KR101043099B1 - Method and Device for Providing Distance Information for MAC Ranging in TDM-PON, and TDM-PON System Therewith - Google Patents

Abstract

The present invention relates to a distance information providing method for MAC ranging in a time division passive optical communication network, a distance information providing apparatus, and a time division passive optical communication network system having the same. More specifically, in the case where a relay device is provided between an optical line terminal and a remote node of a time division passive optical network in order to extend the transmission distance, the central office terminal of the relay device and Distance information providing method, distance information providing device, and distance information for MAC ranging in time division passive optical communication network capable of automatically providing accurate distance information for MAC ranging by calculating distance between remote terminals One time division passive optical network system.

TDM-PON, passive optical network, MAC ranging, MAC, relay

Description

Method for providing distance information for MAC ranging in time division passive optical communication network, distance information providing device, and time division passive optical communication network system having same.Method and Device for Providing Distance Information for MAC Ranging in TDM-PON, and TDM-PON System Therewith}

The present invention relates to a distance information providing method for MAC ranging in a time division passive optical communication network, a distance information providing apparatus, and a time division passive optical communication network system having the same. More specifically, in the case where a relay device is provided between an optical line terminal and a remote node of a time division passive optical network in order to extend the transmission distance, the central office terminal of the relay device and Distance information providing method, distance information providing device, and distance information for MAC ranging in time division passive optical communication network capable of automatically providing accurate distance information for MAC ranging by calculating distance between remote terminals One time division passive optical network system.

FTTH (Fiber to the Home) refers to a technology that can provide high quality-based broadband communication services by installing optical communication lines to subscribers' homes. FTTH has been spotlighted as a Broadband Integrated Network (BcN) that can support wired / wireless integration, communication convergence, etc. due to the advantage of providing high speed data and multimedia information as well as voice calls through IP communication networks. Although ADSL, VDSL, and cable modem, which are used as general high speed internet network, speed 10 ~ 50Mbps, FTTH is stable at 100Mbps and maximum 1Gbps. In addition to speed, almost infinite information can be sent without transmission loss and there is little interference from electromagnetic waves. In particular, it is possible to fully enable TPS (Triple Play Service), which provides integrated telephone, internet, and broadcasting, which has attracted much attention recently.

In the implementation of an optical communication network for implementing FTTH, a passive optical network (PON) using a passive optical element is generally employed. Representative methods of a passive optical communication network include a time division multiple access (TDMA) method and a wavelength division multiple access (WDMA) method. The TDM-PON method has been mainly used until now, and the evolution to the WDM-PON is gradually being made.

The TDM-PON basically includes an optical line terminal (OLT), a remote node (RN), and an optical network terminal (ONT). The RN distributes the optical signals transmitted from the OLT into several optical signals and transmits them to the ONT, or performs the function of adding the various optical signals transmitted from the ONT. The RN in the TDM-PON does not require a power supply, so it is not affected by power defects, is insensitive to electromagnetic interference, and has low maintenance costs.

In TDM-PON, downstream data is composed of continuous cells in the form of broadcasting and is provided to all OLTs. Upstream data uses a time division multiplexing scheme in which ONT is occupied by occupying a predetermined time slot in burst mode. Therefore, when ONTs at different distances simultaneously transmit cells upward, there is a possibility that they overlap in the RN, which may cause the OLT to not detect the correct bit stream or cause cell loss.

In order to solve this problem, a technique is required to place ONUs virtually at the same distance, which is called MAC ranging because it is controlled by OLT's Media Access Control (MAC). The ranging protocol solves this problem by providing an equalization delay for each ONT. In other words, the ONT at close range transmits a cell with a long delay, and the ONT at long range transmits a cell with a short delay, so that it is logically at the same distance.

For this purpose, Mac ranging has the function to identify the exact location of each subscriber, and only the subscribers within 20km of distance can be identified. Therefore, in the TDM-PON technology, the logical transmission distance is limited to within 20 km. Therefore, the distance between the OLT and ONT should be within 20 km in any case.

However, as the FTTH network construction proceeds, the necessity of effectively accommodating subscribers outside the 20km range emerges, and a technology for extending the transmission distance by placing a relay between the OLT and the RN has been proposed.

1 is a block diagram showing the configuration of a time division passive optical communication network (TDM-PON) having a relay device. FIG. 1 illustrates a hybrid time division passive optical network (TDM-PON) in which a wavelength division multiplexing (WDM) method is combined with a relay device to accommodate a plurality of subscribers. In the basic TDM-PON structure, one optical transmitter of an OLT is set to transmit an optical signal of a TDM method. However, in order to accommodate a plurality of subscribers, an optical communication network combining a WDM scheme with a TDM-PON may be preferable. FIG. 1 illustrates a TDM-PON combining a WDM scheme.

Referring to FIG. 1, the TDM-PON includes an OLT 100, an RN 400, and an ONT 500, and a relay device for extending a transmission distance between the OLT 100 and the RN 400 is provided. Include. The relay device includes a Central Office Terminator (COT) 200 provided at a Central Office (CO) side and a Remote Terminator (RT, 300) provided at a remote site. The COT 200 is installed at or near the OLT 100 to perform a photoelectric conversion function. The RT 300 is installed in the branch station near the subscriber and optically connected to the RN 400, and similarly performs a photoelectric conversion function. In addition, as a method for accommodating a plurality of subscribers, the COT 200 further includes a function of multiplexing a plurality of TDM optical signals by the WDM scheme, and the RT 300 demultiplexes the optical signals multiplexed by the WDM scheme. It also includes a function to do.

However, in the above case, in order for the OLT 100 to perform MAC ranging for each ONT 500, the exact location of the RT 300 must be determined. If the RT (300) as the starting position is the same effect as the OLT (100) is placed on the branch station, so if you know the position of the RT (300) by using the RT (300) installed in the branch station as the start position Covering 20km of distance for Mac ranging. The reason for this is as follows. Referring to the photoelectric conversion in the RT (300), the optical signal transmitted from the OLT (100)-that is, the COT (200)-is received using the optical transmitter and receiver of the RT (300), converted into an electrical signal, and processed into a signal. Afterwards, it is transmitted as an optical signal. However, the component receiving the optical signal of the COT 200 at the RT 300 is the same as the optical transmitter of the ONT 500, and the component transmitting the optical signal from the RT 300 to the ONT 500 is the OLT 100. Is the same as the optical transmitter of. Therefore, if the RT (300) to the starting position is obtained as if the OLT (100) is located in the branch station, there is no problem in Mac ranging.

However, in order to determine the location of the RT, in the past, the operator grasps the geopolitical installation location of the RT in advance, or directly measures the distance and grasps the distance information and inputs it to the OLT. This method has a number of problems, such as the need to know the location of the RT, the operator has to measure the distance, and if there is a mobile installation of the RT, there can be confusion.

In order to solve the above problems, the present invention is to provide the relay station between the optical line terminal and the remote node (Remote Node) of the time division passive optical communication network for extending the transmission distance A method of providing distance information for MAC ranging in a time division passive optical communication network capable of automatically providing accurate distance information for MAC ranging by calculating a distance between a central office terminal and a remote terminal; An object of the present invention is to provide a distance information providing apparatus, and a time division passive optical communication network system having the same.

In order to achieve the above object, the present invention provides a method for providing MAC ranging distance information of a time division passive optical communication network having a relay device, the method comprising: (a) a distance between a central office terminal (COT) and a remote terminal (RT) of a relay device; Generating a measurement signal for measuring information and transmitting it through an optical path between the COT and the RT; (b) receiving a reflected signal for the transmitted measurement signal; (c) calculating distance information between the COT and the RT by using a difference between a transmission time of the measurement signal and a reception time of the reflection signal; And (d) storing the calculated distance information in a distance information database according to a PON ID for identifying a PON interface of an optical line terminal (OLT) and a COT ID for identifying the COT.

Preferably, the measurement signal includes pattern information indicating that the signal for measuring the distance information.

In one embodiment, in the step (a), the measurement signal is characterized in that the transmission through the COT optical transmission and reception of the COT.

In another embodiment, the step (a) and the step (b) is characterized in that the optical time domain reflectormetry (OTDR) method for the optical path connecting the COT and the RT.

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Meanwhile, when the OLT is provided with at least two PON interfaces sharing the COT, when the distance information of any one PON interface is stored in the distance information database, another PON interface may share the distance information. have.

Preferably, in the method of providing MAC ranging distance information of a time division passive optical communication network according to the present invention, when the OLT requests distance information according to a specific PON ID, the distance information according to the specific PON ID is stored in the distance information database. If stored, the distance information is provided; otherwise, the method further includes the steps of (a) to (c) to provide the distance information.

In addition, according to another aspect of the invention, the present invention is a distance information providing apparatus for providing MAC ranging distance information of a time division passive optical communication network having a relay device, OLT (Optical Line Terminal) of the time division passive optical communication network An information control unit for requesting distance information between a central office terminal (COT) and a remote terminal (RT) constituting the relay device; A measurement signal control unit generating a measurement signal under the control of the information control unit, transmitting the measurement signal through the optical path between the COT and the RT, and receiving a reflection signal; A distance analyzer for calculating distance information between the COT and the RT by using a difference between a transmission time of the measurement signal and a reception time of the reflection signal; And a distance information database for storing the calculated distance information according to the COT ID for identifying the COT that matches the PON ID for identifying the PON interface of the OLT.

In one embodiment, the measurement signal control unit is characterized in that the measurement signal is transmitted through the COT optical transmitter and receiver of the COT.

In another exemplary embodiment, the measurement signal controller may directly transmit the measurement signal through the optical path connecting the COT and the RT, and directly receive the reflection signal at the RT with respect to the measurement signal.

In addition, according to another aspect of the present invention, the present invention provides an optical signal terminal (OLT) for transmitting and receiving optical signals in a time division manner; An optical network terminal (ONT) positioned at a subscriber end and transmitting and receiving an optical signal in a time division manner with the OLT; A remote node (RN) for distributing the optical signal of the OLT or integrating the optical signal from the ONT; A relay device including a central office terminal (COT) and a remote terminal (RT) to relay the optical signal between the OLT and the RN to extend a transmission distance; And a time division passive optical communication network including the above-described distance information providing apparatus.

According to the present invention as described above, there is an effect that the operator of the TDM-PON can increase the convenience of operation by eliminating the need to individually grasp the distance information between the COT and RT of the relay device. Also, even when the RT is moved, the distance information can be calculated immediately, thereby improving operational efficiency.

In addition, when a single OLT includes a plurality of PON interfaces, a plurality of PON interfaces can share the distance information with one distance measurement.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible, even if shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the following will describe a preferred embodiment of the present invention, but the technical idea of the present invention is not limited thereto and may be variously modified and modified by those skilled in the art.

2 is a diagram illustrating a part of a configuration of a TDM-PON having a distance information providing apparatus for MAC ranging according to a preferred embodiment of the present invention.

As mentioned above, the TDM-PON includes an OLT 100, a COT 200, an RT 300, an RN 400, and an ONT 500. The TDM-PON according to the present invention further includes a distance information providing apparatus 130.

The OLT 100 includes a PON OAM function unit 110 in charge of OAM (Operation, Administration, and Maintenance) and a PON MAC processor 120 for transmitting an optical signal. As illustrated in FIG. 2, two or more PON MAC processors 120 may be provided in the OLT 100. In the embodiment of FIG. 2, a plurality of PON MAC processing units 120 are provided in one OLT 100 to form individual PON interfaces for each PON MAC processing unit 120. In this case, more ONTs can be accommodated and managed in the OLT. Each PON interface of the OLT 100 is given an individual ID (hereinafter, referred to as a 'PON ID') for identification and is managed by the OLT 100.

The COT 200 includes a COT optical transmitter / receiver 210 to receive an optical signal from the PON MAC processor 120 of the OLT 100. When a plurality of PON MAC processing unit 120 is provided in the OLT 100, the COT optical transmitting and receiving unit 210 is provided with a number corresponding thereto. In this case, the COT 200 includes a COT optical multiplexer 220 and multiplexes a plurality of TDMA optical signals by using wavelength division multiplexing (WDM) to transmit them to the RT 300.

The RT 300 includes an RT optical multiplexer 310 for demultiplexing an optical signal transmitted from the COT optical multiplexer 220 of the COT 200. The demultiplexed optical signal from the RT optical multiplexer 310 is transmitted to the RT optical transmitter / receiver 320 and transmitted to the RN 400. Although not shown, the optical signal transmitted from the ONT 500 is transmitted to the OLT 100 in the reverse direction as described above.

The distance information providing apparatus 130 may include an information controller 132 connected to the PON OAM function unit 110, a distance analyzer 136 analyzing the distance between the COT 200, and the RT 300, and for measuring the distance. The measurement signal control unit 138 constituting the signal, and the distance information database 134 for storing and managing the measured distance.

The information control unit 132 provides distance information between the COT 200 and the RT 300 according to a request of the PON OAM function unit 110, and, if necessary, the COT 200 and the RT ( Calculate the distance between 300). When a request of the PON OAM function unit 110 is requested, the information controller 132 first searches the distance information database 134 to determine whether distance information of a corresponding section is stored. If the distance information of the section exists, the information controller 132 provides the distance information of the section to the PON OAM function unit 110. If the distance information of the corresponding section does not exist, the information controller 132 measures the distance information through the distance analyzer 136 and the measurement signal controller 138.

In general, the distance information between the COT 200 and the RT 300 is managed by the PON OAM function unit 110. Therefore, the case of requesting the distance information between the COT 200 and the RT 300 from the PON OAM function unit 110 may be largely the following two ways. One is a case where the TDM-PON operator selects a PON interface to be operated and requests confirmation of distance information for operation. The other is a case in which the connection configuration of the COT 200 or the RT 300 is changed to require confirmation of the changed distance information.

Meanwhile, when a plurality of PON MAC processing units 120 are included in one OLT 100 as shown in FIG. 2, distance information between the COT 200 and the RT 300 for the PON interface according to any one of the PON IDs is included. If is known, PON interfaces according to different PON IDs may share that information.

The distance information database 134 stores distance information between the COT 200 and the RT 300 according to the PON ID. The COT 200 is assigned a COT ID for identification and the RT 300 is also assigned an RT ID for identification. Accordingly, the distance information database 134 configures a COT ID and an RT ID mapped to the PON ID, initializes the database, and stores distance information according to the actually measured result value.

The distance analyzer 136 calculates a distance between the COT 200 and the RT 300 based on the transmission and reception time information of the measurement signal of the measurement signal controller 138. This distance calculation can be determined by the following equation (1).

In Equation 1, d is a distance between the COT 200 and the RT 300, RTT (Round Trip Time) is the round trip time, v _c is the transmission speed of the measurement signal on the optical cable.

The measurement signal controller 138 performs a function of generating a measurement signal for distance measurement. Preferably, the measurement signal has a separate pattern to be distinguished from the optical signal of the PON MAC processing unit 120. As a method, it may be considered to include information indicating that the measurement signal is included in the header of the measurement signal packet. Alternatively, it may be considered that the optical signal constituting the measurement signal is made in such a manner that the intensity of the signal is adjusted according to a series of time intervals. Meanwhile, the measurement signal includes transmission time information.

The measurement signal generated by the measurement signal controller 138 is transmitted to the RT 300 through the COT optical transmitter / receiver 210 of the COT 200. In the RT optical transmitter / receiver 320 of the RT 300, light reflection of the measurement signal transmitted through the COT optical transmitter / receiver 210 occurs, and some signals are returned to the RT optical transmitter / receiver 320. The measurement signal controller 138 receives the measurement signal returned to the RT optical transmitter 320 and confirms the reception time of the returned measurement signal.

The difference between the transmission time and the reception time of the measurement signal constitutes the RTT information, and the distance analyzer 136 calculates the distance between the COT 200 and the RT 300 based on Equation 1 based on the RTT information. .

3 is a diagram illustrating a part of a configuration of a TDM-PON having a distance information providing apparatus for MAC ranging according to another preferred embodiment of the present invention.

The configuration according to FIG. 3 is substantially the same as the configuration according to FIG. 2 except for the configuration of the measurement signal controller 138.

In FIG. 3, the measurement signal controller 138 is configured to directly generate and directly transmit a measurement signal, and directly receive a measurement signal that is reflected. The configuration and function of the measurement signal controller 138 is substantially the same as an optical time domain reflector (OTDR).

To this end, the measurement signal controller 138 is connected to any one of both ends of the optical path connecting the COT 200 and the RT (300). As one embodiment, the measurement signal controller 138 may utilize a patch section such as an optical fiber distribution (DFB) provided in the telephone company.

Next, a method of providing distance information for MAC ranging in a time division passive optical communication network according to the present invention will be described.

4 is a flowchart illustrating a method of providing distance information for MAC ranging in a time division passive optical communication network according to an exemplary embodiment of the present invention.

The PON OAM function unit 110 of the OLT 100 requests the distance information between the COT 200 and the RT 300 from the information controller 132 of the distance information providing apparatus 130 (S10). That is, in step S10, the distance information between the COT 200 according to the COT ID matched to the PON interface according to the specific PON ID and the RT 300 according to the RT ID is transmitted to the information controller 132 by the PON OAM function unit 110. It may be understood as equivalent to querying whether it is stored in the distance information database 134.

The information controller 132 determines whether the corresponding distance information exists in the distance information database 134 (S20).

If the corresponding distance information exists in the distance information database 134, the information controller 132 provides the corresponding distance information to the PON OAM function unit 110 of the OLT 100 (S100).

If the requested distance information does not exist in the distance information database 134, the information controller 132 configures the relay device COT ID mapped to the PON ID in the distance information database 134 and initializes the database for the PON ID. (S30).

The distance analysis can be completed once but can be repeated two or more times to improve accuracy. When the distance analysis is repeated N times, the measurement count is set to N (S40).

The information control unit 130 causes the measurement signal control unit 138 to generate and transmit the measurement signal (S50). If we repeat the distance analysis N times, we subtract 1 from Count. On the other hand, it is preferable that a specific pattern indicating that the measurement signal is inserted into the measurement signal, and the measurement signal includes the transmission time information.

The measurement signal is reflected by the RT 300, and it is determined whether the reflection signal is received by the measurement signal controller 138 (S60), and when the measurement signal controller 138 does not receive the reflected signal, the measurement signal controller 138. ) Transmits the measurement signal again.

When the measurement signal controller 138 receives the reflected signal, the distance analyzer 136 calculates distance information between the COT 200 and the RT 300 by using a difference (RTT) between the transmission time and the reception time of the measurement signal. (S70).

The steps S50 to S70 are performed until the distance analysis is repeated N times (S80).

The distance analyzer 136 averages the distance information according to N repetitions and provides it to the information controller 132, and the information controller 132 stores the distance information in the distance information database 134 corresponding to the PON ID ( S90), the PON OAM function unit 110 is provided (S100).

According to this process, the OLT 100 may acquire distance information requested by the PON MAC processing unit 120. In addition, the plurality of PON MAC processing unit 120 connected to the same COT 200 in the OLT 100 is a distance between the COT 200 and the RT 300 for the PON ID of any one of the PON MAC processing unit 120. Information can be shared.

The above description is merely illustrative of the technical idea of the present invention, and various modifications, changes, and substitutions may be made by those skilled in the art without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. . The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a block diagram showing a configuration of a time division passive optical communication network (TDM-PON) having a relay device;

2 is a view showing a part of a configuration of a TDM-PON having a distance information providing apparatus for MAC ranging according to a preferred embodiment of the present invention;

3 is a diagram illustrating a part of a configuration of a TDM-PON having a distance information providing apparatus for MAC ranging according to another embodiment of the present invention;

4 is a flowchart illustrating a method of providing distance information for MAC ranging in a time division passive optical communication network according to an exemplary embodiment of the present invention.

<Description of reference numerals for the main parts of the drawings>

100: Optical ray termination unit (OLT) 110: PON OAM function

120: PON MAC processing unit 130: distance information providing device

132: information control unit 134: distance information database

136: distance analysis unit 138: measurement signal control unit

200: national terminal (COT) 210: COT optical transmission and reception unit

220: COT optical multiplexing unit 300: remote terminal (RT)

310: RT optical multiplexer 320: RT optical transmitter and receiver

400: Remote Node (RN) 500: Optical Network Terminator (ONT)

Claims (13)

In the Mac ranging distance information providing method of a time division passive optical communication network having a relay device, (a) generating a measurement signal for measuring distance information between a central office terminal (COT) and a remote terminal (RT) of a relay device and transmitting the measured signal through an optical path between the COT and the RT; (b) receiving a reflected signal for the transmitted measurement signal; (c) calculating distance information between the COT and the RT by using a difference between a transmission time of the measurement signal and a reception time of the reflection signal; And (d) storing the calculated distance information in a distance information database according to a PON ID for identifying a PON interface of an optical line terminal (OLT) and a COT ID for identifying the COT; Mac ranging distance information providing method of a time division passive optical communication network comprising a. The method of claim 1, The method of claim 1, wherein the measurement signal includes pattern information indicating that the signal is a signal for measuring the distance information. The method of claim 1, In the step (a), the measurement signal is Mac ranging distance information providing method of a time division passive optical communication network, characterized in that the transmission through the COT optical transmission and reception of the COT. The method of claim 1, Step (a) and step (b) are Mac ranging distance information providing method of a time division passive optical communication network, characterized in that the optical time domain reflectormetry (OTDR) method for the optical path connecting the COT and the RT. . delete The method according to any one of claims 1 to 4, When the OLT is provided with at least two PON interfaces for sharing the COT, when the distance information for any one PON interface is stored in the distance information database, another PON interface shares and uses the distance information Mac ranging distance information providing method of a time division passive optical network. The method according to any one of claims 1 to 4, (e) When the OLT requests distance information according to a specific PON ID, if distance information according to the specific PON ID is stored in the distance information database, the distance information is provided; otherwise, (a) Providing distance information by performing steps (c) to (c). Mac ranging distance information providing method of a time-division passive optical communication network characterized in that it further comprises. A distance information providing device for providing MAC ranging distance information of a time division passive optical communication network having a relay device, comprising: An information control unit for requesting distance information between a central office terminal (COT) and a remote terminal (RT) constituting the relay device from an optical line terminal (OLT) of the time division passive optical communication network; A measurement signal control unit generating a measurement signal under the control of the information control unit, transmitting the measurement signal through the optical path between the COT and the RT, and receiving a reflection signal; A distance analyzer for calculating distance information between the COT and the RT by using a difference between a transmission time of the measurement signal and a reception time of the reflection signal; And A distance information database for storing the calculated distance information according to a COT ID for identifying a COT matching a PON ID for identifying a PON interface of the OLT Mac ranging distance information providing apparatus of a time division passive optical communication network comprising a. The method of claim 8, The measuring signal controller is Mac ranging distance information providing apparatus of a time division passive optical communication network, characterized in that for transmitting the measurement signal through the COT optical transmission and reception of the COT. The method of claim 8, The measurement signal controller directly transmits the measurement signal through the optical path connecting the COT and the RT and directly receives the reflection signal at the RT with respect to the measurement signal. Ranging distance information providing device. delete An optical signal terminal (OLT) for transmitting and receiving optical signals in a time division manner; An optical network terminal (ONT) positioned at a subscriber end and transmitting and receiving an optical signal in a time division manner with the OLT; A remote node (RN) for distributing the optical signal of the OLT or integrating the optical signal from the ONT; A relay device including a central office terminal (COT) and a remote terminal (RT) to relay the optical signal between the OLT and the RN to extend a transmission distance; And The apparatus for providing distance information according to any one of claims 8 to 11 Time division passive optical communication network comprising a. 13. The method of claim 12, The OLT includes at least two PON interfaces sharing the COT, and the OLT requests the distance information providing apparatus for the distance information on any one PON interface. And when the distance information for another PON interface is stored, the distance information providing device provides the distance information to the OLT.

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