KR100671052B1 - An Optical transceiver having a function of multiplexing in hybrid fiber coaxial network - Google Patents

Abstract

The present invention provides a coaxial cable network by converting a coaxial cable available frequency band abnormal band (L band) from a headend system to a different frequency for each subscriber subcell in a hybrid fiber coaxial (HFC) network. Optical transmission / reception apparatus having a multiplexing function in an optical coaxial mixed network for transmitting to a headend system by converting an uplink signal (US band) inputted from a plurality of subcells into different channels of a coaxial cable available frequency band And it relates to a method, the present invention, frequency up-converting means for up-converting the plurality of downlink channels received from the cable modem to the band of the coaxial cable available frequency band corresponding to the destination sub-cell of the optical cable network; Frequency combining means for combining a plurality of coaxial cable available frequency bands or more downlink channel signals received from the frequency upconverting means with broadcast signals of the coaxial cable available frequency bands; First all-optical converting means for converting the signal combined by said frequency combining means into an optical signal and transmitting it to an outdoor optical transmitter of said optical cable network; First photoelectric conversion means for converting the multiplexed uplink signal received from the outdoor optical transceiver through the optical cable network into an electrical signal; Frequency distribution means for demultiplexing the uplink signal converted by the first photoelectric conversion means into an electrical signal and outputting a plurality of channel signals equal to or greater than the coaxial cable available frequency band corresponding to the subcell and a broadcast signal of the coaxial cable available frequency band; And a frequency downconverting means for receiving the uplink signal demultiplexed by the frequency distribution means, downconverting to an intermediate frequency, and outputting the intermediate signal to the cable modem.

Optical coaxial network, outdoor optical transceiver, subcell, L band, In band, signal multiplexing

Description

An optical transceiver having a function of multiplexing in hybrid fiber coaxial network

1 is a configuration diagram of an embodiment of an HFC network-based digital CATV transmission system to which the present invention is applied;

2 is a block diagram of an optical transmission and reception device having a multiplexing function in an optical coaxial mixed network according to an embodiment of the present invention;

3A, 3B, 3C, 3D, and 3E are explanatory diagrams of a downlink signal processing process of an optical transmission / reception apparatus having a multiplexing function in an optical coaxial mixed network according to an embodiment of the present invention;

4 is a block diagram of an optical transmission and reception device having a multiplexing function in an optical coaxial mixed network according to another embodiment of the present invention;

5A, 5B, and 5C are explanatory diagrams for an uplink signal processing process of an optical transmission / reception apparatus having a multiplexing function in an optical coaxial mixed network according to another embodiment of the present invention;

6 is a block diagram of an optical transmission and reception device having a multiplexing function in an optical coaxial mixed network according to another embodiment of the present invention;

7 is a circuit diagram of a downlink signal processor and an uplink signal processor of an optical transmission / reception apparatus having a multiplexing function in an optical coaxial mixed network according to another embodiment of the present invention.

* Explanation of symbols on the main parts of the drawing

100: head end system 111,112,113: outdoor optical transmission and reception device

212 up-converter 214 frequency combiner

216: photoelectric converter 218: photoelectric converter

220: frequency divider 222: down-converter

321: photoelectric conversion unit 322: downlink signal processing unit

323: uplink signal processor 324: all-optical converter

The present invention relates to an optical transmission and reception apparatus having a multiplexing function in an optical coaxial mixed network, and more particularly, to more than a coaxial cable available frequency band from a headend system in a hybrid fiber coaxial (HFC) network. The downlink signal of the band (L band) is converted into a different frequency for each subscriber subcell and transmitted to the coaxial cable network, and the uplink signal (US band) input from a plurality of subcells is different from the coaxial cable available frequency band. The present invention relates to an optical transmission / reception apparatus having a multiplexing function and a method for transmitting the same to a headend system.

In the recent information age, the use of the Internet has increased exponentially and the demand for multimedia data has increased, causing bottlenecks in the transmission network. In order to solve the bottleneck and provide high speed data service, ISDN (Universal Information Network), ADSL (Asymmetric Digital Subscriber Line), Cable TV Network, Satellite, and Wireless Subscriber Network (WLL) are used. . Among them, cable TV network has wider bidirectional bandwidth than other networks, and it is considered one of the most valid networks because many cables are already installed to subscribers.

However, since cable TV networks are designed for broadcasting rather than interactive multimedia services, there is a need to improve existing transmission networks in order to provide high-speed data services using cable TV networks. The emergence of this demand is the hybrid fiber coaxial (HFC) network.

A hybrid fiber coaxial (HFC) network refers to a network connected to a fiber node from a broadcaster by an optical cable, and a line from the remaining optical distribution point to a subscriber is connected by a coaxial cable.

The simplest form of HFC is the use of optical cables from broadcast stations to optical distribution points that serve 500 to 2,000 households. Coaxial lines are then provided from one optical distribution point to the home, and connected to set-top boxes, cable modems, etc., depending on the service.

Referring to Figure 1 will be described the configuration of a typical CATX transmission system based on a hybrid fiber coaxial (HFC) network.

1 is a configuration diagram of an embodiment of an HFC network-based digital CATV transmission system to which the present invention is applied.

As shown in FIG. 1, the HFC network-based digital DATV transmission system to which the present invention is applied includes a headend system 100 and a plurality of outdoor optical transmitting and receiving devices (ONUs) 111, 112, and 113.

The headend system 100 exchanges signals with a plurality of cells 121, 122, and 123 through a plurality of outdoor optical transmitting and receiving devices (ONUs) 111, 112, and 113. Here, the head end system 100 and the outdoor optical transceivers 111, 112, and 113 are connected by an optical cable network, and the outdoor optical transceivers 111, 112, 113 and the plurality of cells 121, 122, and 123 are connected by a coaxial cable network. .

As described above, an optical fiber coaxial (HFC) network is composed of an optical cable network and a coaxial cable network, and an optical signal unit (ONU: Optical Node Unit) (111, 112, 113) is used to convert an optical signal into an electrical signal or Do the reverse process.

Meanwhile, when transmitting a cable signal in a general digital CATV transmission system, the headend system 100 first modulates a signal using a cable modem to convert the signal into a specific frequency band, and then broadcasts a specific channel, that is, a coaxial cable available frequency band. It is combined with the in-band signal and outputs to the optical cable network through an all-optical converter.

The modulated output signal is received by the outdoor optical transceivers (ONU) 111, 112, and 113 through an optical cable network, and the outdoor optical transmitters (ONUs) 111, 112, and 113 convert the optical signals into electrical signals and then each outdoor unit. Outputs to a coaxial cable network through one or more coaxial cables connected to the optical transmitting and receiving unit (ONU) (111, 112, 113). Finally, subscribers receive the cable broadcast signal through the coaxial cable network.

However, the conventional outdoor optical transmitter and receiver (ONU) (111, 112, 113) is a device used for the connection between the optical cable network and the coaxial cable network, the role of simply transmitting the up / down signal through the photoelectric signal conversion. That is, the conventional outdoor optical transmitter and receiver (ONU) serves to simply connect the optical cable network and the coaxial cable network through mutual conversion of optical signals and electrical signals.

Therefore, in the case of downlink signal transmission, a plurality of subcells 121, 122, and 123 connected to one outdoor type optical transmitting / receiving device (ONU) 111, 112, and 113 receive the same signal, thereby causing inefficiency.

That is, the conventional outdoor optical transmitter / receiver (ONU) 111, 112 and 113 divides the signal by the number of coaxial cables connected thereto and transmits the signal to the coaxial cable network. In this case, the subscriber included in a specific sub cell The signal transmitted to the broadcaster is also broadcast to all other subscribers connected to the outdoor optical transmitter / receiver (ONU) 111, 112, and 113, which is very inefficient in terms of frequency efficiency.

As a method for improving such a problem and increasing transmission efficiency, a cell division method for dividing into smaller cells has been proposed, but there is a problem in that cell division requires much economic and time expenditure.

On the other hand, in the case of uplink signal transmission, conventionally, the uplink signals inputted from the subscriber through the coaxial cable by the outdoor type optical transmitting / receiving devices (ONUs) 111, 112, and 113 were signals of the same band (for example, 5 to 42 MHz). Since the outdoor optical transmitting / receiving device (ONU) 111, 112, and 113 transmits the uplink signals of the same frequency band (US band, 5 to 42 MHz) to the headend system 100 by simply combining them, they are input through different coaxial cables. There is a high possibility that the cable signals collide, resulting in a decrease in transmission efficiency.

In addition, in the conventional cable TV system, since a subscriber included in a cell shares and uses a specific uplink frequency channel within a preset frequency range, there is a problem in that uplink resource allocated to each subscriber decreases when the number of subscribers per cell increases.

In addition, in the conventional digital CATV transmission system, although the optical cable network between the headend system 100 and the outdoor optical transceiver (ONU) 111, 112, and 113 has a higher usable frequency band than the coaxial cable network, the coaxial cable available frequency band By using only the same band (In band), there was a problem in not using the network resources properly.

The present invention has been proposed in order to solve the above problems, and it is possible to provide a subcarrier subband (L band) downlink signal from a coaxial cable available from a headend system in a hybrid fiber coaxial (HFC) network. Cell division by converting each cell into a different frequency and transmitting it to the coaxial cable network, and converting an uplink signal (US band) inputted from a plurality of subcells into different channels of the coaxial cable available frequency band and transmitting it to the headend system. It is an object of the present invention to provide an optical transmission / reception apparatus having a multiplexing function and a method thereof in an optical coaxial mixed network, which can improve a transmission speed without enormous economic and time expenditure required for the present invention.

In addition, the present invention, in the head-end system of a hybrid fiber coaxial (HFC) network, a plurality of downlink channels received from the outside frequency in a band above the coaxial cable available frequency band corresponding to the destination sub-cell of the optical cable network Another object of the present invention is to provide an optical transmission / reception apparatus having a multiplexing function in an optical coaxial mixed network for converting and transmitting and demultiplexing and transmitting a multiplexed upstream signal received from an outdoor optical transmission / reception apparatus through an optical cable network. have.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The apparatus of the present invention for achieving the above object, in the optical transmission and reception device having a multiplexing function in an optical coaxial mixed network, a plurality of downlink channels received from the cable modem corresponding to the destination subcell of the optical cable network available coaxial cable available Frequency up-converting means for frequency up-converting to a band above the frequency band; Frequency combining means for combining a plurality of coaxial cable available frequency bands or more downlink channel signals received from the frequency upconverting means with broadcast signals of the coaxial cable available frequency bands; First all-optical converting means for converting the signal combined by said frequency combining means into an optical signal and transmitting it to an outdoor optical transmitter of said optical cable network; First photoelectric conversion means for converting the multiplexed uplink signal received from the outdoor optical transceiver through the optical cable network into an electrical signal; Frequency distribution means for demultiplexing the uplink signal converted by the first photoelectric conversion means into an electrical signal and outputting a plurality of channel signals equal to or greater than the coaxial cable available frequency band corresponding to the subcell and a broadcast signal of the coaxial cable available frequency band; And a frequency downconverting means for receiving the uplink signal demultiplexed by the frequency distribution means, downconverting to an intermediate frequency and outputting the intermediate signal to the cable modem.

In addition, the method of the present invention, in the optical transmission and reception method in the optical coaxial mixed network, the head-end device for frequency up-converting a plurality of downlink channels to a band or more than the coaxial cable available frequency band corresponding to the destination sub-cell of the optical cable network step; Combining, by the headend device, a downlink channel signal of a plurality of coaxial cable available frequency bands or more bands up-converted with a broadcast signal of a coaxial cable available frequency band; Converting the combined signal into an optical signal by the headend device and transmitting the converted signal to the outdoor optical receiver; After converting the optical signal received by the outdoor optical transceiver into an electrical signal, a plurality of downlink channel signals of the frequency band above the available frequency band is separated and frequency downconverted, respectively, the downlinked downlink channel signal and the coaxial cable Combining the available frequency band signals with each other and transmitting them to the subscriber station of the corresponding subcell; Transmitting, by the outdoor optical transceiver, an uplink signal transmitted from a subscriber device in the subcell to multiplex by upconverting to a different frequency in an available frequency band of a coaxial cable, and converting and transmitting the multiplexed uplink signal into an optical signal; And converting, by the headend device, the multiplexed uplink signal received from the outdoor optical transmitter into an electrical signal, demultiplexing the signal, and converting the demultiplexed uplink signal into an intermediate frequency.

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The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an optical transmission / reception apparatus having a multiplexing function in an optical coaxial mixed network according to an embodiment of the present invention. In the following description, four downlink channels A, B, C, and C in one cell will be described. An example of transmitting a signal through D) and eight uplink channels E, F, G, H, I, J, K, and L will be described as an example. Here, the eight uplink channels are four channels (E, F, G, H) using a band of 5 to 42 MHz and four channels using an in-band upstream channel (IUC). , J, K, L).

On the other hand, the optical transmission and reception apparatus 200 having a multiplexing function in the optical coaxial mixed network according to an embodiment of the present invention is provided in the head-end system 100, as shown in Figure 2, up-converter (up-converter) ) 212, frequency combiner 214, all-optical converter 216, photoelectric converter 218, frequency divider 220, and down-converter 222.

The cable modem 210 of the headend system 100 may include a system server (eg, SI, SMS, CAS, etc.) 202, an application server (eg, a VOD server, a game server, etc.) within the headend system. 204, data to be transmitted to the subscriber through an audio / video (A / V) encoder 206, an Internet backbone 208, and the like, and each sub-cell corresponding to the final destination is received. After a one-to-one (1: 1) mapping with the (Sub Cell), it is output through downlink channels A, B, C, and D as shown in FIG. 3A through four intermediate frequency (IF) output ports. Here, 'A', 'B', 'C', and 'D' are intermediate frequency (IF) downlink signals.

The up-converter 212 frequency converts the downlink channel received from the cable modem 210 into a band (L band) of the coaxial cable available frequency band corresponding to the destination subcell of the optical cable network. At this time, the output signal is A [RF1], B [RF2], C [RF3], D [RF4] shown in FIG. 3B, where RF1, RF2, RF3, RF4 have a center frequency equal to or greater than the available frequency band of the coaxial cable. Represents a downlink RF signal present in the band (L band).

The frequency combiner 214 is a downlink channel signal of a coaxial cable available frequency band or higher band (L band) received from an up-converter 212 and a broadcast signal in the coaxial cable available frequency band (in-band). (In-Band) signal) is combined and output.

The all-optical converter 216 outputs the output signal from the frequency combiner 214 to the optical signal {A [RF1] + B [RF2] + C [RF3] + D [RF4] as shown in FIG. 3E. } + Coaxial cable is converted into a broadcast signal (in-band signal) in the available frequency band) and output to the outdoor optical transceiver (ONU) (300). Here, RF1, RF2, RF3, RF4 represents a downlink RF signal in which the center frequency is present in the band (L band) of the coaxial cable available frequency band or more.

The photoelectric converter 218 receives a multiplexed uplink optical signal from an outdoor type optical transmitter / receiver 300 through an optical cable network, converts the uplink optical signal into an uplink electrical signal, and outputs the uplink electrical signal to a frequency splitter 220.

The frequency splitter 220 uses four signals E [RF5], F [RF6], and G [RF7] as shown in FIG. 3C to convert the uplink electric signals multiplexed from the outdoor optical transmitter / receiver 300. FIG. , H [RF8]) is demultiplexed and output to the down-converter 222.

The down-converter 222 receives a demultiplexed uplink electrical signal from a frequency splitter 220 and down-converts the frequency to an intermediate frequency (IF) signal, respectively, to provide a cable modem ( 210). Here, the output signal of the down-converter 222 is four intermediate frequency (IF) uplink signals of 'E', 'F', 'G', and 'H' as shown in FIG. 3D.

The cable modem 210 transmits an upstream signal received from a down-converter 222 to a corresponding place such as a system server 202, an application server 204, an Internet backbone 208, and the like. Output

4 is a block diagram of an optical transmission and reception device having a multiplexing function in an optical coaxial mixed network according to another embodiment of the present invention, and shows an example applied to an outdoor type optical transmission and reception device (ONU) 300.

The outdoor optical transmitter / receiver (ONU) 300 is a coaxial cable available with a downlink channel signal of a plurality of coaxial cable available frequency bands or more bands (L band) as shown in FIG. 3E from an all-optical converter 216 through an optical cable network. Optical signal combined with in-band broadcasting signal (in-band signal) {A [RF1] + B [RF2] + C [RF3] + D [RF4]} + Coaxial cable Available frequency band broadcasting signal (in-band Signal)), and down-convert the downlink signals of a plurality of coaxial cable available frequency band abnormal bands (L band) into signals of different coaxial cable available frequency bands as shown in FIG. 5A. At this time, the center frequency of each converted downlink signal is [RF13] MHz, which is a value within an available frequency band of a coaxial cable.

In addition, the outdoor optical transmitter / receiver (ONU) 300 combines four downlink channels, which are frequency-converted to the center frequency [RF13] MHz, with a coaxial cable available frequency band broadcast signal (in-band signal), and then each coaxial cable. It transmits to the corresponding sub cell through.

That is, the outdoor optical transmitting / receiving device (ONU) 300 transmits the sub-cell 1 through 'A [RF13] + coaxial cable available frequency band in-band signal (in-band signal)' of FIG. 5A through each coaxial cable. 2, 'B [RF13] + coaxial cable available frequency band broadcast signal (in-band signal) of FIG. 5A, and subcell 3 is' C [RF13] + coaxial cable available frequency band broadcast signal (in- Band signal) 'and' D [RF13] + coaxial cable available frequency band broadcast signal (in-band signal) 'of FIG. 5A. Here, RF13 represents a downlink RF signal in which the center frequency is present in the coaxial cable available frequency band.

On the other hand, the outdoor optical transceiver 300 is an uplink channel (E, F, G, H) using a 5 to 42MHz uplink band from each sub-cell and IUC (In-) using another band Band Upstream Channel) (I, J, K, L) is input through 4 coaxial cables. That is, the outdoor type optical transceiver 300 is E [RF14] of FIG. 5B from subcell 1, F [RF14] of FIG. 5B from subcell 2, G [RF14] of FIG. 5B from subcell 3, The subcell 4 receives the H [RF14] of FIG. 5B. Here, RF14 represents an uplink RF signal having a center frequency of 5 to 42 MHz.

In addition, the outdoor optical transmitter / receiver 300 uses the coaxial cable available for E [RF14], F [RF14], G [RF14], and H [RF14] signals of FIG. 5B received from a plurality of subcells through a coaxial cable network. Each frequency is converted into a frequency band and then multiplexed and output to the headend system 100. At this time, the output signal of the outdoor type optical transmitter / receiver 300 is the same as the signal combining E [RF5], F [RF6], G [RF7], H [RF8], as shown in FIG. 5C.

To this end, as shown in FIG. 6, the outdoor type optical transmitter / receiver 300 according to the present invention includes a photoelectric converter 321, a downlink signal processor 322, an uplink signal processor 323, and an all-optical light beam. The conversion unit 324 is included.

The photoelectric conversion unit 321 converts an optical signal in which a plurality of coaxial cable available frequency bands or more downlink channel signals received from the headend system through an optical cable network and a coaxial cable available frequency band signal are combined into an electrical signal. . That is, the photoelectric conversion unit 321 is a coaxial cable available frequency band signal (In-Band signal) and the band 'A', 'B', 'C', 'D' from the head-end system 100 It receives the combined optical signal and converts it into an electrical signal.

 The downlink signal processor 322 separates down channel signals of a plurality of coaxial cable available frequency bands or more bands which are converted into electrical signals by the photoelectric converter 321, respectively, and then frequency downconverts the downlink signals. The channel signal and the coaxial cable available frequency band signal converted by the photoelectric conversion unit 321 into electrical signals are respectively combined and output to the corresponding subcells in the coaxial cable network. That is, the downlink signal processor 322 transmits the coaxial cable available frequency band broadcast signal (in-band signal) and the band 'A', 'B', 'C', and 'D' from the photoelectric converter 321. 'Receives a downlink signal including a signal and separates the signal into respective signals, and then separates each of the separated available frequency bands (In-Band)' A ',' B ',' C 'and' D 'signals. The signal is converted to a coaxial cable available frequency band broadcast signal (in-band signal) and output to the corresponding subcell.

The uplink signal processor 323 up-converts the uplink signals received from a plurality of subcells in the coaxial cable network to different frequencies in the coaxial cable available frequency band, and then combines and multiplexes them. That is, the uplink signal processor 323 receives uplink signals E [RF14], F [RF14], G [RF14], and H [RF14] of different bands from a plurality of subcells, respectively, and uplink signals of 5 to 198 MHz bands. The frequency is up-converted into E [RF5], F [RF6], G [RF7], and H [RF8] and combined and output.

The all-optical converter 324 converts the multiplexed uplink signal combined by the uplink signal processor 323 into an optical signal and transmits the multiplexed uplink signal to the headend system 100 through an optical cable network.

Hereinafter, a detailed circuit configuration of the downlink signal processor 322 and the uplink signal processor 323 will be described in more detail with reference to FIG. 7.

7 is a circuit diagram of a downlink signal processor 322 and an uplink signal processor 323 of an optical transmission / reception apparatus having a multiplexing function in an optical coaxial mixed network according to another embodiment of the present invention.

The AMP1 402 amplifies a signal in the 50 to 1500 MHz band while minimizing noise generation for a weak input signal input from the commonATT 401 as an amplifier.

VariableATT1 403 is a variable attenuator that corrects the dB change in the input signal level and the dB change in the input signal level according to the system temperature change under the control of an automatic gain controller (AGC) 493. Typically, the variable attenuator has a total attenuation range of 8 dB. In addition, the attenuation degree of VariableATT1 403 has a linearity with respect to the control voltage in order to be compatible with a power detector having a linear voltage output with a linear power change.

Divider1 404 divides the signal received from VariableAtt1 403 into two signals and outputs it to LPF1 405 and switch1 411 as a divider.

The LPF1 405 is a low pass filter that removes a signal of 1.1 GHz to 1.5 GHz that may act as an interference or noise. Here, the LPF1 405 preferably suppresses signals other than the signal (1.1 GHz or more) as little as possible while reducing the distortion of the signal within the pass band. It is also preferable to use an order of 8 steps or less so that the size of the filter is not too large.

Att1 406 is a fixed attenuator that maintains the level of the incoming signal at the input of AMP2 407 as appropriate. System performance (CNR (Carrier to Noise Ratio), Composite Triple Bit (CTB), Composite Second Order (CSO), etc.) It is designed to adjust the attenuation by changing the degree of attenuation when the system needs to be optimized and the system-wide gain adjustment is required.

AMP2 407 amplifies a signal between 50 and 870 MHz to a desired level.

Divider2 (408) divides the output of AMP2 (407) into two signals as a divider and outputs to Divider4 (409) and Divider5 (410), Divider4 (409) and Divider5 (410) is a signal received from Divider2 (408) Are divided into two signals and output to Att3 (426) and Att5 (428), Att7 (430) and Att9 (494).

Switch1 411 serves as a switch to prevent a signal from being output to the Att2 413 when the outdoor optical transmitter / receiver 300 is operated using an existing in-band instead of using an L band.

The BPF1 412 is a bandpass filter including a coaxial cable available frequency band signal (in-band) and a coaxial cable available frequency band signal (L band) 'A', 'B', 'C', and 'D'. It extracts the 'A', 'B', 'C' and 'D' signals from the signal.

Att2 413 is a fixed attenuator that maintains the proper level of the signal coming into the input of Switch1 411 to optimize system performance (CNR, CTB, CSO, etc.) and to adjust the overall system gain if necessary. It adjusts the degree of attenuation by adjusting it.

The AMP3 414 amplifies the 'A', 'B', 'C' and 'D' signals extracted from the Att2 413 to an appropriate signal strength.

Divider 3 415 divides the output of AMP3 414 into two signals as a divider and outputs them to Divider 6 416 and Divider 7 417. Divider 6 (416) and Divider 7 (417) divide the signals received from Divider 3 (415) into two signals and output them to Mixer 1 (418), Mixer 2 (419), Mixer 3 (420), and Mixer 4 (421), respectively.

Mixer1 (418), Mixer2 (419), Mixer3 (420), and Mixer4 (421) are mixers, and RF13 signals 'A', 'B', 'C' and 'D' located at RF1, RF2, RF3, and RF4. Performs down conversion (down converting) to position. To this end, Mixer1 418 receives a local oscillation frequency from PLL1 456, Mixer2 419 receives a local oscillation frequency from PLL2 457, and Mixer3 420 receives a local oscillation frequency from PLL3 458. Mixer 4 (421) receives a local oscillation frequency from the PLL4 (459).

BPF2 (422), BPF3 (423), BPF4 (424), and BPF5 (425) are bandpass filters that extract signals 'A', 'B', 'C', and 'D' down-converted to RF13. Do this. The signals filtered by the BPF2 422, BPF3 423, BPF4 424, and BPF5 425 are output to Att4 427, Att6 429, Att8 431, and Att10 495, respectively.

Att4 (427), Att6 (429), Att8 (431), and Att10 (495) are fixed attenuators that adjust the levels of coaxial cable available frequency band signals (in-band) and signals above coaxial cable available frequency bands (L bands). Adjust

Combiner1 432 combines the outputs of Att3 426 and Att4 427 as a combiner and outputs them to EQ1 436. Combiner2 433 combines the outputs of Att5 428 and Att6 429 and outputs them to EQ2 437. Combiner3 434 combines the outputs of Att7 430 and Att8 431 and outputs them to EQ3 438. Combiner4 433 combines the outputs of Att9 494 and Att10 495 and outputs them to EQ4439.

EQ1 436, EQ2 437, EQ3 438, and EQ4 439 are equalizers that serve to attenuate large low frequency signals and small high frequency signals. The reason for this is that the signal attenuation in the high frequency band is large due to the characteristics of the cable, so that the signal is compensated in advance before the signal is output to the cable.

The AMP4 440, the AMP5 441, the AMP6 442, and the AMP7 443 are used to generate a signal of the output level of the outdoor type optical transceiver 300 set as the amplifier.

The directional coupler 444 outputs a portion of the signal output from the AMP4 440 to the automatic gain controller 493 as a 20 dB coupler.

Diplexer1 (445), Diplexer2 (446), Diplexer3 (447), and Diplexer4 (448) output downlink signals corresponding to the 54 to 864 MHz band to subcell 1, subcell 2, subcell 3, and subcell 4, respectively. The uplink signals received from the sub-cell 1, the sub-cell 2, the sub-cell 3, and the sub-cell 4 are output to the AMP8 464, AMP9 465, AMP10 466, and AMP11 467, respectively. Play a role.

The automatic gain control unit 493 performs a function of maintaining the strength of the output signal within an appropriate range. In general, the outdoor optical transceiver 300 is a starting point of all the relay amplifiers present on the coaxial cable. Therefore, the distortion of the signal generated in the outdoor type optical transceiver 300 may be further increased by amplification of other relay amplifiers.

As such, one of the methods for minimizing the distortion of the signal generated in the outdoor optical transmitter / receiver 300 is to prevent the distortion due to nonlinearity that may occur in the active device by keeping the signal level below a proper line at all times. In addition, there is a lower limit of the output power for the reception of the appropriate level of signal at the receiving end, and the output signal should be within the appropriate range. For this reason, an automatic gain control unit 493 is required which keeps the strength of the output signal within an appropriate range.

The operation of the automatic gain control unit 493 is as follows. First, a frequency band (552 MHz to 612 MHz) signal of a specific channel to control gain is extracted from an output signal input through the directional coupler 444 in the BPF 9. The extracted frequency band signal of the specific channel is down-converted to the center frequency of the SAW filter 451 through the MIXER8 450. At this time, the MIXER8 450 obtains the local oscillation frequency through the PLL8 455.

The SAW filter 451 passes (filters) only signals of a specific channel band among signals received through the PLL8 455. The filtered signal is amplified to an appropriate signal strength through the AMP12 452 and then input to the detector 453.

The detector 453 outputs a corresponding DC voltage to the side circuit 454 according to the power level of the signal input through the AMP12 452.

The side circuit 454 attenuates the variable attenuator when the power of the signal transmitted from the detector 453 increases, for proper voltage matching between the detector 453 and the variable att1 403. It transmits a signal to control to increase the, and vice versa to a signal to control to reduce the degree of attenuation.

Switch2 491 serves to determine whether to use the automatic gain control unit 493 as a switch. In other words, when the automatic gain control unit 493 is used, the switch 2491 is turned on, and when the automatic gain control unit 493 is not used, the switch is turned off.

If Switch2491 is turned on, Variable Att1 403 receives a constant voltage of -2.5V 492, and as a result, Variable Att1 403 maintains a constant attenuation.

The TCXO 460 generates a frequency source necessary to generate a local oscillation signal at PLL1 456 to PLL8 455 as a resonator.

PLL1 (456), PLL2 (456), PLL3 (457), PLL4 (458), PLL5 (461), PLL6 (462), PLL7 (463), and PLL8 (455) are phase locked loops that generate local oscillation signals. (PLL: Phase Locked Loop) module generates MIXER1 (418), MIXER2 (419), MIXER3 (420), MIXER4 (421), MIXER5 (480), MIXER6 (481), and MIXER7 (482). ), And MIXER8 (450).

AMP8 (464), AMP9 (465), AMP10 (466), and AMP11 (467) are uplink signals received from Diplexer1 (445), Diplexer2 (446), Diplexer3 (447), and Diplexer4 (448) as amplifiers. 42 MHz band signal) is amplified with minimum noise.

Att11 (468), Att12 (476), Att13 (469), Att14 (477), Att15 (470), Att16 (478), Att17 (471) and Att19 (479) are used as fixed attenuators to properly match signal levels. do.

EQ5 472, EQ6 473, EQ7 474, and EQ8 475, as equalizers, compensate for the frequency attenuation of the upstream signal. It is the same function as the lower equalizer.

MIXER5 480, MIXER6 481, and MIXER7 482 serve as a mixer to separate signals located in the same band into different frequency bands. At this time, the required local oscillation frequency is input from the PLL5 461, the PLL6 462, and the PLL7 463, respectively. Here, MIXER5 480 up-converts (up-converts) the output of EQ6 473 to the 57-94 MHz band, MIXER6 481 up-converts the output of EQ7 474 to the 109-146 MHz band, and MIXER7 ( 482 upconverts the output of EQ8 475 to the 161-198 MHz band.

BPF6 (483), BPF7 (484), and BPF8 (485) removes the interference signal from the signals received from MIXER5 (480), MIXER6 (481), and MIXER7 (482) to filter only signals of a desired band. Perform.

Divier8 486 combines the signals received from Att12 476 and BPF6 483 as a combiner and outputs them to Divider 10 488. Divider 9 487 combines the signals received from BPF 7 484 and BPF 8 485 and outputs them to Divider 10 488.

In addition, the Divider 10 488 combines the signals received from the Divider 8 486 and the Divider 9 487 and outputs them to the AMP 13 489.

The AMP13 489 amplifies a signal received from the Divider 10 488 as an amplifier to a signal level that can be input by the photoelectric converter 310.

As described above, the present invention transmits signals in the same frequency band as the existing frequency band in the coaxial cable network, thereby increasing the transmission efficiency without changing the coaxial cable network equipment including the receiving terminal.

That is, in the optical cable network between the headend system 100 and the outdoor optical transceiver device (ONU), the downlink signal is transmitted in the L band and the uplink signal is transmitted in the coaxial cable available frequency band. In the cable network, it is possible to transmit a signal of the same band as the existing frequency band, there is an effect that can significantly increase the utilization of network resources and transmission efficiency without changing the coaxial cable network equipment including the receiving terminal.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

As described above, in the digital CATV transmission system and the like, unlike the existing technology of dividing the cell into smaller cells in order to increase the transmission speed, a plurality of sub cells exist in one cell. By transmitting different downlink signals to each other, it is possible to improve the transmission speed while reducing the enormous economic and time expenditure required for cell division.

In addition, the present invention, by transmitting only the downlink signal for each sub cell using a high available frequency band of the optical cable network, there is an effect that can greatly improve the utilization of network resources and transmission efficiency.

In addition, the present invention, by converting the frequency of the uplink signal input from each coaxial cable connected to the outdoor optical transmission and reception unit (ONU) to different channels in the available frequency band of the coaxial cable, thereby preventing mutual collision between the uplink signals There is an effect that can improve the transmission efficiency.

Claims (13)

In the optical transmission and reception apparatus having a multiplexing function in an optical coaxial mixed network, Frequency up-converting means for up-converting the plurality of downlink channels received from the cable modem to a band equal to or greater than the coaxial cable available frequency band corresponding to the destination subcell of the optical cable network; Frequency combining means for combining a plurality of coaxial cable available frequency bands or more downlink channel signals received from the frequency upconverting means with broadcast signals of the coaxial cable available frequency bands; First all-optical converting means for converting the signal combined by said frequency combining means into an optical signal and transmitting it to an outdoor optical transmitter of said optical cable network; First photoelectric conversion means for converting the multiplexed uplink signal received from the outdoor optical transceiver through the optical cable network into an electrical signal; Frequency distribution means for demultiplexing the uplink signal converted by the first photoelectric conversion means into an electrical signal and outputting a plurality of channel signals equal to or greater than the coaxial cable available frequency band corresponding to the subcell and a broadcast signal of the coaxial cable available frequency band; And Frequency downconverting means for receiving the uplink signal demultiplexed by the frequency distribution means and downconverting to an intermediate frequency to output to the cable modem Optical transmission and reception device having a multiplexing function in an optical coaxial mixed network comprising a. The method of claim 1, The outdoor optical transmitter, Second photoelectric conversion means for converting an optical signal received through the first all-optical conversion means into an electrical signal; Down-signal processing means for demultiplexing the electrical signal converted by the second photoelectric conversion means, and then down-converting each channel to output the sub-cell to the subscriber device of the corresponding subcell; Up-signal processing means for up-converting and multiplexing an uplink signal transmitted from the subscriber device of each sub-cell to a different frequency in an available frequency band; And And second all-optical converting means for converting the uplink signal multiplexed by the uplink signal processing means into an optical signal. The downlink signal processing means, First branching means for separating a plurality of coaxial cable available frequency band signals and a plurality of coaxial cable available frequency band signals, each of which is converted into an electrical signal by the second photoelectric conversion means; Distribution means for distributing coaxial cable available frequency band signals separated by the first branching means according to the number of subcells in the coaxial cable network; Second branching means for separating down channel signals each of a plurality of coaxial cable available frequency bands or more bands separated from the first branching means; Frequency downconverting means for downconverting the downlink channel signal of each available frequency band or higher band separated by the second branching means into a coaxial cable available frequency band; Down-combining means for combining each down-channel signal down-converted by the frequency down-converting means and the coaxial cable available frequency band signal distributed by the distribution means to output to a corresponding subcell in the coaxial cable network; And Automatic gain control means for automatically controlling the gain by changing the level of the signal input to the first branch means based on the strength of the signal output to the corresponding subcell in the coaxial cable network through the down coupling means Optical transmission and reception device having a multiplexing function in an optical coaxial mixed network comprising a. The method of claim 2, The first branch means, An attenuator for attenuating the strength of the input signal to a preset value; A first amplifier for amplifying the signal attenuated by the attenuator; A regulator for correcting the signal amplified by the first amplifier to a predetermined level; A first divider for branching a signal corrected by the controller into a down channel signal of a plurality of coaxial cable available frequency bands or more and a coaxial cable available frequency band signal; A filter for filtering a down channel signal of a plurality of coaxial cable available frequency bands or more bands branched from the first divider; A second amplifier for amplifying the signal filtered by the filter; And A second divider for separating down channel signals of a plurality of coaxial cable available frequency bands or more bands amplified by the second amplifier into respective signals; Optical transmission and reception device having a multiplexing function in an optical coaxial mixed network comprising a. The method of claim 3, wherein A switch for blocking a signal from flowing into the subsequent stage when the signal branched from the branching means is not a down channel signal of a band equal to or greater than the available frequency band Optical transmission and reception device having a multiplexing function in the optical coaxial mixed network further comprising. The method of claim 2, The distribution means, A filter for filtering the coaxial cable available frequency band signal separated by the first branch means; An adjuster for correcting the signal filtered by the filter to a predetermined level; An amplifier for amplifying the signal corrected by the controller; Splitter for distributing the signal amplified by the amplifier according to the number of subcells in the coaxial cable network Optical transmission and reception device having a multiplexing function in an optical coaxial mixed network comprising a. The method of claim 2, The frequency down conversion means, A first filter for filtering a down channel signal of each coaxial cable available frequency band or more band separated by said second branching means; A plurality of mixers for downconverting the down channel signal of each coaxial cable available frequency band or more band filtered by the first filter to the coaxial cable available frequency band; And A plurality of second filters for filtering down-converted signals through the plurality of mixers Optical transmission and reception device having a multiplexing function in an optical coaxial mixed network comprising a. The method of claim 2, The down coupling means, A combiner for combining the respective down channel signals down-converted by the frequency down-converting means and the coaxial cable available frequency band signals distributed by the distribution means; A plurality of equalizers for compensating for attenuation of each signal combined in the combiner; And A plurality of amplifiers for amplifying each signal passed through the equalizer and outputting the amplified signals to corresponding subcells in the coaxial cable network Optical transmission and reception device having a multiplexing function in an optical coaxial mixed network comprising a. The method of claim 7, wherein Each equalizer, The optical transmission / reception apparatus having a multiplexing function in an optical coaxial mixed network, wherein the low frequency signal is largely attenuated and the high frequency signal is attenuated with respect to the combined specific signal. The method of claim 2, The upward signal processing means, Frequency up-converting means for receiving an uplink signal from a plurality of subcells in the coaxial cable network and up-converting to different frequencies in an available frequency band of the coaxial cable; And Up-combining means for combining a plurality of up-signals, up-converted by the frequency up-converting means, into one signal Optical transmission and reception device having a multiplexing function in an optical coaxial mixed network comprising a. The method of claim 9, The frequency up-conversion means, A plurality of amplifiers for receiving and amplifying an uplink signal from a plurality of subcells in the coaxial cable network; A plurality of first regulators for correcting a signal amplified by the plurality of amplifiers to a predetermined level; A plurality of equalizers for compensating for attenuation of each signal corrected by the plurality of first regulators; A plurality of second adjusters for correcting each signal passing through the plurality of equalizers to a predetermined level; A plurality of mixers for upconverting each signal corrected by the plurality of second regulators to different frequencies in an available frequency band of the coaxial cable; And A plurality of filters for filtering each up-converted signal through the plurality of mixers Optical transmission and reception device having a multiplexing function in an optical coaxial mixed network comprising a. delete delete In the optical transmission and reception method in optical coaxial mixed network, Frequency up-converting a plurality of downlink channels by a head-end device to a band above a coaxial cable available frequency band corresponding to a destination subcell of an optical cable network; Combining, by the headend device, a downlink channel signal of a plurality of coaxial cable available frequency bands or more bands up-converted with a broadcast signal of a coaxial cable available frequency band; Converting the combined signal into an optical signal by the headend device and transmitting the converted signal to the outdoor optical receiver; After converting the optical signal received by the outdoor optical transceiver into an electrical signal, a plurality of downlink channel signals of the frequency band above the available frequency band is separated and frequency downconverted, respectively, the downlinked downlink channel signal and the coaxial cable Combining the available frequency band signals with each other and transmitting them to the subscriber station of the corresponding subcell; Transmitting, by the outdoor optical transceiver, an uplink signal transmitted from a subscriber device in the subcell to multiplex by upconverting to a different frequency in an available frequency band of a coaxial cable, and converting and transmitting the multiplexed uplink signal into an optical signal; And Converting, by the headend device, the multiplexed uplink signal received from the outdoor optical transceiver into an electrical signal, demultiplexing and converting the demultiplexed uplink signal to an intermediate frequency Optical transmission and reception method in the optical coaxial mixed network comprising a.

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