KR100767898B1 - Optical transmission system and method for sharing optical fiber cable between hybrid fiber coaxial network and coarse wavelength division multiplexing passive optical network - Google Patents

Abstract

The present invention relates to an optical transmission system and method for sharing an optical path in an optical coaxial mixed network and an optical wavelength multiplexed transmission network in order to provide an efficient Internet service. The optical transmission system of the present invention comprises a CMTS; An OLT having a multiplexing / demultiplexer for multiplexing optical signals having different wavelengths and outputting them to an optical communication line, and demultiplexing and outputting the multiplexed optical signal inputted through the optical communication line; An optical transmitter and receiver for receiving an RF signal from a CMTS and transmitting an optical signal obtained by photoelectric conversion of the RF signal to an OLT, or photoelectrically converting an optical signal from an OLT into an RF signal; Receive multiplexed optical signal from OLT through optical communication line and demultiplex the optical signal to transmit to HFC ONU or CWDM-PON ONU, or multiplex the optical signal received from HFC ONU or CWDM-PON ONU Including an optical splitter for transmitting to the OLT, the optical signal of the optical signal having a different wavelength between the optical transceiver and the OLT is transmitted and received, the optical splitter transmits the optical signal having a predetermined center wavelength to the ONF for HFC or HFC And an optical signal having a center wavelength rather than a predetermined wavelength to the CWDM-PON ONU or received from the CWDM-PON ONU. According to this, data transmission by the CWDM-PON method and the HFC method is independently possible by sharing the optical path in one optical transmission system.

Description

OPTICAL TRANSMISSION SYSTEM AND METHOD FOR SHARING OPTICAL FIBER CABLE BETWEEN HYBRID FIBER COAXIAL NETWORK AND COARSE WAVELENGTH DIVISION MULTIPLEXING PASSIVE OPTICAL NETWORK}

1 is a schematic configuration diagram of an optical transmission system using an HFC network according to the prior art.

2 is a schematic configuration diagram of an optical transmission system using a CWDM-PON network according to the prior art.

3 is a schematic diagram of an optical transmission system in which an HFC network and a CWDM-PON network are mixed according to a preferred embodiment of the present invention.

4 illustrates the configuration of the OLT and the optical splitter in the optical transmission system shown in FIG. 3 according to an embodiment of the present invention.

5 is a flowchart illustrating an optical transmission method according to an exemplary embodiment of the present invention.

The present invention relates to an optical transmission system and method for sharing optical paths in an optical coaxial mixed network (HFC NETWORK) and a wavelength multiplexed transmission network (CWDM-PON NETWORK) to provide an efficient Internet service.

Conventional high-speed Internet services use Hybrid Fiber Coaxial (HFC) for CATV, Coarse Wavelength Division Multiplexing (CWDM) -Passive Optical Network (PON), DDM (Dense) using passive optical subscriber networks. WDM) -PON or the like.

HFC network is composed of optical fiber and coaxial cable. Broadband transmission network that can transmit large amount of data by using optical cable to broadcasting station and optical station (ONU) and coaxial cable from optical station to subscriber. to be. In addition, for the optical cable section from the broadcasting station to the ONU (ONU for HFC) located at the subscriber center, the uplink and downlink optical transmission lines are separately configured, and the coaxial cable section has a coaxial amplifier (TBA), a passive element (Splitter, Tap-off, etc.) The coaxial cable is used to separate the frequency bands from the same coaxial cable to form up and down transmission lines.

1 is a block diagram showing an optical transmission system using such an HFC network. The CMTS (Calbe Modem Termination System) 110 is a station equipment that transmits CM (Cable Modem 150) data to the Internet through an IP network or vice versa for downlink data. . The optical transmitter 120 converts an electrical signal from the CMTS into an optical signal and transmits the optical signal to the HFC ONU (HFC outdoor transceiver 130) and the optical signal from the HFC ONU to receive the electrical signal. Is composed of an optical receiver (ORX) which transmits to the CMTS after conversion to (hereinafter, referred to as an optical transmitter and an optical receiver). In this case, optical cables are provided as transmission paths to CMTS and ONU for HFC. The ONFC 130 for HFC provides up / down optical transmission / reception function with the CMTS 110 and RF transmission / reception function with the CM 150, or converts a data signal into an optical signal and an RF signal. to provide. In this case, a coaxial cable is provided as a transmission path between the HFC ONU 130 and the CM 150. The CM 150 transmits and receives a packet as an RF signal.

In the path in which data is transmitted, the data generated at the subscriber PC is modulated into an RF signal through the CM 150 and transmitted to the ONU 130 for HFC, and the ONU 130 for HFC transmits an RF signal to 1310 nm or 1550 nm. The optical signal is converted into an optical signal using the optical wavelength of the optical transmitter 120, and the optical transmitter 120 converts the received optical signal into an RF signal and transmits it to the CMTS 110, CMTS 110 is a cable modem After processing authentication, subscriber authentication and IP assignment, data is transmitted to internet network. On the other hand, such data transfer may proceed in the reverse direction for downlink optical transmission.

On the other hand, the CWDM-PON method used in the passive optical subscriber network has a large wavelength spacing and low installation cost compared to the DWDM (Dense WDM, high-density wavelength division multiplexing) -PON method. CWDM-PON method is a passive optical network sharing optical fiber, and the optical line terminal (OLT) on the network side, the ONU (Optical Node Unit) for CWMD-PON on the subscriber side, and multiplexed signals from the OLT It consists of an optical splitter (Splitter or RN; Remote Node) and an optical fiber to demultiplex the signal to branch to the optical fiber of the fiber.

2 is a configuration diagram of an Internet service by CWDM-PON network. The OLT 260 is connected to a router as a station equipment and provides services such as high speed Internet, VoIP, and IPTV, and provides a plurality of CWDM-PON ONUs 280 or ONTs through a branching device (Splitter or RN, 270). The optical node terminal 290 is connected to perform an optical transmission function and the reverse function. The optical splitter 270 is a wavelength division passive branch coupler installed outdoors or indoors, receives the multiplexed optical signal from the OLT 260, demultiplexes the CWDM-PON ONU 280 or ONT 290, and transmits the OLT. Provide a physical optical transmission path between 260 and ONU 280 or ONT 290 for CWDM-PON. The ONU 280 for the CWDM-PON is installed at the subscriber end and terminates the optical signal branched from the optical splitter and provides an interface with the subscriber PC. The ONT 290 is installed indoors in the subscriber and terminates the optical signal branched from the optical branch and provides an interface with the subscriber PC.

In the data transmission path, data generated at the subscriber PC is optically transmitted to the optical branch 270 through the ONU 280 or the ONT 290 for the CWDM-PON, and the optical branch 270 is the ONU for the CWDM-PON. The optical signal transmitted from the 280 or the ONT 290 is multiplexed and loaded on one optical core and transmitted to the OLT 260. The OLT 260 receives the multiplexed optical signal, demultiplexes it through a multiplexer / demultiplexer, photoelectrically converts the optical signal, and transmits the optical signal to the Internet network. On the other hand, such data transfer can proceed in the reverse direction.

Since the HFC network is shared by a plurality of users, the transmission speed is reduced when data is transmitted to a plurality of subscribers, and there is a problem in that it is vulnerable to security because it is physically used by a plurality of users. On the other hand, according to the CWDM-PON method described above, by multiplexing / demultiplexing a plurality of wavelengths at a wavelength interval of 20 nm in a manner of simultaneously transmitting a plurality of different wavelengths to one strand of optical cable, 100 per wavelength It is possible to provide a band of M to 1 G. However, there is a problem in terms of technology and cost in efficiently replacing the conventional transmission infrastructure with the CWDM-PON method (excellent than the DWDM method). Accordingly, what is needed is a system and method for efficiently replacing the aforementioned conventional transmission techniques with the CWDM-PON scheme.

The present invention is to solve the above problems, the object is to provide a system and method that can be used to extend the existing service by adding the CWDM-PON transmission scheme to the already established HFC network.

Other objects and advantages other than the above objects and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

An optical transmission system according to a first aspect of the present invention includes an optical transmission system for sharing an optical path in an optical coaxial mixed network (HFC) and an optical wavelength multiplexed transmission network (CWDM-PON), comprising: a cable modem termination system (CMTS); An optical line termination (OLT) having a multiplexing / demultiplexer for multiplexing and outputting optical signals having different wavelengths to an optical communication line, and demultiplexing and outputting the multiplexed optical signal inputted through the optical communication line; An optical transmitter (OTX / ORX) for receiving an RF signal from the CMTS and transmitting an optical signal obtained by photoelectric conversion of the RF signal to the OLT, or photoelectrically converting an optical signal from the OLT into an RF signal and transmitting it to the CMTS Wow; Receive the multiplexed optical signal from the OLT through the optical communication line and demultiplex the optical signal to transmit to the ONU for HFC or the CWDM-PON ONU, or the optical signal received from the ONFC for HFC or ONU for CWDM-PON And an optical splitter for multiplexing and transmitting the optical splitter to the OLT, wherein a part of an optical signal of an optical signal having a different wavelength is transmitted and received between the optical receiver and the OLT, and the optical splitter receives an optical signal having a predetermined center wavelength. And transmit to the HFC ONU or receive from the HFC ONU, and transmit an optical signal having a wavelength other than the predetermined wavelength to the CWDM-PON ONU or from the CWDM-PON ONU.

In a preferred embodiment according to the first aspect, the different wavelengths are determined at intervals of 20 nm within a range of 1260 nm to 1620 nm, and the predetermined center wavelength is preferably 1310 nm or 1550 nm.

In a preferred embodiment according to the first aspect, the OLT preferably further includes an optical transmission / reception channel unit connected to the multiplexer / demultiplexer for transmitting and receiving optical signals of respective wavelengths.

In addition, in a preferred embodiment according to the first feature, the OLT preferably further comprises a switching unit connected to the optical transmission and reception channel unit and providing switching and routing for connecting the OLT and the Internet network.

The optical transmission method according to the second aspect of the present invention is an optical transmission method in which an optical path is shared in an optical coaxial mixed network (HFC) and an optical wavelength multiplexed transmission network (CWDM-PON), and the data converted into an RF signal by the CM is used for the HFC. Transmitting to the ONU; Converting the data into an optical signal by the HFC ONU and transmitting the optical signal to an optical splitter; Multiplexing the optical signal from the ONFC for HFC and the optical signal from the CWDM-PON ONU by the optical splitter to transmit to the OLT; The optical signal from the ONFC for HFC and the optical signal from the CWDM-PON ONU are demultiplexed by the OLT multiplexer / demultiplexer to transmit the optical signal from the demultiplexed HFC ONU to an optical transceiver, Providing an optical signal from the ONU for the demultiplexed CWDM-PON to the Internet network; Converting the transmitted optical signal from the ONFC for HFC to an RF signal by the optical transceiver and transmitting the RF signal to a CMTS; And providing the RF signal to the internet network by the CMTS.

In a preferred embodiment according to the second aspect, the central wavelength of the optical signal from the ONU for HFC is 1310 nm or 1550 nm, and the wavelength of the optical signal from the ONU for CWDM-PON is in the range of 1260 nm to 1620 nm. It is preferable to exclude the 1310 nm or 1550 nm among the wavelengths determined at 20 nm intervals within.

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

FIG. 3 schematically illustrates a configuration of an optical transmission system in which an HFC network and a CWDM-PON network are mixed according to a preferred embodiment of the present invention.

Referring to FIG. 3, the optical transmission system 300 includes a cable modem termination system (CMTS) 310, an optical transmitter (OTX / ORX, 320), an optical line terminal (OLT) 360, an optical splitter 370, It consists of an ONU 330 for HFC and an ONU 380 for CWDM-PON.

Hereinafter, the optical transmission operation by the optical transmission system having the above-described configuration will be described.

The data generated by the subscriber PC is modulated into an RF signal through the CM 301 and transmitted to the ONU 330 for HFC. The HFC ONU 330 optically converts the RF signal and transmits the optical signal to the optical splitter 370. Data generated at subscriber PC 302 is sent to ONU 380 for CWDM-PON. The optical splitter 370 connects the optical signal from the ONFC 330 for HFC to one wavelength, and converts the optical signal from the CWDM-PON ONU 380 to the wavelength to which the optical signal from the ONFC 330 for HFC is connected. Connect to a different wavelength. The optical splitter 370 multiplexes the optical signal from the ONFC 330 for the HFC and the optical signal from the ONU 380 for the CWDM-PON and transmits the optical signal to the OLT 360. The OLT 360 demultiplexes the multiplexed optical signal received from the optical splitter 370 and transmits the optical signal from the ONFC 330 for HFC to the optical transceiver 320 according to the wavelength, and the ONU for CWDM-PON. The optical signal from 380 is provided to the Internet network after predetermined processing such as subscriber authentication, IP allocation, and the like. On the other hand, the optical transceiver converts the received optical signal into an RF signal, and then transmits the optical signal to the CMTS 310, and the CMTS 310 performs predetermined processing such as subscriber authentication, IP allocation, and the like, and then transfers the data to the Internet. Provided by net.

On the other hand, the downlink transmission of such an optical transmission system proceeds in reverse to the above-described uplink transmission. That is, the OLT 360 connects the optical signal transmitted through the CMTS 310 and the optical transmitter 320 to one wavelength, and multiplexes it with the other wavelength for the CWDM-PON to shear the front end of the ONU 330 for the HFC. The optical splitter 370 transmits the optical signal for the HFC and the CWDM-PON optical signal multiplexed from the OLT 360 to the optical splitter 370 installed in the optical splitter 370. The signal of the wavelength for the CWDM-PON is transmitted to the ONU 380 for the CWDM-PON to provide a communication service.

4 illustrates the configuration of the OLT 360 and the optical splitter 370 according to the preferred embodiment of the present invention.

The OLT 360 is connected to a router or the like as a station equipment and provides a service by connecting to a plurality of ONUs through an optical splitter (or RN), and providing a function of optical transmission and its reverse direction. The switching unit 361 and optical transmission and reception And a channel card 362, a multiplexer / demultiplexer 363, and the like. The switching unit 361 is connected to a plurality of optical transmission / reception channel cards to provide a photoelectric conversion function, and a switching / routing function for connecting the photoelectrically converted data to the Internet network. The switching unit 361 may be configured independently of the OLT 360. The optical transmission / reception channel card 362 is composed of channel cards associated with a plurality of wavelengths. In one embodiment, these optical transmit and receive channel cards 362 have wavelengths of 1270 nm, 1290 nm, 1310 nm, 1330 nm, 1350 nm, 1410 nm, 1430 nm, 1450 nm, 1470 nm, 1490 nm, 1510, respectively. A total of 16 optical transmit and receive channel cards, including optical transmit and receive channel cards for nm, 1530 nm, 1550 nm, 1570 nm, 1590 nm, and 1610 nm, are capable of transmitting and receiving capacity of 100 Mbps / 1 Gbps for each channel card. The multiplexer / demultiplexer 363 multiplexes 16 wavelengths from 1270 nm to 1610 nm of these 16 optical transmit / receive channel cards and loads them on one optical core to optical splitter 370, or at optical splitter 370 Optically transmitted optical signal is demultiplexed into 16 wavelengths and transmitted to each optical transceiver channel card according to the corresponding wavelength.

In a preferred embodiment of the present invention, the ONU for HFC is to perform optical transmission using a wavelength of 1310 nm or 1550 nm, these wavelengths described above 16 CWDM-PON wavelengths (1270 nm, 1290 nm, 1310 nm) 1330 nm, 1350 nm, 1410 nm, 1430 nm, 1450 nm, 1470 nm, 1490 nm, 1510 nm, 1530 nm, 1550 nm, 1570 nm, 1590 nm and 1610 nm), and CWDM-PON In the OLT for multiplexing / demultiplexing the signals of the CWDM-PON wavelength and the HFC ONU signal, each independent service can be provided. Referring back to FIG. 3 for more detailed description, the CMTS 310 is connected to the demultiplexer of the OLT 360 (1310 nm or 1550 nm portion) and the multiplexing / demultiplexing of the OLT 360 is connected to the OLT 360. It is connected to the wavelengths of other optical transmission / reception channel cards except 1310 nm or 1550 nm, and multiplexes optical signals of all wavelengths to transmit the multiplexed optical signals to the optical splitter 370. Upon receiving the multiplexed optical signal, the optical splitter 370 splits the optical signal having a wavelength of 10 nm or 1550 nm into the HFC ONU 330 and splits the remaining optical signals into the CWDM-PON ONU. Done. ONU 330 for HFC receives the 1310 nm or 1550 nm branched optical signal, converts it into an RF signal and transmits it to the CM through a coaxial cable, and the ONU 380 for CWDM-PON diverges the optical branch from the optical splitter. Receives the signal, photoelectric conversion, and then transmits the data to the subscriber PC.

Now, the procedure of the optical transmission method for sharing the optical path in the optical coaxial mixed network (HFC) and the optical wavelength multiplexed transmission network (CWDM-PON) will be described.

5 is a flowchart illustrating an optical transmission method according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the CM connected to the subscriber PC transmits the data converted into the RF signal to the ONU for the HFC (step 400). The ONU for HFC transmits the optical signal obtained by photoelectric conversion to the optical splitter (step 410), and the optical splitter multiplexes the optical signal from the ONFC for HFC and the optical signal from the ONDM for CWDM-PON to the OLT. (Step 420). The OLT multiplexer / demultiplexer demultiplexes this multiplexed optical signal into the optical signal from the ONU for HFC and the optical signal from the CWDM-PON ONU, and transmits the optical signal from the HFC ONU to the optical transceiver and transmits CWDM The optical signal from the ONU for PON is provided to the Internet network (step 430). On the other hand, the transmitted optical signal from the ONFC for HFC is converted into an RF signal by the optical transceiver and transmitted to the CMTS (step 440), and the CMTS provides the RF signal to the Internet network (step 450).

This procedure is by the uplink optical transmission method according to a preferred embodiment of the present invention, it is apparent that such an optical transmission method can proceed in the reverse direction for the downlink transmission.

While the present invention has been described with reference to the preferred embodiments, those skilled in the art will understand that changes may be made without departing from the spirit and scope of the invention. In other words, the present invention may be modified within the scope of the appended claims and should not be considered as being limited to the above-described exemplary embodiments.

The CWDM-PON method is applied between the CMTS equipment (including the optical transceiver) of the HFC network already established and the ONU for HFC to transmit the optical signal transmitted from the CMTS of the NHFC to one wavelength of the OLT of the CWDM-PON configuration. And multiplex with the other wavelengths of CWDM-PON and transmit them to the optical splitter installed in front of the ONU for HFC, and the optical splitter demultiplexes the wavelength of the HFC optical signal and CWDM-PON multiplexed from the OLT to the existing HFC. Optical signal is transmitted to ONFC for HFC and CWDM-PON wavelength signal is transmitted to ONDM for CWDM-PON to provide communication service, and HFC ONU sends signal from each subscriber in reverse direction to HFC. The signal is connected to one wavelength of the optical splitter and the ONU for CWDM-PON is connected to a wavelength other than the wavelength of the signal from the HFC ONU of the optical splitter. The optical splitter multiplexes the optical signals received from the subscriber and transmits them to the OLT, and the OLT demultiplexes the optical signals from the subscriber to provide a communication service. Through this configuration, the present invention adds the CWDM-PON configuration to the existing HFC network configuration, and shares the optical path from the optical transceiver of the HFC network to the ONU for HFC by using the CWDM-PON method and the CWDM-PON method. The HFC method can provide internet services independently of each other.

Claims (6)

In the optical transmission system for sharing the optical path in the optical coaxial mixed network (HFC) and optical wavelength multiplexed transmission network (CWDM-PON), Cable Modem Termination System (CMTS); An optical line termination (OLT) including a multiplexer / demultiplexer for multiplexing optical signals having different wavelengths and outputting them to an optical communication line and demultiplexing and outputting the multiplexed optical signal inputted through the optical communication line; An optical transceiver (OTX / ORX) for receiving an RF signal from the CMTS and transmitting an optical signal obtained by converting the RF signal to the OLT, or converting an optical signal from the OLT into an RF signal and transmitting the RF signal to the CMTS; And Receives the multiplexed optical signal from the OLT through the optical communication line and demultiplexes the optical signal to transmit to the ONU for HFC or the CWDM-PON or the optical signal received from the ONFC for HFC or ONU for CWDM-PON Including; optical splitter for multiplexing and transmitting to the OLT; An optical signal of a part of optical signals having different wavelengths is transmitted and received between the optical transmitter and the OLT, and the optical splitter transmits or receives an optical signal having a predetermined center wavelength to or from the HFC ONU, And an optical signal having a wavelength other than the predetermined center wavelength to the CWDM-PON ONU or from the CWDM-PON ONU. The optical transmission system of claim 1, wherein the different wavelengths are determined at 20 nm intervals within a range of 1260 nm to 1620 nm, and the predetermined center wavelength is either 1310 nm or 1550 nm. The method of claim 1, The OLT further comprises an optical transmission / reception channel unit connected to the multiplexer / demultiplexer to transmit and receive optical signals of respective wavelengths. The optical transmission system according to claim 3, wherein the OLT further comprises a switching unit connected to the optical transmission / reception channel unit and providing switching and routing to connect the OLT and the Internet network. In the optical transmission method for sharing the optical path in the optical coaxial mixed network (HFC) and optical wavelength multiplexed transmission network (CWDM-PON), Transmitting the data converted into the RF signal by the cable modem CM to the ONU for HFC; Converting the data into an optical signal by the HFC ONU and transmitting the optical signal to an optical splitter; Multiplexing the optical signal from the ONFC for HFC and the optical signal from the CWDM-PON ONU by the optical splitter and transmitting to the OLT;  The optical signal from the ONFC for HFC and the optical signal from the CWDM-PON ONU are demultiplexed by the OLT multiplexer / demultiplexer to transmit the optical signal from the demultiplexed HFC ONU to an optical transceiver, Providing an optical signal from the demultiplexed CWDM-PON ONU to an internet network; Converting the transmitted optical signal from the ONFC for HFC to an RF signal by the optical transceiver and transmitting the RF signal to a CMTS; And Providing the RF signal to the internet network by the CMTS. The optical wavelength of the optical signal from the ONU for HFC is any one of 1310 nm or 1550 nm, and the wavelength of the optical signal from the ONU for CWDM-PON is 20 within a range of 1260 nm to 1620 nm. and a wavelength excluding the 1310 nm or 1550 nm among wavelengths determined at nm intervals.

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