JP2000124881A - Transmission line interface switching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arbitrarily set a parameters. SOLUTION: At a frame data transmission part 1, data to be transmitted are divided into binary data of certain digits and added to a fixed number, sum check data are calculated for certain digits of the added value and added to the data to be transmitted, and they are transmitted to plural transmission lines as frame data. At a frame data reception part 2, frame data are divided into binary data of certain digits and added, a data error is detected for each frame based on that value and when one or plural conditions previously arbitrarily set are satisfied by the detection of that error, a sum check error signal is transmitted and a transmission line interface is switched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for switching a transmission line interface based on a data error in a data transmission system having redundancy. In particular, the present invention relates to switching based on a data error tolerance of a terminal device.

[0002]

2. Description of the Related Art When data is transmitted between terminal devices, a transmission path for transmitting data is usually provided. This transmission path is constituted by, for example, an optical fiber cable, a metallic cable, or the like.

[0003] Here, in the transmission path, some cause may affect the data being transmitted, resulting in a data error. In a transmission medium such as an optical fiber cable, deterioration of an optical device is the cause. In a transmission medium such as a metallic cable, noise due to lightning induction or the like causes the noise.

Therefore, in this system, the transmission line interface and the transmission line are multiplexed to provide redundancy. On the transmission side, the same data is transmitted to each transmission path. On the receiving side, the transmission line interface is switched based on the data error, so that data transmitted from the transmission line with many data errors is not used as data received by the terminal device. In this way, the failure time is reduced and the data transmission quality is improved. Generally, when data is multiplexed and framed and transmitted, this data error detection is performed by, for example, a CRC (Cyclic Redundancy Check) enter system. The switching of the transmission line interface is performed when it is determined that an error has occurred within a certain period of time over a certain frequency. Here, the error is a bit error,
Refers to frame errors, synchronization errors, etc.

[0005]

However, in the conventional transmission line interface switching method described above,
Some are not adapted to the connected terminal device. This is because, depending on the terminal device, a condition for a data error is more severe than a switching condition that "a certain error has occurred more than a certain frequency within a certain time".
In such a terminal device, if there are many data errors, the transmitted data may be discarded.

[0006] In order to satisfy the criteria for data error determination of the terminal equipment, "error measurement time" and "error frequency", which are necessary for switching transmission lines, for a certain error.
It has been desired to realize a transmission line interface switching method capable of arbitrarily changing a parameter of “error protection”.

[0007]

According to the switching method of the transmission line interface according to the present invention, the data to be transmitted is set to two digits of a certain digit.
Dividing the binary data into a fixed number, calculating a complement value for a digit having the added value, adding the complement value to the data to be transmitted, Transmitting the data to a transmission path, dividing the received data into binary data of a certain digit, adding the data, detecting a data error in the received data based on the added value, A step of transmitting an alarm signal when it is determined that a result of detecting a data error satisfies one or more predetermined alarm signal transmission conditions based on a plurality of predetermined alarm signal transmission conditions; And The present invention relates to a method for switching a transmission line interface to select one of data transmitted from a plurality of transmission lines in a case of data transmission with redundancy. The transmitting side divides the data to be transmitted into binary data of a certain digit, adds a certain number, and calculates a complement value for a certain number of the added value. The calculated complement value is transmitted to a plurality of transmission paths in addition to the data to be transmitted. On the other hand, the receiving side divides one piece of data (received data) selected to be used as data out of the data to be transmitted into binary data of a certain digit and adds them. A data error of the received data is detected based on the added value. A data error is detected based on one or a plurality of arbitrarily preset alarm signal transmission conditions. As a result, when it is determined that one or a plurality of arbitrarily set conditions are satisfied, an alarm signal is transmitted and the transmission line interface is switched.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. FIG. 1 shows the first embodiment of the present invention.
FIG. 9 is a block diagram mainly illustrating a data transmission system for realizing the transmission line interface switching method according to the embodiment. In the figure, reference numeral 1 denotes a frame data transmission unit. The frame data transmitting unit 1 includes a multiplexed data input unit 1A, a check data calculating unit 1B, a frame data creating unit 1C, and a frame data transmitting unit 1D. The multiplexed data input means 1A is data multiplexed and transmitted by the multiplexing means 5 (hereinafter referred to as multiplexed data).
Is divided into 4-bit binary data (hereinafter, referred to as binary data) and transmitted to the check data calculation means 1B. The check data calculation means 1B calculates sum check data which is a value which becomes "0000" by adding all data obtained by dividing binary data transmitted from the multiplexed data input means 1A into four bits. The frame data creation means 1C adds the sum check data calculated by the check data calculation means 1B to the multiplexed data to create frame data. The frame data transmitting means 1D includes:
The frame data is transmitted to the transmission paths 3a and 3b using light or the like.

Reference numeral 2 denotes a frame data receiving unit. The frame data receiving unit 2 includes a transmission line interface unit 2
A, frame data calculation means 2B, counter means 2C,
It comprises an error counting means 2D, an error counting means 2E and an error checking means 2F. The transmission line interface means 2A includes transmission lines 3a and 3
b and two transmission path interface boards (not shown). Transmission line interface means 2
A switches between the two transmission line interface boards based on the sum check error signal transmitted from the error check means 2F. Then, the frame data received by the active board selected by the switching is transmitted to the demultiplexing means 7. In addition, the data is divided into 4-bit binary data and transmitted to the frame data calculating means 2B. The frame data calculation means 2B is provided with the transmission path interface means 2
The binary data transmitted from A is added, and a result signal is transmitted based on the addition result. The counter unit 2C transmits a count signal based on an arbitrarily set error measurement time. Here, the error measurement time is a unit time set for counting the number of errors. The error counting means 2D and the error counting means 2E count the number of data errors in error measurement time units based on the result signal transmitted from the frame data calculation means 2B and the count signal transmitted from the counter means 2C. ,
If it is determined that the condition arbitrarily determined in advance is satisfied, an error output signal is transmitted. The error check means 2F is an OR circuit for transmitting a sum check error signal serving as an alarm signal based on the error output signals transmitted from the error count means 2D and the error count means 2E.

Reference numerals 3a and 3b denote transmission paths. Transmission line 3a
And 3b transmit the same frame data transmitted from the frame data transmitting means 1D. 4-1 to 4-n are transmission terminal devices. The transmission terminal devices 4-1 to 4-n are connected to the multiplexing means 5. Transmission terminal devices 4-1 to 4
-N transmits data such as voice to the multiplexing means 5. 6
-1 to 6-n are receiving terminal devices. Receiving terminal device 6-
1 to 6 -n are connected to the demultiplexing means 7. The receiving terminal devices 6-1 to 6-n receive the data transmitted from the demultiplexing unit 7.

Reference numeral 5 denotes multiplexing means. The multiplexing means 5 converts signals transmitted from the transmitting terminal devices 4-1 to 4-n into PCM signals.
Encode, multiplex and transmit to multiplexed data input means 1A. Reference numeral 7 denotes a demultiplexing unit. The demultiplexing unit 7 separates the frame data transmitted from the transmission line interface unit 2A and transmits the frame data to the receiving terminal devices 6-1 to 6-n.

In this embodiment, the frame data receiving unit 2 on the receiving side has a data error based on the frame data to which the sum check data transmitted from the frame data transmitting unit 1 on the transmitting side is added. It checks whether or not there is any, and transmits a sum check error signal based on the check result to switch between two transmission line interface boards. Error counting means 2
In D and the error counting means 2E, by changing the conditions for transmitting the error output signal arbitrarily, the transmission line interface boards are switched under the conditions corresponding to the receiving terminal devices 6-1 to 6-n, etc. It is intended to improve the reliability of transmission by not using frame data transmitted by a transmission path as received data.

FIG. 2 is a diagram showing a frame configuration in the case of the primary group of PCM (24CH). One frame of the PCM primary group uses 193 digit time slots (= number of bits). Of these, one bit is used at the beginning of a frame for data used for a frame synchronization signal called F bit. In addition, as data such as audio, 24 channels × 8 bits = 192 bits are used. Here, among the time slots of 24 channels (192 bits), the transmitting terminal devices 4-1 to 4-n transmit 8 bits each of 23 bits for transmitting data such as voice.
H time slots (184 bits) are used.
Therefore, the maximum value of n is 23. Of the subsequent time slots for one CH, for example, for a line such as a telephone (ISDN), a 4-bit time slot is used as signaling data for call control. In the present embodiment, the remaining time slots of 4 bits are used for transmitting the sum check data.

Next, the operation of the system according to the present embodiment will be described with reference to FIGS. The multiplexed data is input from the multiplexing means 5 to the multiplexed data input means 1A. This multiplexed data is serial data. The multiplexed data input unit 1A divides the multiplexed data into four bits and transmits the multiplexed data to the check data calculation unit 1B. Further, the multiplexed data is transmitted to the frame data creating means 1C. The check data calculating means 1B adds data (23 bits) (data of 184 bits) + data obtained by dividing signaling data (4 bits) by 4 bits (that is, 47 4-bit binary data). Then, a value that becomes "0000" is calculated by adding all the lower four digits of the added value. The check data calculation means 1B transmits this value to the check data generation means 1C as sum check data (4 bits). The frame data creating means 1C inserts the sum check data into the latter four bits of the last time slot transmitted in frame units,
Frame data is created by adding an F bit to the head of 2-bit data. The frame data transmitting means 1D transmits the frame data to the transmission paths 3a and 3b.

The frame data is transmitted to the transmission line interface means 2A. Transmission line interface means 2
A detects synchronization, transmits 192 bits of data to the demultiplexing unit 7, divides the 192 bits of data into 4 bits, and transmits the data to the frame data calculation unit 2B. The frame data calculation means 2B adds the transmitted data (48 4-bit binary data). If there is no data error in the frame data, the lower four digits of the added value should be “0000”. Therefore, if any other value is calculated, it means that an error always occurs somewhere in the frame data. The frame data calculating means 2B determines that the last four digits of the added value are "000".
If it is not 0 ", a result signal is transmitted. The error counting means 2D and 2E use the error measurement time as a unit time,
If a predetermined condition is satisfied based on the transmitted result signal, an error output signal is transmitted. Here, the predetermined condition is a condition that, for example, when the error measurement time is set as a unit, the result signal is transmitted for two consecutive units. When the result signal is transmitted in the second unit, the error output signal is set to be transmitted. Also,
Another condition is that when the error measurement time is used as a unit, the result signal is transmitted twice within the same error measurement time. When the result signal is transmitted for the second time, an error output signal is set to be transmitted. The transmission of the error output signal is continued until the unit of the next error measurement time ends unless a new result signal is transmitted. The error check means 2F transmits a sum check error signal while the error output signal is being input from either of the error count means. The predetermined conditions can be changed, and even if the measurement time unit is three or four times, three times or four times during the measurement time.
The number of times, the measurement time may be 1 msec or 1 sec.

The transmitted sum check error signal is input to at least the transmission line interface means 2A. When detecting the rise of the sum check error signal, the transmission line interface unit 2A switches between the two transmission line interface boards. By switching
The other system left as the standby system is used as the active system, and data transmission is continued using data transmitted through the transmission path.

FIG. 3 is a diagram showing a frame configuration for showing an example in the present system. In this example, PCM1
Assuming the next group, the data transmission speed (HW (High Way) unit) is 1.544 bps, and the period of one frame is 125 μs.
(8 kHz). In the error counting means 2D and the error counting means 2E, the following two conditions are used as transmission conditions of the respective error output signals. (1) As an error measurement time, 16 multiframes (1 multiframe = 24 frames) (48 ms) are used as units,
When a sum check error occurs once during the error measurement time and it is repeated twice (2) 16 multiframes (48 m
When a sum check error occurs twice during the same error measurement time in units of s)

The error counting means 2D and the error counting means 2E are set to transmit an error output signal when the respective conditions are satisfied, using the error measurement time as a unit. Therefore, switching of the transmission line interface board is performed. On the other hand, the receiving terminal device 6-1
6-n are set, for example, to issue an ALM or to discard data. Receiving terminal devices 6-1 to 6-
n detects an error, detects a sum check error signal before the system goes down, and sets to switch the transmission line interface board.

FIG. 4 is a time chart showing the relationship between the occurrence of an error and the sum check error signal. The example of FIG. 4A is a case where an error is detected within one error measurement time (one result signal is transmitted), and this occurs twice consecutively. When the second result signal is transmitted, a sum check error signal is transmitted, and the transmission line interface board is switched. If the result signal is not transmitted within the next error measurement time, the sum check error signal is not transmitted (canceled).

The example of FIG. 4B is a case where the result signal is transmitted once within the error measurement time and is transmitted twice. When the second result signal is transmitted, the transmission path interface board is switched. If the result signal is not transmitted within the next error measurement time, the sum check error signal is not transmitted.

FIG. 4C shows an example in which two result signals are transmitted within the same error measurement time. When the second result signal is transmitted, the transmission path interface board is switched. If the result signal is not transmitted within the next error measurement time, the sum check error signal is not transmitted.

The example of FIG. 4 (4) is a case where the result signal is transmitted twice within the same error measurement time, and the result signal is transmitted also in the next error measurement time. When the second result signal is transmitted, the transmission path interface board is switched. Since the result signal has been transmitted even within the next error measurement time, the sum check error signal will continue to be transmitted based on another condition. If the result signal is not transmitted within the next error measurement time, the sum check error signal is not transmitted.

Referring to the above example, if the receiving terminal device is 25 m
When a data error is detected at an interval of s and an error of consecutive data is detected three times, an ALM is issued, and in the case of a system down condition, a data error is detected in a worst case of 50 ms or more. Therefore, the error measurement time is set to 24 ms.
, The switching is performed at 24 ms × 2 (48 ms), and the data error of 50 ms can be prevented from continuing.

As described above, in the system according to the first embodiment, the frame data transmitting unit 1 generates the sum check data and transmits the frame data added to the multiplexed data. , Based on the frame data, checks whether a data error has occurred for each frame, determines the check result based on an arbitrarily determined error measurement time and the number of occurrences of an error, and outputs a sum check error signal. Is transmitted to switch the two transmission line interface boards. In the determination of the check result, the error counting means 2D and the error counting means 2E can arbitrarily set conditions to be satisfied for transmitting the error output signal. The transmission line interface board can be switched under conditions corresponding to error detection and the like, and a highly reliable transmission system can be constructed. In addition, the settings can be arbitrarily changed according to the terminal device, and a quick and efficient system can be constructed. In addition, by configuring in frame units,
It is possible to clarify which error a data error is detected.

The arbitrary condition for transmitting the error output signal by the error counting means of the system of the first embodiment is 1 which is a multiple of the transmission time in frame units.
Since the error measurement time, which is a unit time, is set for the six multiframes and the condition is set based on the number of data errors occurring in the error measurement time, it is possible to set a condition corresponding to the necessary switching condition. Further, since the data errors occurring more than a predetermined number of times within the error measurement time are set to arbitrary conditions based on the continuous occurrence, the conditions can be set in a time sequence. .

Embodiment 2 FIG. In the above embodiment, the error counting means 2D and the error counting means 2
By using E, the transmission condition of the error output signal is set to 2
However, the present invention is not limited to this, and the number of error output means may be set by increasing or decreasing the number of error counting means.

Embodiment 3 Further, in the above-described embodiment, the configuration of the frame data is shown by the primary group of PCM.
The present invention is not limited to this, and may be applied to higher-order groups and the like. Further, the data to be transmitted does not necessarily have to be multiplexed data as in the above embodiment. In addition, when calculating the sum check data, the data is not limited to binary data of 4 bits each.
The data may be transmitted as binary data of each bit or 16 bits and operated.

Embodiment 4 Further, in the above-described embodiment, the description has been made on the assumption that the transmission path is a transmission by a wire such as an optical fiber.

[0029]

As described above, according to the present invention, on the transmitting side, data to be transmitted is divided into binary data of a certain digit, and a certain number is added, and the added value is divided into a certain number of digits. Then, a complement value is calculated, and in addition to the data to be transmitted, the data is transmitted to a plurality of transmission paths. On the receiving side, the received data is divided into binary data of a certain digit, and the received data is divided based on the added value. A data error is detected, and an alarm signal is transmitted based on one or a plurality of arbitrarily set alarm signal transmission conditions and the detected data error, and the transmission line interface is switched, so that the conditions are arbitrarily determined. The transmission line interface can be switched under conditions corresponding to terminal devices connected to transmit and receive data. Therefore, a highly reliable transmission system can be constructed. Further, it is only necessary to arbitrarily change the settings according to the terminal device, and a system can be quickly constructed.

[Brief description of the drawings]

FIG. 1 is a block diagram focusing on a data transmission system for realizing a transmission line interface switching method according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a frame configuration in the case of a primary group of PCM (24CH).

FIG. 3 is a diagram showing a frame configuration for showing an example in the present system.

FIG. 4 is a time chart showing a relationship between an error occurrence and a sum check error signal.

[Description of Signs] 1 Frame data transmission unit 1A Multiplexed data input unit 1B Check data calculation unit 1C Frame data creation unit 1D Frame data transmission unit 2 Frame data reception unit 2A Transmission path interface unit 2B Frame data calculation unit 2C Counter unit 2D 2E Error counting means 2F Error checking means 3a, 3b Transmission path 4-1 to 4-n Transmission terminal device 5 Multiplexing means 6-1 to 6-n Receiving terminal device 7 Demultiplexing means

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Claims (4)

[Claims] 1. A transmission side transmits the same data to a plurality of transmission paths, and a reception side processes one of the plurality of data transmitted by each of the transmission paths as reception data. In the data transmission system, the receiving side detects a data error of the received data, based on the detection result, to process data transmitted by another transmission path as the received data,
In the transmission line interface switching method for transmitting a warning signal and switching a transmission line interface, the transmitting side divides data to be transmitted into binary data of a certain digit, and divides the divided binary data by a predetermined number. Adding, for the given digit of the added value, calculating a complement value, and adding the complement value to the data to be transmitted, and transmitting the data to a plurality of transmission paths, On the receiving side, dividing the received data into the binary data of a certain digit and adding the data; and detecting a data error of the received data based on the added value. When it is determined that the result of detecting the data error based on one or more conditions satisfies the one or more conditions set arbitrarily in advance, the alarm Transmission path interface switching method characterized by a step of transmitting the item. 2. The method of detecting a data error in the received data,
2. The transmission line interface switching method according to claim 1, wherein the switching is performed in units of a frame composed of a predetermined number of bits. 3. The condition arbitrarily set in advance is that a unit time is set to a multiple of a transmission time of a data length in units of the frame, and based on the number of occurrences of errors in the received data in the unit time. 3. The transmission line interface switching method according to claim 2, wherein the conditions are set. 4. The condition arbitrarily set in advance is that a unit time is set to a multiple of a transmission time of a data length in a unit of the frame, and the condition occurs more than an arbitrarily set number of times in the one unit time. 3. The transmission line interface switching method according to claim 2, wherein the error of the received data is a condition set on the basis that the error occurs continuously for a predetermined number of unit times.