KR100923503B1 - WDM-PON system with video overlay - Google Patents

Abstract

PURPOSE: A WDM-phone system having a video overlay function is provided to simplify a overlay WDM-PON system and drastically reduce the cost required for constructing a network. CONSTITUTION: A WDM-phone system having a video overlay function comprises the first AWG multiplexer(22), a combining unit, and the second AWG multiplexer. The first AWG multiplexer couples data optical signals for data transmission outputted from an OLT(20) with an optical cable. The combining unit combines a video optical signal for the transmission of a video signal with the optical cable. The second AWG multiplexer has plural input ports and plural output ports.

Description

WDM-PON system with video overlay}

The present invention relates to a WDM-PON system, and more particularly, to a WDM-PON system having a video overlay function capable of transmitting a video signal in a broadcasting manner for each home by having a video overlay function. will be.

As the demand of multimedia information increases with the spread of the Internet, the so-called FTTH (Fiber-To-The-Home) network, which enables data transmission at tens to hundreds of Mbps for general households, is rapidly increasing. It is spreading. Current methods for constructing an FTTH network include AON (Active Optical Network), E-PON (Ethernet Passive Optical Network), and WDM-PON (Wavelength Division Multiplexing-PON).

In the case of PON, the device installed at the subscriber end is composed of passive optical components that do not require a driving power. Therefore, PON is more widely used because the cost for network configuration and maintenance is lower than that of AON.

1 is a configuration diagram schematically showing a network configuration of an E-PON.

E-PON is configured by combining a plurality of optical network terminals (ONT) 14: 14-1 ~ 14-n through the optical splitter 12 to the optical line terminal (OLT) 10. Here, the OLT 10 is installed at a telephone station or a head-end, and the ONT 14 is installed at a subscriber end, respectively. The OLT 10, the optical splitter 12, and the ONT 14 are coupled through the optical cables 11 and 13, respectively.

In the above configuration, data transmitted from the OLT 10 to the ONT 14 is transmitted through light having a wavelength of 1490 nm, for example, and the optical signal transmitted in this manner is distributed by the optical splitter 12 so that each ONT 14 Is sent to. The data transmitted from the ONT 14 to the OLT 10 is transmitted through light having a wavelength of, for example, 1310 nm, and the optical signal transmitted in this way is coupled to the optical cable 11 through the optical splitter 12 so that the OLT ( 10) is sent. In this case, since the plurality of ONT 14 transmits data through light of the same wavelength, the ONT 14 performs data transmission through a time division method.

2 is a configuration diagram schematically showing the network configuration of the WDM-PON.

In the WDM-PON, the optical signal wavelengths for the downlink and the uplink are individually allocated to the ONTs 26: 26-1 to 26-n. That is, in the OLT 20, for example, wavelength signals are divided into L-band bands (1570-1600 nm), and data transmission is performed to the ONT 26, respectively. In the ONT 26, for example, the C-band is performed for each ONT 26. The optical signals of the bands 1530-1560 nm are wavelength-divided to transmit data to the OLT 20.

The optical signal for each wavelength transmitted from the OLT 20 is applied to the arrayed waveguide grating (AWG) multiplexer 22 through the optical cable 21, multiplexed, and then transmitted to the subscriber terminal through the single optical cable 23. The transmitted optical signal is demultiplexed again in the AWG multiplexer 24 and provided to the ONT 26 through the optical cable 25, respectively. On the subscriber side, the optical signal for each wavelength transmitted from the ONT 26 through the optical cable 25 is multiplexed by the AWG multiplexer 24 to be transmitted through the optical cable 23, and the optical signal thus transmitted is AWG multiplexer. It is demultiplexed again at 22 to be applied to the OLT 20.

Therefore, in the case of E-PON, since a plurality of ONTs 14 are used by time-assigning a single optical wavelength, the network configuration is simple, but the data transmission rate is slightly lower than that of WDM-PON. In the case of WDM-PON, since many ONTs 26 perform data transmission using separate optical wavelengths, the data transmission rate is very high, while the network configuration is somewhat complicated compared to E-PON. Will be.

On the other hand, in recent years, attempts have been made to provide a video overlay function for transmitting a video signal through a PON to all communication subscribers by broadcasting.

3 is a configuration diagram illustrating a configuration of broadcasting video signal through E-PON. In FIG. 3, the same parts as those in FIG. 1 are given the same reference numerals, and detailed description thereof will be omitted.

In FIG. 3, an optical signal having a wavelength of 1550 nm is used for transmission of a video signal. This video optical signal is amplified by the optical amplifier 31 and then applied to the WDM (Wavelength Division Multiplexer) 32 to be coupled to the optical cable 11. The combined video optical signal is distributed by the optical splitter 12 together with the data optical signal from the OLT 10 and supplied to the plurality of ONTs 14.

As a result, a data light signal of 1490 nm and a video light signal of 1550 nm are applied to each ONT 14 from the OLT 10. The ONT 14 filters these two optical signals through a filter and inputs them respectively.

In the case of the E-PON, the optical signal of a single wavelength is used for data transmission from the OLT 10 to the ONT 14, and thus the optical signal transmitted from the OLT 10 is distributed through the optical splitter 12 only. It is supplied to each ONT 14. Accordingly, in the case of the E-PON, the optical signal for data transmission, that is, the optical signal for the video signal, that is, the optical signal for the video signal, that is, the optical signal for 1550 nm, is transmitted through the optical cable 11 only. It is possible to transmit to all ONT 14 in a broadcasting manner.

However, as shown in FIG. 2, in the case of the WDM-PON, the wavelength of the optical signal transmitted from the OLT 20 to the ONT 26 is set differently according to the ONT 26, and these optical signals are set in the AWG multiplexer 24. Are separated through and provided to each ONT 26. Therefore, in the case of the WDM-PON, unlike the E-PON, it is not easy to provide a video signal to all ONTs 26 in a broadcasting manner.

Accordingly, an object of the present invention is to provide a WDM-PON system capable of providing a video overlay function with a simple configuration.

The WDM-PON system having a video overlay function according to the present invention for realizing the above object combines the OLT and a plurality of ONTs through an optical cable, and transmits and receives data between the OLT and ONT using optical signals having different wavelengths, respectively. A WDM-PON system, comprising: a first AWG multiplexer for coupling a plurality of data optical signals for data transmission output from an OLT to an optical cable, and coupling means for coupling a video optical signal for transmission of a video signal to the optical cable, A second AWG multiplexer having a plurality of input ports and a plurality of output ports; and an optical distribution for splitting a plurality of video optical signals applied from the second AWG multiplexer by being coupled to an output port to which the video optical signals of the second AWG multiplexer are output; Means comprising a means for coupling said optical cable to one input port of said second AWG multiplexer. And an output of the optical distribution means is coupled to another input port except for an input port to which the optical cable of the second AWG multiplexer is coupled, and an output other than an output port to which a video optical signal is output among the output ports of the second AWG multiplexer. The ports are each configured to be coupled to the ONT.

In addition, the wavelength of the video optical signal is characterized in that it is assigned within the range of the minimum wavelength and the maximum wavelength of the data optical signal output from the OLT.

In the above configuration, N × N AWG multiplexer and optical distribution means are provided at the subscriber end to distribute the video optical signal to optical distribution means and input to the input port of N × N AWG multiplexer. The video signal can be supplied. Therefore, in the present invention, the configuration of the overlay WDM-PON system is simplified, and the network construction cost is greatly reduced.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. However, the embodiments described below are not intended to limit the scope of the present invention, but one exemplary embodiment of the present invention is shown as an example. The present invention can be carried out in various modifications without departing from the spirit thereof.

First, the basic concept of the present invention will be described.

As described above, in the WDM-PON system, since the wavelength of the optical signal transmitted and received between the OLT and the ONT is set differently for each ONT, it is easy to transmit an optical signal having a specific wavelength, for example, 1550 nm to all ONTs by broadcasting. You will not.

FIG. 4 is a diagram illustrating a configuration in which the concept illustrated in FIG. 3 is simply applied to a WDM-PON system. In addition, in FIG. 4, the same part as FIG. 2 mentioned above is attached | subjected with the same reference number, and the detailed description is abbreviate | omitted.

In FIG. 4, for example, a 1550 nm video optical signal is amplified in the optical amplifier 41 and then coupled to the optical cable 23 through the WDM 42. The combined video optical signal is transmitted to the subscriber side. The subscriber end is provided with a WDM 43 for separating and outputting the video optical signal from the optical cable 23. The video optical signal output from the WDM 43 is applied to the optical splitter 44 and divided into a plurality of optical signals.

In addition, a WDM 45 is installed in the optical cable 25 between the AWG multiplexer 24 and the ONT 26, and the optical signal separated from the optical splitter 44 is connected to the optical cable 25 through the WDM 45. Are coupled to and transmitted to the ONT 26, respectively.

When the WDM-PON is configured in the above-described configuration, the video signal can be transmitted to the plurality of ONTs 26 by broadcasting. However, for such a configuration, a plurality of high-priced WDMs 45 must be used as well as an optical cable must be connected to each of these WDMs 45, resulting in high manufacturing costs and complicated construction.

In the present invention, a video overlay WDM-PON system is constructed with a simple configuration using an N × N AWG multiplexer.

First, the operating characteristics of the AWG multiplexer will be described. Incidentally, in the following description,? 1,? 2,... , λn-1, and λn are optical signals having different wavelengths, respectively, and are assumed to be long wavelength optical signals from λ1 to λn.

5 is an explanatory diagram for explaining input / output characteristics of a 1 × N AWG multiplexer having one input port and n output ports.

When a 1 × N AWG multiplexer inputs an optical signal having a wavelength of λ1 to λn through an input port 1, optical signals of λ1 to λn are sequentially output from an output port 1 to n. On the contrary, when the optical signals of λ1 'to λn' having different wavelengths are input through the output ports 1 to n, the optical signals of λ1 'to λn' are output together through the input port 1. . Of course, the input / output characteristics of such an optical wavelength are suitably set at the time of manufacture of an AWG multiplexer.

6 is an explanatory diagram for explaining input / output characteristics of an N × N AWG multiplexer having n input ports and n output ports.

6, reference numerals A1, A2,... , An denotes an optical signal output through the output ports 1 to n by the optical signal input through the input ports 1 to n, respectively. In the N × N AWG multiplexer, when a plurality of optical signals are input through an arbitrary input port, optical signals for each wavelength are sequentially output from an output port corresponding to the input port through the output port. For example, when optical signals of λ1 to λn are input through the input port 1, the output ports are output such that the optical signals of λ1 to λn are output in order from output port 1 to output port n as shown by A1 in the figure. do. In addition, when optical signals of λ1 to λn are input through input port 2, the output ports output λ1 to λn-1 optical signals from output port n to output port n, respectively, as indicated by A2 in the figure. Then, the optical signal of λn is outputted through the first output port.

Therefore, referring to the optical signal of λ n in FIG. 6, the λ n optical signal input to the AWG multiplexer through input port 1 is output through output port n, and λ n input through output ports 2 to n. The optical signals are output through the output ports 1 to n-1, respectively.

In addition, in the case of the N × N AWG multiplexer in FIG. 6, when the optical signals of λ 1 ′ to λ n ′ are inputted through output ports 1 to n like the 1 × N AWG multiplexer of FIG. 5, the optical signals are numbered 1. It will be output together through the input port. Of course, even in this case, the above-described optical wavelength input / output characteristics of the AWG multiplexer should be properly considered in manufacturing the AWG multiplexer.

7 and 8 illustrate input and output characteristics of an N × N AWG multiplexer for explaining the basic concept of the present invention in more detail.

In Fig. 7, the optical terminals 1 through n-1 of the N × N AWG multiplexer are coupled to the subscriber end, that is, the ONT 26 of Fig. 2, and the optical wavelengths of the data signals transmitted to the subscribers are respectively λ1 to λn-1. Assuming an allocated case, when λ1 to λn optical signals are input to the input terminal 1 of the N × N AWG multiplexer, respectively, λ1 to λn-1 through the output terminals 1 to n-1 of the N × N AWG multiplexer, respectively. The optical signal is output and provided to each subscriber.

In addition, when the optical signal for the video signal to be provided to all subscribers in Figure 7 is λ n, when the optical signal of λ n is input to the input port 2 to n of the N × N AWG multiplexer, As described in FIG. 6, optical signals of λn are outputted through output ports 1 to n-1 of the N × N AWG multiplexer.

Therefore, when the subscriber end is configured using the N × N AWG multiplexer as described above, the data of the λn together with the data optical signals of λ1 to λn-1 through the 1 to n-1 output ports of the N × N AWG multiplexer, respectively. Since the video light signal is output, the overlay function of the video signal is implemented.

In addition, the above-described configuration can be applied in the same manner even when any other optical signal is used without using [lambda] n as an optical signal for the video signal.

8 shows a case where an optical signal of λ 3 is used as an optical signal for a video signal. In FIG. 8, optical signals of λ1 to λn are input to input port 1 of the N × N AWG multiplexer, and optical signals of λ3 are input through input ports 2 to n. In this case, optical signals of λ1 to λn are sequentially outputted through the output ports 1 to n by λ1 to λn inputted through the first input port, respectively. And, the optical signal of λ 3 input through the second to n input ports are sequentially output through the fourth through n output ports and the first and second output ports, respectively, through all the output ports of the first to n times The optical signal of [lambda] 3 is output.

9 is a block diagram showing the configuration of a video overlay WDM-PON system according to an embodiment of the present invention to which the above concept is applied. 9 illustrates an example in which an optical signal of λ1 to λn is used as light for a data signal transmitted from the OLT 20 to the ONT 26, and an optical signal of λn + 1 is used as light for a video signal. It is shown as. In addition, in FIG. 9, the same reference numeral is attached | subjected to the substantially same part as FIG. 2 and FIG. 4 mentioned above, and the detailed description is abbreviate | omitted.

In FIG. 9, the optical signal for the data signal transmitted from the OLT 20 to the ONT 26 is set to λ1 to λn, and the optical signal for the video signal is set to λn + 1. The optical signal λ1 to λn transmitted from the OLT 20 is coupled to the optical cable 23 through the AWG multiplexer 22, and the video optical signal λn + 1 is amplified by the optical amplifier 41 and then WDM. It is coupled to the optical cable 23 through 42. Therefore, optical signals of [lambda] 1 to [lambda] n and [lambda] n + 1 are transmitted to the subscriber end via the optical cable 23.

The optical cable 23 is coupled to the first input port of the N × N AWG multiplexer 90 at the subscriber end. Output ports 1 to n of the AWG multiplexer 90 are respectively coupled to the inputs of ONT 26-1 to 26-n, and output ports n + 1 of the AWG multiplexer 90 are respectively connected to the optical splitter 91. Are coupled to the input.

As described above, the optical signals λ1 to λn and λn + 1 input through the input port 1 of the AWG multiplexer 90 are sequentially output ports 1 to n + 1 of the AWG multiplexer 90 according to their wavelengths. Is output via Accordingly, the optical signals λ1 to λn transmitted from the OLT 20 are output to output ports 1 to n of the AWG multiplexer 90, respectively, and are input to the corresponding ONTs 26, and the video optical signals λn + 1 are AWG. The signal is output to the n + 1 output port of the multiplexer 90 and input to the optical splitter 91.

The optical splitter 91 divides the input optical signal into a plurality of, for example, n optical signals and outputs the same. The output of the optical splitter 91 is an input port 2 to n + 1 of the AWG multiplexer 90. Is applied. As described above, the video optical signal of λn + 1 applied to input ports 2 to n + 1 of the AWG multiplexer 90 is output through the output ports 1 to n of the AWG multiplexer 90 and then ONT. Provided by 26.

Therefore, in the above configuration, the data optical signals of λ1 to λn are output through the output ports 1 to n of the AWG multiplexer 90, and the video optical signals of λn + 1 are output to be input to each ONT 26. do.

Further, the optical signal for the data signal transmitted from the ONTs 26-1 to 26-n to the OLT 20 is the optical signal of λ1 'to λn' having a wavelength different from that of the optical signals λ1 to λn for the downlink. The call is assigned. The optical signals λ 1 ′ to λ n ′ for the uplink output from the ONT 26 are applied to output ports 1 to n of the AWG multiplexer 90, and these optical signals are inputted to No. 1 of the AWG multiplexer 90. Output through the input port is transmitted through the optical cable (23). The optical signals λ1 'to λn' thus transmitted are divided by wavelength by the AWG multiplexer 22 and transmitted to the OLT 20.

Accordingly, in the above-described embodiment, the OLT 20 and the ONT 26 transmit and receive data with optical signals having different wavelengths, and broadcast the video optical signal lambda n + 1 to all ONTs 26 by broadcasting. It can be provided for.

On the other hand, the above-described embodiment shows a case where λ n + 1 is used as the video optical signal by way of example, and as an optical signal for transmitting the video signal, it is possible to use an optical signal having a wavelength other than λ n + 1 as described above. Do.

FIG. 10 shows a case where an optical signal of, for example, λ3 is used instead of λn + 1 as an optical signal for transmitting a video signal. In addition, in FIG. 10, the same reference numeral is attached | subjected to the substantially same part as FIG. 9, and the detailed description is abbreviate | omitted.

In FIG. 10, other optical signals other than λ 3, that is, λ 1, λ 2, and λ 4 to λ n are used as optical signals for the downlink signal from the OLT 20 to the ONT 26, and the optical signals are transmitted for the video signal. As a signal, an optical signal of lambda 3 is used. Incidentally, as the optical signal for the uplink signal from the ONT 26 to the OLT 20, the optical signals of λ1 'to λn' are used in the same manner as in the above embodiment.

In FIG. 10, the optical signals λ1, λ2, and λ4 to λn output from the OLT 20 are coupled to the optical cable 23 through the AWG multiplexer 22, and the optical signal λ3 for the video signal is WDM 42. It is coupled to the optical cable 23 through). Therefore, optical signals of λ 1 to λ n are transmitted through the optical cable 23, and these optical signals are applied through the input port 1 of the N × N AWG multiplexer 90.

On the other hand, the AWG multiplexer 90 is coupled to the input port 3 of the optical splitter 91, the output port 3, the video optical signal λ 3 is output, the other output port is coupled to the ONT (26). In addition, the output of the optical splitter 91 is coupled to input ports 2 to n of the AWG multiplexer 90.

As described above, the video optical signal λ3 applied to the second through nth input ports of the AWG 90 is output through the fourth through second output ports of the AWG multiplexer 90 to the entire ONT 26. To be supplied. Therefore, in this embodiment, the OLT 20 and the ONT 26 provide the video optical signal lambda 3 to all ONTs 26 in a broadcasting manner while performing data transmission and reception with optical signals having different wavelengths. It becomes possible. In addition, since other parts are the same as the above-mentioned embodiment of FIG. 9, the detailed description thereof will be omitted.

The embodiment according to the present invention has been described above. In the present invention, the subscriber end is provided with an N × N AWG multiplexer 90 and an optical splitter 91 to distribute a video optical signal to the optical splitter 91 and input the input port of the N × N AWG multiplexer 90. The simple structure makes it possible to supply a video signal to all ONTs 26 in a broadcast manner.

Therefore, in the present invention, the configuration of the overlay WDM-PON system is simplified, and the network construction cost is greatly reduced.

In addition, this invention is not limited to the above-mentioned embodiment, It can implement in a various deformation | transformation in the range which does not deviate from the technical idea of this invention.

1 is a schematic view showing a network configuration of a general E-PON.

Figure 2 is a schematic diagram showing the network configuration of a typical WDM-PON.

3 is a block diagram showing the configuration of a video overlay E-PON system.

Figure 4 is a block diagram showing the configuration of a conventional video overlay WDM-PON system.

5 to 8 are explanatory diagrams for explaining the optical wavelength input and output characteristics of the N × N AWG multiplexer.

9 is a block diagram showing the configuration of a video overlay WDM-PON system according to an embodiment of the present invention.

10 is a block diagram showing the configuration of a video overlay WDM-PON system according to a modification of the present invention.

Claims (2)

In the WDM-PON system that combines the OLT and a plurality of ONT through an optical cable, and transmits and receives data between the OLT and ONT using optical signals of different wavelengths, respectively, A first AWG multiplexer for coupling a plurality of data optical signals for data transmission output from an OLT to an optical cable; Coupling means for coupling a video optical signal for transmission of a video signal to an optical cable, A second AWG multiplexer with multiple input ports and multiple output ports, A light distribution means coupled to an output port for outputting the video optical signal of the second AWG multiplexer for dividing the video optical signal applied from the second AWG multiplexer into a plurality of parts; The optical cable is coupled to one input port of the second AWG multiplexer, The output of the optical distribution means is respectively coupled to the other input port except the input port to which the optical cable of the second AWG multiplexer is coupled, WDM-PON system having a video overlay function, characterized in that the other output port of the output port of the second AWG multiplexer other than the output port for outputting the video signal is configured to be coupled to the ONT, respectively. The method of claim 1, The wavelength of the video optical signal is assigned within the range of the minimum wavelength and the maximum wavelength of the data optical signal output from the OLT WDM-PON system with a video overlay function.

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