CN104426739B - A kind of method, remote node and the optical line terminal of fusion Metropolitan Area Network (MAN) and access net - Google Patents

Abstract

The invention specifically discloses a method for integrating a metropolitan area network and an access network, a remote node and an optical line terminal, wherein the downlink transmission signal received from the metropolitan area network is demultiplexed into at least one common wavelength , a dedicated wavelength downlink signal corresponding to the remote node and other wavelength signals, converting the downlink data on the dedicated wavelength downlink signal to a common wavelength to obtain a common wavelength signal, and sending the common wavelength signal to the access network, removing the downlink data on the dedicated wavelength downlink signal to obtain a dedicated wavelength, converting the uplink data on the uplink transmission signal received from the access network to a dedicated wavelength to obtain a dedicated wavelength upload signal, and uploading the uplink data to the metropolitan area network Dedicated wavelength for uploading signals.

Description

A method for merging metropolitan area network and access network, remote node and optical line terminal

technical field

The invention relates to the technical field of communication, and more specifically, to a method for integrating a metropolitan area network and an access network, a remote node and an optical line terminal.

Background technique

Metro Network and Access Network are usually two completely different types of networks, and their differences include technologies, protocols, and transmission media. Maintaining both types of networks simultaneously is complex and expensive. And the transmission of data from one type of network to another type of network must be carried out on the interconnection node for photoelectric conversion and electrical processing. With the development of Passive Optical Network (PON) in the access network, optical fiber has become a common transmission medium in the metropolitan area network and the access network. This makes it possible to fuse the two types of networks using similar technologies, thereby gaining economies of scale and reducing maintenance costs.

A promising approach is to achieve metropolitan access to converged optical networks by extending the passive optical network (PON) to the scope of the metropolitan area network. Originally separated multiple access networks are aggregated into the metropolitan area network ring through remote nodes to form a unified network. Multiple optical line terminals (OLTs) in the traditional passive optical network are combined into one optical line terminal, which greatly saves the construction cost and maintenance cost of the operator. The remote node (RN) is used to upload and download the wavelength pair (Wavelength Pair) carrying uplink and downlink data from the metro ring network (Metro Ring) to the converged access network, and compensate for the attenuated signal power due to long-distance transmission . In consideration of cost and upgradeability, Wavelength Division Multiplexing (WDM) technology is used in the metropolitan area network to replace the Synchronous Digital Hierarchy (SDH) technology used in the existing metropolitan area network. Since it will still be very expensive to allocate a dedicated wavelength to each user for a long period of time in the future, the time-division multiplexing technology of the existing access network is still used in the access network. Therefore, the converged network structure combining the wavelength division multiplexing ring (WDM-ring) of the metropolitan area network and the time division multiplexing tree (TDM-tree) of the access network is regarded as the most promising way to realize the metropolitan access converged optical network. One of the structures, it uses mature and low-cost optical devices, and can support current and future bandwidth requirements.

The International Organization for Standardization ITU-T Q2/SG15 is currently working on the research on the above topics, with a view to "drafting a new standard proposal for the general characteristics of the new long-distance access network oriented to access/metro integrated applications". Several research projects, such as OLI launched in 2010, are also based on this background.

Although a lot of research has been done, how to design a more optimized metro-access (Metro-Access) converged optical network, especially the remote node as a key component, is still an unresolved problem. Network design ultimately hopes to achieve the following goals:

●Low-cost metro-access converged optical network

● Transparent to bit rate and protocol

● Unified technical specifications for all users

●Meet the upgrading needs of more users and larger bandwidth

●It is best to be compatible with various passive optical networks that have been deployed

So far, there is no solution that can fully meet the above requirements. As shown in Figure 1, Nokia Siemens Networks (NSN) proposes a converged optical network solution for metropolitan access only compatible with Gigabit Passive Optical Network (GPON). In a common time-division multiplexing passive optical network, such as a gigabit passive optical network, traffic between an optical network unit (ONUS) and an optical line terminal (OLT) is time-division. The bearer wavelength of the uplink and downlink services is regulated by the standard, that is, the downlink uses a wavelength of 1490nm, and the uplink uses a wavelength of 1310nm. However, in the metropolitan-access converged optical network, when multiple time-division multiplexed passive optical networks are connected to the same metropolitan ring network and use the same uplink and downlink Service congestion occurs on the ring network. Therefore, when there are N access networks connected to the same metropolitan ring network, N different wavelength pairs (2N wavelengths) need to be used in the metropolitan ring network to bear the uplink and downlink of each access network respectively. conduct business. Each remote node (RN) uses a dedicated wavelength pair to upload or download data between the MAN and the corresponding access network.

As shown in Figure 1, in order to be compatible with the standard Gigabit passive optical network and keep all optical network units "colorless", the data carried on the dedicated wavelength pair (Wavelength Pair) in the metropolitan area network, in each local interface In network access, it needs to be converted to the bearer wavelength of downlink 1490nm and uplink 1310nm. The above-mentioned wavelength conversion is realized by using a downlink wavelength converter (DWC) and an uplink wavelength converter (UWC) in a specially designed remote node. When the downlink data bearing wavelength in the metropolitan ring network is within the downlink receiving band (1480nm-1500nm) of the access part Gigabit Ethernet, the downlink wavelength converter may not be used.

However, the above scheme has many shortcomings: First, in order to meet the requirements of the "downlink receiving band", it will be subject to the following two restrictions. On the one hand, the downlink bearer wavelength of the WDM ring network is limited to a specific band, which is not conducive to flexible Network planning; on the other hand, in order to ensure that the central wavelengths of each downlink passband have sufficient intervals, the number of access networks that can be connected to the metropolitan ring is limited (the number of connections is equal to the number of wavelength pairs in the metropolitan ring). Secondly, if the requirement of "downlink receiving band" is not considered, a downlink wavelength converter (DWC) must be used. Since the wavelength converter is realized based on the cross-gain modulation (XGM) effect of a semiconductor optical amplifier (SOA), each remote node needs to additionally deploy a laser that emits continuous light, and its emission wavelength and the expectation of carrying data after wavelength conversion the same wavelength. This means that a CW laser with a wavelength of 1490nm is required in each remote node, which is not economical, however. Third, the above solution is opaque to network upgrades. When a Gigabit passive optical network and a 10 Gigabit passive optical network exist simultaneously in the same converged optical network, since the two follow different The downlink wavelength of Gigabit PON is 1490nm, and the downlink wavelength of 10G PON is 1577nm), the remote nodes of Gigabit PON and the remote nodes of 10G PON need to respectively deploy continuous optical cables with different output wavelengths. laser. Fourth, another shortcoming of the above solution is that too much spectrum resources are occupied in the MAN, and the number of wavelengths used is twice the number of actual access networks. When the number of users increases sharply, a bottleneck will be encountered. Therefore, it is particularly urgent to design a scalable, colorless, and high-spectrum utilization remote node that is compatible with existing deployed networks for metropolitan access converged optical networks.

Contents of the invention

In order to design a more optimized metro-access (Metro-Access) converged optical network, especially the key component therein: the colorless remote node, the problems in the above-mentioned prior art are solved, so according to a method of the present invention Aspects, a method for merging a metropolitan area network and an access network on a remote node is proposed, which includes the following steps: A. demultiplexing the downlink transmission signal received from the metropolitan area network into at least one common wavelength, a dedicated wavelength downlink signal corresponding to the remote node and other wavelength signals, the common wavelength is distributed as a transparent transmission part and a download part through the optical coupler power; B. convert the downlink data on the dedicated wavelength downlink signal Go to the download part of the public wavelength to obtain the public wavelength signal and the dedicated wavelength downlink attenuation signal; C. remove the downlink data in the dedicated wavelength downlink attenuation signal to obtain the dedicated wavelength; D. send to the access network The public wavelength signal; E. receiving the uplink transmission signal sent by the access network; F. converting the uplink data on the uplink transmission signal to the dedicated wavelength to obtain a dedicated wavelength upload signal; and G . Uploading the dedicated wavelength upload signal, the transparent transmission part of the common wavelength and the other wavelength signals to the MAN through wavelength division multiplexing.

Specifically, in step B, the downlink signal of the dedicated wavelength is the first pump light, the download part of the common wavelength is the first probe light, and the dedicated wavelength is converted to The downlink data on the wavelength downlink signal is converted to the download part of the common wavelength. This method can effectively convert the signal on one wavelength to another wavelength.

In particular, in step F, the uplink transmission signal is used as the second pump light, and the dedicated wavelength is the second probe light. Through the cross-gain modulation effect of the second semiconductor optical amplifier, the uplink transmission signal on the Uplink data is converted to the dedicated wavelength.

Particularly, in step B: the first pumping light and the first probe light are incident simultaneously from the first end and the second end of the active layer of the first semiconductor optical amplifier; in step F : The second pump light and the second probe light are incident simultaneously from the first end and the second end of the active layer of the second semiconductor optical amplifier. Through this method, the converted pump light and probe light can be effectively separated only by a circulator without using a band-pass filter.

Specifically, in step C: reduce the optical signal-to-noise ratio of the dedicated wavelength downlink attenuated signal through the gain saturation characteristic of the third semiconductor amplifier, so as to remove the downlink data on the dedicated wavelength downlink attenuated signal. In this way, a dedicated wavelength can be obtained without the need for a laser transmitter, saving costs and resources.

According to another aspect of the present invention, a method for assisting in the fusion of a metropolitan area network and an access network on an optical line terminal is disclosed, including the following steps: setting at least one common wavelength; generating a dedicated wavelength downlink signal, each dedicated wavelength downlink The signal corresponds to a remote node; the downlink signal of the dedicated wavelength and at least one common wavelength are wavelength-division multiplexed into a downlink transmission signal, and transmitted to the metropolitan area network.

According to another aspect of the present invention, a remote node for merging a metropolitan area network and an access network is disclosed, which is characterized in that it includes: The downlink transmission signal received in the network is demultiplexed into at least one common wavelength, a dedicated wavelength downlink signal corresponding to the current remote node, and other wavelength signals. Part; downlink wavelength converter, which receives the download part of the common wavelength and the downlink signal of the dedicated wavelength, and converts the downlink data on the downlink signal of the dedicated wavelength to the download part of the common wavelength to obtain a common wavelength signal and a dedicated wavelength downlink attenuation signal; a downlink modulation removal module, which receives the dedicated wavelength downlink attenuation signal, and removes the downlink data in the dedicated wavelength downlink attenuation signal to obtain a dedicated wavelength; access network wavelength division multiplexing module , its downlink input end receives the common wavelength signal, its uplink input end receives the uplink transmission signal from the access network, it performs wavelength division multiplexing on the common wavelength signal and the uplink transmission signal, and passes through its downlink output end Sending the public wavelength signal to the access network, while sending the uplink transmission signal at its uplink output end; an uplink wavelength converter, which receives the dedicated wavelength and the uplink transmission signal, and converts the uplink transmission signal on the uplink The uplink data is converted to the dedicated wavelength to obtain a dedicated wavelength upload signal; the metropolitan area network wavelength division multiplexing module receives the dedicated wavelength upload signal, the transparent part of the public wavelength, and the other wavelength signals, performing wavelength division multiplexing on the dedicated wavelength upload signal, the transparent part of the common wavelength and the other wavelength signals and uploading to the MAN.

In particular, the downlink wavelength converter is composed of a first semiconductor optical amplifier working in the saturation region, the dedicated wavelength downlink signal is the first pump light, and the download part of the common wavelength is the first probe light, through the The cross-gain modulation effect of the first semiconductor optical amplifier is used to convert the downlink data on the downlink signal of the dedicated wavelength to the download part of the common wavelength.

In particular, the uplink wavelength converter is composed of a second semiconductor optical amplifier working in the saturation region, the uplink transmission signal is used as the second pump light, and the dedicated wavelength is the second probe light, which passes through the second semiconductor optical amplifier The cross-gain modulation effect of the optical amplifier converts the uplink data on the uplink transmission signal to the dedicated wavelength.

Particularly, the first pumping light and the first probe light are incident simultaneously from the first end and the second end of the active layer of the first semiconductor optical amplifier; the second pumping light and the The second probe light is incident simultaneously from the first end and the second end of the active layer of the second semiconductor optical amplifier.

In particular, it is characterized in that it also includes: the downlink modulation removal module is composed of a third semiconductor optical amplifier working in the saturation region, and the optical power of the dedicated wavelength downlink attenuation signal is reduced by the gain saturation characteristic of the third semiconductor amplifier. Signal-to-noise ratio to remove downlink data on downlink attenuated signals of dedicated wavelengths.

In particular, it also includes: an optical coupler, which couples and distributes the power of the common wavelength obtained by the MAN demultiplexing module through at least one way of transmission into the download part of the common wavelength through one way of transmission , and the transparent part of the common wavelength transmitted through one path.

In particular, it also includes:

The first circulator, which is connected to the first end of the active layer of the first semiconductor optical amplifier, separates the common wavelength signal; the second circulator, which is connected to the active layer of the first semiconductor optical amplifier connected to the second end of the dedicated wavelength to separate the downlink attenuation signal of the dedicated wavelength; the third circulator is connected to the first terminal of the active layer of the second semiconductor optical amplifier to separate the dedicated wavelength uplink signal.

In particular, it also includes: a first optical amplifier, which is connected to the input end of the MAN demultiplexing module, and the downlink transmission signal is amplified by the first optical amplifier and then input to the MAN demultiplexer. In the wavelength division multiplexing module; a second optical amplifier, which is connected to the access network wavelength division multiplexing module, and the second optical amplifier amplifies signals transmitted in the access network. Amplifying the downlink transmission signal through the first amplifier is conducive to increasing the power of the pump light, so as to more effectively perform data conversion in the downlink wavelength converter

According to another aspect of the present invention, an optical line terminal for assisting the fusion of a metropolitan area network and an access network is characterized in that it includes: a public wavelength laser emitting module, which is used to emit at least one common wavelength; a dedicated wavelength downlink signal A transmitting module, each of which transmits a dedicated wavelength downlink signal corresponding to a remote node; a wavelength division multiplexing module, which is connected with the common wavelength laser transmitting module and a dedicated wavelength downlink signal transmitting module, and the dedicated wavelength downlink signal and At least one of the common wavelengths is wavelength-division multiplexed into a downlink transmission signal and transmitted to the metropolitan area network.

The present invention combines the metropolitan area network with multiple types of access networks through "colorless" remote nodes to achieve unified metropolitan access to the converged optical network, while ensuring compatibility with existing networks and improving The utilization rate of spectrum resources and the flexibility of wavelength planning save resource overhead and cost, which is conducive to network expansion and upgrade.

Description of drawings

Through the following detailed description of the embodiments shown in conjunction with the drawings, the above-mentioned and other features of the present invention will be more obvious, and the same or similar symbols in the drawings of the present invention represent the same or similar steps;

Shown among Fig. 1 the scheme that the metropolitan area network that a Nokia Siemens Networks (NSN) develops merges GPON;

Fig. 2 shows a network structure diagram implementing the method of the present invention to merge the metropolitan area network and the access network;

Figure 3 shows a flow chart of a method for converging a metropolitan area network and an access network on a remote node

Figure 4(a) shows a structural block diagram of a remote node for the fusion of the metropolitan area network and the access network; Figure 4(b) shows an optical line terminal for assisting the fusion of the metropolitan area network and the access network The structural block diagram;

Figure 5(a) shows the detailed structure and working principle of the downlink wavelength conversion module (DWC), and Figure 5(b) shows the simulation results of the input and output signals of the downlink wavelength conversion module;

Figure 6(a) shows the characteristic curve of the input and output of the downlink modulation removal module, and Figure 6(b) shows the simulation results of the input and output signals of the downlink modulation removal module; and

Figure 7(a) shows the functional block diagram of the optical network unit of the commercial xPON in the metro access converged optical network, and Figure 7(b) shows the commercial 10G-PON in the metro access converged optical network The functional block diagram of the optical network unit;

Fig. 8(a) shows the detailed structure and working principle of the uplink wavelength conversion module (UWC), and Fig. 8(b) shows the simulation results of the input and output signals of the uplink wavelength conversion module.

Detailed ways

The method for solving the above technical problems and the remote node device will be introduced in detail below in combination with the network structure diagram in FIG. 2 , the method flow chart in FIG. 3 , and the module diagram in FIG. 4 . It should be noted that although the steps of the method are described in a specific order in FIG. 3, this does not require or imply that these operations must be performed in this specific order, or that all of the shown operations must be performed to achieve the desired result, on the contrary , the steps depicted in the flowcharts may be performed in a different order. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step for execution, and/or one step may be decomposed into multiple steps for execution.

Fig. 2 shows a network structure diagram for implementing the method of the present invention to integrate the metropolitan area network and the access network. As shown in the figure, in the embodiment disclosed in the present invention, the data exchange between the access network and the metropolitan area network is realized through the remote node device disclosed in the present invention, so as to achieve the integration of different types of access networks and metropolitan area networks into a network as a whole. In the present invention, the metropolitan area access fusion optical network refers to the optical network that integrates the metropolitan area network and the access network into a whole.

In the present invention, each remote node (RN) corresponds to an access network and is responsible for the integration of the corresponding access network and the metropolitan area network. Remote nodes are located at the connection between the access network and the metropolitan area network to implement data exchange between the access network and the metropolitan area network. N access networks are connected to a metro ring network through N remote nodes to form a metro access converged optical network. The optical line terminal (OLT) in the metropolitan area network can be located at the convergence edge of the metropolitan area network and the backbone network to connect the upper network.

In an embodiment of the present invention, each remote node corresponds to a dedicated wavelength, and the dedicated wavelength is: continuous light with a specific value, and there is no modulated data in the dedicated wavelength, when the dedicated wavelength is modulated with downlink data Afterwards, the dedicated wavelength becomes a dedicated wavelength downlink signal. The optical line terminal sends downlink data to each remote node through a dedicated wavelength downlink signal corresponding to each remote node. As shown in Figure 2, the dedicated wavelength downlink signal corresponding to remote node RN _i is an optical signal λ _i with wavelength i; the dedicated wavelength downlink signal corresponding to remote node RN _j is an optical signal λ j with wavelength _j .

There is also at least one common wavelength on the ring network of the metropolitan area network, and the common wavelength is continuous light with a specific wavelength. The common wavelength cannot be a dedicated wavelength, that is, the common wavelength cannot be any dedicated wavelength in the MAN. In the present invention, an embodiment with two common wavelengths in the metropolitan area access fusion network is listed to illustrate the situation where a metropolitan area network, an xPON access network and a 10G-PON access network are integrated. In this embodiment The two common wavelengths are the light wave λ ₁₄₉₀ with a wavelength value of 1490 nm and the light wave λ ₁₅₇₇ with a wavelength value of 1577 nm.

It should be noted that although the embodiment of the present invention only discloses the situation that there are two common wavelength signals in the metropolitan area network, those skilled in the art can know that the number of the common wavelengths may be equal to one, or greater than two, and the number of common wavelength signals can be determined according to the number of types of access networks integrated with the metropolitan area network, for example, when there are three different types of access networks integrated with the metropolitan area network, Then the common wavelengths may be three.

In addition, it should be noted that the wavelength value of the common wavelength is not limited to the wavelength value disclosed herein, and can be determined according to the wavelength value used by normal downlink signals of various access networks. For example, when all Use the wavelength value of the downlink signal to be Xnm, then the wavelength value of the public wavelength can be set to Xnm, the purpose of this setting is to make the public wavelength compatible with the access network standard, so that the optical network in the access network will not be changed In the case of a unit, the public wavelength signal can be transmitted and received in the access network, so as to realize the integration of the metropolitan area network and the access network. The specific content will be described in detail below.

Figure 4(a) shows a modular unit in a remote node device 400 for merging metropolitan area network and access network (xPON and 10G-PON) according to an embodiment of the present invention, including:

First optical amplifier 402, MAN demultiplexing module 404, downlink wavelength converter 406, access network WDM module 408, downlink modulation removal module 410, uplink wavelength converter 412, MAN WDM Multiplexing module 414 , optical coupler 418 , second optical amplifier 416 .

As shown in Figure 3, in step 302, the MAN demultiplexing module 404 demultiplexes the downlink transmission signal received from the MAN into two common wavelengths and one dedicated wavelength corresponding to the current remote node. wavelength downlink signals and other wavelength signals corresponding to other remote nodes, wherein the common wavelength is continuous light that does not carry data, the dedicated wavelength downlink signal carries downlink data sent to the current remote node, and the other wavelength signals Including dedicated wavelength downlink signals of other remote nodes, and dedicated wavelength upload signals of other remote nodes. The dedicated wavelength upload signal refers to the light wave signal after the dedicated wavelength modulates the uplink data of the access network, that is, the dedicated wavelength upload signal carries the uplink data of the access network.

In the embodiment of the remote node RN _i shown in Figure 4, the dedicated wavelength corresponding to this node is i, after passing through the MAN demultiplexing module 404, the downlink transmission signal received from the MAN is dewave The division multiplexing is divided into three parts, which are respectively: other wavelength signals corresponding to other remote nodes, which are directly bypassed to the wavelength division multiplexing module 414 of the metropolitan area network; corresponding to the dedicated wavelength downlink signal λ _i of the current remote node RN _i , the signal is input into the downlink wavelength converter 406, wherein the dedicated wavelength downlink signal λ _i is loaded with downlink data sent to the current remote node RN _i ; two common wavelengths λ ₁₄₉₀ and λ ₁₅₇₇ , the common wavelength is input to the optical coupler 418 .

The optical coupler 418 couples and distributes the power of the two common wavelengths obtained by the MAN demultiplexing module through the two-way transmission into the download part of the two common wavelengths through the one-way transmission, and through the one-way transmission The transparent transmission part of the two common wavelengths, the download part is sent to the downlink wavelength converter 406, and the transparent transmission part is sent to the MAN wavelength division multiplexing module 414. Among them, the transparent transmission part and the download part of the common wavelength redistribute the signal power through the optical coupler 418 .

It should be noted that when two or more access networks are merged with the metropolitan area network, the number of common wavelengths will increase, so the input ports of the optical coupler 418 will also increase accordingly, but there are still two output ports, one end is The output of the transparent transmission part, and the other end is the output of the download part.

In a preferred embodiment, there is also a first optical amplifier 402 before the MAN demultiplexing module 404, which is used to amplify the downlink transmission signal received from the MAN.

In step 304, the downlink wavelength converter 406 converts the downlink data on the dedicated wavelength downlink signal λ _i to the download part of the two common wavelengths.

Specifically, in this embodiment, the downlink wavelength converter 406 is connected to the optical coupler 418 to receive the download part of the two common wavelengths λ ₁₄₉₀ and λ ₁₅₇₇ , and demultiplexes with the MAN The multiplexing module 404 is connected to receive the dedicated wavelength downlink signal λ _i , the downlink wavelength converter 406 converts the downlink data on the dedicated wavelength downlink signal to the download part of the two common wavelengths, and outputs The converted two common wavelength signals and the dedicated wavelength downlink attenuated signal, wherein the converted two common wavelength signals carry downlink data. The optical signal-to-noise ratio of the converted downlink attenuated signal of the dedicated wavelength is reduced.

Wavelength conversion can be achieved in several ways. The simplest and most effective method is to use the cross-gain modulation (XGM) effect of semiconductor optical amplifiers to realize the conversion. A pump light with high optical power and a probe light with low power are simultaneously injected into a semiconductor optical amplifier (SOA). Due to the gain saturation effect caused by carrier depletion, the probe light carries a signal that is inverse to the pump light signal. Information modulated in light waves can thus be transferred between light waves of different wavelengths.

Figure 5(a) shows the detailed structure and operating principle of the downlink wavelength conversion module (DWC). In a preferred embodiment, the downlink wavelength converter 406 is composed of a first semiconductor optical amplifier 506 working in the saturation region, the dedicated wavelength downlink signal λ _i is used as the first pump light, and the two common wavelength The download part of λ ₁₄₉₀ and λ ₁₅₇₇ is the first probe light, through the cross-gain modulation effect of the first semiconductor optical amplifier 506, the downlink data on the dedicated wavelength downlink signal is converted to the download of the two common wavelengths partly on.

It should be pointed out that the phase of the downlink data converted to the download part of the two common wavelengths is opposite to the phase of the downlink data on the dedicated wavelength downlink signal. The optical signal-to-noise ratio of the dedicated wavelength downlink signal passing through the first semiconductor optical amplifier 506 is reduced due to the gain saturation characteristic of the first semiconductor optical amplifier 506 .

The first pumping light and the first probe light can be injected from the same side of the active layer of the semiconductor optical amplifier 506 together, or respectively injected from opposite sides of the active layer. When the first pumping light and the first probe light are jointly incident from the same side of the active layer of the semiconductor optical amplifier 506, an optical filter needs to be connected at the output end of the semiconductor optical amplifier 506 to gate and obtain the converted pump light or converted probe light.

In a preferred embodiment, the first pump light and the first probe light are incident from opposite sides of the active layer of the semiconductor optical amplifier 506 respectively and simultaneously. Both sides of the semiconductor optical amplifier 506 are also provided with a first circulator 504 and a second circulator 502, the first circulator 504 is connected to the first end of the active layer of the first semiconductor optical amplifier 506, Separate the two common wavelength signals that carry the downlink data after being converted by the downlink wavelength converter; the second circulator 502 is connected to the second end of the active layer of the first semiconductor optical amplifier 506, and separates out the downlink signal via the downlink wavelength converter. The dedicated wavelength downlink attenuation signal converted by the wavelength converter;

Fig. 5(b) shows the simulation result of the input and output signals of the downlink wavelength conversion module. The first group of waveforms shows the waveform of the dedicated wavelength downlink signal injected into the active layer through the first circulator at the downlink input 2 on the right side of the first semiconductor optical amplifier 506; Three groups of waveforms show the waveforms of two common wavelength signals carrying downlink data separated by the first circulator at the downlink output 1 on the right side of the first semiconductor optical amplifier 506; the fourth group of waveforms shows The waveform of the dedicated wavelength downlink attenuated signal separated by the second circulator at the downlink output 2 on the left side of the first semiconductor optical amplifier 506 is shown.

In step 306, the downlink modulation removal module 410 removes downlink data in the dedicated wavelength downlink attenuated signal to obtain a dedicated wavelength from which downlink data is removed.

Specifically, in this embodiment, the downlink modulation removal module 410 is connected to the downlink wavelength converter 406 to receive the converted dedicated wavelength downlink attenuation signal, and the downlink modulation removal module 410 downlinks the dedicated wavelength The downlink data in the attenuated signal is removed, and a dedicated wavelength for removing downlink data is output.

In a preferred embodiment, the downlink modulation removal module 410 is composed of a third semiconductor optical amplifier operating in the saturation region, and the dedicated wavelength downlink attenuated signal is input into the active layer of the third semiconductor optical amplifier, The optical signal-to-noise ratio of the downlink attenuation signal of the dedicated wavelength is reduced by using the gain saturation characteristic of the third semiconductor amplifier, so as to remove the downlink data in the downlink signal of the dedicated wavelength, thereby obtaining the dedicated wavelength.

Figure 6(a) shows the characteristic curve of the input and output of the downlink modulation removal module, as shown in the figure, when the third semiconductor optical amplifier works in the saturation region, its gain saturation characteristic makes the optical signal-to-noise ratio of the optical signal reduce . After the _λi signal at the input end is converted in the saturation region, the _λi signal with a very low OSNR is output at the output end, so the _λi signal output at the output end can be approximately regarded as a _λi light wave without modulated data.

Figure 6(b) shows the simulation results of the input and output signals of the downlink modulation removal module, the first group of waveforms shows the waveforms at the input of the third semiconductor optical amplifier, and the second group of waveforms shows the waveforms at the third semiconductor optical amplifier Waveform at the output of the optical amplifier. From the second set of waveforms, it can be found that the optical signal-to-noise ratio of the optical signal is greatly reduced by the gain saturation characteristic of the third semiconductor optical amplifier, so the optical signal output from the output terminal can be approximately regarded as an optical wave without modulated data.

It should be pointed out that the dedicated wavelength obtained by removing the downlink data through the above method may still contain some interference signals, and the glitch waveform in the second group of waveforms in Figure 6(b) is the interference signal, which is due to It is caused by the inability to completely remove the downlink data. However, the downlink data on the dedicated wavelength downlink attenuated signal has basically been removed by the method disclosed in the present invention.

In steps 308 and 310, the access network wavelength division multiplexing module 416 sends two common wavelength signals carrying the downlink data to the access network, and receives the uplink transmission signal sent by the access network, The uplink transmission signal carries uplink data sent from the access network.

Specifically, in this embodiment, the downlink input end of the access network wavelength division multiplexing module 408 is connected to the downlink wavelength converter 406 to receive the common wavelength signal carrying downlink data, and the access network wavelength division multiplexing The uplink input terminal of the module 408 receives the uplink transmission signal (λ ₁₃₁₀ or λ ₁₂₇₀ ) carrying uplink data from the access network, and the wavelength division multiplexing module 408 of the access network performs two common wavelengths carrying downlink data The signal and the uplink transmission signal carrying the uplink data are subjected to wavelength division multiplexing, and the common wavelength signal carrying the downlink data is sent to the access network through the downlink output terminal, and at the same time, the uplink transmission signal carrying the uplink data is obtained at the uplink output terminal. For transmitting signals (λ ₁₃₁₀ or λ ₁₂₇₀ ), the downlink output port and the uplink input port of the access network wavelength division multiplexing module 408 are the same port.

The wavelength value of the uplink transmission signal is determined by the type of the access network. The wavelength value of the uplink transmission signal λ ₁₂₇₀ of 10G-PON is 1270nm, and the wavelength value of the uplink transmission signal λ ₁₃₁₀ of xPON is 1310nm.

In a preferred embodiment, the access network wavelength division multiplexing module 408 is connected to a second optical amplifier 416, and the second optical amplifier 416 amplifies signals transmitted in the access network.

As shown in Figure 7(a) and 7(b), at the user side of the local access network, a wavelength blocking filter (WBF) has been embedded in the optical network unit (ONU) in the existing network to filter out unwanted wavelengths signal and out-of-band noise to leave the downstream wavelength signal expected to be received. Therefore, in the present invention, there is no need to make any modification to the optical network unit (ONU) of xPON or 10G-PON in the existing network.

Taking the optical network unit in the xPON access network in FIG. The passive optical splitter (SPL) in the network is sent to the optical network unit (ONU) in the access network, and the optical network unit of xPON obtains the common wavelength signal carrying the downlink data through the wavelength division multiplexer, according to The xPON access network standard specification, the downlink data in the xPON access network is carried on the 1490nm wavelength, so the wavelength blocking filter (WBF) 702 filters out the public wavelength signal with a wavelength of 1577nm, and makes the wavelength consistent with the xPON standard 1490nm The common wavelength signal passes through the filter, and then the photodetector demodulates the passed common wavelength signal to obtain downlink data. Similarly, an optical network unit (ONU) in 10G-PON can also filter out a common wavelength signal with a wavelength of 1490nm through its existing wavelength blocking filter (WBF) 704 . From this we can find that applying the method disclosed in the present invention to integrate the MAN and the access network eliminates the modification of the optical network unit in the access network, thereby ensuring the "colorless" of the optical network unit.

In step 312, the uplink wavelength converter 412 converts the uplink data on the uplink transmission signal to a dedicated wavelength downlink signal from which downlink data has been removed.

Specifically, in this embodiment, the uplink wavelength converter 412 is connected with the downlink modulation removal module 410 to receive a dedicated wavelength downlink signal from which downlink data has been removed, and is connected with the access network wavelength division multiplexing module 416 connected to the uplink output terminal to receive the uplink transmission signal, the uplink wavelength converter 412 converts the uplink data on the uplink transmission signal to the dedicated wavelength downlink signal from which the downlink data has been removed, and outputs a Converted dedicated wavelength downlink signal carrying uplink data.

As shown in Figure 8(a), in a preferred embodiment, the uplink wavelength converter 412 is composed of a second semiconductor optical amplifier 806 operating in the saturation region, and the uplink transmission signal (λ ₁₃₁₀ or λ ₁₂₇₀ ) As the second pump light, the dedicated wavelength for removing the downlink data is the second probe light, through the cross-gain modulation effect of the second semiconductor optical amplifier, the uplink data on the uplink transmission signal is converted to the removed on the dedicated wavelength for downlink data to obtain the dedicated wavelength for uploading signals.

The second pumping light and the second probe light can be injected from the same side of the active layer of the semiconductor optical amplifier 806 together, or respectively injected from opposite sides of the active layer. When the second pumping light and the second probe light are jointly incident from the same side of the active layer of the semiconductor optical amplifier 806, an optical filter needs to be connected at the output end of the semiconductor optical amplifier 806 to gate and obtain the converted pump light or converted probe light.

In a preferred embodiment, the second pumping light and the second probing light are simultaneously injected from opposite sides of the active layer of the semiconductor optical amplifier 806 respectively. One side of the semiconductor optical amplifier 806 is also provided with a third circulator 802, and the third circulator 802 is connected to the first end of the active layer of the first semiconductor optical amplifier 806 to separate the converted Dedicated wavelength uplink signal carrying uplink data. The phase of the data on the dedicated wavelength uplink signal is opposite to the phase of the uplink data on the uplink transmission signal.

Fig. 8(b) shows the simulation results of the input and output signals of the uplink wavelength conversion module. The first group of waveforms shows that at the uplink input 2 on the left side of the second semiconductor optical amplifier 806, the third circulator radiates The waveform of the uplink transmission signal entering the active layer; the second group of waveforms shows the removal of the downlink data entering the active layer at the uplink input 1 on the right side of the second semiconductor optical amplifier 806 The waveform of the dedicated wavelength; the third group of waveforms shows the converted dedicated wavelength upload signal carrying upload data separated by the third circulator at the upstream output on the left side of the second semiconductor optical amplifier 806 waveform.

In step 314, the MAN wavelength division multiplexing module 414 transmits the dedicated wavelength upload signal carrying uplink data, the transparent transmission part of the public wavelength, and other wavelength signals of other remote nodes to the MAN through wavelength division multiplexing. load.

Specifically, in this embodiment, the MAN wavelength division multiplexing module 414 is connected to the uplink wavelength converter 412 to receive a dedicated wavelength upload signal carrying uploaded data, and the MAN wavelength division multiplexing The module 414 is connected with the MAN demultiplexing module 404 to receive the transparent part of the at least one common wavelength and the other wavelength signals corresponding to other remote nodes, the MAN wavelength division multiplexing module performing wavelength division multiplexing on the dedicated wavelength upload signal carrying uplink data, the transparent transmission part of the public wavelength and other wavelength signals corresponding to other remote nodes, and uploading the wavelength division multiplexed signal to the metropolitan area network.

The invention also discloses a method for assisting in the fusion of the metropolitan area network and the access network, wherein the optical line terminal is located in the metropolitan area network, comprising the following steps:

Set at least one common wavelength; generate a dedicated wavelength downlink signal, each dedicated wavelength downlink signal corresponds to a remote node, and the dedicated wavelength downlink signal is loaded with downlink data sent to the corresponding remote node; the wavelength value of the public wavelength and the dedicated wavelength downlink The wavelength values of the signals are different. The downlink signal of the dedicated wavelength and at least one common wavelength are wavelength-division multiplexed into a downlink transmission signal, and transmitted to the metropolitan area network.

According to the above method, the present invention also discloses an optical line terminal that assists in the fusion of the metropolitan area network and the access network, as shown in Figure 4(b), the optical line terminal includes:

A common wavelength laser emitting module 422, configured to emit at least one common wavelength. The number of common wavelengths can be determined according to the number of types of access networks integrated with the MAN. No data is modulated on the common wavelength.

In the dedicated wavelength downlink signal transmitting module 424, each dedicated wavelength downlink signal transmitted corresponds to a remote node; each dedicated wavelength downlink signal carries downlink data sent to the corresponding remote node.

Wherein, the wavelength value of the common wavelength is different from the wavelength value of the downlink signal of the dedicated wavelength.

A wavelength division multiplexing module 426, which is connected to the common wavelength laser transmitting module 422 and the dedicated wavelength downlink signal transmitting module 424, and is used for performing wavelength division multiplexing on the dedicated wavelength downlink signals of each remote node and at least one common wavelength, And transmit to the metropolitan area network.

The above description of the present disclosure is provided to enable any person of ordinary skill in the art to make or use the present invention. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other modifications without departing from the spirit and scope of the invention. Thus, the invention is not to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (15)

1. A method for merging a metropolitan area network and an access network on a remote node, comprising the following steps: A. Demultiplex the downlink transmission signal received from the metropolitan area network into at least one common wavelength, a dedicated wavelength downlink signal corresponding to the remote node, and other wavelength signals, and the common wavelength passes through an optical coupler Power allocation is divided into transparent transmission part and download part; B. converting the downlink data on the dedicated wavelength downlink signal to the download part of the common wavelength to obtain the common wavelength signal and the dedicated wavelength downlink attenuation signal; C. removing the downlink data in the downlink attenuation signal of the dedicated wavelength to obtain the dedicated wavelength; D. sending the common wavelength signal to the access network; E. receiving an uplink transmission signal sent by the access network; F. converting the uplink data on the uplink transmission signal to the dedicated wavelength to obtain a dedicated wavelength upload signal; and G. Uploading the dedicated wavelength upload signal, the transparent part of the common wavelength, and the other wavelength signals to the MAN through wavelength division multiplexing. 2. The method according to claim 1, wherein, in step B, the downlink signal of the dedicated wavelength is the first pump light, and the download part of the common wavelength is the first probe light, which passes through the first semiconductor optical amplifier The cross-gain modulation effect converts the downlink data on the dedicated wavelength downlink signal to the download part of the common wavelength. 3. The method according to claim 2, wherein, in step F, the uplink transmission signal is used as the second pump light, and the dedicated wavelength is the second probe light, which is modulated by the cross-gain of the second semiconductor optical amplifier effect, converting the uplink data on the uplink transmission signal to the dedicated wavelength. 4. The method of claim 3, wherein, In step B: the first pump light and the first probe light are simultaneously injected from the first end and the second end of the active layer of the first semiconductor optical amplifier; In step F: the second pump light and the second probe light are simultaneously injected from the first end and the second end of the active layer of the second semiconductor optical amplifier. 5. The method according to any one of claims 1 to 4, wherein, in step C: The optical signal-to-noise ratio of the dedicated wavelength downlink attenuated signal is reduced by using the gain saturation characteristic of the third semiconductor amplifier, so as to remove the downlink data on the dedicated wavelength downlink attenuated signal. 6. A method for assisting the fusion of a metropolitan area network and an access network on an optical line terminal, comprising the following steps: Setting at least one common wavelength based at least on the type of at least one access network integrated with the metropolitan area network; Generate a dedicated wavelength downlink signal, each dedicated wavelength downlink signal corresponds to a remote node, and the remote node is responsible for the integration of the corresponding access network in the at least one access network and the metropolitan area network; The downlink signal of the dedicated wavelength and at least one common wavelength are wavelength-division multiplexed into a downlink transmission signal, and transmitted to the metropolitan area network. 7. A remote node for merging a metropolitan area network and an access network, characterized in that it comprises: A MAN demultiplexing module, which is used to demultiplex the downlink transmission signal received from the MAN into at least one common wavelength, a dedicated wavelength downlink signal corresponding to the current remote node, and other A wavelength signal, the common wavelength is divided into a transparent transmission part and a download part through an optical coupler power distribution; Downlink wavelength converter, which receives the download part of the common wavelength and the downlink signal of the dedicated wavelength, converts the downlink data on the downlink signal of the dedicated wavelength to the download part of the common wavelength to obtain the common wavelength signal and the dedicated wavelength Wavelength downlink attenuation signal; A downlink modulation removal module, which receives the dedicated wavelength downlink attenuation signal, and removes the downlink data in the dedicated wavelength downlink attenuation signal to obtain a dedicated wavelength; The access network wavelength division multiplexing module, whose downlink input terminal receives the common wavelength signal, and whose uplink input terminal receives the uplink transmission signal from the access network, performs wavelength division multiplexing on the common wavelength signal and the uplink transmission signal use, and transmit the common wavelength signal to the access network through its downlink output terminal, and simultaneously transmit the uplink transmission signal through its uplink output terminal; An uplink wavelength converter, which receives the dedicated wavelength and the uplink transmission signal, converts the uplink data on the uplink transmission signal to the dedicated wavelength to obtain a dedicated wavelength uplink signal; The MAN wavelength division multiplexing module receives the dedicated wavelength upload signal, the transparent transmission part of the public wavelength and the other wavelength signals, and transmits the dedicated wavelength upload signal, the transparent transmission part of the public wavelength and the other wavelength signals. performing wavelength division multiplexing on the other wavelength signals and uploading them to the MAN. 8. In the remote node according to claim 7, it is characterized in that: the downlink wavelength converter is composed of a first semiconductor optical amplifier working in a saturation region, and the dedicated wavelength downlink signal is the first pump light, so The download part of the common wavelength is the first probe light, and the downlink data on the downlink signal of the dedicated wavelength is converted to the download part of the common wavelength through the cross-gain modulation effect of the first semiconductor optical amplifier. 9. In the remote node according to claim 8, it is characterized in that: the uplink wavelength converter is composed of a second semiconductor optical amplifier working in the saturation region, the uplink transmission signal is used as the second pump light, the The dedicated wavelength is the second probe light, and the uplink data on the uplink transmission signal is converted to the dedicated wavelength through the cross-gain modulation effect of the second semiconductor optical amplifier. 10. In the remote node according to claim 9, characterized in that: The first pump light and the first probe light are simultaneously injected from the first end and the second end of the active layer of the first semiconductor optical amplifier; The second pump light and the second probe light are incident simultaneously from the first end and the second end of the active layer of the second semiconductor optical amplifier. 11. The remote node according to any one of claims 9 or 10, further comprising: the downlink modulation removal module is composed of a third semiconductor optical amplifier working in the saturation region, through the third The gain saturation characteristic of the semiconductor amplifier reduces the optical signal-to-noise ratio of the downlink attenuated signal of the dedicated wavelength, so as to remove the downlink data on the downlink attenuated signal of the dedicated wavelength. 12. In the remote node according to claim 11, it is characterized in that it also includes: an optical coupler, which couples the common wavelength obtained by the MAN demultiplexing module through at least one transmission and The power is divided into the download part of the common wavelength transmitted through one channel, and the transparent transmission part of the common wavelength transmitted through one channel. 13. In the remote node according to claim 12, it is characterized in that, further comprising: a first circulator, which is connected to the first end of the active layer of the first semiconductor optical amplifier, and separates the common wavelength signal; A second circulator, which is connected to the second end of the active layer of the first semiconductor optical amplifier, and separates the downlink attenuation signal of the dedicated wavelength; The third circulator is connected to the first end of the active layer of the second semiconductor optical amplifier, and separates the dedicated wavelength upload signal. 14. In the remote node according to claim 13, it is characterized in that, further comprising: The first optical amplifier is connected to the input end of the MAN demultiplexing module, and the downlink transmission signal is amplified by the first optical amplifier and then input into the MAN demultiplexing module ; The second optical amplifier is connected to the access network wavelength division multiplexing module, and the second optical amplifier amplifies the signal transmitted in the access network. 15. An optical line terminal for assisting in the fusion of a metropolitan area network and an access network, characterized in that it comprises: A common wavelength laser transmitting module, which is used to transmit at least one common wavelength based at least on the type of at least one access network integrated with the metropolitan area network; A dedicated wavelength downlink signal transmitting module, each of the transmitted dedicated wavelength downlink signals corresponds to a remote node, and the remote node is responsible for the fusion of the corresponding access network in the at least one access network and the metropolitan area network; A wavelength division multiplexing module, which is connected to the common wavelength laser transmitting module and the dedicated wavelength downlink signal transmitting module, and multiplexes the dedicated wavelength downlink signal and at least one of the common wavelengths into a downlink transmission signal, and transmitted to the metropolitan area network.