KR100358356B1 - Transponder including SDH Multiplexer in WDM Transmission System - Google Patents

Abstract

The present invention relates to an optical transponder that can be applied when a client signal of a wavelength division multiplex (WDM) network is a synchronous digital hierarchy (SDH) signal. The multiplexing scheme used in the synchronous transmission scheme is applied to the optical transponder to make efficient use of the allocated wavelengths in the WDM network and to provide reliability in terms of protection switching of the received client signals.

Description

Optical transponder of wavelength division multiplexing system using synchronous digital staging multiplexing {Transponder including SDH Multiplexer in WDM Transmission System}

The present invention relates to a wavelength division multiplex (WDM) optical transmission system. More specifically, the present invention relates to an optical transformer applied when a client signal is a synchronous digital hierarchy (SDH) signal. It's about a fender.

1 is a diagram illustrating a configuration of a general WDM optical transmission system. Referring to FIG. 1, the WDM optical transmission system is composed of an optical wavelength multiplexer 130, an optical wavelength demultiplexer 140, and an optical transponder 110 and 120. The optical wavelength multiplexer 130 multiplexes input signals of different wavelengths and transmits them to one optical cable, and the optical wavelength demultiplexer 140 demultiplexes the wavelength multiplexed signal into client signals of several different wavelengths. . In addition, the optical transponders 110 and 120 convert the received client signals into wavelengths and connect them to the optical wavelength multiplexer 130 and the optical wavelength demultiplexer 140.

2 is an internal configuration diagram of a conventional optical transponder. The receiving optical transponder 110 and the transmitting optical transponder 120 are paired, and the receiving photoelectric converter 111 of the receiving optical transponder 110 converts the received client signal into an electrical signal. Then, the receiving side all-optical converting unit 112 converts and fixes the electric signal into an optical signal of one wavelength and outputs it to the optical wavelength multiplexing unit 130. On the contrary, the client signal extracted from the optical wavelength demultiplexer 140 may be directly transmitted to the client or, if necessary, passed through the transmitting optical transponder 120 and then output as the transmitting client signal.

The overall network configuration when the SDH signal is connected to the WDM optical transmission system mentioned above as a client signal is shown in FIG. The part indicated by the dotted line in FIG. 3 indicates that the signal is configured in redundancy for protection switching of the signal. The client signal accommodated in the WDM network 330 of FIG. 3 is an STM-64 (10Gb / s) signal or an STM-16 (2.5Gb / s) signal depending on the type of the SDH nodes 310 and 320. As mentioned above, the received client signal is converted into a new optical wavelength through the optical transponder 331 of the WDM optical transmission system, and the optical wavelength multiplexed by the optical wavelength multiplexer 333 by binding several signals of the converted wavelength to one optical cable. Send it through.

The optical signal thus transmitted is demultiplexed by the optical wavelength demultiplexer 334 of the WDM optical transmission system of the other station and transmitted to the SDH nodes 340 and 350 as the corresponding clients.

In the conventional WDM optical transmission system, the SDH signals received are treated the same regardless of whether they are STM-64 or STM-16 to perform optical wavelength multiplexing. In other words, a WDM optical transmission system that performs 16 wavelength multiplexing has a transmission capacity of 160 Gbps when all client signals are STM-64 and 40 Gbps when the client signal is STM-16. Therefore, when high speed and low speed signals are mixed and accommodated as client signals of the WDM network 330, the transmission capacity of the WDM optical transmission system must be maximized because they must be allocated to the same wavelength, which is a 10 Gbps signal or a 2.5 Gbps signal. It has the disadvantage of not being able to.

For signal protection switching in the WDM network 330 in which the SDH signal is accommodated, the SDH signal is provided with both a working line and a protection line having a 1 + 1 structure, and operated to accommodate the WDM network. Provide tracks and reserve tracks. That is, the SDH signal provided to the WDM network through the operation line (A) is transmitted to the power station through the operation line of the WDM network, and the DSH signal provided to the WDM network through the protection line is used as a reserve line (B) of the WDM network. It is delivered to the power. When the STM-16 signal is received as a client signal in the WDM network, if the operation line A of the two lines connecting the STM-16 node 320 and the receiving optical transponder 332 of FIG. No switching takes place inside the transmission system, but switching takes place between the WDM network 330 and the SDH nodes 320 and 350. The receiving optical transponder 332 is a reserve line connected by dotted lines from the STM-16 node 320. The STM-16 signal received through the signal is multiplied and transmitted to the other station through the reserve line (B). However, at this time, if the preliminary line B, which is indicated by the dotted line, of the two lines between the optical wavelength multiplexing 333 inside the WDM network 330 and the optical wavelength demultiplexing unit 334 of the counterpart station is broken again, this preliminary line B Since the transmission between the STM-16 nodes 320 and 350 transmitted through the communication is cut off, a problem arises in that signal transmission is lost.

As described above, in the conventional WDM optical transmission system, the WDM wavelength is allocated regardless of the transmission speed of the client signal. Therefore, when the WDM optical transmission system is mixed with the low and high speed client signals, the WDM transmission capacity is somewhat inefficient in terms of WDM transmission capacity. There is this. In addition, if the operation line is disconnected between the STM-16 node and the WDM network, and the spare line between the optical wavelength multiplexer and the optical wavelength demultiplexer in the WDM network is broken, the STM-16 node cannot transmit a signal to the other station. There is this.

Accordingly, the present invention has been made to solve the above problems of the prior art, by applying the multiplexing concept used in the synchronous transmission method to the optical transponder of the WDM optical transmission system, thereby multiplexing the low-speed signal at high speed in the SDH. By transmitting at one wavelength, the WDM transmission capacity is maximized, and the protection switching structure of the received client signal is improved to improve transmission reliability in WDM transmission.

1 is a block diagram of a typical wavelength division multiplexing optical transmission system,

2 is a structural diagram of a conventional optical transponder,

3 is a diagram illustrating an entire network when the synchronous digital threshold signal is a dependent signal;

4 is a block diagram of a wavelength division multiplex optical transmission system using an optical transponder having a new structure;

5 is a block diagram of an optical transponder of a wavelength division multiplexing transmission system using the synchronous digital phase multiplexing method according to an embodiment of the present invention.

In order to achieve the above object, an optical transponder of a wavelength division multiplexing transmission system using the synchronous digital phase multiplexing system according to the present invention includes a plurality of client nodes for transmitting and receiving optical signals at different transmission rates, and the plurality of client nodes. In a wavelength division multiplexing system consisting of a wavelength division multiplexing network which transmits an optical signal by multiplexing / demultiplexing between client nodes, a plurality of transmission client signals having different transmission speeds are used for two lines (operation line, backup line). It converts the signal into a single wavelength after converting it into a single wavelength, and transmits it to the optical wavelength multiple part through two lines (operation line and reserve line), and inputs the demultiplexed signal from the optical wavelength inverse multiple part through two lines (operation line and reserve line). After receiving and converting the wavelength, the optical transformer delivers to a plurality of receiving client nodes through two lines (operation line and backup line). In the fender, each of the four client nodes is connected one by one to receive an STM-16 signal through two lines (operation line and reserve line) from each of the connected client nodes to reframe and overwrite the input STM-16 signal. After processing the head and processing the SDH pointer, it synchronizes with the reference clock and outputs the signal to the STM-64 signal processor through the normal operation of the operation line and the reserve line, and inputs the signal from the STM-64 signal processor through the operation line or the reserve line. Four STM-16 signal processing units configured to simultaneously bridge the signals to the management line and the spare line, receive the data to be delivered to the client node, and output the STM-16 frame to the client node; 16 STM-16 signal processing units connected between the signal processing unit and the optical wavelength multiplexer and the optical wavelength demultiplexer Signals received through the operation line or the reserve line from the bridge to the operation line and the reserve line at the same time received and reconstructed to the STM-64 frame and output to the optical wavelength multiplex, and two lines (operational line from the optical wavelength demultiplexer) And the STM-64 signal through the preliminary line), and reframes the input STM-64 signal, processes the overhead, and then synchronizes the reference clock to synchronize the reference clocks. And the STM-64 signal processor outputting the STM-16 signal processor.

Preferably, the STM-16 signal processing unit includes a low speed photoelectric conversion unit for converting an STM-16 signal input from the client node into an electrical signal, and an STM-16 electric signal output from the low speed photoelectric conversion unit 1: A low speed demultiplexer which demultiplexes to 48 a low speed demultiplexer, a low reframe part which reframes the demultiplexed STM-16 electrical signal outputted from the low speed demultiplexer, and processes STM-16 overhead according to a synchronous transmission method; And a pointer processor for synchronizing the signals output from the pregnant woman to the high-speed signal processor in synchronization with the reference clock, wherein the STM-64 signal processor includes a high-speed signal output from the pointer processor of the four STM-16 signal processors. High speed frame unit reconstructing STM-64 frame according to the synchronous transmission method, and high speed to multiplex the STM-64 frame output from the high speed frame unit to 192: 1 And a high-speed all-optical converting unit for converting a multi-signal output from the high-speed multi-part into an optical signal and transferring the multi-signal to the optical-wavelength multi-part. More preferably, the STM-64 signal processing unit includes the optical wavelength. A high speed photoelectric conversion unit for converting a high speed optical signal input from the multiple unit into an electrical signal, a high speed demultiplexer for demultiplexing the electric signal output from the high speed photoelectric conversion unit at 1: 192, and outputting the high speed demultiplexer And a high speed reframe unit for reframes the demultiplexed signal and processes the STM-64 overhead according to a high speed synchronous transmission scheme to the STM-16 signal processor, wherein the STM-16 signal processor includes the STM- signal. A low speed frame unit for reconstructing a signal output from the high speed reframe unit of the 64 signal processor into an STM-16 frame according to a low speed synchronous transmission method; And a low speed multiplier for multiplexing the low speed frame output from the inner frame unit by 48: 1, and a low speed all-optical converter for converting the multi-signal output from the low speed multiplier into an optical signal and providing the same to the client node. do.

Hereinafter, an optical transponder of a wavelength division multiplexing transmission system using synchronous digital phase multiplexing according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a block diagram of a WDM optical transmission system to which an optical transponder to which SDH multiplexing is newly designed according to an embodiment of the present invention is applied.

Referring to FIG. 4, when the received SDH signal is an STM-16, four STM-16 signals are multiplexed to an STM-64 signal using an SDH multiplexing scheme in an optical transponder and transmitted to an optical wavelength multiplexer. By inserting the SDH multiplex into the optical transponder in this way it is possible to maximize the transmission capacity of the above-mentioned WDM optical transmission system. In other words, even when the STM-64 and STM-16 signals are mixed as client signals, the signals multiplexed in the actual optical wavelength multiplex are all STM-64 signals, which is advantageous in terms of WDM transmission efficiency.

FIG. 5 is an internal configuration diagram of an optical transponder to which the SDH multiplex method shown in FIG. 4 is applied. The optical transponder of FIG. 5 is largely composed of four low-speed signal processing units STM-16 signal processing unit 510, one high-speed signal processing unit STM-64 signal processing unit 520, and a system clock control unit 530. First, the STM-16 signal processor 510 receives four STM-16 optical signals, which are client signals, by duplexing them into working lines and transfer protection lines, respectively. The STM-64 signal processor 520 selects one of the operation line or the transfer protection line of the STM-16 signal processor 510 to generate the operation line signal and the transfer protection line signal to be transmitted to the optical wavelength multiplexer. That is, the operational line and the transfer protection vessel of the STM-16 signal processor 510 are selectively bridged and transferred to the STM-64 signal processor 520, and the operation line and the transfer protection vessel of the STM-64 signal processor 520 are selectively provided. The bridge is delivered to the STM-16 signal processor 510.

The STM-16 photoelectric conversion unit 511 performs photo / electric conversion of the received optical signal, and the 1:48 demultiplex unit 512 demultiplexes the converted electric STM-16 signal by 1:48 and the STM-16 reframe unit ( 513 extracts and processes the STM-16 overhead from the demultiplexed signal according to the synchronous transmission scheme. Thereafter, the SDH pointer processing unit 514 performs a pointer processing function according to the synchronous transmission scheme in order to synchronize with the reference clock supplied from the system clock control unit 530.

The system clock controller 530 receives clocks from the four STM-16 signal processors 510 and one STM-64 signal processor 520 to generate a reference clock to be used in the optical transponder. The four STM-16 signals which have passed through the pointer processing unit in each STM-16 signal processing unit 510 are sent to the STM-64 signal processing unit 520. The STM-64 frame unit 521 of the STM-64 signal processor 520 reconstructs four received STM-16 signals into STM-64 signals, and the 192: 1 multiplexer 522 multiplexes them, and the all-optical converter 523 converts and outputs the light of the wavelength.

In the reverse direction, the STM-64 signal transmitted from the optical wavelength demultiplexer is transmitted to the photoelectric conversion section 526, 1: 192 demultiplexer 525, STM-64 reframe section 524, etc. of the STM-64 signal processing section 520. Through the STM-16 signal, each STM-16 signal is transmitted to four signal processors. The STM-16 frame portion 517 of the STM-16 signal processor 510 reconstructs the received STM-16 signal according to the STM-16 signal frame, and the 48: 1 multiplexer 516 decodes the STM-16 frame. : 1 is multiplexed, and the all-optical converter 515 transmits the all-optical conversion to the corresponding client node.

In the optical transponder having the above structure, the signal connection between the STM-16 signal processor 510 and the STM-64 signal processor 520 is connected at 51.84 Mbps, which is the STS-1 class of the synchronous transmission method. By configuring the signal connection between the two in a 1 + 1 structure, it is possible to solve the switching problem that occurs when using a conventional optical transponder. This will be described with reference to FIG. 4.

4 is a block diagram of a WDM optical transmission system employing a new optical transponder. It is connected to the WDM network 430, SDH nodes 410, 420, 440, 450 in a bundle of four STM-16. This WDM network 430 includes a new structure of reception optical transponders 431 and 432, an optical wavelength multiplexer 433, an optical wavelength demultiplexer 434, and a transmission optical transponder 435 and 436.

When the operation line C of the SDH node 420 is disconnected among the STM-16 signals input to the WDM optical transmission system of FIG. 4, the optical transponder 432 transmits the STM-16 signal through the reserve line of the SDH node 420. Is received, and the received TM-16 signal is bridged inside the optical transponder 432 and simultaneously delivered to the optical wavelength multiplexer 433 via the operation line and the reserve line. At this time, even if the preliminary line (D) between the optical wavelength multiple part inside the WDM network and the optical wavelength demultiplex part of the opposite station is disconnected, the data flowing in the standby line (D) is transmitted through the operation line of the optical multiplex part and the optical wavelength demultiplex part. The signal can be transmitted to the receiving side. Therefore, according to the present invention, unlike the conventional scheme, communication disconnection between both SDH nodes does not occur, and signal switching is performed by an optical transponder to protect the signal, thereby enabling more reliable protection switching.

As described above, when the WDM optical transmission system is configured by using the optical transponder having the structure as shown in FIG. 5, the disadvantage that the transmission capacity of the conventional optical transponder cannot be maximized can be overcome, and the signal protection The reliability of transfer can be improved.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

According to the present invention as described above, it is possible to maximize the transmission capacity of the WDM transmission network and improve the reliability in terms of protection switching of the signal.

Claims (4)

In a wavelength division multiplex transmission system comprising a plurality of client nodes for transmitting / receiving optical signals at different transmission rates and a wavelength division multiplex network for multiplex / demultiplexing optical signals between the plurality of client nodes, A plurality of transmission client signals having different transmission speeds are inputted through two lines (operational line and reserve line), converted into a single wavelength, and transmitted to the optical wavelength multiple part through two lines (operation line and reserve line). The optical transponder receives the demultiplexed signal from the demultiplexer through two lines (operation line, reserve line), converts the wavelength, and delivers the signal to a plurality of receiving client nodes through two lines (operation line and reserve line). In It is connected to each of the four client nodes one by one to receive the STM-16 signal through the two lines (operation line and reserve line) from each of the connected client node to reframe the input STM-16 signal and to handle the overhead After processing the SDH pointer, it synchronizes with the reference clock and outputs the signal to the STM-64 signal processor through the normal operation line of the operation line and the reserve line, and operates the signal input from the STM-64 signal processor through the operation line or the reserve line. Four STM-16 signal processing units configured to simultaneously bridge the lines and the spare lines, receive the data to be delivered to the connected client node, and output the STM-16 frame to the client node; It is connected between the four STM-16 signal processor and the optical wavelength multiplexer and the optical wavelength demultiplexer, and simultaneously bridges signals input from the four STM-16 signal processor through the operation line or the reserve line to the operation line and the reserve line. After receiving the STM-64 frame, it reconstructs the STM-64 frame and outputs it to the optical wavelength multiplexer, and receives the STM-64 signal through two lines (operation line and reserve line) from the optical wavelength demultiplexer. And the STM-64 signal processing unit which outputs to the four STM-16 signal processing units through a line operating normally among the operation line and the reserve line in synchronization with the reference clock after reframes and processes the overhead. Optical transponder of wavelength division multiplex transmission system using synchronous digital hierarchy multiplexing. The STM-16 signal processor of claim 1, wherein the STM-16 signal processor comprises: a low speed photoelectric conversion unit for converting an STM-16 signal input from the client node into an electrical signal; and an STM-16 electric signal output from the low speed photoelectric conversion unit. A low speed demultiplexer for demultiplexing at 1:48, a low speed reframer for reframed the demultiplexed STM-16 electrical signal outputted from the low speed demultiplexer, and processing STM-16 overhead according to a synchronous transmission method; A pointer processing unit which outputs the signal output from the low speed reframe unit to the high speed signal processing unit in synchronization with the reference clock, The STM-64 signal processing unit includes a high speed frame unit for reconstructing signals output from the pointer processing units of the four STM-16 signal processing units into an STM-64 frame according to a high speed synchronous transmission method, and an STM output from the high speed frame unit. And a fast all-optical converting unit for converting -64 frames to 192: 1 and converting the multiple signals outputted from the high-speed multiplexing into optical signals and transferring the optical signals to the optical wavelength multiplexing unit. Optical transponder of wavelength division multiplexing transmission system using the method. The high-speed photoelectric conversion unit according to claim 1 or 2, wherein the STM-64 signal processing unit converts a high-speed optical signal input from the optical wavelength multiplexing unit into an electrical signal, and the electricity output from the high-speed photoelectric conversion unit. A high speed demultiplexer for demultiplexing a signal at 1: 192 and a demultiplexed signal output from the high speed demultiplexer and reprocessing the STM-64 overhead according to a high speed synchronous transmission method to the STM-16 signal processor. Including a high-speed reframe portion to deliver, The STM-16 signal processor may include a low speed frame unit configured to reconstruct a signal output from the high speed reframe unit of the STM-64 signal processor to an STM-16 frame according to a low speed synchronous transmission method, and a low speed frame output from the low speed frame unit. And a low speed multiplexer for multiplexing the signal to 48: 1, and a low speed all-optical converter for converting the multiple signals outputted from the low speed multiplexer to an optical signal and providing the same to the client node. Optical transponders in wavelength division multiplexing systems. delete