JPH02125538A - Sub signal switching system - Google Patents

Abstract

PURPOSE:To avoid switching due to line instaneous interruption at the restoration of a fault by inserting an intermediate repeater station fault signal to a sub signal of a line having a fault together with a frame signal when the line fault is detected by an intermediate repeater station and switching the line without any fault signal with priority when a station after the intermediate repeater station detects the signal. CONSTITUTION:Frame synchronizing detectors 23, 24 control fault detection signal switches 33, 34. Thus, the switches 33, 34 select a frame pulse outputted from frame pulse generators 31, 32 in place of a main signal separated by separators 21, 22. Moreover, at the detection of a fault detection signal, the detectors 23, 24 control intermediate repeater station fault detection signal generators 35, 36 to output an intermediate repeater station fault signal to multiplexers 29, 30. Intermediate repeater station fault detectors 25, 26 detect the presence of an intermediate repeater station fault and send the result of detection to a sub signal switch controller 27. The sub signal switch controller 27 sends a switching control signal 128 to a sub signal switch 28 so as to select a sub signal of a line having no intermediate repeater station fault signal with priority.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to digital wireless transmission, and particularly to a sub-signal switching method in sub-signal transmission.

[Conventional technology]

With the development of multiplexing technology, digital wireless transmission not only transmits main signals but also transmits various sub-signals at low transmission speeds. Sub-signal transmission requires not only transmission of the main signal in the switching terminal station (transmission terminal station and receiving terminal station) section, but also transmission between intermediate relay stations within the switching terminal station section of the main signal. By the way, in conventional sub signal transmission, if a line failure occurs within the main signal transmission section and the main signal is switched to the protection line, or if the protection line also has a line failure and the main signal is completely cut off. However, by inserting a frame signal into the sub-signal at the first failure detection station, the sub-signal can be transmitted through the working and protection lines at intermediate relay stations and receiving terminal stations after that station.

[Problem to be solved by the invention]

Consider the case where hitless switching control between a working line and a protection line, which is generally used in main signal transmission, is applied to the conventional sub-signal transmission system described above. A line fault is detected at the first fault detection station, and a frame signal is inserted into the sub-signal of the faulty line.

As a result, the intermediate relay stations and receiving terminal stations subsequent to that station synchronize with the frame signal newly inserted at the failure detection station, and the sub-signal transmission line becomes normal. The sub signal line that has become normal is used as a working line or a protection line.

Here, if the sub-signal transmission line that became normal by inserting a frame signal at the intermediate relay station is used for sub-signal transmission, when the fault is restored, the frame signal insertion at the fault detection temperature is canceled. , frame synchronization occurs until the frame synchronization at the intermediate relay station is synchronized with the frame pulse of the transmitting terminal station. When the frame synchronization is lost, the sub signal is switched to the protection line or the working line. As described above, the conventional sub-signal transmission system has the disadvantage that hitless switching is not possible because the switching is caused by frame synchronization.

[Failure to solve the problem]

In the present invention, when a line failure is detected at an intermediate relay station,
An intermediate relay station fault signal is inserted together with a frame signal into the sub-signal of the faulty line. Furthermore.

When this intermediate relay station fault signal is detected at the intermediate relay station and receiving terminal station after that station, switching control is performed so as to preferentially switch to a line to which no intermediate relay station fault signal is output.

〔Example〕

Next, two aspects of the present invention will be explained with reference to one drawing.

FIG. 2 is a block diagram of a digital wireless transmission system to which the present invention is applied. Here, Tll and T12 are assumed to be transmitting terminal stations, and T21 and T22 are assumed to be receiving terminal stations. R
11, R12, R21, R22° R3, 1, R32 indicate intermediate relay stations, respectively.

The line from Tll to T21t is the protection line, and the line from T12 to T22 is the working line. Here, regarding the sub signal, T1
1 to R11 and T1.2 to R12 are sub signal switching sections 1. R11 to R31, R12 to R32
up to sub-signal switching section 2. “R31 to T21
．． The period from R32 to T22 is defined as sub-signal switching section 3.

FIG. 3 is a configuration diagram of the sub-signal multiplexing section of the transmitting terminal station Tl1T12 shown in FIG. 2. Transmitting terminal station Tll, T12
have the same configuration, and in the sub-signal multiplexing section, sub-signal 1
05 to the first distributed sub-signal 106.05 at the distributor 13. The multiplexer 11°I2 of the protection line and the working line each distributes the first distributed sub-signal 10 to the second distributed sub-signal 107.
6. The second distributed sub-signal 107 is multiplexed with the main signal 101.102. The multiplexed signals 103 and 104 are as follows.

The signal is sent to a modulator (not shown).

FIG. 1 shows intermediate relay stations R11°R12 shown in FIG.
, R31, R32, a sub-signal separation section, a multiplexing section, etc. are shown. Intermediate relay stations R11, R12, R shown in FIG.
31 and R32 have the same configuration.

The sub-signal separation unit 19 includes two separators 21 and 22.

Multiplexed signals 111, 112 from demodulators (not shown)
are the separators 21, 22. and frame synchronization detector 23.2
4. In the separator 21 (22), the sub signal 11
5 (116) and the main signal 113 (114), and extracts the intermediate relay station failure signal and sends it to the intermediate relay station failure detector 25 (26). Intermediate relay station fault detector 25 (
26) detects the presence or absence of an intermediate relay station failure, and sends the detection result to the sub-signal switching controller 27. The sub-signal switching controller 27 sends the switching control signal 12 to the sub-signal switching unit 28 so as to preferentially select the sub-signal of the line on which no intermediate relay station failure signal is issued.
Send 8. The sub signal switch 28 receives the switching control signal 128
The sub-signal 119 selected based on the selected sub-signal 119 is output.

The frame synchronization detector 23 (24) detects the presence or absence of the two-line fault detection signal, and when the fault detection signal is detected, the switch 3
3 (34). With this control, the switch 33 (
34) selects the frame pulse output from the same frame pulse generator 31 (32) instead of the main signal separated by the separator 21 (22). Frame synchronization detector 23
(24,) also controls the intermediate relay station failure detection signal generator 35 (36) to output the intermediate relay station failure signal to the multiplexer 29 (30) when the failure detection signal is detected.

The multiplexing section 20 includes multiplexers 29 and 30. Distributor 37
outputs the sub signal 133 to the first . Second distribution sub-signal 134, 13
5 and supplied to multiplexers 29 and 30, respectively.

The multiplexer 29 (30) receives the first (second) distributed sub-signal 13.
4 (135), the output of the switch 33 (34,), and the output of the intermediate relay station failure detection signal generator 35 (36). The multiplexed signal 120 (121) is sent to a modulator (not shown).

Note that the intermediate relay stations R21 and R22 shown in FIG. 2 do not separate or multiplex sub-signals, so the intermediate relay station failure detectors 25, 26 . Sub-signal switching controller 27. Sub-signal switch 28. And the distributor 37 is unnecessary.

FIG. 4 is a configuration diagram of the sub-signal separation section of the receiving terminal station T21T22 shown in FIG. Receiving terminal station T21, T22
have the same configuration, and the operation of separating and switching sub-signals is exactly the same as that of the sub-signal separation unit 19 in the intermediate relay station shown in FIG.

〔Effect of the invention〕

As explained above, (1) the present invention, when a line failure is detected at an intermediate relay station, inserts the intermediate relay station failure signal together with a frame signal into the sub-signal of the line where the failure has occurred, and furthermore, the intermediate relay station after that station When the terminal station detects this intermediate relay station failure signal, it performs switching control so as to preferentially switch to a line to which no intermediate relay station failure signal has been issued. In this way, by inserting a frame signal at the intermediate relay station, the line switching priority of the sub-signal transmission line that has become normal is lowered, thereby eliminating the need for switching due to instantaneous line interruption when a failure is recovered. In other words, there is an effect that the line quality of the sub signal can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a sub-signal separation section, multiplexing section, etc. of an intermediate relay station, which is the main part of the present invention, and FIG. 2 is a block diagram of a digital wireless transmission system to which the present invention is applied. Figure 3 is the second
A configuration diagram of the multiplexing unit in the transmitting terminal station shown in the figure, No. 4
This figure is a block diagram of a sub-signal separation unit in the receiving terminal station shown in FIG. 2. 11.12, 29, 30... multiplexer, 13.37.
...Distributor, 21, 22, 51, 52... Separator. 23.24...Frame synchronization detector, 25, 26°5
3.54... Intermediate relay station failure detector, 27.55...
- Sub signal switching controller, 28.56... Sub signal switching device. 31.32...Flame noggle occurrence i, 33
, 34... Switching device, 35. 36... Intermediate relay station failure detection signal generator.

Claims (1)

[Claims] 1) In a digital wireless transmission system that transmits a main signal and a sub-signal, an intermediate relay station fault signal is detected at the station where the sub-signal is separated, and depending on whether there is a fault at the intermediate relay station, the working line or protection line A sub-signal switching method characterized by controlling the switching priority of.