Patent Application
20080075461
The above-described WDM PON system, which was proposed in previously filed Korean Pat. Appl. No. 2003-98904, employs a single CO, and does not employ a redundant structure so as to substitute for a CO and assume the control of the CO when a problem occurs in the CO, so that a problem occurs in that the system is downed.
Therefore, the inventor of the present invention carried out research into a WDM PON system having a dual CO that guarantees system stability by employing a plurality of COs on a ring type optical communication line and, therefore, allowing another CO to assume control when a problem occurs in one CO.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a WDM PON system having a dual CO, in which system stability can be guaranteed by employing a plurality of COs on a ring type optical communication line and, therefore, allowing another CO to assume control when a problem occurs in one CO.
Another object of the present invention is to provide a WDM PON system having a dual CO, which can appropriately compensate for various types of loss caused by various environmental factors, such as insertion loss caused by interfacing various devices with a ring type optical communication line and loss caused by the degradation of an optical cable.
A WDM PON system having a dual CO according to the present invention has advantages in that system stability can be guaranteed by employing a plurality of COs on a ring type optical communication line and, therefore, allowing another CO to assume control when a problem occurs in one CO, and in that various types of loss caused by various environmental factors, such as insertion loss caused by interfacing various devices with a ring type optical communication line and loss caused by the degradation of an optical cable, can be appropriately compensated for.
In order to accomplish the above objects, the present invention provides Wavelength Division Multiplexing (WDM) Passive Optical Network (PON) system having a dual Central Office (CO), including a ring type optical communication line; a CO including a plurality of optical transmission units for generating optical signals having different wavelengths, a plurality of optical reception units for forming pairs with respective optical transmission units, receiving optical signals having the same wavelengths as the corresponding optical transmission units, converting the received optical signals into electrical signals and then outputting the converted electrical signals, a multiplexer/demultiplexer for multiplexing input optical signals having different wavelengths and then outputting a multiplexed optical signal to the optical communication line, and demultiplexing a multiplexed optical signal input through the optical communication line and then outputting demultiplexed optical signals, and a plurality of optical circulators for outputting an optical signal, output from an assigned optical transmission unit, to the multiplexer/demultiplexer, and outputting input optical signals, demultiplexed by the multiplexer/demultiplexer, to the assigned optical transmission unit; and at least one remote node having an optical add/drop multiplexer for dropping only signals having wavelengths in a specific band, from optical signals transmitted through the optical communication line and outputting to a subscriber side, and outputting optical signals transmitted from the subscriber side to the optical communication line, and an optical circulator for outputting the optical signals, dropped by the optical add/drop multiplexer, to the optical reception units of subscribers' devices, and outputting the optical signals, received from the optical transmission units of the subscribers' devices, to the optical add/drop multiplexer; the WDM PON system comprising: a plurality of COs; a first connection unit having a connection of an odd number of 1×2 couplers, the one side branched ends of one of which are alternately connected to one side branched ends of another 1×2 coupler, and which divide and transmit multiplexing signals, output from multiplexer/demultiplexers of the plurality of COs, and input signals, transmitted through branched paths, to the multiplexer/demultiplexers; a second connection unit having n signal compensation units, whose number is identical to the number of the 1×2 couplers of the first connection unit, that are connected to the branched paths of the first connection unit and compensate the signals transmitted and received through the multiplexer/demultiplexers; and a third connection unit for connecting the signal compensation units with at least one ring type optical communication line, thereby allowing signals to be transmitted and received between the multiplexer/demultiplexers and the ring type optical communication line.
The present invention is described in detail below using preferred embodiments described with reference to the accompanying drawings so as to be easily understood and implemented by those skilled in the art.
The technical gist of a WDM PON system having a dual COs according to the present invention resides in being implemented by applying a plurality of COs to the WDM PON system proposed in Korean Pat. Appl. No. 2003-98904, previously filed by the applicant of the present invention, connecting a plurality of multiplexer/demultiplexers 230 with at least one optical communication line 100 using a first connection unit 410, a second connection unit 420 and a third connection unit 430 and, therefore, allowing another CO to assume control when a problem occurs in any one of the COs.
The first connection unit 410 includes a connection of an odd number of 1×2 couplers, the one side branched ends of one of which are alternately connected to the one side branched ends of another coupler, and which divide and transmit multiplexed signals, which are output from the multiplexer/demultiplexers of the plurality of the COs, and input signals, which are transmitted through branched paths, to the multiplexer/demultiplexers.
The second connection unit 420 includes n signal compensation units whose number is identical to the number of the 1×2 couplers of the first connection unit 410, and which are connected to the branched paths of the first connection unit 410, and compensate signals transmitted and received through the plurality of multiplexer/demultiplexers.
The signal compensation units are used to compensate for various types of loss caused by various environmental factors, such as insertion loss caused by interfacing various devices with an optical communication line and loss caused by the degradation of an optical cable, and detailed embodiments thereof are shown in
The signal compensation unit shown in
The first circulator allows signals output from the first connection unit 410 and signals input to the first connection unit 410 to be transmitted and received through different paths.
The second circulator allows signals output from the third connection unit 430 and signals input to the third connection unit 430 to be transmitted and received through different paths.
The amplifiers are installed on two respective paths between the first and second optical circulators in opposite directions, and amplify and compensate signals transmitted and received through the two paths.
Input and output paths are different due to the configuration of the optical circulators, so that signals output from the CO 200 are transmitted to the ring type optical communication line 100 through one of two paths formed by the first and second optical circulators, and signals input from the ring type optical communication line 100 are output to the CO 200 through the other one. Transmitted signals are amplified by the amplifiers installed on the two paths in opposite directions, so that various types of loss caused by various environmental factors, such as insertion loss caused by interfacing various devices with the optical communication line and loss caused by the degradation of an optical cable, are compensated for.
The signal compensation unit shown in
The 1×2 coupler divides and outputs a signal output from the first connection unit 410, and outputs signals, which are transmitted through branched paths, to the first connection unit 410.
The optical circulator allows signals output from the third connection unit 430 and signals input to the third connection unit 430 to be transmitted and received through different paths.
The amplifiers are installed on two respective paths between the 1×2 coupler and the optical circulator in opposite directions, and amplify and compensate signals transmitted and received through the two paths.
This configuration reduces the cost by using one optical circulator, unlike the example shown in
Input and output paths are different due to the configuration of the optical circulator, so that signals output from the CO 200 are transmitted to the ring type optical communication line 100 through one of two paths formed by the 1×2 coupler and the optical circulator, and signals input from the ring type optical communication line 100 are output to the CO 200 through the other one. Transmitted signals are amplified by the amplifiers installed on the two paths in opposite directions, so that various types of loss caused by various environmental factors, such as insertion loss caused by interfacing various devices with an optical communication line and loss caused by the degradation of an optical cable, are compensated for.
The signal compensation unit shown in
The optical circulator allows signals output from the first connection unit 410 and signals input to the first connection unit 410 to be transmitted and received through different paths.
The 1×2 coupler divides and output a signal output from the third connection unit 430, and outputs signals, which are transmitted through branched paths, to the third connection unit 430.
The amplifiers are installed on two respective paths between the optical circulator and the 1×2 coupler in opposite directions, and amplify and compensate signals transmitted and received through the two paths.
This configuration reduces the cost by using one optical circulator, as in the example shown in
Input and output paths are different due to the configuration of the optical circulator, so that signals output from the CO 200 are transmitted to the ring type optical communication line 100 through one of two paths formed by the optical circulator and the 1×2 coupler, and signals input from the ring type optical communication line 100 are output to the CO 200 through the other one. Transmitted signals are amplified by the amplifiers installed on the two paths in opposite directions, so that various types of loss caused by various environmental factors, such as insertion loss caused by interfacing various devices with an optical communication line and loss caused by the degradation of an optical cable, are compensated for.
The third connection unit 430 connects each of the signal compensation units of the second connection unit with at least one ring type communication line 100, so that signals are transmitted and received between the multiplexer/demultiplexers 230 and the ring type optical communication line 100.
With reference to
The WDM PON system having a dual CO according to the first embodiment of the present invention employs an n×2 coupler as the third connection unit 430.
The n×2 coupler is connected between the n signal compensation units of the second connection unit 420 and the single ring type optical communication line 100, outputs signals, which are output through the second connection unit 420, to the optical communication line 100, and output signals, which are input to the optical communication line 100, to the plurality of COs 200 via the second connection unit 420.
Accordingly, when a problem occurs in a currently used CO while signals are exchanged with the local nodes 300 through the ring type optical communication line 100 using any one of the plurality of COs, the signals are exchanged the local nodes 300 through the ring type optical communication line 100 using another CO, so that system stability can be guaranteed.
The WDM PON system having a dual CO according to the second embodiment of the present invention employs n 1×2 couplers as a second connection unit 420.
The n 1×2 couplers are configured such that the one side branched ends of one of the 1×2 couplers are alternately connected to the one side branched ends of another coupler, thus dividing a signal, which is received from a single ring type communication line 100, and then outputting the branched signals to the second connection unit 420, or outputting signals, which are transmitted from the n signal compensation units, to the single ring type communication line 100.
Accordingly, when a problem occurs in a currently used CO while signals are exchanged with the local nodes 300 through the ring type optical communication line 100 using any one of the plurality of COs, the signals are exchanged with the local nodes 300 through the ring type optical communication line 100 using another CO, so that system stability can be guaranteed.
The WDM PON system having a dual CO according to the third embodiment of the present invention is provided with n ring type optical communication lines 100 so as to accommodate a large number of subscribers, and employs n 1×2 couplers as a third connection unit 430.
The n 1×2 couplers are connected between the n signal compensation units of a second connection unit 420 and the n ring type communication lines 100, respectively, thus transmitting signals, which are output from the second connection unit 420, to the ring type optical communication lines 100, or outputting signals, which are input from ring type optical communication lines 100, to the second connection unit 420.
Accordingly, when a problem occurs in a currently used CO while signals are exchanged with the local nodes 300 through the ring type optical communication lines 100 using any one of the plurality of COs, the signals are exchanged with the local nodes 300 through the ring type optical communication line 100 using another CO, so that system stability can be guaranteed.
The WDM PON system having a dual CO according to the fourth embodiment of the present invention is provided with (n+1)/2 ring type optical communication lines 100 so as to accommodate a large number of subscribers, and employs a connection of (n−1)/2 1×2 couplers connected to the signal compensation units of a second connection unit 420 and (n+1)/2 2×2 couplers connected to (n+1)/2 ring type optical communication lines 100 as a third connection unit 430.
The (n+1)/2 1×2 couplers and the (n−1)/2 2×2 couplers are installed such that the one side branched ends of one of the couplers are alternately connected to the one side branched end of another coupler, thus allowing signals transmitted and received between the second connection unit 420 and (n+2)/2 ring type optical communication line 100 to be transmitted the paths connected thereby.
Accordingly, when a problem occurs in a currently used CO while signals are exchanged with the local nodes 300 through the ring type optical communication lines 100 using any one of the plurality of COs, the signals are exchanged with the local nodes 300 through the ring type optical communication lines 100 using another CO, so that system stability can be guaranteed.
Therefore, by doing so, the objects of the multi-ring type WDM PON system having a dual CO according to the present invention can be accomplished.
Although the present invention has been described with reference to the accompanying drawings with emphasis on the preferred embodiments, it is apparent to those skilled in the art that various modifications can be made based on the above description without departing from the scope of the present invention defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2004-0028756 | Apr 2004 | KR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/KR05/01162 | 4/22/2005 | WO | 00 | 11/30/2007 |
