Sdh transmission system

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a transmission method in an SDH (Synchronous Digital Hierarchy) transmission device.

【0002】

[Conventional technology]

In recent years, optical transmission methods and wireless transmission methods capable of transmitting large volumes of data have been developed, and along with this, standardization of a new synchronization method called the SDH method has been promoted. In this standardized SDH system, CCITT recommends a multiplexing structure as shown in Fig. 5.

【0003】

In this multiplexed structure, as shown in Fig. 6, it is possible to accommodate one VC-4 as AU-4 (AU pointer + VC-4) in the payload of STM-1 and perform data transmission. However, in a conventional SDH transmission device, as shown in Fig. 7, three VC-3s (see Fig. 8 for the configuration of VC-3) and three AU-3s (AU pointer + VC-3) The STM-1 frame was constructed by byte multiplexing as a data transmission (according to CCITT Recommendation G.708).

【0004】

FIG. 9 is an explanatory diagram showing a configuration of multiplexing processing in a conventional SDH transmission device. As shown in this figure, in a conventional SDH transmission device, when three VC-3s are byte-multiplexed to form an STM-1 frame, the justification (synchronous operation) is VC-3 The TUG-2 conversion / staff processing unit 42 uses the frame phase signal extracted by the STM-1VC-3 conversion unit 41, and the staff operation is performed independently for each of the three VC-3s. It was.

【0005】

In this case, the signal on the transmitting side is composed of 3 VC-3s by adding POH (path overhead) to 21 TUG-2s by the VC-3 TUG-2 converter 43, and STM- 1 VC-3 conversion unit 41 adds SOH (section overhead) to configure STM-1 and send it to the transmission line.

【0006】

Further, the conventional SDH transmission device does not have a means for inserting the inter-device control data into the payload of the STM-1 without deteriorating the transmission efficiency of the actual data.

【0007】

[Problems to be Solved by the Invention]

However, in the SDH transmission method in which one VC-4 is accommodated in the payload of the STM-1 frame, justification is performed by one VC-4, so that a device or circuit using a conventional VC-3 is used. There is a problem that the transmission efficiency of actual data is lowered due to the transmission of control data between devices.

【0008】

An object of the present invention is to facilitate migration from a conventional device and to transmit inter-device control data without deteriorating data transmission efficiency when the VC-4 is housed in a payload of an STM-1 frame. Is to be.

【0009】

[Means for solving problems]

According to the present invention, in an SDH transmission device that transmits data by accommodating VC-4 in the payload of an STM-1 frame, VC-4 is configured by byte-multiplexing VC-3 and adding path overhead. In addition, by separating the frame phase signal of VC-4 into three frame phase signals of VC-3, the synchronization operation in VC-4 is replaced with the synchronization operation of VC-3, and staff synchronization is performed. SDH transmission method.

【0010】

In the above configuration, it is preferable to perform transmission by inserting inter-device control data at the position of the fixed staff of VC-3.

【0011】

[Action]

According to the present invention, by separating the frame phase signal of VC-4 into the frame phase signals of three VC-3s, the synchronous operation of one VC-4 is replaced with the synchronous operation of three VC-3s. Synchronize. Therefore, the STM-1 frame can be created using the conventional VC-3 conversion / staff processing device.

【0012】

Also, when transmitting data, insert the inter-device control data on the transmitting side at the position of the fixed staff of VC-3, and at the time of data reception, separate the inter-device control data on the receiving side from the position of the fixed staff of VC-3. Therefore, it is possible to transmit the control data between devices without reducing the transmission amount of the actual data.

【0013】

[Example]

Hereinafter, the present invention will be described in detail based on the examples shown in the drawings. It should be noted that this does not limit the invention.

【0014】

FIG. 1 shows a staff synchronization device used in the SDH transmission method of the present invention. In this figure, 1 is the STM-1VC-4 converter that converts STM-1 and VC-4, and 2 is the VC-4C-4 converter that converts VC-4 and C-4. Reference numeral 3 is a frame phase signal separator. The frame phase signal separation unit 3 receives the VC-4 frame phase signal on the receiving side from the VC-4C-4 conversion unit 2, and converts this VC-4 frame phase signal into three VC-3 frame phase signals. Convert and output.

【0015】

4 is C-4 VC-3 multiplexing section that byte-multiplexes 3 VC-3s and converts them to C-4, and 5 is C-4 VC that separates C-4 into 3 VC-3s. -3 Separator, 6 converts 21 TUG-2 to 3 VC-3 VC-3 TUG-2 converter, 7 converts 3 VC-3 to 21 TUG-2 At the same time, it is a VC-3 TUG-2 conversion / stuff processing unit that performs stuff processing by the frame phase signal from the frame phase signal separation unit 3.

【0016】

FIG. 2 is an explanatory diagram showing an insertion position of inter-device control data according to the present invention. As shown in this figure, the inter-device control data is inserted at the position of the fixed staff of the VC-3 to transmit the actual data without deteriorating the transmission efficiency.

【0017】

FIG. 3 is an explanatory diagram showing an insertion / separation method of inter-device control data of the present invention. In this figure, 11 is the C-4 VC-3 multiplexing unit that multiplexes the three VC-3s on the transmitting side and the control data between devices, and 12 is the C-4 data on the receiving side that is three VC-. C-4 VC-3 separation unit, which separates 3 and device-to-device control data, 13 is a transmission side timing generation circuit that generates a transmission side timing signal from the system clock.

【0018】

14 is a receiving side timing generation circuit that generates a receiving side timing signal by the system clock, and 15 is a speed to match the inter-device control data on the transmitting side with the multiplexing timing of C-4 VC-3 multiplexing unit 11. The transmitting side speed conversion unit that performs conversion, and 16 is a receiving side speed conversion unit that performs speed conversion of inter-device control data on the receiving side.

【0019】

Among the timing signals generated by the transmission side timing generation circuit 13, the timing of the transmission timing signal of the inter-device control data is determined by the inter-device control data speed setting signal. As a result, the inter-device control data can have a plurality of transmission speeds.

【0020】

That is, by providing a setting signal that can generate the timing for inter-device control data generated by the timing generation circuits 13 and 14 on the transmitting side and the receiving side according to the transmission speed of the control data, a plurality of transmission speeds can be obtained. It is possible to transmit control data in.

【0021】

FIG. 4 is a configuration diagram of an embodiment of the present invention and shows a part of the SDH transmission device. In this figure, 21 adds SOH (section overhead) to VC-4 and converts it to STM-1, and conversely extracts SOH from STM-1 and converts it to VC-4 STM-1VC- 4 Conversion unit.

【0022】

22 is a VC-4C-4 converter that adds POH (path overhead) to C-4 and converts it to VC-4, and conversely extracts POH from VC-4 and converts it to C-4. is there.

【0023】

Reference numeral 23 denotes a SOH / POH terminal, which receives or controls SOH and POH inserted or extracted by the STM-1VC-4 conversion unit 21 and the VC-4C-4 conversion unit 22 from the control unit 24. Send to unit 24.

【0024】

25 is a C-4 VC-3 multiplexing unit that byte-multiplexes three VC-3s and converts them to C-4, and inserts inter-device control data at the fixed staff position of VC-3. It is a C-4 VC-3 separation unit that separates C-4 into three VC-3s and extracts inter-device control data from the positions of fixed staff of VC-3.

【0025】

27 is a VC-3 TUG-2 converter that adds POH to TUG-2 and converts it to VC-3, and 28 is a frame phase signal separation that extracts POH from VC-3 and converts it to TUG-2. This is a VC-3 TUG-2 conversion / staff processing unit that performs staff processing using the frame phase signal from unit 31.

【0026】

The frame phase signal of the VC-4 on the receiving side extracted by the VC-4C-4 conversion unit 22 is converted into three VC-3 frame phase signals by the frame phase signal separation unit 31, and the VC-3. Sent to TUG-2 conversion / staff processing department 28.

【0027】

29 is the transmission side inter-device control data speed conversion unit that performs speed conversion to insert the inter-device control data from the control unit 24 into the position of the fixed staff of VC-3, and 30 is the position of the fixed staff of VC-3. It is a receiving side inter-device control data speed conversion unit that performs speed conversion in order to transmit the inter-device control data inserted in the control unit 24 to the control unit 24.

【0028】

In such a configuration, the frame phase signal separator 31 separates the frame phase signal of the VC-4 into three frame phase signals of the VC-3, thereby achieving justification of one VC-4. Replace with justification of one VC-3, and perform staff operation in VC-3 TUG-2 conversion / staff processing unit 28.

【0029】

Further, in the C-4 VC-3 multiplexing unit 25, the inter-device control data on the transmitting side is inserted at the position of the fixed staff of the VC-3, and conversely, the C-4 VC-3 separating unit 26 By separating the inter-device control data on the receiving side from the position of the fixed staff of VC-3, the control data between the devices is transmitted without reducing the transmission amount of the actual data.

【0030】

[Effect of the invention]

As described above, according to the present invention, when the VC-4 is housed in the STM-1 frame, the synchronization operation in the VC-4 is replaced with the synchronization operation of the VC-3 to perform staff synchronization. In addition to facilitating the transition from conventional devices, it is possible to accommodate inter-device control data without degrading the transmission efficiency of actual data, which greatly contributes to improving the performance of SDH transmission devices.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram of the staff synchronization apparatus used in the SDH transmission system of this invention.

[Figure 2]

It is explanatory drawing which shows the insertion device of the control data between devices by this invention.

[Fig. 3]

It is explanatory drawing which shows the insertion / separation method of the control data between devices of this invention.

[Fig. 4]

It is a block diagram of the Example of this invention.

[Fig. 5]

It is explanatory drawing of SDH multiplexing structure.

[Fig. 6]

It is explanatory drawing which shows the relationship between STM-1 and one AU-4.

[Fig. 7]

It is explanatory drawing which shows the relationship between STM-1 and three AU-3.

[Fig. 8]

It is a block diagram of VC-3.

[Fig. 9]

It is explanatory drawing which shows the structure of the multiplexing processing in the conventional SDH transmission apparatus.

[Explanation of symbols]

1,21 STM-1 VC-4 converter 2,22 VC-4C-4 converter 3,31 Frame phase signal separator 4,11,25 C-4 VC-3 Multiplexing section 5,12,26 C-4 VC-3 separator 6,27 VC-3 TUG-2 converter 7,28 VC-3 TUG-2 conversion / staff processing department 13 Transmitter timing generation circuit 14 Receiving side timing generation circuit 15 Transmitter speed converter 16 Receiving speed converter 23 SOH, POH end 24 Control unit 29 Transmission-side device-to-device control data speed converter 30 Control data speed converter between receivers