JPS62281629A - Circuit switching system - Google Patents

Abstract

PURPOSE:To perform the titled system capable of synchronously switching in a short time with no intermission despite the temporary cut-off of a spare circuit, by putting a secondary data signals related to the synchronizing switch into at least a signal working circuit as well as at least a signal spare circuit having no synchronizing switch with the working circuit, and transmitting these data signals in parallel with each other. CONSTITUTION:The secondary data signals related to the synchronizing switch are put into at least one of the 2nd main data signals transmitted through working circuits SYS1 and SYS2 as well as at least one of data signals transmitted through a spare circuit SP having no synchronizing switch with the working circuit transmitting a single main data signal. Then these secondary data signals are transmitted in parallel with each other, and never cut off even with the temporary cut-off of the circuit SP in a synchronizing switch mode. As a result, the synchronizing switch is carried out in a short time with no intermission.

Description

Detailed Description of the Invention [lambda] Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a line switching system, and more particularly to a line switching system used in a multicarrier transmission type digital microwave communication system.

[Conventional technology]

Digital microwave communication systems sometimes employ a multi-carrier transmission method in order to improve the recovery rate for line failures.

In such a system, one main data signal output by a carrier terminal station at the sending end is divided into N (an integer greater than or equal to Nfi1) main data signals, and each of the n1 divided main data signals uses a different carrier wave. Each data signal transmitted through the working line is combined into one main data signal and output to the carrier terminal station at the receiving end. The protection line also consists of N lines each using a different carrier wave, and synchronous switching between the working line and the protection line can be performed for each carrier wave, so the line failure recovery rate of such a system is high.

In such a system, a test signal can be passed through the protection line in order to check the transmission quality while the protection line is on standby. That is, a test signal, which is a data signal of a specific pattern, is divided into N data signals,
Each divided data signal is transmitted on each standby line, and each transmitted data signal is converted into an original test signal, which is monitored by a test signal detector.

When one of the working lines is synchronously switched to the protection line, first the working line and the protection line are connected in parallel at the sending end using a transmission switch.

That is, the transmission switch switches the data signal to be output to the protection line from the data signal that has been output (obtained by dividing the test signal) to the same data signal as the main data signal being transmitted on the working line. Since both data signals to be switched are asynchronous with each other, this switching changes the clock of the data signal output to the protection line. If the clock changes discontinuously, the protection line may become out of synchronization and it may take a long time of several tens of milliseconds to recover.

Therefore, the transmitting switch is provided with a phase-locked loop that is synchronized with the clock of the input data signal, and the input data signal 't1.1 is output at the output of this phase-locked loop. Even if the input data signal is switched, the output frequency of the phase-locked loop changes continuously with the loop filter's time constant (several milliseconds), so the clock of the output data signal changes continuously, causing the protection line to become out of sync. can be prevented. However, during the clock change time of several m8, data may be read at the change point, so the protection line is disconnected at this time.

Conventional line switching methods used in such systems completely improve reliability by inserting sub-data signals related to synchronous switching into one of the working lines and a protection line that is required to be switched synchronously with the working line and transmitting them in parallel. I was supposed to let them do it. Therefore,
When switching synchronously to the protection line due to deterioration in the line quality of all working lines, the sub data signal via the protection line is temporarily interrupted, and during this time the sub data signal via the working line cannot be used due to the line quality deterioration. , all the sub data signals may be disconnected. In this case, the synchronous switching operation is suspended until the sub data signal via the protection line is recovered.

[Problem to be Solved by the Invention 1] As explained above, the conventional line switching method used in a digital microwave communication system that uses a multicarrier transmission method is to transfer the sub data signal related to synchronous switching to one of the working lines. , is inserted into the working line and the protection line to be synchronously switched and transmitted in parallel, so when the working line is synchronously switched to the protection line, the sub data signal via the working line and the protection line are temporarily switched. Since the sub data signal and the sub data signal are both disconnected and the synchronous switching operation may be interrupted during this period, there is a drawback that the synchronous switching takes a long time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a line switching system that solves the above drawbacks and allows synchronous switching in a short time without interrupting the synchronous switching operation even when the protection line is temporarily disconnected.

[Means for solving problems]

The line switching system of the present invention transmits N (N is an integer of 1 or more) second king data signals obtained by dividing one first king data signal using different carrier waves. At least one working line group consisting of N working lines numbered from 1 to N, and a protection line consisting of N (tlil) protection lines numbered 1 to N using different carrier waves. 8! In a multi-carrier transmission system including at least one q line switching system in which the working line and the protection line have all the same numbers and are synchronously switched in number units, sub data signals related to synchronous switching are transferred to the working line. At least one of the second king data signals being transmitted on the second king data signal and the working line transmitting this one king data signal cannot be switched synchronously, and at least one of the data signals being transmitted on the protection line cannot be switched synchronously. Both are inserted into each other and transmitted in parallel.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments.

FIG. 1 is a block diagram showing a first embodiment of the line switching system of the present invention.

The embodiment shown in FIG. 1 is based on the current system 8YSl/5YS.
2, backup system SP, and test signal generator (hereinafter referred to as PG).
) 11 and 12, and test signal detectors (hereinafter referred to as PD) 71 and 72.

The current system 5YSI is a transport terminal station (not shown) at the sending end.
A hybrid (hereinafter referred to as HYB) 101 and 102 that branches one column of data signals DIOI and D102, each of which is a king data signal output by
One of the two data signals D10111D102 which are branched and outputted by each of 2 and the current system 5YS.
Switchers (hereinafter referred to as SW) 111 and 112 input one column of two data signals from each of the HYBs 101 and 102, and two data signals D101 and D102 are branched and output from each of the HYBs 101 and 102, respectively. The other one and f) SC signals S1 and S3 and DEC signals S2 and S4 are input, respectively, and data signals D121 and D123 of 4 columns are input.
and data signals D122-D124 to the transmitter (not shown) at the sending end of each working line, and also outputs data signals D121, D123 and data signals D122, D124 to the protection system SP. Data signals D121, D123 and data signals D122, D124 output by devices (hereinafter referred to as TXDPU) 121 and 122 and receivers (not shown) at the receiving end of the respective working lines
is input and output as is, and the DEC signals S1 and S
Frame synchronizers (hereinafter referred to as F8YNC) 141 and 142 that output 3 and DEC signals S2 and S4, and data signals D21 and D23 and data signals D22 and F'5YNCI41 and 14 that output DEC signals S2 and S4, respectively, and data signals D21 and D23 that are output by the backup system SP.
2 output data signals D121-D123 and data signals D122 and D124 are inputted, and data signals D131 and D133 of four columns and data signals D132 and D are inputted, respectively.
Synchronous switching device # (hereinafter referred to as 5YNC8W) 151 fist 152 that outputs 134 and data signal D131@D13
3 and data signals D132 and D134, and output one column of data signals D141 and D142, respectively (hereinafter referred to as RXI PU) 161-162
, data signals D141 and D142 and backup system SP
inputs data signals D41 and D42 outputted by
8 Wl 71 and 172 which output to 2.

The current system 5YS2 is configured in the same manner as the current system 5Y81, except that there is no input/output for the DSC signals S1 to S4. Each reference numeral in the current system 5YSI with the number (1) in the hundredth series changed to 2 represents those in the current system 5YS2 that correspond to each component and each signal in the current system 5YS1. SW211 and 212 (not shown) of the current system 5YS2 output either one column of data signals D1 and D2 output from the PGII and 12, or data signals D201 and D202 (not shown) that are branch outputs of the HYB201 and 202, respectively. Either one is the current system 8YS1 osWx 11
・Output to 112. 5VV2 of current system 5YS2
71 and 272 (not shown) are the output signals of 5W171-172 of the current system 5YSI and the data signals D241 and D241.
D242 (not shown), and one side is connected to the data signal D242 (not shown).
201 and D202 (not shown) are outputted to the carrier terminal station of the receiver, and the other is outputted to PU71 and PU72.

The backup system SP is 5W11 of the current system 8Y81.
TXI) PUs 21 and 22 which input the output data signals of 1 and 112, the DEC signals S3 and S1, and the DSC signals S4 and S2, and output the data signals Dll and D13 of 4 columns and the data signals D12 and D14, respectively, and the data Signal D11~
1) Data signals D121 to D124, D221 to D224 and DS from 14 and current systems 5Y81 and 5YS2
A transmission switch 30 receives C signals S3, S4, Sl, and S2 and outputs four columns of data signals D21 to D24 to the transmitter at the sending end of each protection line, and a reception switch at the receiving end of each protection line. Data signal output by the machine 1) 21
-D23 and data signals D22/D24 are input and output as they are, and D8C signals S3/Sl and DSC signals S
F8YNC41 and 42 that output 4 and S2, and FSY
Input data signals D21 to D24 output by NC41 and NC42, and input data signals D21 and D23 and data signal D22.
-D24 to the XDPUs 61 and 62, and data signals D21 to L) 24 to the current system 5YSI and 8Y.
A reception distributor 50 that also outputs to S2 and a data signal D21
・D23 and data signals D22 and D24 are input, and each data signal D41 and D42e are in one column. Current system 5Y
RXD output to 81 SWI 71 and 8WI 72
It is configured to include PUs 61 and 62.

DS C (digital 5 service cha)
The nnel ) signal is a sub data signal including a line switching control signal, a line monitoring signal, an interoffice meeting signal, etc. related to line switching.

First, when all protection lines are on standby,
The operation of the embodiment shown in FIG. 1 will be explained.

The data signal D101 input from the carrier terminal station at the sending end to the current system 5YSI is 1 (TXDPU via YBIOI).
121. TXI) PU121 converts the data signal DIOI from bipolar to unipolar, and
Serial-to-parallel conversion is performed from column to 8 columns, speed conversion is performed, additional bits such as frame synchronization bits and parity check bits for wireless transmission section monitoring, and DSC signals S1 and S2 are inserted, and further scrambled to create 4 columns of data for each column. Signal D1
21・D122e output. The DEC signal 81 is inserted into the data signal D121, and the DSC signal S2 is inserted into the data signal D122. Data signals D121 and D122 are transmitted through two working lines (
Hereinafter, for example, the working line that transmits the data signal D121 will be referred to as the working line D121, etc.). FSYNC141 is the transmitted data signal D121
The frame synchronization bit of φD122 is detected and frame synchronization is performed, and the DSC signal S is output from the data signals D121 and D122.
1.Extract S2. In this case, 5YNC8WI51 is the data signal D121/D1 from FSYNCI 41.
22 are output as they are as data signals D131 and D132. RXL) PU161 converts data signals D131 and D13 by inverse conversion of the conversion performed by TXDPU121.
2 is code-converted and output as one column of data signal D141. , SWI 71, in this case data signal D14
1 is output as a data signal D101 to the carrier terminal station at the receiving end.

The data signal D102 input from the carrier terminal station at the sending end to the current system 5YSI, or the two data signals input to the current system 5YS2, is also the above data signal DIOL.
It is transmitted in the same manner as above and output to the carrier terminal station at the receiving end.

1) SC signals S3 and S4 are data signals D123 and D12
4 and is transmitted.

In this case, the data signal D1 which is the test signal is
TXDPU21 of the backup system 8P via 1-111
Enter. The TXDPU 21 converts the data signal D1 and the DSC signals S3 and S4 into data signals Dll and D12 in the same way as the TXDPUI 21. DSC signal S
3.S4 is inserted into the data signal Dll.D12. In this case, the transmission switch 30 transmits the data signal Dll.
D12 (and D13 and D14) are output as they are as data signals D21-D22 (and D23-D24). The data signals D21 and D22 are transmitted on two protection lines (hereinafter, for example, the protection line that transmits the data signal D21 will be referred to as protection line D21, etc.). FSY
NC41 outputs DEC signals S3 and 84' from the transmitted data signals D21 and D22! il-extract. F8YNC
The data signals D21 and D22 from 41 are sent to the receiving distributor 5.
0 to the RXDPU 61 and the data signal 1) 4
Converted to 1. In this case, data signal D41 is a transmitted version of data signal D1. The data signal 1) 41 is sent to S'yV171/271 via 1. - (Input to PD71. PD71 receives data signal 1) Due to the quality of 41,
Protection line I) 21/D22' (monitor. Data signal D
2 is similarly transmitted and input to the PD 72. DSC
The signals S1 and S2 are inserted into the data signals D13 and D14 and transmitted.

Next, one of the working lines deteriorates (due to fading),
For example, the operation of the embodiment shown in FIG. 1 will be described in the case where the working line D121 is normally synchronously switched to the standby protection line D21. In addition, the working lines D121 and D2
21 is synchronously switched only to the protection line L)21. Working line 1) 122 to D124 and working line D222 to
D224 is also synchronously switched only to protection lines D22 to D24.

Each FSYNC monitors the line quality of the line that transmits the data signal using the parity check bit of the input data signal, and if the line quality deteriorates and the transmission code error of the data signal increases, an alarm signal (Fig. (not shown) is output to the 9-line switching control device at the receiving end.

In this case, the line switching control device detects the deterioration of the working line D121, confirms that the protection line D21 is normally on standby, and then controls the transmission switch 30 using the DSC signal of the line in the opposite direction. The working line D121 and the protection line D21 are connected in parallel at the sending end. As a result, the data signal D
21 is switched from the data signal Dll to the data signal D121 (from TXDPUI 21). However, at the time of this switching, the transmission switch 30 inputs the data signal D1.
The DSC signal S1 inserted in 21 is converted into the DSC signal S3.
Replace with. Therefore, the data signal "fD21" is equal to the data signal D121 except for the DSC signal part,
Also, FSYNC41 is connected to the DSC signal S even after this sending end is paralleled.
Continue outputting 3.

The transmission switching control device transmits the answerback signal (not shown) from the transmission switch 30 to the DEC via the backup line D24.
Is it detected during signal S1 and the sending end is parallel? Confirm and further FSYN
Protective line D21 depending on whether there is an alarm signal from C41
After confirming that the signal has returned to normal, the reception distributor 50 controls the data signal D21 to output the data signal D21 to the 5YNC8WI 51 (the reception distributor 50 normally outputs the data signal D21 to D
24 is not output to the current systems 3YS1 and 8YS2).

As a result, data signal D121 is applied to 5YNC8WI 51.
tl of φD122 or data signal D21 is also input. The timings of the υ data signals D121 and D21 generally do not match due to the propagation delay difference between the working line D121 and the protection line D21. The fixed component of the propagation delay difference is 5YNC8WI 5
1 is compensated in advance. 5YNC8WI 51
The frame synchronization bit detected by FSYNC41 and FSYNC141 automatically compensates for the fluctuation component of the propagation delay difference to match the timing of data signals D121 and D21, so that both data signals are the same (except for the DSC signal part). After confirming that this is the case, a match signal (not shown) is output.

The line switching control device detects this matching signal and switches the 5YNC8
Controls WI 51 and sends data signal D131 to working line D.
121 is switched to the data signal D21 (equal to the data signal D121 except for the DSC signal portion) transmitted via the protection line D21, and the synchronous switching is completed. Since the 5YNC8WI 51 matches the timing of the data signals D121 and D21, the bits of the data signal D131 will not be lost or duplicated due to synchronous switching, and the code ib will not be generated due to synchronous switching.

As already mentioned in the [Prior Art] section, the protection line D21 may be temporarily disconnected when the sending ends are paralleled. However, since the SC signal S1 required for this synchronous switching is being transmitted without interruption on the protection line D24 during this time, the synchronous switching operation continues without interruption during this time as well.

Note that if synchronous switching is not possible due to line disconnection due to equipment failure, etc., system switching is performed using 5W111, 171, etc. For example, if the working line D121 is disconnected and synchronous switching to the protection line D21 cannot be performed, the line switching control device switches 5W111 and 5W171, and transmits the data signal DIOIH1) to T via fYBlol and SWI 11.
It is input to the XDPU 21, converted into data signals Dll and D12, and sent to the protection line 1) 11 via the transmission switch 30.
・f) Input to 12 and transmit ε turtle P S Y N C4
1. The signal is inputted to the XDPU 61 via the reception distributor 50, converted into a data signal D41 (ie, data signal DIOI), and outputted to the carrier terminal station at the receiving end via the 5W171. During system switching, bits may be missing or duplicated due to the propagation delay difference between the working line and the protection line, resulting in code errors.
Since a mechanical switch is normally used for the first class, the switching time is longer.

FIG. 2 shows the correspondence between each line in the embodiment shown in FIG. 1 and the DSC signals transmitted by each line.

In the embodiment shown in FIG.
It is assumed that the DEC signal 3i includes a signal related to the synchronization requirement of 22i (i is an integer from 1 to 4).

Regarding transmission of data signals, the configuration is the same as in the embodiment shown in FIG. 1, and the working lines D121, D122,
All signals related to synchronous switching of D221 and D222 are removed and included in the SC signal S2, and the working line D123-1)1
In the second embodiment of the present invention, in which all signals related to synchronous switching of D.24, D223, and D224 are included in the DSC signal S3, each line and the DSC signal transmitted by each line are
Although the correspondence relationship with the SC signal may be the one shown in FIG. 2, it is also possible to make the correspondence relationship as shown in FIG. 3. In this case, the protection line D21 transmits the DSC signal S1,
The protection line D22 transmits the DSC signal S3, the protection line D23 transmits the DSC signal S2, and the protection line D24 transmits the DSC signal S4. Each working line and the DSC transmitted by each working line
The correspondence with the signals is the same as in the embodiment shown in FIG.

[Effects of the Invention] As explained in detail above, the line switching system of the present invention transfers sub data signals related to synchronous switching to at least one working line and at least one protection line that is not synchronously switched to the working line. The sub data signal is inserted into one and transmitted in parallel, and even if the backup line is temporarily cut off during synchronous switching, this sub data signal will not be cut off. This has the effect of allowing synchronous switching.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the line switching system of the present invention, and FIG. 2 is a correspondence relationship between each line and the DSC signal transmitted by each line in the embodiment shown in FIG. FIG. 3 is a drawing showing an example of the correspondence between each line and the DSC signal transmitted by each line in the second embodiment of the line switching system of the present invention. 21, 22, 121, 122... Transmission code processing device, 30...- Transmission switch, 50...
・Receiving distributor, 61, 62, 161, 162...-
Reception code processing device, 151/152... Synchronous switching device, 1, sp... Backup system, 5YS11
1SYS2... Current system.

Claims (1)

[Scope of Claims] N (N is an integer of 1 or more) second main data signals obtained by dividing one first main data signal are transmitted using different carrier waves. At least one working line group consisting of N working lines numbered up to N, and a small number of protection line groups consisting of N protection lines numbered from 1 to N using different carrier waves. In a line switching system in which the working line and the protection line of a multi-carrier transmission system are synchronously switched between the same numbers and in units of numbers, sub data signals related to synchronous switching are transmitted on the working line. and at least one of the data signals being transmitted on the protection line that is not switched synchronously with the working line that is transmitting this one main data signal, respectively. A line switching method characterized by insertion and parallel transmission.