KR20110050413A - Optical access network apparatus based on wavelength division multiplexing technology - Google Patents

Abstract

PURPOSE: An optical subscriber network device of a wavelength division multiplex is provided to supply a single optical divider node and a various types of work and multi subscriber devices of their own multi subscriber. CONSTITUTION: An optical main network of a wave division multi method is formed such as cyclic structure, a bus structure, a tree structure. An Ethernet router, a local wavelength distribution (reverse)multiplexer, a main optical path, a wave division (reverse)multiplexer for remote distribution node, and an optical path for branch has a physical layer.

Description

Optical Participation Network Device of Wavelength Division Multiplexing {OPTICAL ACCESS NETWORK APPARATUS BASED ON WAVELENGTH DIVISION MULTIPLEXING TECHNOLOGY}

The present invention relates to an optical subscriber network device, and more particularly, to a wavelength division multiplex optical subscriber network.

1 is a configuration diagram schematically showing a wavelength division multiplex optical transmission system for a conventional point-to-point communication. Referring to Fig. 1, a wavelength division multiplexer, a wavelength division demultiplexer, an optical transmitter, and an optical receiver are configured. For wavelength division multiplexing, a light source of a specific wavelength that matches the wavelength assigned to each input terminal of the wavelength division multiplexer is used as the optical transmitter. The point-to-point wavelength division multiplexing method is mainly used for medium to long distance transmission, such as intercity and interstate history, thereby reducing the number of optical paths required and enabling high-speed large-capacity transmission.

In addition to point-to-point communication systems, various types of optical distribution networks, such as annular, tree, and bus types, using wavelength division multiplexing have been developed and utilized. In particular, annular wavelength division multiplexing is widely used in metro optical communication systems.

Conventional wavelength division multiplexing has been widely used only in medium to long distance optical transmission systems, although it has the advantage of increasing the efficiency of optical paths and enabling large-capacity transmission. This is because the wavelength division multiplexing requires accurate wavelength matching between the wavelength division multiplexer and the light source, thereby greatly increasing installation / maintenance / maintenance costs.

This restriction has been a major obstacle for the wavelength division multiplex optical communication system to enter the general subscriber network. However, recently, as the light source does not need to select a light source of a specific wavelength for each subscriber, the development of the optical subscriber network device using the wavelength division multiplexing method has been actively developed.

In the subscriber network, various types of equipments are mixed and needs various types of subscriber networks suitable for the service and subscriber environment used. Therefore, it is necessary to develop various network structures suitable for the subscriber environment according to the characteristics of the optical devices and the services used for the wavelength division multiplexing optical subscriber network device.

Currently, with the development of the Internet, the subscriber network has been widely used with various Ethernet-based devices. Typically, various devices such as IP-xDSL, Ethernet switch, and access point (AP) provide optical Ethernet access terminal for subscriber aggregation function and higher network interworking, except for end subscriber acceptance method.

2 is a structure of an optical subscriber network device for accommodating various existing subscriber devices. The existing method requires a separate light path for each device, which increases the installation cost. Therefore, it is essential to develop an efficient optical subscriber network device capable of independently accommodating various services. There is also a need to develop equipment that is compatible with existing equipment.

The present invention has been proposed to solve the above-mentioned problems of the prior art, and an object thereof is to provide a wavelength division multiple access optical subscriber network device capable of providing various types of services. The wavelength division multiplex optical subscription network device has an advantage of providing independent services for each wavelength by using different wavelengths. The purpose of this is to accommodate various existing subscriber devices in one optical distribution network.

In addition, another object of the present invention is to increase the utilization of the Ethernet-based subscriber equipment widely used in subscriber networks by using wavelength division multiplexing technology.

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

In the annular wavelength division multiplexing optical subscriber network device of the present invention, different optical signals of the same wavelength are transmitted from the central station to the downward annular optical path in different directions.

The wavelength division multiplexing optical subscriber network device according to the present invention enables various types of subscriber devices to be connected through a single optical distribution network. The optical distribution network according to the present invention increases the utilization of the optical trunk network and provides a single optical trunk network and a multi-stage optical branch node that can accommodate various subscriber distributions.

In addition, the wavelength division multiplexing annular optical distribution network using the external injection light according to the present invention extends the bandwidth in a normal state and can operate normally even in a failure state, thereby providing stable service.

1 is a block diagram showing a conventional point-to-point wavelength division multiplex optical transmission system.
Figure 2 is an optical subscriber network device that accommodates a number of conventional optical subscriber devices.
Figure 3 is a schematic diagram showing a structure of a wavelength division multiplexing optical subscriber network device for accommodating multiple optical subscriber devices in one optical distribution network according to the present invention.
4 is a wavelength division multiplexing optical distribution network according to the present invention.
5 is a wavelength division multiplexing optical distribution network having multiple stage branching according to the present invention.
Figure 6 is a schematic diagram showing an optical transceiver using a subcarrier according to the present invention.
Figure 7 is an annular wavelength division multiplexing optical subscriber network device using an external injection light according to the present invention.

Hereinafter, with reference to the accompanying drawings, the configuration and operation of the embodiment of the present invention will be described in detail.

3 is an embodiment of a wavelength division multiple access optical subscriber network device for accommodating multiple subscriber equipments according to the present invention. The optical fiber network of the wavelength division multiplexing system according to the present invention may be implemented in an annular structure, a bus structure, a tree structure, and the like.

Ethernet routers with wavelength division multiplex optical transceivers in central offices as physical layers, wavelength division (reverse) multiplexers for trunks, trunk lines, wavelength division (reverse) multiplexers for remote distribution nodes, branch lines, An optical subscriber terminal having a wavelength division multiplex optical transmitter as a physical layer. Typical optical subscriber termination devices are subscriber concentrators for IP-xDSL, Ethernet switches, wireless access devices, and home gateways. A single optical distribution network consisting of trunk lines, remote distribution nodes and branch lines has a large number of homogeneous or heterogeneous optical subscriber termination devices.

In the optical subscriber network device according to the present invention, since a plurality of optical subscriber terminal devices utilize a common trunk line, the efficiency of the optical line can be increased. In addition, since each individual optical subscriber device is connected to the upper station of the central office by an independent wavelength, it is possible to provide independent services, and can be utilized by changing only the physical layer interface of various existing subscriber equipment.

As the wavelength allocation method of the wavelength division multiplexing method, a dense wavelength division multiplexing method, a coarse wavelength division multiplexing method, and the like are used.

Figure 4 (a) is an embodiment of a wavelength division multiplexing optical distribution network according to the present invention. When using the existing scheme of FIG. 1 as an optical subscriber network, the downlink trunk line and the uplink trunk line are separately required. In order to improve the speed of subscribers, the optical subscriber network must be deployed in or near the subscriber generation, and in this case, the number of trunk lines required increases. Therefore, there is a need for an efficient optical subscriber network that reduces the trunk path needed. The remote distribution node of the embodiment of FIG. 3 has a group wavelength division multiplexer 401 for separating uplink and downlink optical signals, a wavelength division multiplexer 402 for multiplexing uplink optical signals, and demultiplexing downlink optical signals. It consists of a wavelength division demultiplexer (403).

4 (b) is an embodiment of a wavelength allocation method for an uplink signal and a downlink signal according to the present invention. The band allocation method is a method of separating an allocated band of an uplink signal and a downlink signal. On the other hand, the wavelength shift method allocates an uplink signal and a downlink signal alternately adjacent to each other.

In the group wavelength division multiplexer 401, a micro-optic optical device using a thin film filter, an optical device using a planar optical waveguide, or the like is used in the band division method. On the other hand, in the wavelength shift method, an optical interleaver having periodic pass wavelength characteristics is used as a group wavelength division multiplexer.

5 is an embodiment of a wavelength division multiplexing optical distribution network having a multi-stage branch according to the present invention. In the case of the optical subscriber network device, an optical distribution network having multiple stage branches is required to accommodate various subscriber distributions. Multi-stage branching is required if the subscriber distribution is distributed into multiple groups or depending on the type of optical laying pipeline.

The optical distribution network consists of multiple remote distribution nodes. The first remote distribution node from the central office consists of a group wavelength division multiplexer 501 and a small group wavelength division multiplexer 502, 503. As described above in FIG. 4, the group wavelength division multiplexer 501 separates / combines a downlink signal and an uplink signal. The small group wavelength division multiplexers 502, 503 are provided for the downlink signals [lambda] 1 ', [lambda] 2',... , λn ') are a plurality of small groups λ1',... , λa ', λb',... , lambda d ',... , lambda e ',... a plurality of small groups λ 1,... , λa, λb,... , λd,... , lambda m,... , combines λn into one. 5 is a case where two small groups are used for simplicity of explanation.

One uplink signal small group λ1,... , λa and one downlink signal small group λ1 ',... , λa 'is connected to the second remote distribution node using different photovoltaic lines. In the second remote distribution node, demultiplexing 505 for the downlink signal and multiplexer 504 for the uplink signal are used to assign one uplink signal and one downlink signal to each end optical subscriber device. For more multi-branch structures, a small group wavelength division multiplexer that splits into smaller small groups can be used again at the second remote node.

The traditional Ethernet switches and Ethernet switches in IP-xDSL concentrators, which are used by service providers, mostly provide two upstream ports. In the case of initial installation, one up port is used, and in the case of requesting an additional up port later, there is a problem of additionally securing an optical path. In particular, in the case of wavelength division multiplexing, an additional wavelength must be allocated in addition to the optical path, which is possible only when there is an available idle wavelength of the remote distribution node.

6 is an embodiment of a scheme for increasing the number of transmission channels using subcarriers according to the present invention. In the present invention, a physical layer using subcarriers for accommodating one or more communication channels in an existing optical path is used. FIG. 6 is a representative embodiment, by changing only a physical media dependent (PMD) layer, which is the lowest physical layer of an existing Ethernet device supporting two upstream ports, and independently using a single optical path or one optical wavelength. It is a way to transmit. When used in a wavelength division multiplex optical subscriber network device, the use of subcarriers does not require additional wavelength allocation and may increase the channel. This method is also applicable to optical transmission systems using media converters or optical transmission systems of SONET and ATM series.

7 is an embodiment of an annular light distribution network of a wavelength division multiplexing scheme using externally injected light according to the present invention. As described above, the wavelength division multiplexing optical subscriber network device using the external injection light is automatically made in the physical layer of each subscriber, thereby greatly solving the installation / maintenance / management problems. Conventional wavelength division multiplexing using externally injected light is mainly used for distribution network of molded structure, and Korean Patent Application No. 10-2002-0060868 (Invention: Bi-directional wavelength using light source which is wavelength immersed in injected non-coherent light) Segmented Multiple Passive Optical Network, Inventors: Choo Kwang-wook, Chang-hee Lee, and Tae-won Oh). The present invention provides a wavelength division multiplexing optical distribution network using external injection light suitable for an annular network.

The annular optical subscriber network device of the present invention comprises a central office 700, remote nodes 723 to 725, a downward annular beam, and an upward annular beam. The central office consists of an optical transceiver, wavelength division multiplexers 711 and 714, wavelength division demultiplexers 712 and 713, optical circulators 715 to 718, and a broadband light source. The broadband light source may branch and use one broadband light source in the same band. The broadband light generated by the downlink wideband light sources BLS I and BLS IV is transmitted to the wavelength division multiplexers 711 and 714 by the optical circulators 715 and 718, and thus the optical transmitters 701, 703, 706 and 708. Becomes external injection light. Downlink signals generated from the optical transmitters 701, 703, 706, 708, which are wavelength-locked by external injection light, are multiplexed by the wavelength division multiplexers 711, 714, and the multiplexed signals are passed through the optical circulators 715, 718. Is sent to.

The central office has broadband light sources (BLS II, BLS III) for remote nodes. Broadband light for the remote node is delivered by the optical circulators 716 and 717 to the remote node via an upward annular optical path. In addition, the uplink optical signal injected by each remote node is multiplexed and transmitted to the central station. Is passed to.

The remote nodes 723, 724, 725 are composed of four-terminal wavelength division multiplexers 719, 720 for λi, and optical transceivers 721, 722. The operating characteristics of the 4-terminal wavelength division multiplexer for lambda i of the remote node are shown in Fig. 7 (b). Of the optical signals input to the first common terminal of the 4-terminal wavelength division multiplexer for λi, the optical signal of the λi wavelength is output to the first branch terminal, and the optical signal of the other wavelength is output to the second common terminal. Further, of the optical signals input to the second common terminal of the 4-terminal wavelength division multiplexer for λi, an optical signal of wavelength λi is output to the second branch terminal, and an optical signal of other wavelengths is output to the first common terminal. The optical receiver is connected to the branch terminal of the 4-terminal wavelength division multiplexer for λ i used in the downlink optical path. On the contrary, an optical transmitter is connected to a branch terminal of the 4-terminal wavelength division multiplexer for λ i used in an uplink optical path.

In the annular distribution network according to the present invention, different optical signals of the same wavelength are transmitted from the central station to the downward annular optical path in different directions. The downlink optical signal of λ1 wavelength-locked to the optical transmitter 701 reaches the remote node 723 in a clockwise direction, and the downlink optical signal of λ1 wavelength-locked to the optical transmitter 706 is counterclockwise to the remote node 723. ) The optical signal of [lambda] 1 transmitted through the downward annular optical paths of different directions is branched by the branch terminal 719 of the 4-terminal [lambda] 1 wavelength division multiplexer at the remote node 723 and transmitted to the optical receiver.

In addition, the broadband external injection light provided from the central office reaches the 4-terminal λ1 wavelength division multiplexer 720 of the remote distribution node 723 through upwardly annular optical paths in different directions so that the broadband light in the λ1 wavelength region is branched. Through the light is injected light for the transmitter.

Two communication channels having different optical paths are formed between the central office and the remote node 723. The optical transceiver 709 of the central office and the optical transmitter 721 of the remote node are connected to the communication channel by a clock ray and a light signal having a wavelength of? 1 from the central office. In addition, the optical transceiver 710 of the central office and the optical receiver 722 of the remote node are connected to the communication channel by an optical signal of λ1 wavelength and a counterclockwise light beam from the central office. The annular optical distribution network of the present invention provides compatibility between optical transmitters of a remote node and provides line protection between a central office and a remote node.

As described above, two independent optical channels are connected in a normal state between the central office and the remote node. In addition, even if a failure occurs in a specific area of the beam, the bypass beam will operate normally.

These functions provide useful functions when the optical transceivers of the central office and remote nodes are used as the physical layer of the Ethernet switch. Ethernet switches provide Link Aggregation (IEEE 802.3 ad), which makes multiple physical links one logical link. Therefore, when the Ethernet switch is used as both end devices of the annular optical distribution network having the 1: 1 function as described above, and the link aggregation function is set, the bandwidth corresponding to two channels is guaranteed in the normal state, and in case of failure, The band can be guaranteed.

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

Claims (1)

In the annular wavelength division multiplexing optical subscriber network device,
An annular wavelength division multiplexing optical subscriber network device in which different optical signals of the same wavelength are transmitted from a central station to a downward annular optical path in different directions.

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