JP3343904B2 - Transmission line switching system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for switching a transmission line to be used according to a state of a transmission line in a redundant transmission line including an active and a standby.

[0002]

2. Description of the Related Art Conventionally, in order to ensure communication reliability,
Parity check and CRC for received data on the receiving side
(Cyclic Redundancy Check)
Error detection, and if an error is detected,
A method of requesting the transmitting side to retransmit data has been adopted. Further, the transmission path is constituted by an active transmission path and a backup transmission path, and when a failure that cannot be dealt with by retransmission of data as described above occurs in the current transmission path, the transmission path is replaced by the backup transmission path. There is also a method of switching to a road.

[0003]

However, any method has a problem that it takes a long time to acquire normal data after detecting an error on the receiving side. That is, in the former case, depending on the state of the transmission path, it may be necessary to request data retransmission not only once but also many times. In the latter case, as a result of performing the above-described error detection, the transmission path is switched, so that it takes more time.

[0004] In particular, when an auxiliary signal is transmitted separately from a main signal such as a voice signal and information of a game is collected by the auxiliary signal or control is performed on the game, communication using the main signal is performed. For maintenance, the auxiliary signal must be transmitted without interruption, and it is very important to respond quickly to a failure.

It is an object of the present invention to provide a transmission line switching system that allows communication to be continued without interruption even if a failure occurs.

[0006]

In order to achieve the above object, the present invention intermittently transmits two transmission signals each indicating the same information through each of a first transmission line and a second transmission line. A transmission line switching system for selecting one of the two transmission signals transmitted through the first and second transmission lines, wherein a transmitting side transmits one of the two transmission signals. Signal delay means for delaying the other transmission signal by a predetermined delay time, and one of the first and second transmission paths, which is selected based on a given transmission path selection signal, A non-delayed transmission signal which is a transmission signal before being delayed by the signal delay means, and a transmission signal delayed by the signal delay means to the other of the first and second transmission paths. Is a delay Transmission path selection means for supplying a transmission signal, wherein the receiving side receives the non-delayed transmission signal and the delayed transmission signal transmitted through the first and second transmission paths based on a given signal selection signal. Signal selecting means for selecting either one of them; fault detecting means for detecting whether or not a fault has occurred in the first and second transmission paths; and means for detecting the fault in the first and second transmission paths. When detecting the occurrence of a failure in the transmission path for transmitting the non-delayed transmission signal, the signal selection signal is used to select the delayed transmission signal transmitted through the transmission path for transmitting the delayed transmission signal. Outputting the transmission path selection signal to the transmission path selection means so as to supply the non-delayed transmission signal to a transmission path in which a failure has not occurred among the first and second transmission paths. Selection Characterized in that a control means.

When no fault has occurred in any of the transmission paths, a non-delayed transmission signal before delay is transmitted from the transmission side via the first transmission path, and the signal selection means on the reception side transmits through the first transmission path. It is assumed that the transmitted non-delayed transmission signal is selected, and that a failure occurs in the first transmission line in this state. At this time, the selection control means outputs a signal selection signal to the signal selection means to select the transmission path on which no fault has occurred, that is, the delayed transmission signal from the second transmission path. The delay transmission signal transmitted through the second transmission path is selected. Since the delayed transmission signal sent through the second transmission path is delayed by the signal delay means, by selecting the delayed transmission signal from the second transmission path as described above, It is possible to reliably acquire a transmission signal that could not be correctly received through one transmission path.

Further, the selection control means outputs a transmission path selection signal to the transmission path selection means to select the transmission path on which no fault has occurred, that is, the second transmission path. , A non-delayed transmission signal before delay is supplied to the second transmission path, and a delayed transmission signal after delay is supplied to the first transmission path. Therefore, when a failure occurs in the second transmission line after the failure in the first transmission line is resolved, the switching is performed in the reverse of the above-described case, and the reception is correctly performed through the second transmission line due to the occurrence of the failure. The transmission signal that could not be obtained can be reliably obtained from the first transmission path.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of the transmission line switching system according to the present invention, and FIG. 2 is a timing chart showing the operation of the transmission line switching system of FIG. The transmission line switching system 2 shown in FIG. 1 intermittently transmits the same auxiliary signal 4 through the first and second transmission lines 6 and 8, and the first and second transmission lines 6, 8 on the receiving side. One of the auxiliary signals 4 transmitted through is selected. In the transmission line switching system 2, a main signal such as an audio signal is transmitted through the first and second transmission lines 6 and 8, and the auxiliary signal 4 is multiplexed with the main signal and transmitted. The auxiliary signal 4 includes, for example, information relating to the state of the transmission side such as switching of the line in use and whether or not the transmission side has generated an alarm signal.

The transmitting side 10 shown in FIG. 1 includes a signal delay section 12 (signal delay means according to the present invention) for delaying a transmission signal, and first and second transmission paths based on a given transmission path selection signal 52A. One of the paths 6 and 8 is selected to supply a transmission signal (non-delayed transmission signal) before being delayed by the signal delay unit, and the transmission signal (delayed transmission signal) delayed by the signal delay unit is And a transmission path selecting means 14 for supplying the transmission path to the other transmission path.

On the other hand, the receiving side 16 selects one of the two transmission signals transmitted through the first and second transmission paths 6 and 8 based on the supplied signal selection signal 52B. Means 18, a fault detecting means 20 for detecting whether or not a fault has occurred in the first and second transmission paths 6, 8, and a fault detecting means 20 for determining which of the first and second transmission paths 6, 8 On the other hand, when the occurrence of a failure is detected, a signal selection signal 52B is output to the signal selection means 18 to select a transmission signal transmitted through the other transmission path where no failure has occurred, and the failure has occurred. A selection control unit 22 that outputs a transmission line selection signal to the transmission line selection unit 14 in order to select the transmission line that does not exist.

The transmitting side 10 further includes a transmission path selecting means 14
The signal multiplexing units 24 and 26 multiplex the auxiliary signal 4 before delay and the auxiliary signal after delay output by the main signal 5 to be transmitted through the first and second transmission paths 6 and 8, respectively.
, And the main signal and the auxiliary signal 4 multiplexed by the signal multiplexing units 24 and 26 are transmitted to the first and second transmission paths 6 and 8 through the transmission units 28 and 30, respectively.

The transmission line selection means 14 of the transmission side 10 includes an idle signal detection unit 32, a transmission line selection control unit 34,
And a transmission path selector 36. The idle signal detector 32 detects an idle signal included in the auxiliary signal 4 and specifies an idle period of the auxiliary signal 4 that is generated intermittently. The transmission path selection control unit 34 controls the transmission path selection unit 36 based on the idle period specified by the idle signal detection unit 32 and the transmission path selection signal from the transmission side 10, and outputs the auxiliary signal before the delay and the delay after the delay. The auxiliary signal is output to one of the signal multiplexing units 24 and 26, respectively.

The receiving side 16 further includes signal separation units 38 and 40
, And the signal separation units 38 and 40 each include the reception unit 4
2 and 44 separate the main signal 5 and the auxiliary signal 4 from the multiplexed main signal 5 and auxiliary signal 4 received through the first and second transmission paths 6 and 8. The fault detecting means 20 of the receiving side 16 includes fault detecting units 46 and 48, and performs one or both of parity check and CRC error check on the auxiliary signal 4 separated by the signal separating units 38 and 40, respectively. I do. Signal selection means 1
8 is constituted by a switching unit 50. The switching unit 50 receives the two auxiliary signals 4 separated by the signal separation units 38 and 40 as inputs and outputs any one of the two auxiliary signals 4 based on a signal selection signal 52B. Select and output one. The selection control unit 22 includes a switching control unit 52, and the switching control unit 52 controls the switching unit 50 based on the result of the error check performed by the failure detection units 46 and 48.

Next, the operation of the transmission line switching system 2 configured as described above will be described with reference to the timing chart of FIG. As shown in FIG. 2A, the auxiliary signal 4 is intermittently input to the signal delay unit 12 with a fixed idle period ti.
2 generates the auxiliary signal 4 as shown in FIG.
The signal is output to the transmission path selector 36 after being delayed by a certain time td. In this specification, the time from the end of the preceding auxiliary signal 4 to the start of the delayed auxiliary signal 4 is defined as a delay time td.

First, in a period ta of FIG.
No failure has occurred in any of the transmission lines 6 and 8 at this time, and at this time, the transmission line selection unit 36 of the transmission side 10 outputs the undelayed auxiliary signal 4 to the signal multiplexing unit 24. It is assumed that the auxiliary signal 4 delayed by the signal delay unit 12 is output to the signal multiplexing unit 26. Therefore, in this state, the pre-delay auxiliary signal 4 and the post-delay auxiliary signal 4 are multiplexed with the main signal 5 input to the signal multiplexing units 24 and 26, respectively. The auxiliary signal 4 before the delay and the multiplexed main signal 5 and the auxiliary signal 4 after the delay are transmitted to the first and second transmission paths 6 and 8 through the transmission units 28 and 30, respectively.
FIG. 2C shows the auxiliary signal 4 transmitted through the first transmission line 6, and FIG. 2D shows the auxiliary signal 4 transmitted through the second transmission line 8. At this time, on the receiving side 16, the switching unit 50 selects and outputs the auxiliary signal 4 from the signal separation unit 38, that is, the auxiliary signal 4 that has not been delayed, as shown in FIG. It is assumed that Therefore, in this case, the first transmission line 6 is a working transmission line, and the second transmission line 8 is a spare transmission line.

Here, for some reason, the timing T
Assuming that a failure has occurred in the first transmission line 6 in 1,
The failure detection unit 46 performs an error check on the auxiliary signal 4 separated by the signal separation unit 38 to detect an error. As a result, first, the switching control unit 52 outputs a signal selection signal 52B to the switching unit 50 in order to select a transmission signal transmitted through the second transmission line 8 where no failure has occurred. Thereby, the switching unit 50 selects and outputs the auxiliary signal 4 from the signal separation unit 40. Since the auxiliary signal 4 ((D) in FIG. 2) transmitted through the second transmission path 8 is delayed by the time td, the auxiliary signal 4A (FIG. (E))
Is the same as the auxiliary signal 4B (FIG. 2C) that could not be correctly received through the first transmission line 6 due to the occurrence of a failure. That is, in the transmission line switching system 2, when a failure occurs in the transmission line, the auxiliary signal 4 which cannot be received through the failed transmission line but is delayed by the time td can be reliably received through the other transmission line. Can be. Therefore, even if a failure occurs, communication can be continued without interruption.

The switching control unit 52 also transmits a transmission line selection signal 52A to select a second transmission line 8 in which no failure has occurred.
Is output to the transmission path selection control unit 34. Upon receiving the transmission path selection signal 52A, the transmission path selection control section 34 of the transmission side 10 controls the transmission path selection section 36 based on the transmission path selection signal 52A in the next idle period specified by the idle signal detection means. The auxiliary signal 4 is output to the signal multiplexing unit 26 which outputs the auxiliary signal 4 to the second transmission line 8 before the delay.
And outputs the auxiliary signal 4 after the delay. Therefore,
As shown in (C) and (D) of FIG.
2 and thereafter, the auxiliary signal 4 after the delay is transmitted through the first transmission line 6 and the undelayed auxiliary signal 4 is transmitted through the second transmission line 8, contrary to the case where no failure has occurred. .

For this reason, when a failure occurs in the second transmission line 8 after the failure in the first transmission line 6 is resolved, the switching is performed in the reverse of the above-described case, and the second switching is performed by the occurrence of the failure. The transmission signal that cannot be correctly received through the transmission path 8 is transmitted to the first
Can be reliably received from the transmission path 6.

As described above, the present invention has been described based on the embodiment. However, this is merely an example, and the present invention can be implemented in various forms without being limited to this example. For example, in the above embodiment, the priority is not set for the first and second transmission lines 6 and 8, but, for example, a high priority is set for the first transmission line 6 and the first transmission line 6 is assigned to the first transmission line 6. After a failure occurs and the above-described switching is performed, when the failure is resolved, the original state may be restored and the auxiliary signal 4 which is not delayed may be transmitted through the first transmission line 6. Of course it is possible.

[0021]

As described above, in the transmission line switching system of the present invention, no failure occurs in any transmission line, and the non-delayed transmission signal before delay is transmitted from the transmission side through the first transmission line. When the signal selection means selects the non-transmission signal transmitted through the first transmission path on the receiving side and a failure occurs in the first transmission path, the selection control means determines that the failure has occurred. The transmission path that is not used, that is, the second
The signal selection signal is output to the signal selection means in order to select the delay transmission signal from the transmission path of (1), so that the signal selection means selects the delay transmission signal sent through the second transmission path.
Since the delayed transmission signal sent through the second transmission path is delayed by the signal delay means, by selecting the delayed transmission signal from the second transmission path as described above, It is possible to reliably acquire a transmission signal that could not be correctly received through one transmission path.

Further, the selection control means outputs a transmission path selection signal to the transmission path selection means to select the transmission path on which no fault has occurred, that is, the second transmission path. , A non-delayed transmission signal before delay is supplied to the second transmission path, and a delayed transmission signal after delay is supplied to the first transmission path. Therefore, when a failure occurs in the second transmission line after the failure in the first transmission line is resolved, the switching is performed in the reverse of the above-described case, and the reception is correctly performed through the second transmission line due to the occurrence of the failure. The transmission signal that could not be obtained can be reliably obtained from the first transmission path. Therefore, in the transmission line switching system of the present invention, communication can be continued without interruption even if a failure occurs in the transmission line.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a transmission line switching system according to the present invention.

FIG. 2 is a timing chart showing an operation of the transmission line switching system of FIG.

[Explanation of symbols]

2 ... system, 4 ... auxiliary signal, 5 ... main signal, 6 ...
.. 1st transmission line, 8... 2nd transmission line, 10... Transmission side, 12... Signal delay unit, 14.
6 reception side, 18 signal selection means, 20 failure detection means, 22 selection control means, 24 signal multiplexing section, 26 signal multiplexing section, 28 transmission section, 30 ......
Transmission section 32 ... Idle signal detection section 34 ... Transmission path selection control section 36 ... Transmission path selection section 38 ... Signal separation section 40 ... Signal separation section 42 ... Reception section 44 ... ... Reception unit, 46 ... Fault detection unit, 48 ... Fault detection unit, 50
... Switching unit, 52... Switching control unit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-54738 (JP, A) JP-A-4-157839 (JP, A) JP-A-7-143033 (JP, A) JP-A-8-8 88621 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04B 1/74

Claims (7)

(57) [Claims] 1. Each of two transmission signals indicating the same information.
Les intermittently transmitted through each of the first and second transmission paths, transmission path for selecting one of said first and second transmission paths the two transmission signals sent through the receiving side A switching system, wherein the transmission side transmits one of the two transmission signals to the other transmission signal.
Signal delay means for delaying a transmission signal by a predetermined delay time , and a given transmission line among the first and second transmission lines
The signal is transmitted to one of the transmission paths selected based on the selection signal.
Non-delayed transmission, which is the transmission signal before being delayed by the delay means
Providing a transmission signal, and providing the first and second transmission paths;
Out of which the other transmission path is delayed by the signal delay means.
Transmission path selection means for supplying a delayed transmission signal as a transmission signal, wherein the receiving side performs the first and second transmission based on the given signal selection signal.
The non-delayed transmission signal transmitted through the transmission path of
Signal selecting means for selecting one of the delay transmission signal and the delay transmission signal ; failure detecting means for detecting whether a failure has occurred in the first and second transmission paths; and second transmission path
That is, a failure occurs in a transmission path for transmitting the non-delayed transmission signal.
When detected, it passes through the transmission path for transmitting the delayed transmission signal.
In order to select the delayed transmission signal transmitted
A signal selection signal to the signal selection means, and
And transmission in which no fault has occurred among the second transmission paths
Transmission control means for outputting the transmission path selection signal to the transmission path selection means to supply the non-delayed transmission signal to the transmission path. 2. The non-delayed transmission signal and the non-delayed transmission signal transmitted through the first and second transmission paths .
2. The transmission line switching system according to claim 1, wherein one or both of a parity check of the delayed transmission signal and an error check by a CRC are performed. 3. The non-delayed transmission signal and the non-delayed transmission signal transmitted through the first and second transmission paths .
2. The transmission according to claim 1, further comprising: a switching unit that receives a delayed transmission signal and a delayed transmission signal , and selects and outputs one of the non-delayed transmission signal and the delayed transmission signal based on the signal selection signal. Road switching system. 4. A main signal is transmitted through first and second transmission paths, and the main signal is transmitted through the non-delayed transmission signal and the delayed transmission signal.
2. The transmission line switching system according to claim 1, wherein each of them is multiplexed as an auxiliary signal with the main signal and transmitted. 5. The non-delay output from the transmission path selection means.
A signal multiplexing unit that multiplexes the extended transmission signal and the delayed transmission signal as the auxiliary signal with the main signal transmitted through the first and second transmission paths, on the transmission side, and multiplexes the signal with the main signal. 5. The transmission line switching system according to claim 4, further comprising a signal separation unit on a reception side for separating the auxiliary signal sent through the first and second transmission lines from the main signal. 6. The transmission line switching system according to claim 4, wherein the auxiliary signal includes one or both of information on switching of a used line and a state of a transmission side. 7. The transmission line switching system according to claim 4, wherein said main signal includes an audio signal.