KR100628326B1 - HFC network system and data transmission method therein - Google Patents

Abstract

An HFC network system and a signal transmission method in the HFC network system are disclosed. Each of them receives an optical signal mixed with a broadcast signal and a downlink data signal, converts the optical signal into an electrical signal, provides the converted signal to the subscriber station through the coaxial cable network, and transmits the uplink data transmitted from the subscriber terminal through the coaxial cable network. The HFC network system according to the present invention includes a plurality of ONUs for retransmitting signals and a CMTS for connecting the HFC networks with the Internet network, and includes a combiner, an optical amplification transmitter, a splitter, and a multiplexing transmitter. By applying the PON technology using the optical amplification transmitter 525 and the splitter 530 for downlink data communication, the number of downlink paths can be reduced to a maximum of 1 / n as compared with the conventional art. In addition, by applying the WDM technology for uplink data communication, the number of uplink beams can be reduced to 1 / n at maximum compared to the conventional art. Therefore, the cost of network expansion can be greatly reduced.

Description

HFC network system and data transmission method therein

 1 is a diagram illustrating a CATV service method using an optical / coaxial mixed network (HFC) currently installed.

2 is a diagram illustrating a communication / broadcasting converged HFC transmission network in detail.

3 is a diagram illustrating a satellite broadcasting service in the form of another broadcasting service currently being provided.

Figure 4 is a block diagram schematically showing an HFC network system according to the present invention using the PON technology.

FIG. 5 is a block diagram schematically illustrating the WDM MUX 555 and the WDM DEMUX 550 shown in FIG. 4.

The present invention relates to an HFC (Hybrid Fiber Coaxial) network system that integrates broadcasting and communication services, and in particular, an HFC network that can effectively reduce the number of up / down paths by applying a passive optical network (PON) technology WDM technology. The present invention provides a signal transmission method in a system and the HFC network system.

Recently, in a broadband integrated network (BcN) environment in which wired / wireless convergence and communication and broadcasting are converged, a subscriber network type of high-speed infrastructure for providing high-speed Internet service and digital broadcasting service is copper line-based ASL (Asymmetric Digital Subscriber Line). Very high-data rate Digital Subscriber Line (VDSL), Hybrid Fiber Coaxial (HFC), an optical / coaxial mixed network, and Fiber-to-Home (FTTH) based on fiber. The xDSL and HFC networks are different in terms of network configuration and transmission capability, but they are ultimately approaching FTTH (Fiber To The Home).

Although xDSL and HFC networks are widely used, there are many limitations to use them as broadband integrated networks (BcN) due to system configuration problems along with the limitations of the media's inherent transmission capability. However, HFC network has the advantage of using the existing infrastructure, and the transmission capacity is also very good compared to xDSL. And today, with a transmission capacity of several Gbps at a transmission bandwidth of 750 MHz, and more if the transmission band is extended to 2 GHz and digital technology is further developed. In addition, in the data service using the CMTS, since high-bandwidth services are available in both up and down directions, it is advantageous to apply the HFC network in terms of BcN subscriber network integration.

The recent HFC network is designed to enable 30Mbps up and down data transfer rate by adopting DOCSIS (Data Over Cable Service Interface Specification) 2.0 technology, and it is 3 times more advanced than the existing service that was only capable of 10Mbps. It can serve a variety of applications such as video conferencing, one-to-one or one-to-many data transfer services. However, the main problem of HFC network is that the cable and system interface investment cost is excessive.

1 is a diagram illustrating a CATV service method using an optical / coaxial mixed network (HFC) currently installed. The CATV network of FIG. 1 provides a broadcast service to a subscriber by changing a channel received from a broadcast program producer (Program Provider) 101, a broadcast program producer (PP) and a self-produced program. Service provider SO (System Operator) 102, consisting of CATV delivery network 103 for transmitting broadcast signals to SO and CATV subscriber distribution network (104) for delivering broadcast signals from System Operator (102) to subscribers do. The CATV subscriber distribution network is called a hybrid fiber coaxial (HFC) network because an optical cable and a coaxial cable are mixed from the distribution center to the subscriber 105, and can provide cable TV service and Internet service.

The service provider SO 102 transmits the received content to the subscriber or the broadcasting function unit 106 for inserting its own advertisement or subtitles to the subscriber and the distribution center for transmitting the broadcast signal. It is composed.

The CATV subscriber distribution network 104 has an ONU system 108 for converting an optical signal transmitted from the distribution center 107 into an electrical signal, and broadcast data converted into an electrical signal in the ONU system 108 is transmitted through a coaxial cable line. It is delivered to the subscriber, and accepts the subscriber by using a repeater and a splitter according to the distance.

As shown in Figure 1, the main purpose of the CATV cable network using the HFC is to provide a service of cable TV broadcasting, by utilizing some of the bandwidth of the installed network, Internet service, VOD (Video on demand) service, telephone service, etc. It is attempting to combine and is the most powerful recommendation technology that converges commercially available broadcasting and communication at the same time. However, the CATV network is designed based on the broadcasting network, and the bandwidth for data communication for the Internet service is insufficient, and the VOD broadcast service is not easy due to the problem of bandwidth for data communication. In order to accommodate the VOD broadcasting service, the cable technology standard of the new HFC network is currently enacted, but when the technology standard is completed, the installation of new service equipment is required on the SO and subscriber side. In addition, the CATV distribution network 103 between the broadcast producer 101 and the SO 102 providing content in FIG. 1 uses an ATM network or a dedicated line. When using an ATM network, the transmission efficiency is low, and when using a dedicated line, the service price of the line is high.

2 is a diagram illustrating a communication / broadcasting converged HFC transmission network in detail. Referring to FIG. 2, a cable modem termination device (CMTS) 400 that connects a broadcast HFC network with an Internet network is typically equipped with several line interface cards 401. 2 illustrates a line interface card supporting an uplink 6 channel and a downlink 1 channel, which are generally used.

The broadcast signal and the data signal are combined into one signal having different frequency bands through the combiner 405. The signal integrated by the combiner 405 is transmitted to the optical network unit 402 through the optical transmitter 406 and the downlink optical transmission path 410 of the HFC network. That is, in FIG. 2, the ONU 402 becomes an end device of the optical transmission path. The ONU 402 and the subscriber are connected via a coaxial cable network 403, and the data transmission section of the HFC network started from the CMTS 400 is terminated in a cable modem CM 407. The subscriber may receive the broadcast service 408 and the data service 409 through the CM 407.

Meanwhile, the uplink data signal transmitted from the subscriber is transmitted to the CMTS 400 through the uplink optical transmission path 411.

As described above, the conventional communication / broadcast converged HFC transmission network requires a separate up / down optical transmission path (410, 411) per cell between the CMTS 400 and the ONU 403. Problem arises.

3 is a diagram illustrating a satellite broadcasting service in the form of another broadcasting service currently being provided. Referring to FIG. 3, a satellite broadcast program transmits a radio wave from a broadcasting station to a transmission station in each region. Unlike terrestrial broadcasting, which is transmitted to each home from the broadcasting station, satellite broadcasting programs received from a channel service provider 201 called PP are satellites. A method of transmitting data while transmitting radio waves to the ground through 202. It is currently being serviced under the name of digital satellite broadcasting in Korea, and a separate fee and equipment (satellite antenna, STB) are required to use it. However, the concept of satellite broadcasting requires a separate network such as telephone line 204 and additional costs for VOD or Internet service, and there is no content compatibility with CATV broadcasting service. Difficult to provide.

 An object of the present invention is to provide a HFC network system that can effectively reduce the number of up / down optical path by applying the PON technology and WDM technology.

Another object of the present invention is to provide a signal transmission method in the HFC network system.

In order to achieve the above technical problem, each of which receives an optical signal mixed with a broadcast signal and a downlink data signal and converts it into an electrical signal, and provides the converted signal to the subscriber station through a coaxial cable network, and the coaxial cable from the subscriber terminal The HFC network system according to the present invention includes a plurality of ONUs for retransmitting uplink data signals transmitted through a network and a CMTS for connecting the HFC network with the Internet network. A combiner for combining into a single signal having a band, an optical amplification transmitter for converting and amplifying the combined signal into an optical signal, and transmitting the converted and amplified optical signal through a downlink path, and an optical signal transmitted through an optical path A photo splitter for splitting into multiple ONUs and optical conversion of each of a plurality of uplink data signals provided from the multiple ONUs And, it is preferable to include a multiplexed transmission unit for assigning different wavelengths to each of the photo-converted signal, then multiplexed and transmitted through the uplink, and separates and reconstructs the optical signal transmitted from the terminal for each wavelength to provide to the CMTS. Do.

In order to achieve the above another technical problem, each of them receives an optical signal mixed with a broadcast signal and a downlink data signal, converts it into an electrical signal, provides the converted signal to a subscriber station through a coaxial cable network, and coaxially with a subscriber station. In a HFC network system including a plurality of ONUs for retransmitting uplink data signals transmitted through a cable network and a CMTS for connecting an HFC network to an Internet network, a broadcast signal and a downlink data communication service method are provided in a broadcast signal and a downlink data communication service. (A) transmitting to a plurality of ONUs through one downlink by applying an E-PON technique, and (b) photoconverting each of a plurality of uplink data signals provided from the plurality of ONUs, (C) transmitting different signals by assigning different wavelengths to each signal and transmitting them through the uplink, and optical transmission transmitted through the uplink It is preferable to include the step (d) of separating and reconstructing the call by wavelength to provide the CMTS.

Hereinafter, an HFC network system and a signal transmission method in the HFC network system according to the present invention will be described with reference to the accompanying drawings.

Figure 4 is a block diagram schematically showing an HFC network system according to the present invention using the PON technology. Referring to FIG. 4, the HFC network system according to the present invention includes a head end 500, a distributor 505, a combiner 510, an optical amplification transmitter 525, a splitter 530, a plurality of ONUs 535, and CMTS. 520, an up converter 515, a WDM unit 590, a coaxial cable network 545, and a cable modem 540. Referring to Figure 4 will be described the configuration and signal transmission process of the HFC network according to the present invention.

Referring to FIG. 4, the combiner 510 uses a different frequency band from a broadcast signal transmitted through the head end 500 and the distributor 505 and a data signal transmitted through the CMTS 520 and the upconverter 515. Combine into a single signal.

The optical amplification transmitter 525 converts and amplifies the signal combined in the combiner 510 into an optical signal, and transmits it to the splitter 530 through the optical path 527.

The splitter 530 distributes the optical signal amplified by the optical amplification transmitter 525 to a plurality of ONUs 535. As such, by using the optical amplification transmitter 525 and the splitter 530 for the broadcast service and the downlink data communication, the number of optical paths for the broadcast service and the downlink data communication is reduced to a maximum of 1 / n compared to the conventional HFC network. Can be.

Each of the plurality of ONUs 535 converts an optical signal transmitted from the splitter 530 into an electrical signal and transmits the signal to the coaxial cable network 545, or transmits an uplink data signal transmitted from the coaxial cable network 545 to the WDM MUX. To 555.

The cable modem 540 separates a broadcast signal and a data signal from a signal transmitted from the coaxial cable network 545, and provides a broadcast signal to the set top box STB 575, and provides a data signal to the communication terminal 580. . In addition, the cable modem 540 receives an uplink data signal provided from the communication terminal 580 and transmits the upstream data signal to the ONU 535 through the coaxial cable network 545.

The multiplexing transmitter 590 photoconverts each of the n uplink data signals provided from the plurality of ONUs 535, assigns a different wavelength to each of the photoconverted signals, and multiplexes one optical path 565. And transmits the optical signal to the CMTS 520 by separating and reconstructing the optical signal at the end. The multiplexing transmitter 590 includes a WDM MUX 555 and a WDM DEMUX 550.

The WDM MUX 555 photoconverts each of the n uplink data signals provided from the plurality of ONUs 535 at the end of the plurality of ONUs 535 and assigns a different wavelength to each of the photoconverted signals. After multiplexing, the signal is transmitted through one optical line 565.

The WDM DEMUX 550 separates and reconstructs an optical signal transmitted through the optical path 565 for each wavelength, and provides the separated and reconstructed signal to the CMTS 520. As such, by using the WDM MUX 555 and the WDM DEMUX 550, the number of optical lines used for uplink data communication can be reduced to a maximum of 1 / n as compared to the conventional HFC network.

Subsequently, the CMTS 520 is a device that connects the HFC network with the Internet network as described above, and typically, several line interface cards 560 are mounted. FIG. 5 illustrates a line interface card supporting uplink 6 channels and downlink 1 channels, which are generally used.

As described above, according to the HFC network system and the signal transmission method in the HFC network system according to the present invention, E using the optical amplification transmitter 525 and the splitter 530 for broadcast service and downlink data communication By applying the PON technique, the number of downlink paths can be reduced to a maximum of 1 / n in comparison with the conventional art. In addition, by applying the WDM technology for uplink data communication, the number of uplink beams can be reduced to 1 / n at maximum compared to the conventional art. As a result, the cost of network expansion can be greatly reduced.

FIG. 5 is a block diagram schematically illustrating the WDM MUX 555 and the WDM DEMUX 550 shown in FIG. 4. Referring to FIG. 5, the WDM MUX 555 includes a plurality of optical receivers 635, a plurality of CWDM optical transmitter modules 630, and a CWDM MUX 620, and the WDM DEMUX 550 includes a CWDM DEMUX ( 610 and the CWD light receiving module 600 is configured.

Referring to FIG. 5, in the WDM MUX 555, the plurality of optical receivers 635 respectively correspond to the plurality of ONUs 535, and convert the uplink data signals received from the corresponding ONUs 535 into optical signals to convert the CWDM signals into CWDM signals. Transmit to the optical transmission module 630.

The plurality of CWDM optical transmitter modules 630 correspond to each of the plurality of optical receivers 635, and each of the plurality of CWDM optical transmitter modules 630 allocates different wavelengths to the received optical signals and provides them to the CWDM MUX 620.

The CWDM MUX 620 multiplexes the optical signals assigned different wavelengths by the plurality of CWDM optical transmission modules 630 and transmits the multiplexed optical signals to the WDM DEMUX 550 through one optical path 565.

The CWDM DEMUX 610 in the WDM DEMUX 550 separates optical paths transmitted through the optical path 565 according to wavelengths, and provides the separated optical signals to the corresponding CWDM optical reception modules 600.

The CWDM optical reception module 600 restores the received optical signal separated by wavelength to the original optical signal before the wavelength division and provides the received optical signal to the CMTS 520.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the above-described specific preferred embodiments, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

As described above, according to the signal transmission method in the HFC network system and the HFC network system according to the present invention, PON technology using the optical amplification transmitter 525 and the splitter 530 for broadcast service and downlink data communication is applied. By doing so, the number of downlink paths can be reduced to a maximum of 1 / n in comparison with the conventional art. In addition, by applying the WDM technology for uplink data communication, the number of uplink beams can be reduced to 1 / n at maximum compared to the conventional art. Therefore, the cost of network expansion can be greatly reduced.

Claims (8)

Each receives an optical signal mixed with a broadcast signal and a downlink data signal, converts the optical signal into an electrical signal, provides the converted signal to a subscriber station through a coaxial cable network, and transmits the transmitted signal from the subscriber terminal through the coaxial cable network. In the HFC network system including a CMTS for connecting a plurality of ONU and HFC network to retransmit uplink data signal to the Internet network, A combiner for combining the broadcast signal and the downlink data signal provided from the CMTS into one signal having a different frequency band; An optical amplifying transmitter for converting and amplifying the combined signal from the combiner into an optical signal and transmitting the converted and amplified optical signal through a downlink path; A splitter for distributing an optical signal transmitted through the optical path to the plurality of ONUs; And Photoconvert each of a plurality of uplink data signals provided from the plurality of ONUs, assign a different wavelength to each of the photoconverted signals, multiplex them, transmit the signals through an uplink, and then transmit the optical signals transmitted from an end. HFC network system comprising a multiplexed transmission unit for separating and reconstructing for each wavelength provided to the CMTS. The method of claim 1, wherein the multiplexing transmitter At the ends of the plurality of ONUs, photoconvert each of the uplink data signals provided from each of the plurality of ONUs, multiplex by assigning different wavelengths to each of the photoconverted signals, and multiplex the multiplexed signal to the uplink optical path. Transmitted via WDM mux; And And a WDM demux for separating and restoring the optical signal transmitted through the uplink path for each wavelength and providing the separated and recovered signal to the CMTS. The method of claim 2, wherein the WDM mux A plurality of optical receivers corresponding to each of the plurality of ONUs and converting an uplink data signal received from the corresponding ONU into an optical signal; A plurality of CWDM optical transmitter modules which correspond to each of the plurality of optical receivers and allocate different wavelengths to the optical signals converted from the corresponding optical receivers; And And a CWDM MUX for transmitting the uplink by multiplexing an optical signal assigned with different wavelengths by the plurality of CWDM optical transmission modules. The method of claim 2, wherein the WDM DEMUX is CWDM DEMUX for separating the optical signal transmitted through the uplink according to the wavelength; And And a plurality of CWDM optical reception modules for receiving the optical signals separated by wavelengths in the CWDM DEMUX, reconstructing the original optical signals before wavelength division, and providing them to the CMTS. Each receives an optical signal mixed with a broadcast signal and a downlink data signal, converts the optical signal into an electrical signal, provides the converted signal to a subscriber station through a coaxial cable network, and transmits the transmitted signal from the subscriber terminal through the coaxial cable network. A signal transmission method in an HFC network system including a plurality of ONUs for retransmitting uplink data signals and a CMTS for connecting an HFC network with an Internet network, (a) transmitting the broadcast signal and the downlink data communication service to the plurality of ONUs through one downlink by applying a PON technique; (b) photoconverting each of the plurality of uplink data signals provided from the plurality of ONUs; (c) assigning different wavelengths to each photoconverted signal and multiplexing the same, then transmitting them through an uplink path; And (d) separating and reconstructing the optical signal transmitted through the uplink path for each wavelength and providing the CMTS to the CMTS. The method of claim 5, wherein step (a) (a1) combining the broadcast signal and the downlink data signal into one signal having different frequency bands; (a2) converting and amplifying the signal combined in the step (a2) into an optical signal; (a3) transmitting the optical signal converted and amplified in step (a2) through one downlink path; And (a4) a method of transmitting a signal in the HFC network system, comprising distributing an optical signal transmitted through the downlink path to the plurality of ONUs. The method of claim 5, wherein step (c) (c1) assigning and converting a different wavelength to each of the plurality of optical signals photoconverted in the step (b); And and (c2) multiplexing the optical signal converted in step (c1) and transmitting the multiplexed optical signal through the uplink optical path. The method of claim 5, wherein step (d) (d1) separating the optical signal transmitted through the uplink path according to a wavelength; And and (d2) restoring the optical signals separated by wavelengths in the step (d1) to the original optical signals before wavelength division and providing them to the CMTS.

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