KR20080095570A - Multistage wavelength division multiplexed passive optical network using band add-drop method - Google Patents

Abstract

A multistage WDM-PON using a band add-drop method is provided to improve the usability of the device even in case subscribers are scattered due to freely selecting a division coupling point. A multistage WDM-PON includes OLT(Optical Line Termination) in a central base station, a plurality of the band division remote nodes(RN11, RN21, ...), a plurality of the wavelength division multiplexing/inverse multiplexing remote node (RN12, RN22, ...) and ONT/ONUs which are subscriber devices. The plurality of the wavelength division multiplexing/inverse multiplexing remote node and at least one band division remote node is corresponding to one OLT.

Description

Multistage wavelength division multiplexed passive optical network using band add-drop method

1 shows a simplified structure of a typical WDM-PON.

Figure 2 is a block diagram showing the structure of a multi-stage branched WDM-PON using the band branching of the present invention.

The present invention relates to a Wavelength Division Multiplexed Passive Optical Network (WDM-PON), and more particularly, to a wavelength division multiplexing passive type which accommodates a multi-stage branching distribution network using a band branching scheme. It relates to an optical subscriber network.

Recently, with the rapid spread of the Internet and the conversion of existing voice and text oriented services to video oriented services, the speed of subscriber networks is rapidly increasing. In the near future, the average transmission bandwidth that should be guaranteed to subscribers in the subscriber network should be at least 100 Mb / s in both directions, and the transmission distance must meet at least 20 km, an international standard selected based on the distance from the subscriber to the subscriber.

The only technology that satisfies these conditions is FTTH (Fiber to the Home), which provides single-mode fiber to the home and provides services. Also, among the various FTTH implementations, it saves fiber and provides subscribers the same as point-to-point connection. The wavelength-division multiplexing passive optical subscriber network that can provide more than Mb / s bandwidth and guarantee high quality of service (QoS) is recognized as the ultimate alternative.

1 is a view showing a simplified structure of a general WDM-PON.

WDM-PON is an Optical Line Termination (OLT) existing in a central office (CO), a Remote Node (RN) consisting of a WDM, a Optical Network Termination (ONT), a subscriber device, or It consists of an optical network unit (ONU) and an optical distribution network that physically connects them.

WDM-PON uses different wavelength bands in both up and down directions. The OLT and RN wavelength division multiplexers simultaneously transmit the uplink and downlink bands and multiplex / demultiplex the optical signals with 1 × N. Where N represents the number of ONT or ONU.

From the OLT to the RN, the multiplexed optical signal is connected to one strand of optical fiber, and at RN, the multiplexed optical signal for each wavelength is connected to the ONT or ONU through the N stranded optical fiber.

As such, the conventional WDM-PON has a single-stage branch structure in which N subscriber devices are connected through one RN. Therefore, the location of the RN is preferably located where the cost of using and laying the optical fiber can be minimized in consideration of the location of the subscriber device.

On the other hand, subscribers who want to use WDM-PON are not only scattered spatially, but also have a time distribution in the time of establishing WDM-PON. Therefore, even when considering the future use in the construction of the WDM-PON, it is practically difficult to use all the subscriber equipment due to the increase in the use of fiber and the cost of laying. This is because, in some cases, in order to use a subscriber device considering a future use possibility in a specific region and use the remaining subscriber devices in other regions, the cost of installing the optical fiber may be much higher in some cases. In addition, group residential areas such as apartments cannot accommodate subscribers in other areas due to the limitations in fiber optic entry structure. Therefore, the conventional WDM-PON having a single-stage branching structure suffers a certain loss in terms of subscriber capacity. In order to solve this problem, there is a need for a WDM-PON having a two-stage or more multistage branching structure. It is becoming.

As a WDM-PON having a multi-stage branching structure, a method using a thin film filter, an interleaver and an AWG has been proposed in Korean Laid-Open Patent Publication (10-2005-0099229). However, known conventional methods are each branched in parallel at one point and connected to a second remote node. Therefore, when the distribution of subscribers is scattered, network configuration is inefficient because branching should be performed at the nearest point. Of course, there is a method of branching a single channel sequentially at several points, but in order to branch as many channels as desired, economical efficiency is lowered due to increased insertion loss due to sequential branching.

Accordingly, an object of the present invention to solve the above-described problem is to provide a multi-stage branched WDM-PON that can be applied to subscriber distribution interspersed by overcoming the limitations of the conventional multi-stage branched WDM-PON and freely selecting branch joining points.

A multi-stage branched WDM-PON using the band branching scheme of the present invention for achieving the above object is provided at the front of the subscriber devices to demultiplex the downlink optical signal to transmit to the subscriber devices and upstream from the subscriber devices. A plurality of wavelength division multiplexing / demultiplexing remote nodes for multiplexing uplink optical signals; And branching a predetermined band of the downlink optical signal at the front end of the wavelength division multiplexing / demultiplexing remote node to transmit to the corresponding wavelength division multiplexing / demultiplexing remote node, and upward from the corresponding wavelength division multiplexing / demultiplexing remote node. At least one band-division combining remote node for combining an optical signal with an optical signal transmitted upward from a neighboring remote node and transmitting upward.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

Figure 2 is a block diagram showing the structure of a multi-stage branched WDM-PON using the band branching of the present invention.

The multi-stage branched WDM-PON of FIG. 2 is installed in front of an OLT, a plurality of band-division combining remote nodes (RN ₁₁ , RN ₂₁ , ...), and a subscriber station in the central base station to demultiplex downlink optical signals and And a plurality of wavelength division multiplexing / demultiplexing remote nodes RN ₁₂ , RN ₂₂ ,...

In FIG. 2, the functions of the OLT, wavelength division multiplexer / demultiplexers RN ₁₂ , RN ₂₂ ,..., And subscriber units ONT / ONUs are the same as those of FIG. 1, and thus description thereof will be omitted.

In the multi-stage branched WDM-PON of the present invention, as shown in FIG. 2, a plurality of wavelength division multiplexing / demultiplexing remote nodes RN ₁₂ , RN ₂₂ ,..., RN _k2 correspond to one specific OLT. One less number of band branch-coupled remote nodes (RN ₁₁ , RN ₂₁ , ...) than the multiplexed remote nodes (RN ₁₂ , RN ₂₂ ,..., RN _k2 ) and the multiplexing / demultiplexing remote nodes (RN _12). , RN ₂₂ ,..., RN _k2 ). The band branch combining remote nodes RN ₁₁ , RN ₂₁ ,... Are arranged in front of the multiplexing / demultiplexing remote nodes RN ₁₂ , RN ₂₂ ,... to branch the optical signal of the band multiplexer / demultiplexer that is one-to-one basis _{(RN 12, RN 22, ...} ) transmission, multiplexing / demultiplexing is a one-to-one correspondence to an uplink optical signal from the _{(RN 12, RN 22, ...} ) on their It is combined with the uplink optical signal from the down neighboring remote node (band branch combining remote node or multiplexing / demultiplexing remote node (RN _k2 )) of the uplink transmission. In this case, down-neighboring means that the neighboring neighbors on the same cable are farther from the OLT than themselves.

Each of these band branch combining remote nodes RN ₁₁ , RN ₂₁ ,... Has band separating filters A, A / B and a band combining filter B. FIG.

The band separation filter (A) branches the optical signals of a predetermined band with respect to the downlink optical signal and transmits them to the band separation filter (A / B), and transmits the uplink optical signal as it is.

The band separation filter A / B transmits the optical signal from the band separation filter A to the corresponding wavelength division multiplexing / demultiplexing remote node RN, and corresponds to the corresponding wavelength division multiplexing / demultiplexing remote node RN. The uplink optical signal from the RN is transmitted to the band combining filter B. That is, the band separation filter A / B separates the progress paths of the downlink optical signal and the uplink optical signal so that each of them passes through different paths.

The band combining filter B transmits the downlink optical signal from the band separation filter A as it is, and transmits the uplink optical signals by combining the uplink optical signals. That is, the band combining filter B combines an uplink optical signal from the band separating filter A / B with an uplink optical signal from a neighboring remote node (band branch combining remote node or multiplexing / demultiplexing remote node). Uplink to the band separation filter (A).

The band separation filter (A, A / B) and the band combined filter (B) can be implemented by using a thin film optical filter that is well known.

The operation of the multi-stage branched WDM-PON using the band branch combining of the present invention having the above-described configuration will be briefly described as follows.

First, the downlink optical signals will be described. The multiplexed downlink optical signals from the OLT are first applied to the band branch combining remote node RN ₁₁ closest to the OLT. The band separation filter A ₁ of the band branch combining remote node RN ₁₁ band-branches the optical signals of wavelengths allocated to the subscriber devices n ₁ from the applied downlink optical signals. ₁ ) and transmit the optical signals of the remaining bands as they are and are transmitted downward to the band coupling filter (B ₁ ).

The band separation filter A / B ₁ transmits the optical signals branched from the band separation filter A ₁ as it is and transmits them to the corresponding wavelength division multiplexing / demultiplexing remote node RN ₁₂ , and the band combining filter B _1. ) Transmits the optical signals transmitted and transmitted through the band separation filter A ₁ back downward as it is and transmits them to the neighboring band branch combining remote node RN ₂₁ .

The wavelength division multiplexing / demultiplexing remote node RN ₁₂ demultiplexes the optical signals from the band separation filter A / B ₁ for each wavelength and transmits them to the corresponding subscriber stations n ₁ .

The optical signals transmitted downward from the band branch combining remote node RN ₁₁ are bands of the optical signals allocated to the subscriber stations n ₂ by the band separation filter A ₂ of the band branch combining remote node RN ₂₁ . The branched optical signals are transmitted to the wavelength division multiplexing / demultiplexing remote node RN ₂₂ through the band separation filter A / B ₂ . Further, the downlink optical signals of other bands transmitted downward by the band separation filter A ₂ are transmitted downward through the band combining filter B ₂ again so that neighboring band branching remote nodes (not shown) or wavelength division multiplexing / reversing are performed. Is sent to the neutralizer RN _k2 .

Although Figure 2 has been shown, of the band branch combined remote node (RN ₂₁₎ of the band branch combined remote node installed after the road corresponding to the same manner as in the above-described band branch coupled to the remote node (RN _11, RN ₂₁₎ subscriber unit Band branch the optical signals.

Then in the case of an uplink optical signal, the uplink optical signals from the subscriber devices n ₂ are multiplexed at the wavelength division multiplexing / demultiplexing remote node RN ₂₂ and then the band of the band branch combining remote node RN ₂₁ . The separation filter (A / B ₂ ) is transmitted, and the band separation filter (A / B ₂ ) transmits the multiplexed uplink optical signal from the wavelength division multiplexing / demultiplexer (RN ₂₂ ) to the band combining filter (B ₂ ). .

The band combining filter B ₂ is a band-division combining remote node (not shown) or a wavelength-division multiplexing / demultiplexing remote node (RN _k2 ) that neighbors an uplink optical signal from the wavelength division multiplexing / demultiplexing remote node RN ₂₂ . Combined with the uplink optical signal from) and transmitted upward to the band separation filter (A ₂ ).

The band separating filter A ₂ transmits the uplink optical signal from the band combining filter B _{2 as it} is and transmits it upward to the band branch combining remote node RN ₁₁ .

On the other hand, the uplink optical signals from the subscriber stations (n ₁ ) are multiplexed at the wavelength division multiplexing / demultiplexing remote node (RN ₁₂ ) and then through the band separation filter (A / B ₁ ) to the band combining filter (B ₁ ). Is sent.

The band combining filter B ₁ combines the multiplexed uplink optical signal from the wavelength division multiplexing / demultiplexing remote node RN ₁₂ with the uplink optical signal from the neighboring band branch combining remote node RN ₂₁ . Uplink to (A ₁ ).

The band separation filter A ₁ transmits an uplink optical signal from the band combining filter B ₁ and transmits the uplink optical signal to the OLT.

As described above, in the multi-stage branched wavelength division multiplexing passive optical subscriber network using the band-branching method of the present invention, since the choice of branch-coupling points is free, efficient subscriber network configuration is possible even in the case of scattered subscriber lines. Reduce costs and increase device utilization.

Claims (4)

A plurality of wavelength division multiplexing / demultiplexing remote nodes provided in front of the subscriber devices to demultiplex downlink optical signals and transmit the downlink optical signals to the subscriber apparatuses and to multiplex uplink optical signals from the subscriber apparatuses; And Splitting a predetermined band of the downlink optical signal at the front end of the wavelength division multiplexing / demultiplexing remote node to transmit to the corresponding wavelength division multiplexing / demultiplexing remote node, and upward from the corresponding wavelength division multiplexing / demultiplexing remote node. A multi-stage branched wavelength division multiplex passive optical subscriber network using a band-division combining method comprising at least one band-division combining remote node for combining an optical signal with an optical signal transmitted upward from a neighboring remote node. The method of claim 1, wherein the band branch combining remote node A first band separation filter for branching optical signals of a predetermined band with respect to the downlink optical signal applied thereto and transmitting upwardly with respect to the uplink optical signal; The downlink optical signal from the first band filter is transmitted downward, and the uplink optical signal from the corresponding multiplexer / demultiplexer is combined with the uplink optical signal from the downlink neighboring remote node and transmitted to the first band separation filter. Band combined filter; And A second band separation filter for transmitting the optical signal branched from the first band separation filter to the corresponding multiplexer / demultiplexer and transmitting the uplink optical signal multiplexed from the corresponding multiplexer / demultiplexer to the band combining filter; Multi-stage branched wavelength division multiplexing passive optical subscriber network using a band-branching coupling method characterized in that it comprises. 3. The filter of claim 2, wherein the filters are Passive multi-stage wavelength division multiplexing passive optical subscriber network using the band-branch coupling method characterized in that the thin-film passive optical filter. The method of claim 1, The plurality of wavelength division multiplexing / demultiplexing remote nodes and the at least one band branch combining remote node correspond to one optical line termination (OLT). Passive optical subscriber network.

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