KR20040110153A - Optical access network system - Google Patents

Abstract

PURPOSE: An apparatus for configuring an optical subscriber network is provided to provide a broadcast service without causing data collision even without using a ranging protocol in an Ethernet-based communication network. CONSTITUTION: An OLT(Optical Line Terminal)(22) outputs an Ethernet signal and a broadcast signal having a wavelength different from that of the Ethernet signal as downlink signals and receives uplink signals corresponding to the downlink signals generated from user terminals(51-53). A private telecommunication closet unit(30) splits the downlink signals received from the OLT(22) and outputs them, and wavelength-division-multiplexes the uplink signals and outputs them. ONUs(Optical Network Units)(41-43) select only downlink signals corresponding to the connected user terminals(51-53) among the downlink signals split in the private telecommunication closet unit(30) and transmit them to the corresponding user terminals(51-53), and allocate a specific wavelength of each subscriber to uplink signals received from the user terminals(51-53), wavelength-division-multiplex them, and transmit them to the private telecommunication closet unit(30).

Description

Optical access network system

The present invention relates to an optical subscriber network, and more particularly, to an optical subscription that can accommodate a broadcast service in a communication network without using an alignment protocol by improving its structure in an Ethernet passive optical network (PON) using an optical passive element. It relates to a magnetic net component.

In general, a PON structure is a network structure designed to provide subscribers with various types of high-bandwidth services such as high-speed Internet service, video conferencing, video education, video medical care, and high-definition television at a low price.

95% of data in current local area network (LAN), metropolitan area network (MAN), and wide area network (WAN) is Ethernet data, and a network that provides Ethernet services to subscribers at a low price and simple network. E-PON (Ethernet PON) technology.

Wavelength Division Multiplexing (WDM) is a WDM technology that divides wavelengths at regular intervals, selects channels, loads signals, and multiplexes multiple channels to transmit them through one optical fiber. As a technology that can be used, a lot of researches are being conducted around the world, and WDM technology has been applied to the field from the optical core network to the optical subscriber network.

1 is a diagram illustrating a downlink transmission structure in an optical subscriber network of a conventional E-PON method.

The optical subscriber network structure of the E-PON method is composed of an optical line terminal (OLT) (2) and a main distribution frame (hereinafter referred to as MDF) in the central office (hereinafter referred to as CO). A splitter 4 of (3), a plurality of optical network units (hereinafter referred to as ONUs) 5, and a plurality of end user terminals 6 are provided.

When the Ethernet packet 7 is transmitted from the CO 1 to the MDF 3 which is the communication room of the residential complex, the branching machine 4 of the MDF 3 branches and transmits it to a plurality of connected ONUs 5. The ONU 5 is an optical subscriber device that selects and transmits only the Ethernet packet 9 corresponding to the connected user terminal 6 from the received Ethernet packet 8 to the corresponding user terminal 6.

The branch switch 4 is an optical passive element, which serves to reduce the load of maintenance without using a power supply with a plurality of ONUs 5 connected to one OLT 2 in the CO 1. Do this.

This one-to-many PON structure has the advantage of reducing the collision of signals in the OLT (2), sharing electronic and optoelectronic devices with each other, or half the number of optical transceivers.

The E-PON structure requires only one optical fiber from CO (1) to subscribers, and the CO (1) requires minimal space for mounting the optical fiber and requires less (1/2 * N) +1 than the one-to-one structure. It requires only two transceivers and does not require power at the branching point MDF (3), so it can be usefully used in a downlink network broadcasting such as Ethernet.

2 is a diagram illustrating an uplink transmission structure in a conventional E-PON optical subscriber network.

When each end user terminal 6 transmits the Ethernet packet 11 to the ONU 5, the ONU 5 transmits the Ethernet packet 12 containing the corresponding information to the MDF 3. The diverter 4 of the MDF 3 sends the Ethernet packet 13, which collects the received Ethernet packets 12, to the OLT 2.

3 is a detailed configuration diagram illustrating the ONU of FIGS. 1 and 2 in more detail.

The ONU 5 includes a controller 17 that performs a WDM coupler 14, an optical receiver 15, an optical transmitter 16, a time division multiple access (TDMA) ranging protocol, and A medium access controller (MAC) 18 for Ethernet service is provided. Here, the MAC 18 has an output port 19 and an input port 20 which are connected to the end user terminal 6.

The WDM coupler 14 is a device that allows multiplexing up and down signals to connect to the MDF 3 through one optical fiber. Therefore, the number of optical fibers used can be reduced to 1/2 * N by using the WDM coupler 14.

If the network is configured with an uplink transmission structure of the E-PON method, signals transmitted from a plurality of ONUs (5) must be multiplexed into time slots and transmitted to the CO (1) using the TDMA method. In the conventional TDMA scheme, one wavelength is separated on the time axis, and signals of several channels are transmitted in different time slots. In this scheme, a security problem on the subscriber side occurs and a ranging protocol should be applied. . Here, the ranging protocol means that the data of different subscribers may arrive at the same time because the location of the ONU 5 is not the same, in which case the data is broken by the collision. Used to Using a ranging protocol to measure the logical distance between the OLT (2) and the ONU (5) and do not interfere with the service of the other ONU (5) when configuring a new ONU (5) for each ONU (5) You can do that.

However, the use of a ranging protocol further complicates the functionality of the OLT 2 and ONU 5 and results in expensive devices. In addition, there is a problem that the synchronization of the OLT (2) and ONU (5).

In addition, this problem may become more serious when an optical subscriber network is used to transmit not only Ethernet Ethernet data but also a large broadcast signal for a broadcast service.

Accordingly, an object of the present invention for solving the above problems is to improve the structure of the optical subscriber network so that the problem of data collision does not occur even without using the alignment protocol, simplifying the functions of the OLT and ONU, and economical and stable optical The purpose is to enable the subscriber network.

1 is a diagram illustrating a downlink transmission structure in an optical subscriber network of a conventional E-PON method.

2 is a diagram showing an uplink transmission structure in a conventional E-PON optical subscriber network.

3 is a view showing in more detail the configuration of the ONU in FIGS.

4 is a view showing the configuration of an optical subscriber network configuration apparatus according to an embodiment of the present invention.

5 is a view showing in more detail the configuration of the ONU in FIG.

The optical subscriber network configuration apparatus of the present invention for achieving the above object, in the Ethernet-based optical subscriber network, OLT for outputting the downlink signal to be transmitted to the user terminal and receiving the uplink signal from the user terminal; An internal communication room apparatus for branching the downlink signal and outputting the uplink signal by multiplexing the wavelength; And transmits only a signal corresponding to the connected user terminal among the downlink signals branched from the premises apparatus to the corresponding user terminal, and assigns a unique wavelength to a signal corresponding to the broadcast video signal among the upstream signals from the user terminal. And an ONU for multiplexing the uplink signal to the wavelength division multiplexing device.

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

4 is a diagram illustrating a configuration of an optical subscriber network configuration apparatus according to an embodiment of the present invention.

The optical subscriber network component of the present invention performs different signal processing by dividing the uplink signal and the downlink signal to accommodate a broadcast service in an Ethernet passive optical network (E-PON).

The optical subscriber network of FIG. 4 includes an optical line terminal (OLT) 22, an internal communication room device 30, an optical netowrk unit (ONU) 41, 42, 43, and a user terminal 51, 52, 53. do.

The OLT 22 is installed in the telephone office (or central office (CO) 20) to output data to be transmitted to the user terminals 51, 52, 53 as optical signals, and the user terminals 51, 52, 53. Receive data from an optical signal. In this case, the OLT 22 allocates one wavelength to the broadcast signal separately from the Ethernet signal so that the broadcast signal can be collectively transmitted to the user terminals 51, 52, and 53. That is, in the downlink signal, the broadcast signal is collectively transmitted to the broadcasting terminals (TVs) of all users without user classification, and only one wavelength may be additionally allocated to the broadcasting signal.

The internal communication room apparatus 30 includes a branching device 32, a wavelength division multiplexer (WDM) 34, and couplers 36 and 38.

The breaker 32 branches and outputs the optical signal from the OLT 22 to each ONU 41, 42, 43, and the WDM 34 splits the optical signals from each ONU 41, 42, 43. Split and multiplex the output.

Coupler 36 has OLT 22, tap-off 32 and WDM so that the optical signal from OLT 22 is sent to brancher 32 and the optical signal from WDM 34 is sent to OLT 22. (34) is connected. The coupler 38 divides the optical signal branched from the tap-off 32 to the corresponding ONU 41, 42, 43 and the optical signal from the ONU 41, 42, 43 to the WDM 34. The device 32, the WDM 34, and the corresponding ONUs 41, 42, 43 are connected.

The ONUs 41, 42, and 43 demultiplex the optical signal from the tap-off 32 into an electrical signal, select only a signal corresponding to the connected user terminal 50, and transmit the selected signal to the corresponding user terminal 50. Then, the output signal of the user terminal 29 is converted into an optical signal of a specific wavelength and then multiplexed and transmitted to the WDM 25. That is, the ONUs 41, 42, and 43 receive an optical signal received as a downlink signal, which is an Ethernet signal. ) And broadcast signals ( ) And transmit to the PC and the TV, respectively, and for the uplink signal, output signals from the user terminals 51, 52, and 53 are assigned to the unique wavelengths , , Is converted into an optical signal having the

FIG. 5 is a diagram illustrating the configuration of the ONU 41 in FIG. 4 in more detail.

The ONU 41 receives the WDM 42 for demultiplexing the broadcast signal and the Ethernet signal from the branch 32 and outputs the optical signal 44 for receiving and converting the demultiplexed optical signal from the WDM 42 into an electrical signal. ), The output signal from the user terminal 51 Among the output signals of the optical transmitter 46 and the optical receiver 44, which are converted into an optical signal of the optical receiver 46 and output to the WDM 42, an Ethernet signal corresponding to the user terminal 51 and a broadcast signal are selected, respectively. 51 and a MAC 48 for transmitting to the TV and the TV, and for transmitting the output signal of the user terminal 50 to the optical transmitter 46.

Referring to the operation of the optical subscriber network configuration device having the above configuration is as follows.

OLT (22) is an Ethernet signal ( , , Separately from one wavelength) ) And then combines the Ethernet signal and the broadcast signal with a wavelength and transmits them to the MDF 30 through one optical fiber. Coupler 36 transmits the optical signal from OLT 22 to brancher 32. The breaker 32 is a downlink optical signal from the OLT 22 ) Is outputted, and the couplers 38 transmit the downlink optical signals branched from the brancher 32 to each ONU 41, 42, and 43.

The branched optical signal is demultiplexed in the WDM 42 and converted into an electrical signal in the optical receiver 44 and then transmitted to the MAC 48. The MAC 48 is an Ethernet signal to be transmitted to the connected user terminal 51 among the output signals of the optical receiver 44 ( ) And broadcast signals ( Select) to send to your PC and TV respectively. The transmission method for the downlink signal is the same as in the conventional E-PON except for transmitting the broadcast signal together with the Ethernet signal using a separate wavelength.

When signals are generated in the TV and the PC 51 in response to these downlink optical signals, these signals are sequentially transmitted to the MAC 48. The MAC 48 transmits signals received from the TV and the PC to the optical transmitter 46.

The optical transmitter 46 uniquely assigns a signal from the MAC 48 to each subscription. Is converted into an optical signal having The WDM 34 receives an optical signal (received from each ONU 41, 42, 43). ) Is transmitted to the OLT 22 by wavelength division multiplexing.

As such, by assigning a unique wavelength to each user without diverging the upstream signals from the user terminals 51, 52, and 53 as in the prior art, the signals are wavelength-divided and multiplexed, thereby not using a ranging protocol. There is no data conflict.

As described above, the apparatus for constructing an optical subscriber network of the present invention allocates one wavelength for a broadcast signal to a downlink signal and transmits the same wavelength to each user terminal, and transmits an uplink signal to a signal generated by each user terminal. By assigning unique wavelengths for each subscriber, these signals are wavelength-division-multiplexed and transmitted to the OLT, so that an Ethernet-based communication network can accommodate broadcast services without data collision without using a ranging protocol.

Claims (3)

In the Ethernet-based optical subscriber network, An OLT for outputting an Ethernet signal and a broadcast signal having one wavelength different from the Ethernet signal as a downlink signal, and receiving an uplink signal generated from a user terminal corresponding to the downlink signal; An internal communication room apparatus for branching the downlink signal from the OLT and outputting the uplink signal to the OLT by multiplexing the wavelength; And Only the signal corresponding to the connected user terminal is selected and transmitted to the corresponding user terminal among the downlink signals branched by the premises equipment, and the unique wavelength for each subscriber is allocated to the uplink signal from the user terminal and then the wavelength division is performed. And an ONU configured to multiplex and transmit to the premises communication device. According to claim 1, wherein the internal communication room device A diverter for branching and outputting a downlink signal from the OLT; A first WDM for multiplexing and outputting an uplink signal from the ONU; A first coupler for transmitting an optical signal from the OLT to the tap-changer and an optical signal from the first WDM to the OLT; And And a plurality of second couplers for transmitting a signal from the branch to the corresponding ONU and a signal from the ONU to the first WDM. The method of claim 1, wherein the ONU is A second WDM for multiplexing and demultiplexing an applied signal and outputting the second signal; An optical receiver for receiving the demultiplexed signal from the second WDM and converting the signal into an electrical signal; An optical transmitter for converting an uplink signal from the user terminal into an optical signal having a unique wavelength for each subscriber and transmitting the optical signal to the second WDM; And And selecting only a signal corresponding to the connected user terminal from the downlink signal from the optical receiver and transmitting the signal to the corresponding user terminal, and transmitting the uplink signal from the user terminal to the optical transmitter. Subscriber network component.