KR101794986B1

KR101794986B1 - System of Passive Optical Network using multi-mode optical cable

Info

Publication number: KR101794986B1
Application number: KR1020150180443A
Authority: KR
Inventors: 이영욱; 이광국
Original assignee: 주식회사 케이티
Priority date: 2015-05-12
Filing date: 2015-12-16
Publication date: 2017-11-08
Also published as: KR20160134453A

Abstract

A passive optical network system using a multimode optical line is located between an optical network unit and a remote node and removes radio waves in a high-order mode among a plurality of propagation modes generated in an upstream signal, A first mode filter connected to the optical splitter of the remote node for generating an optical signal having a single mode of radio wave by removing radio waves of a higher mode among a plurality of propagation modes generated in the downstream signal, Mode optical fiber, the first mode filter and the second mode filter are formed of a single mode optical fiber, the first mode filter and the second mode filter are connected by a multimode optical fiber, and the single mode optical fiber and the multi mode The optical fibers are fused and connected.

Description

[0001] The present invention relates to a passive optical network system using a multimode optical line,

The present invention relates to a passive optical network system using a multimode optical line.

In order to provide high-speed Internet service, FTTH (Fiber to the Home) service generally provides high-speed data service by connecting an optical cable from a telephone office to a subscriber's home in a subscriber network environment. The network configuration for providing such FTTH service can be classified into an AON (Active Optical Network) method and a PON (Passive Optical Network) method.

Currently, broadband Internet service providers provide high-speed Internet service with AON technology (L3 / L2 switch interlocking method) in order to provide 100Mbps high-speed Internet service in apartment complexes such as apartments. However, in recent years, the traffic of broadband Internet service has been explosively increased due to the proliferation of PTP, web hard, and quality assurance services such as IPTV and VoIP, and it is required to increase the existing 100 Mbps physical link.

As a method of increasing the physical link, there may be a method of upgrading to 1.25 Gbps or 2.5 Gbps using the AON technique for upgrading a 100 Mbps link of the existing AON scheme to 1 Gbps or a new passive optical network (PON) technique.

Among these methods, PON technology used to upgrade speed by using PON technology reduces the investment cost of optical cable compared to AON technology which is composed of point-to-multipoint (PtM) And has a merit that maintenance is easy by using a passive element called a remote node (RN) at a branch point. However, PON technology can only be applied based on SMF. Therefore, it is impossible to apply PON technology to a common house constructed by multi-mode optical fiber to provide high-speed Internet service using AON technology.

In order to apply PON technology to a common house providing high-speed Internet service using the AON technology, the multimode optical fiber must be replaced with a single mode optical fiber.

In other words, in order to connect a single mode optical fiber and a multimode optical fiber, a solution such as a single mode-multimode mode converter may be applied at an MDF (Main Distribute Frame) connection connection point. However, And mode-selective loss and inter-modal dispersion can be the obstacles to IPTV and high-speed internet quality due to application of the mode converter.

Accordingly, it is required to develop a technology capable of ensuring the quality of IPTV and broadband Internet service without replacing existing multimode optical fiber in a common house equipped with multimode optical fiber.

Accordingly, the present invention provides a system for providing a high-speed Internet service using a passive optical network technology using a multimode optical line.

According to an aspect of the present invention, there is provided a passive optical network system for providing an Internet service using a passive optical network system using a multimode optical line,

A first mode filter which is located between the optical network unit and the remote node and removes radio waves of a high-order mode among a plurality of propagation modes generated in an upstream signal to generate an optical signal having a single mode of propagation; And a second mode filter connected to the optical splitter of the remote node and generating an optical signal having a single mode of radio wave by removing radio waves of a higher mode among a plurality of propagation modes generated in a downstream signal, The mode filter and the second mode filter are formed of a single mode optical fiber, the first mode filter and the second mode filter are connected by a multimode optical fiber, and the single mode optical fiber and the multimode optical fiber are fused and connected.

According to another aspect of the present invention, there is provided a passive optical network system for providing an Internet service using a passive optical network system using a multimode optical line,

An optical line terminating device for transmitting a downlink traffic signal to subscribers in a broadcast manner and controlling uplink traffic signals according to priority; A remote node connected to the optical line terminal through a single mode optical line and performing switching between a single mode and a multimode; An optical network unit transmitting a communication signal from a subscriber terminal to the remote node or transmitting a signal received from the remote node to the subscriber terminal; A first mode filter located between the optical network unit and the remote node and generating only an optical signal having a single mode wave by removing radio waves in a high-order mode among a plurality of propagation modes generated in an upstream signal; And a second mode filter connected to the optical splitter of the remote node and generating only an optical signal having a single mode wave by removing radio waves of a higher mode among a plurality of propagation modes generated in a downstream signal.

According to the present invention, it is possible to guarantee quality of services such as broadband broadband Internet, IPTV, and VoIP by using PON technology without replacing the optical cable already installed with the single mode optical cable by using the multimode optical cable.

In addition, since the PON technology can be applied to existing apartment houses without replacing existing multimode optical fibers, the cost incurred for installing single mode optical fibers can be minimized.

1 is an exemplary diagram of a system for providing a general high-speed Internet service.
FIG. 2 is an exemplary diagram showing all dependency loss and mode dispersion according to a general system.
3 is an exemplary view of an optical signal that is guided in a general optical line.
4 is a diagram illustrating an environment in which a passive optical network system according to a first embodiment of the present invention is applied.
5 is an exemplary diagram illustrating an environment in which a passive optical network system according to a second embodiment of the present invention is applied.
6 is an exemplary diagram of a system in an environment in which a passive optical network system according to an embodiment of the present invention is applied.
7 is an exemplary diagram of an optical signal that is guided in an optical line according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

In this specification, a terminal includes a mobile station (MS), a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS) An access terminal (AT), and the like, and may include all or some of functions of a mobile terminal, a subscriber station, a mobile subscriber station, a user equipment, and the like.

Hereinafter, an optical access network system utilizing a multi-mode optical line according to an embodiment of the present invention will be described with reference to the drawings. Before describing an embodiment of the present invention, a general optical network system will be described with reference to Figs. 1 and 2. Fig.

FIG. 1 illustrates an exemplary system for providing a general high-speed Internet service, and FIG. 2 illustrates exemplary exemplary all dependency loss and mode dispersion according to a general system.

First, as shown in FIG. 1, a system for providing a high-speed Internet service using the AON technology will be described. An AON system for providing a high-speed Internet service includes an L3 switch An L3 switch (hereinafter referred to as "MDF L3 switch") 20 installed in a MDF (Main Distribute Frame) of a multi-family house, an L2 switch 30 installed in the basement of a plurality of buildings, And subscriber terminals 40.

A single mode optical fiber (SMF) is provided between the L3 switch 10 and the MDF L3 switch 20 and a single mode optical fiber or a multimode optical fiber is provided between the MDF L3 switch 20 and the L2 switch 30. [ (MMF: Multi-Mode Fiber). Also, a UTP cable is provided between the L2 switch 30 and the subscriber terminal 40. The function of each of the switches 10, 20 and 30 is already known, and a detailed description thereof will be omitted in the embodiment of the present invention.

As described above, although a single mode optical fiber or a multimode optical fiber can be installed in the interval between the MDF L3 switch 20 and the L2 switch 30 in the apartment optical line path, a multimode optical fiber, Respectively. In the case of providing high-speed Internet service using the AON technology, a single-mode optical fiber or a multimode optical fiber is installed between the MDF and the building, and then the subscriber terminal 40 is provided with a 100Mbps link shared.

On the other hand, a single-mode optical fiber connected between the L3 switch 10 and the MDF L3 switch 20 of the communication station shown in Fig. 1 and a multimode optical fiber connected between the MDF L3 switch 20 and the L2 switch 30 are connected , A mode converter must be installed for mode conversion between single mode and multi mode at the MDF connection connection point. In this case, a cost is incurred because the mode converter is connected to the remote node section where the bifurcation occurs and the building section, and as a result, the mode selective loss and mode dispersion -modal Dispersion) may occur, which may act as an obstacle to IPTV and high-speed Internet quality.

That is, as shown in FIG. 2 (a), mode-dependent loss occurs when the single mode optical fiber and the MDF are connected in the same. This causes unstable optical power due to loss depending on the ambient environment in which the optical line is installed such as temperature and vibration. Also, as shown in FIG. 2 (b), when the single mode optical fiber and the multimode optical fiber are matched, a higher mode is generated in the multimode optical fiber section and a mode dispersion occurs thereby resulting in a deterioration in service quality.

3 is an exemplary view of an optical signal that is guided in a general optical line.

As shown in Fig. 3 (a), an optical signal guided in a single mode optical fiber having a core diameter of 8 m is guided through one optical pattern in a single mode LP01. However, when the optical signal passes through the multi-mode optical fiber section having a diameter of 62.5 μm, various modes of propagation (LP01, LP11, LP02, etc.) are generated as shown in FIG. And a dynamic light pattern called speckle due to inter-mode interference.

That is, various modes generated in the multimode optical fiber section not only make the optical pattern unstable, but also the optical pattern changes depending on the change of the surrounding environment in which the optical line is installed such as temperature or vibration. Therefore, a stable optical pattern that is guided from the single mode optical fiber is generated as a fluid optical pattern while passing through the multimode optical fiber section, and when the floating optical pattern, that is, the speckle is connected to the single mode optical fiber again, some modes are not guided to the single mode optical fiber The power on the receiving side becomes unstable. In addition, the receiving optical module may not correctly recognize the signal, and interference loss may occur in which signal loss occurs.

Also, among various modes of propagating in the multimode optical fiber as shown in Fig. 3 (c), a radio wave having a high-order propagates along the outer periphery of the optical core and has a low-order The radio waves have a characteristic of going straight along the optical core. Therefore, due to the arrival time difference of the various modes, a mode dispersion phenomenon may occur in which a previous signal interferes with a subsequent signal, resulting in loss of the signal.

Therefore, it is necessary to develop a technology to smoothly provide high-speed Internet service in the PON technology system while minimizing inter-mode interference loss and mode dispersion phenomenon, without replacing existing multimode optical fiber in a common house equipped with multimode optical fiber do. This will be described with reference to Figs. 4 to 6. Fig.

FIG. 4 is a diagram illustrating an environment in which the passive optical network system according to the first embodiment of the present invention is applied, and FIG. 5 is a diagram illustrating an environment in which the passive optical network system according to the second embodiment of the present invention is applied.

The embodiment of the present invention can be applied to any one of the environments shown in FIG. 4 or FIG. 5 according to the application method of the passive optical network system. That is, in FIG. 4, optical fibers are connected using a connecting unit between two mode filters. In FIG. 5, optical fibers are connected through fusion splices without a connecting unit.

4, in an embodiment of the present invention, a passive optical network system 100 is provided to provide a high-speed Internet service to a user in a passive optical network technology using a multi-mode optical fiber optical fiber in a multi- A plurality of optical network units (ONUs) 120 are connected to a single optical line termination (OLT) 110 using a 1 × N passive optical splitter, So that the subscriber network structure forming the topology appears.

The OLT 110, which broadcasts downlink traffic signals to subscribers in a broadcast manner and controls uplink traffic signals in a priority order, is connected to a remote node (RN) 130 located in the MDF through a single mode optical line, . The remote node 130 includes an optical splitter 131 having a structure in which a single waveguide of the single mode optical fiber is branched into a plurality of optical waveguides, a first connecting unit 130 connecting the optical fiber drawn from the optical splitter 131 and the multi- 132-1).

The remote node 130 that is connected to the OLT 110 or the ONU 120 through the single mode optical fiber and performs the switching between the single mode and the multi mode is branched from the optical splitter 131 (for example, 1: 4 Or 1: 8, etc.), respectively. The remote node 130 is connected to a plurality of ONUs 120 connected to the installed multi-mode optical line to the building and transmitting the reception signal of the remote node 130 to the subscriber terminal.

At this time, in the embodiment of the present invention, only one optical fiber is shown without showing all the optical fibers branched by the optical splitter 131 for convenience of explanation. That is, the second mode filter 140-2 and the first connecting unit may be further included in the remote node 130 as many as the number of optical fibers branched by the optical splitter 131. [

The ONU 120, which receives an optical signal transmitted from the OLT 110 and transmits the optical signal to a user terminal as an end user or converts data to be transmitted into an optical signal and transmits the optical signal to the OLT 110, And a PON module for transmitting a signal transmitted from the terminal to the OLT 110. The details of the PON module are already known, and a detailed description thereof will be omitted in the embodiment of the present invention.

The first mode filter 140-1 is located between the ONU 120 and the second connecting unit 132-2. The first mode filter 140-1 is located between the ONU 120 and the second connecting unit 132-2. Among the radio waves of various modes occurring in the multi- Thereby generating a single mode optical signal.

The second mode filter 140-2 is located between the first connecting unit 132-1 and the optical splitter 131. Among the radio waves of various modes occurring in the multimode optical line in the process of transmitting the upstream signal, And generates a single mode optical signal by removing radio waves having a high order

In the environment in which the passive optical network system 100 according to the first embodiment described above is applied, the optical fiber 100 includes the connecting units 132-1 and 132-2, Can be used by fusion bonding. This will be described with reference to FIG.

5, in an environment where a passive optical network system is applied according to the second embodiment of the present invention, for convenience of description, not all the optical fibers branched by the optical splitter 131 are represented, but only one optical fiber Respectively. The optical fibers at the positions of the first connecting unit 132-1 and the second connecting unit 132-2 described in FIG. 4 are fused and connected to each other so that the optical fibers .

The functions of the OLT 110, the optical splitter 131, the first mode filter 140-1, the second mode filter 140-2, and the ONU 120 are as described in FIG. The intermodal interference loss can be minimized through the fusion splicing and the mode dispersion is eliminated through the first mode filter 140-1 and the second mode filter 140-2, can do.

In the environment where the passive optical network system 100 described above is applied, a system implementation example for minimizing a mode-to-mode interference loss will be described with reference to FIGS. 6 and 7. FIG.

6 is an exemplary diagram of a system in an environment in which a passive optical network system according to an embodiment of the present invention is applied.

6 illustrates an environment in which the passive optical network system according to the second embodiment of the present invention described above with reference to FIG. 5 is applied. In order to minimize the inter-mode interference loss, the optical fiber of the single- Mode filters 140-1 and 140-2 are formed. In general, a light path connection between the OLT 110 and the ONU 120 is divided into a line for transmitting an upstream signal and a line for transmitting a downstream signal.

Therefore, for the downstream signal from the OLT 110, the optical fiber is bent to form the first mode filter 140-1 after the single mode optical fiber-multimode optical fiber connection section of the same building, that is, after the connecting unit. Install it. For the upstream signal to be transmitted to the OLT 110, the optical fiber is bent in the single mode optical fiber section after the single mode optical fiber-multimode optical fiber connection section in the remote node 130 to form the second mode filter 140-2. Install it.

The optical fiber sections bent in two places are referred to as 'mode filters' 140-1 and 140-2 in the embodiment of the present invention, but the present invention is not limited thereto. The single-mode optical fibers forming the mode filters 140-1 and 140-2 are connected to the multi-mode optical fiber through fusion splicing. The fusion-spliced portion is described as an example in which the optical fiber at the position of the connecting unit described in Fig. 4 is welded and connected, but it is not necessarily limited thereto.

That is, in order to minimize the mode loss and mode dispersion that may occur due to various modes, it is necessary to reduce the number of propagation modes generated in the multimode optical fiber. However, it is a cause of noise to rapidly reduce the mode. Therefore, in the embodiment of the present invention, the mode filters 140-1 and 140-2 are provided so that only the single mode is left in a large number of propagation modes occurring in the multimode optical fiber, -2) through the optical fiber.

In the embodiment of the present invention, the mode filters 140-1 and 140-2 are designed to form the mode filters 140-1 and 140-2 by winding the optical fiber at least five times in a radius of curvature of 5 cm or less, And the number of bends are not necessarily limited to such.

An optical signal guided in the optical line of the passive optical network system 100 will be described with reference to FIG.

7 is an exemplary diagram of an optical signal that is guided in an optical line according to an embodiment of the present invention.

As shown in FIG. 7 (a), a splicing connection is performed in a section where a single mode optical fiber and a multimode optical fiber are connected to each other, and a center launch of the single mode optical fiber and a multi- Only the low-order mode in the multimode optical fiber can be generated. Here, the central launching technique is already known, and a detailed description thereof will be omitted in the embodiment of the present invention.

However, since some higher order modes can be generated in the multimode optical fiber section even after the fusion splicing connection, the single mode optical fiber-multimode optical fiber that is fused and connected as shown in FIG. 7 (b) The mode filters 140-1 and 140-2 may physically bend the mode filters 140-1 and 140-2 so that some of the generated high-order modes are removed through the mode filters 140-1 and 140-2. That is, since the higher-order mode propagation propagates along the outer periphery of the core of the optical fiber, the optical signal totally reflected through the bending can be removed to the outside of the optical fiber to leave only the signal of the single mode.

As described above, the signals of the passive optical network system are minimized in intermodal interference loss through fusion splicing, and mode filters 140-1 and 140-2 are provided to eliminate the mode dispersion, thereby ensuring the quality of the optical signal.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims

A passive optical network system for providing an Internet service using a passive optical network technology using a multimode optical line,
Mode optical fiber is set in advance so as to generate an optical signal having a single-mode radio wave by removing radio waves in a high-order mode among a plurality of propagation modes generated in an upstream signal, which are located between the optical network unit and the remote node A first mode filter formed by winding a predetermined number of times to have a radius of curvature; And
Mode optical fiber is pre-set to have a predetermined radius of curvature so as to generate an optical signal having a single-mode wave by removing radio waves of a higher-order mode among a plurality of propagation modes generated in a downstream signal, A second mode filter formed by being wound a predetermined number of times
/ RTI >
Wherein the first mode filter and the second mode filter are connected by a multimode optical fiber, and the single mode optical fiber and the multimode optical fiber are fused and connected.

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The method according to claim 1,
Wherein the first mode filter and the second mode filter have a radius of curvature of less than 5 cm and are formed by being wound at least five times or more.

A passive optical network system for providing an Internet service using a passive optical network technology using a multimode optical line,
An optical line terminating device for transmitting a downlink traffic signal to subscribers in a broadcast manner and controlling uplink traffic signals according to priority;
A remote node connected to the optical line terminal through a single mode optical line and performing switching between a single mode and a multimode;
An optical network unit transmitting a communication signal from a subscriber terminal to the remote node or transmitting a signal received from the remote node to the subscriber terminal;
Mode optical fiber is disposed between the optical network unit and the remote node and generates only an optical signal having a single-mode wave by removing radio waves in a high-order mode among a plurality of propagation modes generated in an upstream signal, A first mode filter formed by winding a predetermined number of times so as to have a preset radius of curvature; And
Wherein the single mode optical fiber is connected to an optical splitter of the remote node so as to generate only an optical signal having a single mode of radio wave by eliminating a radio wave of a higher mode among a plurality of propagation modes generated in a downstream signal, A second mode filter formed by winding a predetermined number of times
Wherein the optical network system comprises:

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5. The method of claim 4,
Wherein the single mode optical fiber forming the first mode filter and the second mode filter is connected to the multimode optical fiber through fusion splicing.

5. The method of claim 4,
A first connecting unit connecting the single mode optical fiber drawn out from the second mode filter and the multimode optical fiber formed between the optical communication network unit; And
And a second connecting unit connecting the multimode optical fiber drawn out from the first connecting unit and the single mode optical fiber drawn out from the first mode filter,
The optical network system comprising:

5. The method of claim 4,
Wherein the first mode filter and the second mode filter have a radius of curvature of less than 5 cm and are formed by being wound at least five times or more.