KR20010064147A - Transponder including SDH Multiplexer in WDM Transmission System - Google Patents

Abstract

PURPOSE: An optical transponder of a wavelength division multiplex transmission system applied synchronous digital hierarchy is provided to improve transmission reliability and to increase transmission capability. CONSTITUTION: The optical transponder has a plurality of low speed signal processing parts(510), a high speed signal processing part(520) and a system clock controlling part(530). The low speed signal processing parts(510) synchronize client signal with reference signal to output it to the high speed signal processing part(520). The high speed signal processing part(520) multiplexes the client signals to output them to an optical wavelength multiplexing part and demultiplexes the high speed signal from an optical wavelength demultiplexing part to output it to the low speed signal processing parts(510). The system clock controlling part(530) generates the reference clock to apply it to the low speed signal processing parts(510) and the high speed signal processing part(520).

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.

Looking at the signal protection switching in the WDM network 330 in which the SDH signal is accommodated, the SDH signal provides both the working line and the protection line of the 1 + 1 structure, and is reserved for the WDM network to accommodate it. Have a track. 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 action takes place inside the transmission system, and switching takes place between the SDH nodes 320 and 350 outside the WDM network 330, and a dotted line between the STM-16 node 320 and the receiving optical transponder 332. The signal is transmitted through a spare line connected to the network. However, in this case, when the preliminary line B, which is indicated by a 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 other station is broken, the STM-16 node 320, There is a disadvantage that both the operation line and the reserve line between 350) are cut off.

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.

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. The purpose of the present invention is to maximize the WDM transmission capacity and improve the protection switching structure of the received client signal to improve the transmission reliability in the 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 hierarchy multiplexing system according to the present invention includes a plurality of receiving client nodes and transmitting client nodes that transmit / receive optical signals at different transmission speeds. And a wavelength division multiplexing system comprising a wavelength division multiplexing network for multiplexing / demultiplexing an optical signal between the plurality of client nodes and converting wavelengths of a plurality of receiving client signals having different transmission rates. An optical transponder for transmitting to a plurality of transmitting client nodes by converting a wavelength of a signal demultiplexed by an optical wavelength multiplexer to a plurality of transmitting client nodes, and outputting a client signal having a low transmission rate to a high speed signal processor in synchronization with a reference clock. The client inputs a signal from the high speed signal processor. A plurality of low speed signal processing units outputted to a node and a plurality of low speed client signals inputted through the plurality of low speed signal processing units are outputted to the optical wavelength multiplexing unit, and the high speed signals inputted from the optical wavelength demultiplexing unit are demultiplexed for each client. A high speed signal processor which separates and outputs the clocks to the plurality of low speed signal processors, and receives the clocks from the plurality of low speed signal processors and the high speed signal processors to generate the reference clock, and transmits the reference clocks to the plurality of low speed signal processors and the high speed signal processors And a system clock control unit.

Preferably, the optical transponder described above is characterized by multiplexing four low-speed STM (Synchronous Transfer Mode) -16 signals into a high-speed STM-64 signal using a synchronous digital hierarchy multiplexing scheme.

More preferably, the low-speed signal processing unit includes a photoelectric conversion unit for converting an STM-16 optical signal into an electrical signal, a demultiplexer for 1:48 demultiplexing the converted electric signal, and reframes the demultiplexed signal. A STM-16 reframe unit for processing STM-16 overhead according to a synchronous transmission scheme, a pointer processor for synchronously outputting the STM-16 signal to the reference clock, and a signal transmitted from the high speed signal processor STM-16 And an STM-16 frame unit for reconstructing the frame, a multiple unit for 48: 1 multiplexing the reconstructed STM-16 frame, and an all-optical converter for converting the multiplexed signal into an optical signal and providing the same to a client node. do.

More preferably, the high speed signal processing unit includes an STM-64 frame unit configured to reconstruct a plurality of STM-16 signals transmitted from the plurality of low speed signal processing units into an STM-64 frame, and the reconstructed STM-64 frame. : 1 multiplexing multiplexing unit, an all-optical converting unit converting the multiplexed signal into an optical signal and transferring the optical wavelength multiplexing unit, a photoelectric conversion unit converting a signal transmitted from the optical wavelength demultiplexing unit into an electrical signal, and converting the electrical signal into 1 And an STM-64 reframe part for re-multiplexing the demultiplexed signal and processing STM-64 overhead according to a synchronous transmission scheme.

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 comprised of four STM-16 signal processors 510, an STM-64 signal processors 520, and a system clock controller 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-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.

Even when the operation line C of the STM-16 signal input to the WDM optical transmission system of FIG. 4 is cut off or the preliminary line D of the wavelength-multiplexed WDM optical signal is cut off, the signal is transferred by the optical transponder to transfer the signal. Because of the protection, more reliable protection switching can be achieved.

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 STM- The reliability of the signal protection switching can be improved by making the switching point of the 16 signals at the optical transponder in the WDM network.

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)

Wavelength division multiplexing comprising a plurality of receiving client nodes and transmitting client nodes for transmitting / receiving optical signals at different transmission rates, and a wavelength division multiplexing network for multiplexing / demultiplexing optical signals among the plurality of client nodes. In a transmission system, an optical transponder converting wavelengths of a plurality of receiving client signals having different transmission speeds and transmitting them to an optical wavelength multiplexing unit, and converting wavelengths of signals demultiplexed in the optical wavelength multiplexing unit and transmitting them to a plurality of transmitting client nodes. , A plurality of low speed signal processing units for synchronizing client signals with low transmission rates to a high speed signal processing unit in synchronization with a reference clock and outputting signals input from the high speed signal processing unit to the client node; Multiplexing the low-speed client signals inputted through the plurality of low-speed signal processing units at once and outputting them to the optical wavelength multiplexing unit; demultiplexing the high-speed signals input from the optical wavelength inverse multiplexing unit and separating the high-speed signals for each client and outputting the plurality of low-speed signal processing units The high speed signal processor; And And a system clock controller configured to receive clocks from the plurality of low speed signal processors and the high speed signal processors, respectively, to generate the reference clock, and to transmit the reference clocks to the plurality of low speed signal processors and the high speed signal processors. Optical transponder of wavelength division multiplexing system applied. 2. The wavelength division multiplexing method of claim 1, wherein four low-speed STM-16 signals are multiplexed into high-speed STM-64 signals using the synchronous digital phase multiplexing. Optical transponders in transmission systems. 3. The apparatus of claim 2, wherein the low speed signal processor comprises: a photoelectric conversion unit for converting an STM-16 optical signal into an electrical signal, a demultiplexer for 1:48 demultiplexing the converted electrical signal, and the demultiplexed signal; An STM-16 reframe unit for processing STM-16 overhead according to a synchronous transmission method after the frame, a pointer processor for synchronizing the STM-16 signal with the reference clock, and outputting a signal transmitted from the high speed signal processor STM- An STM-16 frame unit for reconstructing 16 frames, a multiple unit for 48: 1 multiplexing the reconstructed STM-16 frame, and an all-optical converter for converting the multiplexed signal into an optical signal and providing the same to a client node; Optical transponder of wavelength division multiplexing system using synchronous digital hierarchy multiplexing. 3. The apparatus of claim 2, wherein the high speed signal processor comprises: an STM-64 frame unit configured to reconstruct a plurality of STM-16 signals transmitted from the plurality of low speed signal processors into an STM-64 frame, and the reconstructed STM-64 frame. 192: 1 multiplexer for multiplexing, an all-optical converter for converting the multiplexed signal into an optical signal and transmitting it to the optical wavelength multiplexer, a photoelectric converter for converting a signal transmitted from the optical wavelength demultiplexer into an electrical signal, the electrical signal 1: 192 demultiplexing, including a demultiplexing unit, and an STM-64 reframe unit reframes the demultiplexed signal and processes STM-64 overhead according to a synchronous transmission scheme. Optical transponder of wavelength division multiplexing system applied.