only when the received signal loses frame synchronization due to a natural phenomenon. Modulated signal processing section 211-1 encodes and modulates signal B, and performs higher-order terminal 1
Send to 00.

When the upper terminal 100 receives the signal A, the receiver 104-1,
The demodulated signal processing unit 1 is transmitted via the demodulated signal processing unit 103-1.
At 03-1, the frame synchronization of the received signal is confirmed, and when synchronization is not achieved, the signal is transmitted to the switching control unit 105 as a frame synchronization loss signal. The switching control unit 105 sends out a system switching command when the out-of-frame signal is input.

In the upper terminal station 100, when the signal B is received, the demodulated signal processing section 103-1 performs signal processing to extract out of frame synchronization of the signal B, a deterioration alarm, an own station number, and the like. Then, by sending the deterioration warning signal S14 to the switching control circuit 105, the line switching can be stopped.

According to the present invention, the pseudo frame generating circuit 3
By transmitting the signal B including the pseudo frame generated by the reference numeral 06 to the upper terminal station 100, the upper terminal station 100 does not lose the frame synchronization, and the line deterioration due to a natural phenomenon occurs in any section of the line. You can check if you are.

In FIG. 6, for example, the pseudo frames of the regenerative relay station 602 between sections 2 and 3 are section 2 and section 1
And transmitted to the terminal station 600. At this time, if the pseudo frame itself deteriorates in the section 2, the pseudo frame is re-inserted in the regenerative repeater station 602 between the sections 1 and 2. If the pseudo frame itself deteriorates in the section 1, the terminal station 600 Will detect line degradation.

Next, another embodiment of the present invention will be described. FIG. 5 shows a demodulated signal processing section 213-1 and a modulated signal processing section 211 of a regenerative relay station according to another embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of -1.

As shown in FIG. 5, in another embodiment of the present invention, the demodulated signal processing section 213-1 includes a demodulation circuit 301.
, An error correction decoding circuit 302, a signal processing circuit (reception unit) 303, a frame synchronization detection circuit 304, a pseudo frame generation circuit 306, a selection circuit 307, and an AND gate 310. Part 211
-1 is composed of a signal processing circuit (transmission unit) 305, an error correction encoding circuit 308, and a modulation circuit 309.

According to this embodiment, selection circuit 307
Is included in the demodulation signal processing unit 213-1. Therefore, if the circuit is a baseband signal circuit, even if the order of the circuit configuration is changed, the same effect is realized only by changing the pseudo frame configuration. can do.

The present invention is not limited to the above-described embodiment, and various changes can be made within the technical scope described in the claims.

For example, in the embodiment of the present invention, the upper and lower terminals are positioned as upper and lower terminals and the line switching is controlled by the upper terminal, and simultaneous uplink and downlink control is assumed. Controlling line switching, simultaneous uplink and downlink control, uplink control by lower terminal, downlink control by upper terminal, uplink control by upper terminal,
Even when the downlink is controlled by the lower terminal station, the same effect can be realized by adopting the same configuration in both the upper and lower stations.

In the embodiment of the present invention, the time difference between the reception level warning signal and the word synchronization generation signal is used to determine the deterioration of the line quality due to a natural phenomenon.
However, the present invention is not limited to this, and if any other method can determine that the deterioration of the line quality is caused by a natural phenomenon, the same effect as the present invention can be realized by using the information.

For example, by monitoring the signal level of the received signal,
The determination may be made by comparing the difference between the occurrence times of the line degradation information generated at two different values set in advance. Further, the bit error rate of the received signal may be monitored, and a determination may be made by comparing the time difference of occurrence of channel deterioration information occurring at two different code error rates set in advance. Furthermore, the determination may be made by comparing the time difference between the line degradation information generated at the bit error rate and the line degradation information generated at the loss of frame synchronization.

[0049]

According to the present invention, it is possible to transmit a pseudo frame signal in place of a signal that has become out of synchronization in the regenerative relay station. The terminal station can also determine line degradation due to natural phenomena occurring after the latest section, and unnecessary line switching can be stopped.

Also, by inserting the station number in the pseudo frame, it is possible to determine which station the pseudo frame is generated from. Therefore, when the line is composed of many sections, the line quality in which section The terminal can identify whether the terminal has deteriorated. As a result, the efficiency of line maintenance by the telecommunications carrier increases.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a hot standby line switching system according to the present invention.

FIG. 2 is a block diagram illustrating a configuration of a demodulation signal processing unit and a modulation signal processing unit of the regenerative relay station.

FIGS. 3A and 3B are explanatory diagrams showing a frame configuration of a signal A and a signal B. FIG.

FIG. 4 is a circuit diagram showing a deterioration cause determination circuit.

FIG. 5 is a block diagram showing a configuration of a demodulation signal processing unit and a modulation signal processing unit of a regenerative relay station according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an example in which a line is composed of a number of sections via a regenerative relay station.

[Explanation of symbols]

 100: upper terminal station 200: regenerative relay station 206: deterioration determination circuit 304: frame synchronization detection circuit 306: pseudo frame generation circuit 307: selection circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/74 H04L 1/22 H04M 3/22 H04M 3/26

Claims (7)

(57) [Claims] A hot switch which has a terminal station and one or more regenerative relay stations provided between the terminal stations, and switches a transmitting / receiving device of the terminal station and the regenerative relay station from an active system to a standby system when a line is deteriorated. In the standby line switching method, the regenerative repeater station receives a reception level warning signal generated when a reception input level of a reception signal falls below a predetermined reference, and a word synchronization signal generated when the reception signal is out of word synchronization. A deterioration cause determination circuit that determines that the cause of deterioration of the received signal is due to a natural phenomenon when a time difference between the occurrence signal and the out-of-sync signal is equal to or longer than a predetermined time; a frame synchronization detection circuit that detects frame synchronization loss of the received signal; A pseudo-frame generation circuit that generates a pseudo-frame signal including determination information by the deterioration cause determination circuit; If it is determined to be due to a natural phenomenon, and the received signal is out of frame synchronization, a pseudo frame signal generated by the pseudo frame generation circuit in place of a signal to be transmitted to the opposite station is sent to the opposite station. A hot standby line switching method, comprising: a selection circuit for transmitting; 2. The hot standby line switching system according to claim 1, wherein said pseudo frame signal includes own station number information. 3. The hot standby line switching system according to claim 1, wherein the selection circuit is provided in a modulation signal processing unit. 4. The hot standby line switching system according to claim 1, wherein said selection circuit is provided in a demodulation signal processing unit. 5. The hot standby line switching system according to claim 1, wherein an upstream line and a downstream line are controlled by an upper terminal station or a lower terminal station. 6. The hot standby line switching method according to claim 1, wherein the down line is controlled by the upper terminal and the up line is controlled by the lower terminal. 7. The hot standby line switching system according to claim 1, wherein an upstream line is controlled by an upper terminal and a downstream line is controlled by a lower terminal.