KR20030087415A - A Large scale Optical Cross Connect Switching System using Optical Switch fabric Modules - Google Patents

Abstract

PURPOSE: A large scale optical cross connect switching system using an optical switch fabric module is provided to easily insert or remove the corresponding OSFM(Optical Switch Fabric Module) while operating a network by securing modularity. CONSTITUTION: An optical switch fabric(704) switches a plurality of optical wavelengths(713) transmitted to an input port, to a wanted output port according to a request of wavelength conversion by wavelengths. A first switching element(709) receives the conversion-requested wavelength in an input port for switching the same to an output port. A plurality of wavelength converters(710) receive the conversion-requested wavelength for converting the same into a wanted wavelength. A second switching element(711) switches to send the converted wavelength to a wanted input port.

Description

A large scale optical cross connect switching system using optical switch fabric modules

The present invention relates to a large capacity optical cross-link switching system using an optical switch fabric module, and more particularly, to an optical switch fabric structure of an optical cross connect (OXC) switching system in an optical network. In the form of a Wavelength Selective Cross Connector (hereinafter referred to as WSXC), a Wavelength Interchange Cross Connector (hereinafter referred to as WIXC), or a hybrid of the WSXC and WIXC. In the case of design, the present invention relates to a high-capacity optical cross-linking switching system using an optical switch fabric module constituting the optical switch fabric in a module unit to form a large optical switch fabric.

The rapidly developing communication technology has been providing convenient and high quality services to users, and is continuously developing to meet the infinite desire for user services. Improving the transmission efficiency of packets through switches in communication networks is considered to be a very important problem. City is very efficient.

A conventional general OXC switch fabric is classified as shown in FIG. 1. As shown in the figure, the OXC 10 can be largely divided into the optical fiber unit switching (FXC) 11 and the wavelength unit switching. The switching of the wavelength unit is again performed without the wavelength conversion (WSXC); 12) and the wavelength conversion switching (WIXC; 13). A structure designed in a hybrid form combining the WSXC 12 and the WIXC 13 in the switching of the wavelength unit is also proposed, and the coupling structure is illustrated in FIGS. 2 to 4.

2 is a diagram illustrating a structure in which a hybrid switch fabric combining WSXC and WIXC is connected to a network network interface (NNI) and a user network interface (UNI), and FIG. 3 is a node shared WSXC proposed by Telcordia Technologies. 4 is a structural diagram of a / WIXC hybrid form, and FIG. 4 is a structural diagram of an OXC having a link-sharing WSXC / WIXC hybrid structure.

In this conventional coupling structure, additional wavelength converters have to be additionally installed at the wavelengths required for wavelength conversion of the wavelengths coming from the add port, and there is also a need for additional control.

5 shows a structural diagram of a conventional OXC system. As shown in FIG. 5, in the conventional OXC system, an optical switch fabric 53 is installed between m wavelength division demultiplexers 52 and wavelength division multiplexers 55. The N signals amplified by the pre-amplifier 51 are converted into m individual signals by the wavelength division demultiplexer 52, and the path is selected by the optical switch fabric 53, and then the wavelength converter. A wavelength division multiplexed by the wavelength division multiplexer 55 via 54 is amplified through a post-amplifier 56 and then connected to the output optical path. The wavelength converter 54 is for converting a wavelength of a signal input from the wavelength division demultiplexer 52 or a signal output from the wavelength division multiplexer 55. The wavelength converter 54 generally includes an optical signal and a probe beam. The wavelength of the signal is converted by using gain modulation, phase modulation, or optical / electric / optical conversion. Although the wavelength converter 54 is illustrated at the front end of the wavelength division multiplexer 55 in the drawing, the wavelength converter 54 may be located at the rear end of the wavelength division demultiplexer 52.

In the conventional OXC system illustrated in FIG. 5, a structure in which all wavelengths multiplexed by each link are separated and crosslinked switching is performed to multiplex the wavelengths again to an output link. When the optical signals from to the optical link N are input, the optical wavelengths multiplexed on these links are separated into a total of N x m wavelengths by the wavelength division demultiplexer 52. The k wavelengths (insertion wavelengths) inputted from the local network 57 are added together, so that the total wavelength of Nm + k is switched in the optical switch fabric 53.

However, the structure of the conventional OXC system as described above does not accommodate the change unless the existing structure is significantly changed when there are variations in the number of insertion / extraction wavelengths, the number of input / output optical links, and the number of wavelengths multiplexed per link. Had. That is, there is a problem that does not have scalability for the above factors. In addition, the capacity of the conventional commercially available optical switch is limited, it was very difficult to implement a large-capacity OXC optical switch fabric.

Furthermore, since the optical switch fabric in the conventional OXC structure has to have a capacity of (N x m) x (N x m), there is a problem in that a large amount of control is performed at a time.

In order to solve the above problems, the present invention, using the optical switch fabric module that can share the wavelength converter for the conversion of the wavelength input and output in the local network and the band network and design a large-capacity fabric structure through the modularization of the optical switch fabric The purpose is to provide a large capacity optical cross-link switching system.

In addition, the present invention is a large-capacity optical bridge using an optical switch fabric module that can ensure the capacity increase, separation of function and performance improvement by configuring a large capacity optical switch fabric (OSF) by arranging several optical switch fabric modules (OSFM) It is also an object to provide a differential switching system.

1 is a classification diagram of a conventional general optical crosslink (OXC).

2 to 4 are structural diagrams illustrating embodiments of the OXC in the form of a combination of the conventional wavelength selective cross connect switch (WSXC) and the wavelength exchange cross connect switch (WIXC).

5 is a structural diagram of a conventional general OXC system.

Figure 6 is an embodiment of a large capacity optical cross-link (OXC) switch structure diagram according to the present invention.

FIG. 7 is an embodiment of an optical switch fabric module (OSFM) structure diagram using a variable wavelength converter in an optical cross-link switching system of the present invention.

FIG. 8 is an embodiment of a structure of an optical switch fabric module (OSFM) using a fixed wavelength converter in an optical cross-link switching system of the present invention.

Explanation of symbols on the main parts of the drawings

600: optical link 601: preamplifier

602: wavelength division demultiplexer 606: optical switch fabric module (OSFM)

612: wavelength division multiplexer 615: post amplifier

709,711,809 MEMS switch 710 Variable wavelength converter

810: Fixed Wavelength Converter

In order to achieve the above object, the present invention comprises a plurality of independent optical switch fabric module having a plurality of input and output ports and connected between the wavelength division demultiplexer and the wavelength division multiplexer for switching signals and optical in the local network. In the large-capacity optical cross-linking switching system using an optical switch fabric module for combining and branching signals, the optical switch fabric module,

An optical switch fabric for switching a plurality of optical wavelengths transmitted to an input port to a desired output port according to a wavelength conversion requirement for each wavelength;

First switching means for receiving a wavelength required for wavelength conversion switched by the optical switch fabric as an input port and switching to an output port;

Wavelength converting means for converting the wavelength required for the wavelength conversion switched by the first switching means into a desired wavelength; And

And a second switching means for switching in order to send the wavelength converted by the wavelength conversion means to a desired input port of the optical switch fabric.

The present invention has a structure capable of constructing an optical switch fabric required for a large-capacity OXC with a small-capacity optical switch, and an OXC system that can share a wavelength converter for wavelength conversion of optical wavelengths coming from the NNI for wavelength conversion of optical wavelengths coming from the UNI. As for the structure of the optical switch fabric structure of the OXC system in the form of a combination of WSXC and WIXC proposed to configure the optical switch fabric in a modular unit. In addition, the unit optical switch module that needs to convert the wavelength has a loop back structure, so that the wavelength when the add / drop wavelengths input / output through the local network user network interface (UNI) need to convert the wavelength. Without using a separate converter, the wavelength converter for the wavelengths input from the NNI can be shared. This enables unified control of wavelength converters, and the modular optical switch fabric structure increases the flexibility of traffic handling and internal structure changes in the system, while increasing scalability and modularity. Guaranteed.

In addition, through modularization, parallel algorithms for switching routing of traffic can be used, resulting in shortening of switching time and insertion and removal of a unit optical switch fabric module by module without affecting other modules even during network operation. Will be.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail the present invention.

6 is an embodiment of a high-capacity optical cross-link (OXC) switching system structure diagram according to the present invention. As shown in FIG. 6, a signal input to an optical link (optical fiber) 600 having m wavelengths may be smoothly switched in the OXC 664 switching system by the photoelectric amplifier 606. The amplified signal is amplified by the signal strength to separate the optical wavelength multiplexed on the optical fiber in optical DMUX (602). In FIG. 6, reference numerals 603 to 605 denote groups in which wavelengths are grouped so that separated wavelengths are input to each optical switch fabric module (hereinafter referred to as OSFM) 606. In the OSFM, the wavelength is switched without wavelength conversion or switched by wavelength conversion. In addition, reference numeral 607 in FIG. 6 denotes an add port for an optical signal entering through a user network interface (UNI) in a local network, and reference numeral 608 denotes a drop port for entering the local network. will be. The optical signals switched by the respective OSFMs 606 are grouped by the wavelengths 609 to 611 to be input to the corresponding optical muxes 612 and multiplex the plurality of optical wavelengths into optical fibers. Wavelengths in the optical multiplexer 612 are multiplexed and enter a post-amplifier 615 through an optical link 663. In the post amplifier 615, the signal output from the OXC system is amplified to a certain level so that long distance transmission is not interrupted and then output from the OXC system. Here, the Optical Switch Fabric (hereinafter referred to as OSF) 614 of the OXC system is a collection of OSFMs 606 composed of a plurality. Although not shown in the figure, the switching of wavelengths for which wavelength conversion is not required or required is controlled by a controller. In addition, the controller not shown controls the operation and overall operation of each component according to the present invention.

FIG. 7 is an embodiment of a structure of one optical switch fabric module (OSFM) using a tunable wavelength converter in an optical cross-link switching system of the present invention. As shown in FIG. 7, the OSFM 700 according to the present invention includes a switch fabric 704 composed of a space division switch, a micro-electromechanical systems (MEMS) optical switch (709,711), and the MEMS optical switch (709,711). It includes a wavelength converter 710 installed between. Here, the MEMS optical switch shown in FIG. 7 shows one embodiment and may use another optical switch having the same function. In addition, the switch fabric 204 may have a switch fabric structure such as lambda-plane and cross with the MEMS optical switch.

The structure according to the embodiment of the OSFM 700 shown in FIG. 7 has a hybrid form in which WSXC / WIXC is combined, and has a symmetrical form. The number of links is N and one link has m wavelengths, and the wavelengths are grouped and grouped into v wavelengths in order from wavelength 6 to wavelength m.

In addition, the number of wavelengths input to the OSFM 700 from the UNI associated with the local network is k. For example, assuming that the OSFM 700 is composed of a λ-plane that switches by separating wavelength units using a MEMS switch as in the above example, the number of wavelengths v of MEMS switches in a bundle is required. . The number of input and output ports of one MEMS switch 709 or 711 is shown in Equation 1 below.

[Equation 1]

Number of input ports = , Number of output ports =

Here, the number of wavelengths that are switched and output by the MEMS switch 711.

The number of input and output ports of the MEMS switch 709 located in front of the wavelength converter 710 is shown in Equation 2 below.

[Formula 2]

Number of input ports = p, number of output ports = q

Where q is the number of wavelength converters 710 and q?

In addition, the number of input and output ports of the MEMS switch 711 located at the rear end of the wavelength converter 710 is expressed by Equation 3 below.

[Equation 3]

Number of input ports = q, number of output ports = p.

When the OSFM 700 is configured using the MEMS switches 709 and 711 having the number of input / output ports as described above, and the OSF is configured by arranging several OSFMs 700, the WSXC / WIXC hybrid OXC according to the present invention is formed. do.

Hereinafter, the switching process in the OSFM 700 will be described. N grouped wavelengths, grouped 701 through 703 by grouping v wavelengths on different links, are input into the switch fabric 704 and switched. If the wavelength is not required after switching in the switch fabric 704, the wavelength is output through the paths of the wavelength bundles 705 to 707.

However, if wavelength conversion is required, it switches to the path 708 from the switch fabric 704 to the MEMS switch 709 to perform a loop back. Subsequently, the MEMS switch 709 receives the wavelength input through the path 708 and switches the received wavelength to the wavelength converter 710 which is not currently used. The wavelength converter 710 receives an arbitrary wavelength and converts the wavelength into a desired wavelength. After the wavelength conversion is performed, the switch is switched to the desired input port of the switch fabric 704 according to the converted wavelength in the MEMS switch 711 at the rear stage. As such, the path 712 of switching the wavelength converted by the MEMS switch 711 to the switch fabric 704 is switched in the switch fabric 704 to output to the desired output port of the OSFM 700. do.

Meanwhile, a set 713 of a predetermined number of wavelengths is input to the OSFM 700 through a UNI associated with a local network. When the input wavelengths 713 are not wavelength-converted, they are switched by the switch fabric 704 to be output to the paths 705 to 707 of the output ports. However, when the wavelengths 713 need to be wavelength-converted, the wavelength converter 710 is loop-backed through the path 708 to share the wavelength converter 710 which is already installed, without having to install an additional wavelength converter. do.

As described above, in the switch fabric 704, wavelengths that do not require wavelength conversion are switched to be directly output to the output port, and wavelengths that require wavelength conversion are switched to be output to the path 708 at the bottom. The wavelengths transmitted through the path 708 are switched from the MEMS switch 709 at the front end to any unused wavelength converter 710 and converted to the desired wavelength at the wavelength converter and desired at the subsequent MEMS switch 711. Switch to the input port of the switch fabric 704. In addition, when the combined / branched wavelengths inputted and outputted through the UNI of the local network to convert the wavelength is used to share the wavelength converter 710, there is no need to install a separate wavelength converter for this.

As such, the switch fabric 704, the MEMS switch 709, 711, and the wavelength converter 710 are configured as one module and implemented as an OSFM. The modular OSFM ensures capacity and separation of functions, and parallels the OSFM in parallel. By implementing the OXC in a list, it has many advantages such as easy insertion and removal by module.

Unexplained reference numeral 714 denotes a port in which incoming and outgoing wavelengths from the NNI are switched in the switch fabric 704 and branched off through the UNI.

FIG. 8 is an embodiment of a structure of one optical switch fabric module (OSFM) using a fixed wavelength converter in an optical cross-link switching system of the present invention. Although FIG. 8 has the same structure and operation as that of FIG. 7, in FIG. 8, a fixed wavelength converter 810 is used to take an arbitrary wavelength and convert the wavelength into a fixed wavelength along each path. There is no need for an additional switch, such as a MEMS switch 711 located at the rear of 710, and is just entered into the switch fabric 804 directly along the path 813. In particular, the fixed wavelength converter 810 as shown in FIG. 8 may be additionally inserted into the structure of FIG. 7. As a result, the optical switch fabric 704 switches the wavelength required for wavelength conversion to a wavelength converter at the bottom, and converts the wavelength to a desired wavelength through a variable wavelength converter or a fixed wavelength converter installed at the bottom, and according to each path, an optical switch fabric. Will enter the desired input port.

As described above, for example, OSFM can be created using small 8x8, 16x16, 32x32 MEMS switches and modularized to implement a large-capacity OXC optical switch fabric, and also because the optical switch is small, low-cost In addition, the insertion loss per unit switch is small. In addition, each OSFM can share a wavelength converter, resulting in lower cost and no additional control.

In the modular optical switch fabric structure as described above, when an OSFM module has an error such as inoperability, there is a spare OSFM that is not in use. After resetting to the redundant OSFM, the failed OSFM can be removed and a new OSFM can be inserted.

The configuration of the optical switch fabric, MEMS switch, wavelength converter, and the like used in the present invention need not be limited in number or wavelength to be applied depending on the applied system. In the above detailed description, the wavelength converter of the present invention is applied to the OSFM, but in practice, the wavelength converter of the present invention is applicable not only to the optical line distribution system but also to any device for converting the wavelength of the optical signal. In addition, the detailed description and drawings of the present invention disclose only preferred examples for describing the present invention, and do not limit the scope of the present invention, and those skilled in the art to which the present invention pertains. Changes, substitutions, or modifications can be made easily without departing from the technical spirit. Accordingly, the scope of the present invention should be determined by the appended claims rather than by the foregoing description.

As described above, the present invention has the following effects.

First, the modular optical switch fabric ensures modularity so that the OSFM can be easily inserted or removed even during network operation.

Second, the number of links and wavelengths inserted / extracted from the input / output terminals connected to the local network and the band network can be easily changed.

Third, the wavelength converter can share the wavelength converter for the wavelength conversion of the wavelength input and output in the local network.

Fifth, internal shape changes do not affect the network to which the OXC is connected.

Sixth, it is easy to adapt to the change in the number of links and the number of wavelengths connecting the networks.

Seventh, the modularization of the optical switch fabric enables the use of parallel algorithms for traffic switching routing, resulting in shorter switching times and improved switching speeds.

Claims (12)

An optical switch that has a plurality of input / output ports and is composed of a plurality of independent optical switch fabric modules connected between a wavelength division demultiplexer and a wavelength division multiplexer to switch signals, and combines and branches optical signals in a local network. In the large-capacity optical cross-linking switching system using a fabric module, the optical switch fabric module, An optical switch fabric for switching a plurality of optical wavelengths transmitted to an input port to a desired output port according to a wavelength conversion requirement for each wavelength; First switching means for receiving a wavelength required for wavelength conversion switched by the optical switch fabric as an input port and switching to an output port; Wavelength conversion means for receiving a wavelength required for wavelength conversion switched by the first switching means and converting the wavelength to a desired wavelength; And Large-capacity optical cross-linking using an optical switch fabric module comprising a second switch means for switching to send the wavelength converted by the wavelength conversion means to a desired input port of the optical switch fabric Switching system. The method of claim 1, wherein the wavelength conversion means, Large-capacity optical cross-linking switching system using an optical switch fabric module, characterized in that for converting the wavelength of the wavelength conversion is required to convert the wavelength of the desired variable. The method of claim 1 or 2, wherein the wavelength conversion means, A large-capacity optical cross-linking switching system using an optical switch fabric module, characterized in that the transponder to perform the optical / all / optical wavelength conversion using a variable laser diode. The method of claim 1, wherein the first switching means, A large-capacity optical cross-linking switching system using an optical switch fabric module, characterized in that for receiving the wavelength conversion is required to switch to the wavelength conversion means that is not in use. The method of claim 1, Third switching means for receiving a wavelength required for wavelength conversion switched by the optical switch fabric as an input port and switching to an output port; And High-capacity optical crossover using an optical switch fabric module, characterized in that it further comprises a high wavelength conversion means for receiving the wavelength converted by the third switching means is converted to a fixed wavelength according to each path. Connection switching system. The method of claim 5, wherein the third switching means, A large-capacity optical cross-linking switching system using an optical switch fabric module, characterized in that for receiving the wavelength conversion is required to switch to the fixed wavelength conversion means that is not in use. The method of claim 5, wherein the fixed wavelength conversion means, A large-capacity optical cross-linking switching system using an optical switch fabric module, characterized in that the transponder to perform the optical / all / optical wavelength conversion using a fixed laser diode. The method of claim 1, A large-capacity optical cross-linking switching system using an optical switch fabric module, characterized in that a plurality of optical switch fabric modules, each of which is independent, in parallel to form a single optical switch fabric. The method of claim 1, Large-capacity optical cross-link switching system using an optical switch fabric module, characterized in that the switch can be switched in the form of wavelength selective cross-link (WSXC), wavelength switched cross-link (WIXC) or WSXC / WIXC hydro. The method of claim 1, A high-capacity optical cross-linking switching system using an optical switch fabric module, characterized in that switching the input wavelength through the user network interface (UNI) of the local network. The method according to claim 1 or 10, Large-capacity optical bridge using the optical switch fabric module characterized in that the wavelength conversion means for converting the wavelength required to convert / add (drop / drop) with the local network through the user network interface (UNI) through the wavelength conversion means Differential switching system. The method of claim 1, Large-capacity optical cross-linking switching system using an optical switch fabric module characterized in that the OSF can be extended by sequentially listing the OSFM when the wavelength is further increased.