Abstract:
Disclosed is an optical communication line monitoring apparatus comprising: an optical transceiver for transmitting management frames to remote devices connected to optical communication lines and receiving response frames transmitted from the remote devices; an optical time domain reflectometer (OTDR) for transmitting optical pulse signals to the optical communication lines and detecting reflection signals reflected from the optical communication lines, which have received the optical pulse signals; an optical switch for switching the optical transceiver and the OTDR at an input terminal thereof and switching each of multiple optical communication lines at an output terminal thereof; and a monitoring unit for determining whether or not a first optical communication line is abnormal based on a response frame transmitted from a first remote device, with the input terminal connected to the optical transceiver and the output terminal connected to the first optical communication line among the multiple optical communication lines.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a National Stage of International Application No. PCT/KR2014/005774, filed Jun. 27, 2014, and claims priority from Korean Patent Applications No. 10-2014-0080212 filed Jun. 27, 2014, the contents of which are incorporated herein by reference in their entireties. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates to an apparatus and a method of monitoring optical communication lines, and more particularly, to an apparatus and a method of monitoring optical communication lines by a polling method. 
         [0004]    2. Description of Related Art 
         [0005]    Optical communication is a communication method of transmitting and receiving information through optical fiber made of dual glazing using total reflection of laser beam. The optical communication does not interfere with external electromagnetic waves, is difficult to eavesdrop, and may process a large amount of information at the same time as compared with electric communication. 
         [0006]    Various methods for monitoring the occurrence of an abnormality in an optical communication line have been used.  FIG. 1  shows a method of monitoring an abnormality of an optical communication line  13  by using an optical time domain reflectometer (OTDR)  11 . 
         [0007]    A small amount of loss occurs due to Rayleigh scattering while light is transmitted through the optical communication line  13 , and some of them are backscatter generated toward a light source. The OTDR  11  measures the backscattering power that is continuously reflected and measures a loss value generated on the optical communication line  13 . However, the OTDR  11  can only measure the loss of one optical communication line  13  at a time. In order to measure another optical communication line, it is necessary to stop the communication through a currently used optical communication line  13  and connect the OTDR  11  to another optical communication line. 
         [0008]    As another method of monitoring whether or not an optical communication line is abnormal,  FIG. 2  shows a method of monitoring an abnormality of an optical communication line using a SuperVisory (SV) channel. The method of monitoring an abnormality of an optical communication line using the SV channel is based on the assumption that the SV channel is always connected to the optical communication line and there is a problem that a plurality of SVUs corresponding to SVUs located at respective remote locations must be located in a central office. 
         [0009]    Therefore, there is a need for a method of effectively monitoring the occurrence of an abnormality of an optical communication line while overcoming the problems of the conventional art described above. 
       SUMMARY 
       [0010]    An apparatus and a method of monitoring optical communication lines according to an example embodiment of the present invention relate to effectively monitoring multiple optical communication lines with a small image area and low cost by combining an OTDR and an SVU through an optical switch. 
         [0011]    Furthermore, an apparatus and a method of monitoring optical communication lines according to an example embodiment of the present invention relate to monitoring whether or not an optical communication line is abnormal without being directly input to a site by an administrator. 
         [0012]    According to an example embodiment of the present invention, there is provided an optical communication line monitoring apparatus, including: an optical transceiver for transmitting management frames to remote devices connected to optical communication lines and receiving response frames transmitted from the remote devices; an optical time domain reflectometer (OTDR) for transmitting optical pulse signals to the optical communication lines and detecting reflection signals reflected from the optical communication lines, which have received the optical pulse signals; an optical switch for switching the optical transceiver and the OTDR at an input terminal thereof and switching each of multiple optical communication lines at an output terminal thereof; and a monitoring unit for determining whether or not a first optical communication line is abnormal based on a response frame transmitted from a first remote device, with the input terminal connected to the optical transceiver and the output terminal connected to the first optical communication line among the multiple optical communication lines. 
         [0013]    The monitoring unit may measure the degree of loss in the first optical communication line based on a reflection signal reflected from the first optical communication line after connecting the input terminal of the optical switch with the OTDR when it is determined that an abnormality has occurred in the first optical communication line. 
         [0014]    The optical switch may connect the output terminal to a second optical communication line instead of the first optical communication line when it is determined that no abnormality has occurred in the first optical communication line. 
         [0015]    The monitoring unit may control a switching operation of the optical switch so that the output terminal of the optical switch is sequentially connected to each of the multiple optical communication lines at predetermined time intervals. 
         [0016]    The monitoring unit may generate the management frames according to a fast ethernet protocol. 
         [0017]    According to another example embodiment of the present invention, there is provided a method of monitoring optical communication lines, including: transmitting management frames to a first remote device connected to a first optical communication line using an optical transceiver when an input terminal of an optical switch is connected to the optical transceiver and an output of the optical switch is connected to the first optical communication line among multiple optical communication lines, wherein the optical switch switches the optical transceiver and an optical time domain reflectometer (OTDR) at the input terminal thereof and switches each of the multiple optical communication lines at the output terminal thereof; receiving a response frame transmitted from the first remote device through the optical transceiver; and determining whether or not the first optical communication line is abnormal based on the received response frame. 
         [0018]    The method of monitoring optical communication lines may further include measuring the degree of loss in the first optical communication line based on a reflection signal reflected from the first optical communication line after connecting the input terminal of the optical switch with the OTDR when it is determined that an abnormality has occurred in the first optical communication line. 
         [0019]    The method of monitoring optical communication lines may further include connecting the output terminal to a second optical communication line instead of the first optical communication line when it is determined that no abnormality has occurred in the first optical communication line. 
         [0020]    The method of monitoring optical communication lines may further include controlling a switching operation of the optical switch so that the output terminal of the optical switch is sequentially connected to each of the multiple optical communication lines at predetermined time intervals. 
         [0021]    The method of monitoring optical communication lines may further include generating the management frames according to a fast ethernet protocol. 
         [0022]    An apparatus and a method of monitoring optical communication lines according to an example embodiment of the present invention may effectively monitor multiple optical communication lines with a small image area and low cost by combining an OTDR and an SVU through an optical switch. 
         [0023]    Furthermore, an apparatus and a method of monitoring optical communication lines according to an example embodiment of the present invention may monitor whether or not an optical communication line is abnormal without being directly input to a site by an administrator. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0024]    Example embodiments of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0025]      FIG. 1  is a view illustrating a method of monitoring an abnormality of an optical communication line using a general optical time domain reflectometer (OTDR). 
           [0026]      FIG. 2  is a view illustrating a method of monitoring an abnormality of an optical communication line using a general SuperVisory (SV) channel. 
           [0027]      FIG. 3  is a view illustrating a configuration of an optical communication line monitoring apparatus according to an example embodiment of the present invention. 
           [0028]      FIG. 4  is a view illustrating a procedure of a method of monitoring optical communication lines according to another example embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0029]    Since the present invention may have diverse modified embodiments, preferred embodiments are illustrated in the drawings and are described in the detailed description. However, this does not limit the present invention within specific embodiments and it should be understood that the present invention covers all the modifications, equivalents, and replacements within the idea and technical scope of the present invention. 
         [0030]    In the description of the present invention, certain detailed explanations of the related art are omitted when it is deemed that they may unnecessarily obscure the essence of the present invention. In addition, numeral figures (for example, 1, 2, and the like) used during describing the specification are just identification symbols for distinguishing one element from another element. 
         [0031]    Further, in the specification, if it is described that one component is “connected” or “accesses” the other component, it is understood that the one component may be directly connected to or may directly access the other component but unless explicitly described to the contrary, another component may be “connected” or “access” between the components. 
         [0032]    In addition, terms such as “ . . . unit”, “ . . . module”, or the like refer to units that perform at least one function or operation, and the units may be implemented as hardware or software or as a combination of hardware and software. 
         [0033]    Furthermore, components of the specification are divided in accordance with a main function of each component. That is, two or more components to be described below may be provided to be combined to one component or one component may be provided to be divided into two or more components for each more subdivided function. In addition, each of the respective components to be described below may additionally perform some or all functions among functions which other components take charge of in addition to a primary function which each component takes charge of and some functions among the primary functions which the respective components take charge of are exclusively charged by other components to be performed, of course. 
         [0034]    Hereinafter, example embodiments of the present invention will be described in detail. 
         [0035]      FIG. 3  is a view illustrating a configuration of an optical communication line monitoring apparatus  300  according to an example embodiment of the present invention. 
         [0036]    In a configuration for optical communication, each of multiple optical communication lines  360  is connected to a light source  350  corresponding to each of the multiple optical communication lines  360 . Each of the multiple optical communication lines  360  may be connected to a remote location  370  corresponding to each of the optical communication lines  360 . The light source  350  may provide an optical signal for a mobile communication service, and the multiple optical communication lines  360  may provide a communication path for an optical signal transmitted from the light source  350 . The remote location  370  may receive optical signals transmitted from each of the multiple optical communication lines  360 . 
         [0037]    An optical multiplexer/demultiplexer may be connected to both ends of each of the multiple optical communication lines  360 . The optical multiplexer/demultiplexer may multiplex an optical signal or demultiplex the multiplexed optical signal. 
         [0038]    Referring to  FIG. 3 , the optical line monitoring apparatus  300  according to an example embodiment of the present invention may include an optical switch  310 , an optical transceiver  320 , an OTDR  330 , and a monitoring unit  340 . 
         [0039]    The optical switch  310 , which is a 2×N type switch, may switch the optical transceiver  320  and the OTDR  330  at an input terminal  312  thereof and switch each of the multiple optical communication lines  360  at an output terminal  314  thereof. In more detail, the input terminal  312  of the optical switch  310  may be selectively connected to the optical transceiver  320  or the OTDR  330  and the output terminal  314  of the optical switch  310  may be connected to any one of the multiple optical communication lines  360 . 
         [0040]    The optical transceiver  320  may transmit the management frame to a remote device connected to an optical communication line through the optical communication line and receive a response frame transmitted from the remote device. The optical transceiver  320  may transmit the response frame to the monitoring unit  340 . 
         [0041]    The OTDR  330  may transmit an optical pulse signal to an optical communication line and detect a reflection signal reflected from the optical communication line. 
         [0042]    The monitoring unit  340  may control the optical transceiver  320 , the OTDR  330 , and the optical switch  310  to determine whether or not an abnormality has occurred in each of the multiple optical communication lines  360 . 
         [0043]    The monitoring unit  340  may generate a management frame for monitoring optical communication lines. The monitoring unit  340  may generate the management frame according to a predetermined communication protocol, and the predetermined communication protocol may include, for example, a fast ethernet protocol. The monitoring unit  340  may use a physical layer and medium access control layer standards as a basic transmission protocol. 
         [0044]    The monitoring unit  340  may control the optical switch  310  so that the input terminal  312  of the optical switch  310  is connected to the optical transceiver  320  and the output terminal  314  of the optical switch  310  may be connected to any one (for example, a first optical communication line  362 ) of the multiple optical communication lines  360 . The monitoring unit  340  may transmit a management frame to the optical transceiver  320  so that the management frame is transmitted to a first remote device  372  connected to the first optical communication line  362  by the optical transceiver  320 . 
         [0045]    When the first remote device  372  transmits a response frame to the optical transceiver  320  in response to the management frame, the optical transceiver  320  transfers the response frame to the monitoring unit  340 . The monitoring unit  340  may determine whether the first optical communication line  362  is abnormal based on loss information of the response frame, received optical power, and the like. 
         [0046]    When it is determined that no abnormality has occurred in the first optical communication line  362  based on the response frame transmitted from the first remote device  372 , the monitoring unit  340  may connect the output terminal  314  of the optical switch  310  to another optical communication line (for example, a second optical communication line  364 ) instead of the first optical communication line  362  to monitor whether or not an abnormality has occurred in another optical communication line. In other words, when it is determined that no abnormality has occurred in any of the multiple optical communication lines  360 , the monitoring unit  340  may control a switching operation of the output terminal  314  of the optical switch  310 , and thus, may automatically determine whether or not all of the optical communication lines  360  are abnormal. To this end, the monitoring unit  340  may control a switching operation of the optical switch  310  so that the output terminal  314  of the optical switch  310  is sequentially connected to each of the multiple optical communication lines  360  at predetermined time intervals. For example, the monitoring unit  340  sequentially connects the output terminal  314  thereof to first through nth optical communication lines for a predetermined time interval to automatically monitor whether or not an abnormality has occurred in the first through nth optical communication lines. 
         [0047]    When it is determined that an abnormality has occurred in the first optical communication line  362  based on the response frame transmitted from the first remote device  372 , the monitoring unit  340  may stop switching of the output terminal  314  of the optical switch  310  and may connect the input terminal  312  of the optical switch  310  to the OTDR  330  to measure the degree of loss in the first optical communication line  362 . When the input terminal  312  of the optical switch  310  is connected to the OTDR  330 , the OTDR  330  may transmit an optical pulse signal to the first optical communication line  362  and may detect a reflection signal reflected from the first optical communication line  362 . The monitoring unit  340  may measure the degree of loss in the first optical communication line  362  based on the reflection signal reflected from the first optical communication line  362 . The monitoring unit  340  may measure the degree of loss in the first optical communication line  362  and specify the position where the abnormality has occurred in the first optical communication line  362 . The monitoring unit  340  may transmit information indicating that an abnormality has occurred in the first optical communication line  362  and information indicating the position where the abnormality has occurred in the first optical communication line  362  to an administrator terminal. 
         [0048]    When the loss of the first optical communication line  362  is measured, the monitoring unit  340  may connect the input terminal  312  of the optical switch  310  to the optical transceiver  320  and the output terminal  314  of the optical switch  310  to the second optical communication line  364 . In addition, the monitoring unit  340  may determine whether the second optical communication line  364  is abnormal based on a response frame transmitted from a second remote device  374  connected to the second optical communication line  364 . 
         [0049]    Since the optical communication line monitoring apparatus  300  according to an example embodiment of the present invention performs both monitoring using the OTDR  330  and monitoring using the SV channel by using the optical switch  310 , it is possible to monitor an abnormality of an optical communication line more effectively than a general monitoring method. 
         [0050]      FIG. 4  is a view illustrating a procedure of a method of monitoring optical communication lines according to another example embodiment of the present invention. Referring to  FIG. 4 , the method of monitoring optical communication lines according to another example embodiment of the present invention includes operations of time series processing in the optical communication line monitoring apparatus  300  of  FIG. 3 . Therefore, even if the descriptions are omitted below, it will be understood that the contents described above with respect to the optical communication line monitoring apparatus  300  of  FIG. 3  are also applied to the method of monitoring optical communication lines of  FIG. 4 . 
         [0051]    In operation S 410 , the monitoring unit  340  transmits a management frame to the first remote device  372  connected to the first optical communication line  362  through the optical transceiver  320  and the first optical communication line  362  when the optical transceiver  320  and the OTDR  330  are switched at the input terminal  312 , the input terminal  312  of the optical switch  310  for switching each of the multiple optical communication lines  360  at the output terminal  314  is connected to the optical transceiver  320 , and the output terminal  314  is connected to the first optical communication line  362  from among the multiple optical communication lines  360 . The monitoring unit  340  may generate a management frame according to a predetermined communication protocol, and the predetermined communication protocol may include a fast ethernet communication protocol. 
         [0052]    In operation S 420 , the monitoring unit  340  receives a response frame transmitted from the first remote device  372  through the optical transceiver  320 . The first remote device  372  may generate a response frame in accordance with a predetermined communication protocol and transmit it to the optical transceiver  320  via the first optical communication line  362 . 
         [0053]    In operation S 430 , the monitoring unit  340  determines whether an abnormality has occurred in the first optical communication line  362  based on the response frame. The monitoring unit  340  may determine whether the first optical communication line  362  is abnormal based on loss information of the response frame, received optical power, and the like. A method of determining whether an optical communication line is abnormal based on a response frame in an SV channel is obvious to those of ordinary skilled in the art, and a detailed description thereof will not be given herein. 
         [0054]    In operation S 440 , the monitoring unit  340  connects the input terminal  312  of the optical switch  310  to the OTDR  330  when it is determined that an abnormality has occurred in the first optical communication line  362 . The input terminal  312  of the optical switch  310  is connected to the OTDR  330  so that the OTDR  330  and the first optical communication line  362  are connected to each other and the connection between the optical transceiver  320  and the first optical communication line  362  will be blocked. 
         [0055]    In operation S 450 , the monitoring unit  340  measures the degree of loss in the first optical communication line  362  based on a reflection signal reflected from the first optical communication line  362  in response to an optical pulse signal transmitted from the OTDR  330  to the first optical communication line  362 . The monitoring unit  340  may transmit information indicating that an abnormality has occurred in the first optical communication line  362  and information indicating the position where the abnormality has occurred in the first optical communication line  362  to an administrator terminal. 
         [0056]    In operation S 460 , when it is determined that no abnormality has occurred in the first optical communication line  362  based on the response frame transmitted from the first remote device  372 , the monitoring unit  340  may connect the output terminal  314  of the optical switch  310  to the second optical communication line  364  instead of the first optical communication line  362  to determine whether or not an abnormality has occurred in the second optical communication line  364 . 
         [0057]    The monitoring unit  340  may sequentially connect the output terminal  314  of the optical switch  310  to each of the multiple optical communication lines  360  at predetermined time intervals. The connection order for each of the multiple optical communication lines  360  may be preset. 
         [0058]    The example embodiments of the present invention can be written as computer programs and can be implemented in general-use digital computers that execute the programs using a computer readable recording medium. 
         [0059]    The computer readable recording medium may be a magnetic storage medium (e.g., a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (e.g., a CD ROM, a DVD or the like), and a carrier wave (e.g., transmission over the Internet). 
         [0060]    While the present invention has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the following claims.