WO2012062119A1

WO2012062119A1 - Passive optical network and signal transmission method of passive optical network

Info

Publication number: WO2012062119A1
Application number: PCT/CN2011/076157
Authority: WO
Inventors: 徐继东; 张德智
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-11-12
Filing date: 2011-06-22
Publication date: 2012-05-18
Also published as: CN101984673A; CN101984673B

Abstract

The present invention discloses a passive optical network and a signal transmission method of passive optical network, the passive optical network comprises a wavelength selection coupler, an optical splitter, an Array Waveguide Grating (AWG) and multi-wavelength selection routers, wherein, the wavelength selection router is set for coupling the downlink signal of the Time Division Multiplexing-Optical Line Terminal (TDM-OLT) from the optical splitter with the downlink signal of the Wavelength Division Multiplexing-Optical Line Terminal (WDM-OLT) from the AWG, transmitting the signal coupled to the branch fiber connected to the wavelength selection router; transmitting the uplink signal in the branch fiber connected to the WDM-ONU to the AWG and transmitting the uplink signal in the branch fiber connected to the TDM-ONU to the optical splitter. The network compatibleness is enhanced and the user experience is improved by the present invention.

Description

TECHNICAL FIELD The present invention relates to the field of communications, and in particular, to a passive optical network and a method for transmitting the same. BACKGROUND With the rapid development of network technologies and the popularity of network applications, network communication, online shopping, and network entertainment have become part of modern life, and existing access network copper (wired) systems have been unable to meet such high speeds. And the need for broadband. Passive optical networks are broadband, high-speed, environmentally-friendly and energy-efficient broadband access technologies. They are the best candidates to replace existing access networks. They are being accepted and deployed by most operators to meet Growing communication users and faster and better service needs. Passive Optical Network (PON) is a point-to-multipoint optical access technology that can be divided into Time Division Multiplexing PON (TDM-PON) and wavelength division multiplexing. PON (wavelength division multiplexing PON, abbreviated as WDM-PON). 1 is a schematic structural diagram of a time division multiplexed PON according to the related art. As shown in FIG. 1, an optical line terminal (Optical Line Terminal, OLT for short), an optical network unit (ONU), and an optical distribution are included. Optical Distribution Network (ODN). Usually, an OLT uses an optical power splitter (which may be simply referred to as a splitter) of an ODN to connect a point-to-multipoint structure composed of a plurality of ONUs. 2 is a schematic structural diagram of a wavelength division multiplexing PON according to the related art. As shown in FIG. 2, an OLT, an ONU, and an ODN are also included. However, its ODN is composed of Array Waveguide Grating (AWG), which is used to split light according to the wavelength of light. In order to better reduce costs and simplify inventory management, the ONU must be colorless. Specifically, there are two typical ONUs, which use a tunable laser (Tunable Laser, TL for short) as the transmitter. The other is a passive transmitter, which itself cannot emit light, and reflects the light incident on it, for example, a Reflected Semiconductor Optical Amplifier (RSOA; for short). The OLT is also special because it requires a series of different wavelengths of light to communicate with the ONU as downstream light, and a passive light source for the passive ONU. At present, a large number of time-division multiplexed PONs can be deployed to solve the needs of existing low-end users for Internet access and communication. The uplink bandwidth generally ranges from 1 Mbits to tens of Mbits. However, for some high-end users, for example, the bandwidth needs to reach 1 Gbits, time-division multiplexed PON can no longer meet its requirements. In the related art, a point-to-point network or a wavelength division multiplexing PON is usually used, but no matter what Which way is incompatible with the original network. For example, for a pure high-end user area, WDM-PON can be directly placed, but for some mixed areas or some gradually upgraded areas, the use of wavelength division multiplexing (PON) is in place, which is somewhat out of date for operators and users. SUMMARY OF THE INVENTION A primary object of the present invention is to provide a signal transmission scheme for a passive optical network, to at least solve the problem of using a point-to-point network or a wavelength division multiplexing PON when upgrading an original time division multiplexed PON in the above related art. The original network is not compatible. In order to achieve the above object, in accordance with an aspect of the present invention, a passive optical network is provided. A passive optical network according to the present invention includes a wavelength selective coupler, a beam splitter, an AWG, and a plurality of wavelength selective routers, wherein the wavelength selective coupler is coupled to the optical splitter and the AWG, and the optical splitter and the AWG are respectively associated with each wavelength selective router Connected, each wavelength selection router is connected to the TDM-ONU or WDM-ONU through the branch fiber connected thereto; the wavelength selection router is set to send the downlink signal of the time division multiplexed optical line terminal TDM-OLT from the optical splitter and the AWG from the AWG The downlink signal of the WDM-OLT is coupled and transmitted to the branch fiber connected to the wavelength selective router; and the uplink signal in the branch fiber connected to the WDM-ONU is transmitted to the AWG, and the uplink signal is transmitted in the branch fiber connected to the TDM-ONU. Give the splitter. Preferably, the passive optical network further comprises a wavelength division multiplexing coupler, wherein the wavelength division multiplexing coupler is connected to the TDM-OLT and the WDM-OLT, and is connected to the wavelength selective coupler through the main kilo fiber; the wavelength division multiplexing The coupler is configured to couple the downlink signal of the TDM-OLT and the downlink signal of the WDM-OLT into the main kilofiber; and separate the uplink signal of the TDM-ONU from the uplink signal of the main kilofiber to the TDM-OLT, and separate The uplink signal of the WDM-ONU is transmitted to the WDM-OLT; the wavelength selective coupler is configured to separate the downlink signal of the WDM-OLT from the downlink signal of the primary kilo-fiber to the AWG, and separate the downlink signal of the TDM-OLT to the downlink signal The optical splitter; and the upstream signal of the TDM-ONU from the optical splitter and the uplink signal of the WDM-ONU from the AWG are coupled and transmitted to the primary kilofiber. Preferably, the AWG is arranged to direct the downlink signal from the WDM-OLT of the wavelength selective coupler to the respective wavelength selection router according to its wavelength; and to direct the upstream signal from the WDM-ONU of the wavelength selective router to the wavelength selective coupler. Preferably, the number of channels of the AWG is the same as the number of branched fibers. Preferably, one or more of the wavelength division multiplexing coupler, the wavelength selective coupler and the wavelength selective router are optical filters. Preferably, the optical filter is a thin film filter or a fiber Bragg grating sensor. Preferably, the optical filter is one of the following: a thin film sideband filter, a single window wideband filter, a dual window wideband filter. Preferably, the TDM-ONU is configured to select a downlink signal for receiving the TDM-OLT from the downlink signals of the branch fiber; and transmit the uplink signal of the TDM-ONU to the wavelength selective router through the branch fiber; the WDM-ONU is set as the slave branch The downlink signal of the optical fiber is selected to receive the downlink signal of the WDM-OLT; and the uplink signal of the WDM-ONU is transmitted to the wavelength selective router through the branch fiber. In order to achieve the above object, according to another aspect of the present invention, a method of transmitting a signal in the above passive optical network is also provided. The method for applying the above passive optical network for signal transmission according to the present invention includes the following steps: The downlink signal of the primary kilo-fiber is separated from the downlink signal of the WDM-OLT by the wavelength selective coupler and transmitted to the AWG according to the WDM-OLT. The wavelength of the downlink signal is directed to the corresponding wavelength selection router, and is transmitted to the WDM-ONU connected thereto through the branch fiber; the downlink signal of the main kilofiber is separated from the downlink signal of the TDM-OLT through the wavelength selective combiner and transmitted to the optical splitter, and then passes through The wavelength selection router transmits to the TDM-ONU connected to the branch fiber. In order to achieve the above object, according to still another aspect of the present invention, a method of transmitting a signal in the above passive optical network is also provided. The method for transmitting signals by using the above passive optical network according to the present invention includes the following steps: The uplink signal of the WDM-ONU is transmitted to the AWG through the wavelength selective router through the branch fiber connected to the WDM-ONU, and the uplink of the TDM-ONU The branch fiber connected to the TDM-ONU is transmitted to the optical splitter through the wavelength selective router; the uplink signal of the WDM-ONU from the AWG and the uplink signal of the TDM-ONU from the optical splitter are coupled by the wavelength selective coupler and transmitted to the main thousand optical fiber. Through the invention, the wavelength selective router is used to couple the downlink signals of the TDM and the WDM to the ONUs connected thereto, and the ONUs select the downlink signals received by the ONU, thereby solving the problem of upgrading the original time division multiplexing in the related art. When using point-to-point network or wavelength division multiplexing, it is incompatible with the original network, which enhances network compatibility and improves user experience. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are set to illustrate,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, In the drawings: FIG. 1 is a schematic structural diagram of a time division multiplexing unit according to the related art; FIG. 2 is a schematic structural diagram of a wavelength division multiplexing unit according to the related art; FIG. 3 is a schematic diagram of a passive optical network according to an embodiment of the present invention. Figure 4 is a block diagram showing the structure of a passive optical network according to a preferred embodiment of the present invention; Figure 5 is a flow chart showing a method for transmitting a downlink signal of a passive optical network according to an embodiment of the present invention; A flowchart of a method for transmitting an uplink signal of a passive optical network according to an embodiment of the present invention; FIG. 7 is a structure of a passive optical network in which a wavelength division multiplexing and a time division multiplexing ΡΟΝ are coexisted according to Embodiment 2 of the present invention; FIG. 8 is a schematic structural diagram of a wavelength division multiplexing coupler according to a second embodiment of the present invention; FIG. 9 is a schematic structural view of a wavelength selective combiner according to a second embodiment of the present invention; FIG. 11 is a schematic structural diagram of a wavelength selective router according to Embodiment 2 of the present invention. FIG. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. According to an embodiment of the invention, a passive optical network is provided. 3 is a structural block diagram of a passive optical network according to an embodiment of the present invention. As shown in FIG. 3, the passive optical network 30 includes a wavelength selective combiner 32, a beam splitter 34, an arrayed waveguide grating AWG 36, and a plurality of Wavelength selection routers 38, wherein wavelength selective coupler 32 is coupled to beam splitter 34 and AWG 36, and splitter 34 and AWG 36 are coupled to each wavelength selective router 38, respectively, each wavelength selective router 38 is connected to a branch fiber Connected to the TDM-ONU or WDM-ONU; the wavelength selection router 38 is configured to combine the downlink signal from the TDM-OLT of the optical splitter 34 and the downlink signal from the WDM-OLT of the AWG 36 to the wavelength selective router 38. The branch fiber is transmitted; and the uplink signal in the branch fiber connected to the WDM-ONU is transmitted to the AWG 36, and the uplink signal in the branch fiber connected to the TDM-ONU is transmitted to the beam splitter 34. Through the above-mentioned passive optical network 30, the wavelength selective router 38 is used to couple the downlink signals of the TDM and the WDM to the ONUs connected thereto, and the ONUs select the downlink signals received by the ONU, thereby solving the upgrade in the related art. Sometimes the point-to-point network or the wavelength division multiplexing PON is used to multiplex the PON to cause incompatibility with the original network, which enhances the compatibility of the network and improves the user experience. In the implementation process, the wavelength selection router 38 can be used to classify the uplink signals of different wavelengths and transmit them to the corresponding light guiding modules. For example, directing the signal of the TDM-ONU to the optical splitter, or directing the signal of the WDM-ONU to the AWG, and coupling all the downlink signals to the branch fiber connected thereto, and finally reaching the corresponding ONU, by different types of ONUs. To select the corresponding downlink signal. It should be noted that the branch fiber in the embodiment of the present invention can transmit downlink signals of TDM and/or WDM. For example, when it is connected to the TDM-ONU, the TDM-ONU only accepts the downlink signal of the TDM, and the WDM signal is discarded; when it is connected to the WDM-ONU, the WDM-ONU only accepts the downlink signal of the WDM. The TDM signal is discarded. Therefore, the branch fiber is not selective for TDM or WDM signals, and the ONU connected to the branch fiber selectively receives TDM or WDM signals. In addition, the embodiment of the present invention is applicable to a case where the uplink and downlink wavelengths of the time division multiplexed PON and the wavelength division multiplexing PON do not overlap. 4 is a structural block diagram of a passive optical network according to a preferred embodiment of the present invention. As shown in FIG. 4, the passive optical network 30 further includes: a wavelength division multiplexing coupler 42, wherein the wavelength division multiplexing coupler 42 Connected to the TDM-OLT and the WDM-OLT, and connected to the wavelength selective combiner 32 through the main kilofiber; the wavelength division multiplexing coupler 42 is configured to couple the downlink signal of the TDM-OLT and the downlink signal of the WDM-OLT Main kilofiber; and separating the TDM-ONU from the upstream signal of the main kilofiber The line signal is transmitted to the TDM-OLT, and the uplink signal of the WDM-ONU is separated and transmitted to the WDM-OLT. The wavelength selective coupler 32 is configured to separate the downlink signal of the WDM-OLT from the downlink signal of the main kilo fiber to the AWG 36. The downlink signal of the TDM-OLT is separated and transmitted to the optical splitter 34; and the uplink signal of the TDM-ONU from the optical splitter 34 and the uplink signal of the WDM-ONU from the AWG 36 are coupled and transmitted to the primary optical fiber. Preferably, the AWG 36 is arranged to direct the downstream signals of the WDM-OLT from the wavelength selective coupler 32 to the respective wavelength selection routers 38 according to their wavelengths; and to direct the upstream signals of the WDM-ONUs from the wavelength selective router 38 to the wavelength selection Coupler 32. This method improves the accuracy of the system. Preferably, the number of channels of the AWG 36 is the same as the number of branched fibers. This method can improve the utilization of resources. Preferably, one or more of wavelength division multiplex coupler 42, wavelength selective coupler 32, and wavelength selection router 38 are optical filters. This method is beneficial to system compatibility and ease of use, as well as low-cost mass production. For example, the wavelength division multiplexing coupler 42, the wavelength selective combiner 32, and the wavelength selective router 38 all use the same type of optical filter. Preferably, the optical filter is a thin film filter or a fiber Bragg grating sensor. The method is simple to implement and has high operability. Preferably, the optical filter is one of the following: a thin film sideband filter, a single window wideband filter, a dual window wideband filter. The method is simple and easy to use, and has high operability. Preferably, the TDM-ONU is configured to select a downlink signal for receiving the TDM-OLT from the downlink signals of the branch fiber; and transmit the uplink signal of the TDM-ONU to the wavelength selective router through the branch fiber; the WDM-ONU is set as the slave branch The downlink signal of the optical fiber is selected to receive the downlink signal of the WDM-OLT; and the uplink signal of the WDM-ONU is transmitted to the wavelength selective router through the branch fiber. In the implementation process, the signal transmitted by the transmission port or the reflection port of the thin film filter may not be bound to the wavelength of the signal, and may be designed according to customer requirements. For example, if you want the transmissive port to transmit the TDM signal, just connect it to the beam splitter 34. If you want to transmit the WDM signal to the reflector port, just connect it to the AWG 36. Similarly, if the transmission port of the thin film filter transmits a WDM-PON letter When the number is transmitted, the transmission port is connected to the AWG 36. When the reflection port of the thin film filter transmits the TDM-PON signal, the reflection port only needs to be connected to the beam splitter 34. It should be noted that, in the implementation process, the passive optical network in the embodiment of the present invention can determine the wavelength of the WDM-PON matched with the TDM-PON according to the wavelength of the TDM-PON, and then according to the WDM-PON. The wavelengths select the corresponding wavelength division multiplexing coupler 42, wavelength selective coupler 32, wavelength selection router 38, and AWG 36. Corresponding to the passive optical network 30, the embodiment of the present invention further provides a method for transmitting signals in the passive optical network 30. FIG. 5 is a flowchart of a method for transmitting a downlink signal of a passive optical network according to an embodiment of the present invention. As shown in FIG. 5, a method for transmitting a downlink signal by using the foregoing passive optical network 30 includes the following steps: S502, the downlink signal of the primary kilo-fiber is separated by the wavelength selective coupler 32 and the downlink signal of the WDM-OLT is transmitted to the AWG 36, and the wavelength of the downlink signal of the WDM-OLT is directed to the corresponding wavelength selection router 38, and passes through the branch fiber. And transmitting to the WDM-ONU connected thereto; Step S504, the downlink signal of the primary kilo-fiber is separated by the wavelength selective coupler 32, and the downlink signal of the TDM-OLT is transmitted to the optical splitter 34, and then transmitted to the branch fiber through the wavelength selection router 38. TDM-ONU. Through the above steps, the wavelength selective router 38 is used to recouple the TDM and WDM signals into the branch fiber, which solves the problem of using the point-to-point network or the wavelength division multiplexing PON when upgrading the original time division multiplexed PON in the related art. The problem of incompatibility of the original network enhances the compatibility of the network and improves the user's body-risk. In the implementation process, the TDM and WDM downlink signals can be transmitted on the same main kilofiber and the same branch fiber after being combined, and the ONU connected to the branch fiber is used to select and match the signal, that is, TDM- The ONU only accepts the downlink signal of the TDM, and the WDM-ONU only accepts the downlink signal of the WDM, and the other signal is discarded. For example, the downstream signal, which may be the primary kilo-fiber, is separated by the wavelength selective coupler 32.

The downlink signal of the WDM-OLT is transmitted to the AWG 36, and then transmitted to the ONU connected thereto through the branch fiber through the wavelength selection router 38, and the downlink signal of the TDM-OLT is separated and transmitted to the optical splitter 34, and then transmitted through the branch fiber through the wavelength selection router 38. For the ONU connected to it, the type of ONU is used to decide the trade-off of the received signal. FIG. 6 is a flowchart of a method for transmitting an uplink signal of a passive optical network according to an embodiment of the present invention. As shown in FIG. 6, the method for transmitting an uplink signal by using the passive optical network 30 includes the following steps: Step S602, The uplink signal of the WDM-ONU is transmitted to the AWG 36 via the wavelength selection router 38 via the branch fiber connected to the WDM-ONU; in step S604, the uplink signal of the TDM-ONU is transmitted to the branch fiber connected to the TDM-ONU through the wavelength selection router 38. The optical splitter 34; and in step S606, the upstream signal from the WDM-ONU of the AWG 36 and the upstream signal from the TDM-ONU of the optical splitter 34 are coupled by the wavelength selective coupler 32 and transmitted to the primary kilo-fiber. Through the above steps, the wavelength selection router 38 is used to branch the fiber to the WDM-ONU or

The TDM-ONU connection method solves the problem that the point-to-point network or the wavelength division multiplexing PON is incompatible with the original network when upgrading the original time division multiplexing PON in the related art, and the compatibility of the network is enhanced and improved. The user experience. For example, the wavelength selection router 38 can be used to separate the uplink signal of the WDM-ONU from the uplink signal of the branch fiber to the AWG 36, the uplink signal of the TDM-ONU is separated and transmitted to the beam splitter 34; and the AWG 36 will come from the wavelength selective router. The upstream signal of the WDM-ONU of 38 is directed to the wavelength selective coupler 32; the wavelength selective coupler 32 couples the upstream signal of the WDM-ONU from the AWG 36 with the upstream signal of the TDM-ONU from the optical splitter 34 and transmits it to the primary kilofiber. . It should be noted that the branch fiber connected to the optical splitter can only be connected to the TDM-ONU in the related art, and the branch fiber connected to the AWG can only be connected to the WDM-ONU, and the wavelength selective router 38 is added in the embodiment of the present invention to make the branch fiber. For TDM-ONU or WDM-ONU—as the same, there is no selectivity, and the ONU selects it, that is, what PON signal is transmitted by what ONU. The following various embodiments incorporate the above-described preferred embodiments. Embodiment 1 This embodiment provides a method for coexisting a time division multiplexing passive optical network and a wavelength division multiplexing passive optical network, thereby solving an application scenario in which a multi-user high bandwidth and a low bandwidth are mixed. The hybrid passive optical network includes: a wavelength division multiplexing coupler, a wavelength selective combiner, an arrayed waveguide grating, and a wavelength selective router connected to the optical splitter and the branch fiber. Among them, wavelength division multiplexing coupler and time division multiplexing OLT And the wavelength division multiplexing OLT is connected, and is connected to the wavelength selective coupler through the main kilo fiber; the wavelength selective combiner is connected to the optical splitter and the arrayed waveguide grating; the arrayed waveguide grating and the optical splitter respectively are combined with the wavelength selective combiner and each The wavelength selection routers are connected; each wavelength selection router is connected to the arrayed waveguide grating and the optical splitter and is connected to the optical network unit ONU through the branch optical fiber connected thereto. The constituent elements will be described in detail below. The wavelength division multiplexing coupler is configured to introduce the downlink signals of the TDM-OLT and the WDM-OLT into the main kilo-fiber, and separate the uplink signals on the independent kilo-fibers into the corresponding OLTs respectively; wavelength selective coupling , configured to separate the downlink signal of the WDM-OLT from the primary kilo-fiber and transmit it to the arrayed waveguide grating; and direct the received uplink signal of the WDM-ONU from the arrayed waveguide grating back to the primary kilo-fiber Up, simultaneously transmitting the uplink signal of the TDM-ONU through the splitter to the primary kilometer fiber; and transmitting the downlink signal of the TDM-OLT to the optical splitter; the arrayed waveguide grating is set to be WDM from the wavelength selective coupler The downstream signal of the OLT is transmitted through the AWG to the wavelength selective router connected to its corresponding branch outlet according to its wavelength, and the uplink signal from the WDM-ONU on the wavelength selective router is passed through the AWG to the wavelength selective coupler; And a wavelength selection router, configured to couple the downlink signal of the TDM-OLT from the optical splitter and the downlink signal of the WDM-OLT from the AWG to the branch fiber; and uplink signals from the branch fiber The signal separating the WDM-ONU is transmitted to the arrayed waveguide grating, and the uplink signal of the separated TDM-ONU is transmitted to the optical splitter. In the implementation process, the wavelength division multiplexing coupler may be an optical filter (which may be composed of a thin film sideband filter), and the light of the wavelength band used for the wavelength division multiplexing PON is transmitted. For example, the C-band and part of the L-band, while the other bands of light are reflected, the transmission interface is connected to the WDM-OLT, and the common port is connected to the main-thousand fiber, and the reflection interface is connected to the TDM-OLT. It is mainly used to couple the downstream light of different OLTs into the main kilofiber, and separate the uplink signals on the main kilofibers and transmit them to the corresponding OLT. The wavelength selective coupler may be an optical filter, which is the same as the filter used in the wavelength division multiplexing coupler, and has a transmission interface connected to the arrayed waveguide grating, and a universal port connected to the main 1000 fiber, and the reflection interface and the beam splitting Connected. Its function is to let the light of the TDM-PON enter and exit through the reflection port and the common port of the filter, and the light of the WDM-PON only enters and exits through the transmission port and the universal port of the filter. The general purpose port of the arrayed waveguide grating (i.e., AWG) can be coupled to a wavelength selective combiner with its grating exit connected to a wavelength selective router on each branch fiber. Its function is that the signal from the WDM-OLT of the wavelength selective coupler is directed to the branch outlet of the different AWG according to its wavelength, enters the wavelength selective router connected thereto, and passes the signal of the WDM-ONU from the wavelength selective router. The AWG is directed to the wavelength selective coupler. The wavelength selection router can also be an optical filter, which is the same as the filter used in the wavelength division selector. The reflection interface is connected to the optical splitter, and the universal port is connected to the branch fiber, and the transmission interface is connected to the arrayed waveguide grating. . Its function is to allow the time-division multiplexed PON uplink and downlink light to enter and exit through the reflection port and the common port of the filter, and the wavelength division multiplexing PON light only enters and exits through the transmission port and the common port of the filter. It should be noted that the transmission port and the reflection port of the optical filter are not bound to the wavelength band of the light, and can be designed according to the needs of the customer. For example, for a sideband filter, there is a set wavelength, the transmission port transmits light larger than the wavelength, and the reflection port reflects light smaller than the wavelength, and of course, the design can be reversed, that is, the transmission port Transmits light having a smaller wavelength than the wavelength, and the reflective port reflects light having a wavelength greater than the wavelength. Therefore, the application of the optical filter in the above example can be changed due to the design of the optical filter, and the system has the same function as the original system. It can be seen that this embodiment can enable the WDM passive optical network and the time division multiplexed passive optical network to coexist at the same time, that is, the time division multiplexed PON takes the main optical fiber, the optical splitter and the branch optical fiber channel, and has its own OLT. And ONU, and the wavelength division multiplexing PON takes the main kilo fiber, the arrayed waveguide grating and the branch fiber channel, and it also has its own OLT and ONU. The user can select the 4 mega-wavelength ONU or the time-division ONU according to the needs of the user. After the operator has modified the ODN, there is no need to modify the ODN due to the change of the user's needs, and only need to replace the corresponding ONU. The second embodiment takes an example as an example to describe the composition of the passive optical network in the embodiment of the present invention. FIG. 7 is a schematic structural diagram of a passive optical network in which a wavelength division multiplexing PON and a time division multiplexed PON coexist according to Embodiment 2 of the present invention. As shown in FIG. 7, the passive optical network includes: wavelength division multiplexing A coupler, a wavelength selective combiner, a beam splitter, an arrayed waveguide grating, and more than one wavelength selective router connected to the splitter. Wherein, the wavelength division multiplexing coupler is connected to the time division multiplexing OLT and the wavelength division multiplexing OLT; connected to the wavelength selective coupler through the main kilo fiber; the wavelength selective coupler is connected to the optical splitter and the arrayed waveguide grating; the arrayed waveguide grating And a splitter is connected to each wavelength selection router; each wavelength selection router is connected to the optical network unit through a corresponding branch fiber. The wavelength division multiplexing coupler is configured to couple the downlink signal of the received time division multiplexing OLT and the downlink signal of the wavelength division multiplexing OLT into the main kilometer fiber, and separate the time division multiplexing on the main kilo fiber. The uplink signal of the ONU is transmitted to the time division multiplexing OLT, and the separated wavelength division multiplexed uplink signal is transmitted to the wavelength division multiplexing OLT; the wavelength selection combiner is set to separate the wavelength division from the main kilo fiber downstream light. Multiplexing the signal and passing it to the arrayed waveguide grating; the remaining time-division multiplexed downstream light is transmitted to the optical splitter; and the received wavelength division multiplexed signal from the arrayed waveguide grating is guided back to the primary kilo-fiber, Simultaneously transmitting the time division multiplexed uplink signal of the optical splitter to the primary kilometer fiber; the optical splitter is arranged to transmit the downlink optical of the TDM-OLT through the wavelength selective coupler to each wavelength selective router connected thereto, and The upstream light from the TDM-ONU on each wavelength selective router is transmitted to the wavelength selective combiner; the arrayed waveguide grating is arranged to direct the wavelength division multiplexed signal to its associated branch outlet according to its wavelength, into and out Connected wavelength selective routers, and the wavelength division multiplexed upstream signals of the branch fibers from the wavelength selective router are sent to the wavelength selective coupler; and the wavelength selective router is arranged to pass the optical signals from the optical splitters and from the arrayed waveguide gratings The signal is transmitted to the branch fiber; the wavelength division multiplexed signal is separated from the uplink signal of the branch fiber and transmitted to the arrayed waveguide grating, and the remaining separated time-division multiplexed uplink signals are transmitted to the optical splitter. It can be seen that, due to the role of the wavelength selective router, there are downlink signals of the WDM-OLT and downlink signals of the TDM-OLT in each branch fiber, and each ONU connected to the branch fiber receives the two signals, but only Different types of ONUs accept different types of signals, that is, WDM-ONU only accepts WDM signals, and TDM-ONU only accepts TDM signals. The above constituent elements will be described in detail below with reference to the accompanying drawings. FIG. 8 is a schematic structural diagram of a wavelength division multiplexing coupler according to Embodiment 2 of the present invention. As shown in FIG. 8, the wavelength division multiplexing coupler may be a Thin-Film Filter (TFF). In composition, the thin film filter transmits light in the optical band of the wavelength division multiplexed PON, but reflects light in other wavelength bands. In the implementation process, the wavelength division multiplexing coupler can be located at the local OLT, its P port is connected to the wavelength division multiplexed OLT, the C port is connected to the main kilo fiber, and the R port is connected to the time division multiplexing OLT. The thin film filter is configured to couple signals from two different OLTs to the primary kilo-fiber and separate the upstream signals to their respective OLTs. It should be noted that the wavelength band of the wavelength division multiplexing PON has two situations: one is that the uplink and the downlink light are in the C band, the second is that the uplight is in the C band, and the descending light is in the L band. For Case 1, the design of the TFF is relatively simple, that is, there is a see-through window at 1530nm-1560nm, and the light in other bands is reflected; the filter can also be designed and produced by FBG. For Case 2, the design of the filter is more complicated. It is mainly necessary to avoid the window of 1575nm - 1581nm in the L-band, which is the window of the downstream wavelength of XG-PON and 10G-EPON. Therefore, this is a two-window filter. Specifically, there is a see-through window at 1530 nm - 1560 nm and another see-through window at 1585 nm - 1615 nm, and light outside the window is reflected. FIG. 9 is a schematic structural diagram of a wavelength selective coupler according to Embodiment 2 of the present invention. As shown in FIG. 9, the wavelength selective combiner may be composed of a filter, and the filter used by the filter and the wavelength division multiplexing coupler. The pieces are the same. In the implementation process, the wavelength selective coupler can be disposed at the entrance of the optical splitter, its R port is connected to the optical splitter, the C port is connected to the main kilo fiber, and the P port is connected to the arrayed waveguide grating. The thin film filter is configured to introduce the wavelength division multiplexed downlink signal onto the arrayed waveguide grating, and direct the wavelength division multiplexed uplink signal of the branch optical fiber back to the main kilometer optical fiber, and simultaneously maintain the time division multiplexed uplink and downlink light Conduct normal communication. FIG. 10 is a schematic structural view of an arrayed waveguide grating according to Embodiment 2 of the present invention. As shown in FIG. 10, an arrayed waveguide grating (AWG) can make different wavelengths of light travel in different channels in the AWG, and the channels thereof. It is connected to the branch fiber through the wavelength selection router. Here, the number of channels of the AWG is preferably the same as the number of branch fibers, which will ensure that each branch fiber can flexibly convert its ONU. If the number of channels of the AWG is less than the number of branch fibers, there will be only one option for users of some branch fibers, that is, the original ONU cannot be upgraded; if the number of channels of the AWG is greater than the number of branches, it will cause some waste. . The AWG channel spacing is typically 100 GHz, and 50 GHz spaced AWGs can be selected as needed. In the implementation process, the arrayed waveguide grating (AWG) can be placed next to the optical splitter of the optical distribution network ODN, which is a passive device. In order for the AWG to be truly passive, its AWG must be independent of ambient temperature, ie, changes in ambient temperature (eg, -20 ° C - 70 ° C) have no effect on AWG operating parameters and performance, otherwise the AWG requires a temperature Controlling the equipment to keep it stable, which will increase the cost of work and maintenance, so the passive working characteristics of the AWG is very important. 11 is a schematic structural diagram of a wavelength selective router according to Embodiment 2 of the present invention. As shown in FIG. 11, the wavelength selective router may be composed of a filter, the filter and the previous wavelength division multiplexing coupler and wavelength selective coupler. The same is used. In the implementation process, a wavelength selection router may be connected in front of each branch fiber of the optical splitter. The R port of the wavelength selection router is connected to the optical splitter, the C port is connected to the branch optical fiber, and the P port is connected to the AWG. This filter is used to be from the array The wavelength division multiplexed downlink signal on the waveguide grating and the time division multiplexed downlink signal from the optical splitter are introduced onto the branch fiber, and the wavelength division multiplexed uplink signal on the branch fiber is guided back to the arrayed waveguide grating or the branch fiber. The time division multiplexed upstream signal is directed to the splitter. It can be seen that this embodiment forms a coexistence system through the above series of auxiliary optical function elements, so that the wavelength division multiplexing PON and the time division multiplexed PON can operate in one ODN. In this way, any user can freely upgrade and downgrade, just need to change one of the required ONUs, which is convenient for operators to operate and manage flexibly. Embodiment 3 In this embodiment, in order to realize the coexistence of the wavelength division multiplexing PON and the time division multiplexing PON, some modifications are made to the passive optical network, and some passive optical function modules are added. First, according to the requirements of Figure 7, a wavelength division multiplexing coupler is added at the OLT. Its main function is the downlink signal of 4 bar from WDM-OLT and the downlink signal of TDM-OLT (for example, GPON or EPON). Coupling into the main kilo-fiber, while separating the uplink signal from the main kilo-fiber, allowing the wavelength-division multiplexed uplink signal to enter the WDM-OLT, and the time-division multiplexed uplink signal to enter the TDM-OLT. Secondly, a wavelength selective coupler is inserted in front of the optical splitter. Its main function is to separate the wavelength division multiplexed downlink signal from the main kilo fiber and transmit it to the arrayed waveguide grating, and to divide the wave from the arrayed waveguide grating. The upstream signal is directed to the primary kilo-fiber, while the separated time-division multiplexed downstream signal is directed to the optical splitter, and the time-division multiplexed upstream signal from the optical splitter is directed to the primary kilo-fiber. Again, an arrayed waveguide grating is placed next to the splitter, as shown in Figure 10, with one end connected to the wavelength selective combiner and the other end connected to each wavelength selective router. Its main function is to pass the AWG shunt according to the wavelength division multiplexing wavelength, the 4 dB corresponding wavelength WDM downlink signal is directed to its corresponding wavelength selection router and branch fiber, and the wave from each wavelength selection router The multiplexed uplink signal is coupled to the wavelength selective combiner via the AWG coupling. Then, a wavelength selective router is inserted in front of each branch fiber after the optical splitter, and its main function is to couple the downlink signal from the wavelength division multiplexing on the arrayed waveguide grating with the time division multiplexed downlink signal from the optical splitter. On the branch fiber, and transmitting the wavelength division multiplexed uplink signal of the branch fiber to the arrayed waveguide grating, or directing the time division multiplexed uplink signal from the branch fiber to the beam splitter. It should be noted that the uplink signal is determined by the ONU, and what type of ONU the wavelength selection router is connected to will have an uplink signal. Finally, when all of these modules are connected as shown in Fig. 7, the time division multiplexed passive optical network and the wavelength division multiplexed passive optical network can coexist in the same ODN system. Embodiment 4 In this embodiment, the time-multiplexed passive optical network is GPON or EPON, and its downlink wavelength range is 1480 nm to 1500 nm, and the uplink wavelength range is 1260 n! ~ 1360nm; Wavelength-multiplexed passive optical network, the upper and lower wavelengths can be in the C-band, or its upstream wavelength in the C-band, the downstream wavelength in the L-band; its technology can be the colorless ONU of the seed source or tunable Lasers, etc. For the coexistence of these two passive optical networks, the key is the design of the filter. For the coexistence of the two PONs, the filter is a sideband filter. The technology is thin film filtering technology, that is, the wavelength of the light is below 1510 nm. The light is reflected, and the light above 1510 nm is transmitted. Wavelength division multiplexers, wavelength selective couplers, and wavelength selective routers can all use the same filter above. Their position and associated connections are shown in Figure 7. Among them, the selection of the arrayed waveguide grating is related to the planning of the wavelength of the wavelength division multiplexed passive optical network. If the up-and-down light is in the C-band, the AWG can be made and selected simply, as long as the AWG is temperature-dependent (the general choice of AWG does not require temperature control, it should be independent of ambient temperature) and the choice of AWG wavelength interval (eg , 50GHz or 100GHz); If the upstream light is in the C-band and the downstream light is in the L-band, the AWG is slightly more complicated to make and select, but there are now dual-band AWG devices available, generally C-band and L-band wavelength spacing. Should be synchronized. The position and connection of the arrayed waveguide grating is shown in Figure 7. It is located next to the splitter and its universal port is connected to the wavelength selective combiner, each of which is connected to its corresponding wavelength selective router. Embodiment 5 In this embodiment, the time-multiplexed passive optical network is XG-PON or 10G-EPON, and its downlink wavelength range is 1575 n! ~ 1580 nm, the upstream wavelength range is 1260n! ~ 1280nm; Wavelength-multiplexed passive optical network, the upper and lower wavelengths can be in the C-band, or its upstream wavelength in the C-band, the downstream wavelength in the L-band; its technology can be the colorless ONU of the seed source or tunable Lasers, etc. Since the downlink of the 10G passive optical network uses some L-bands, the wavelengths overlap some of the wavelength-multiplexed passive optical networks using L-bands. Therefore, the design of the filter and the wavelength-multiplexed passive optical network The use of the band should take this factor into account. Generally, the wavelength division multiplexing passive optical network avoids the 1575nm-1580nm band. Therefore, this is a dual window filter, which can be a thin film filtering technique (TTF) or a fiber Bragg grating (Fiber Bragg grating, referred to as FBG), its design The calculation is as follows: Window 1 is in the C band, that is, 1530nm-1560nm, and window 2 is in the L band, that is, 1585nm~1615nm. The light in the window is transmitted, and the light in the window is reflected. For some passive optical networks that use only C-band wavelength division multiplexing, since the 10G passive optical network already uses L-band light, the filter design needs to consider this factor. The choice of wideband filtering technique is the best method, that is, to open a window in the C-band, 1530nm - 1560nm, the light in the window is transmitted, and the light outside the window is reflected. Therefore, the choice of filters, single window or dual window, is related to the choice of wavelength planning for wavelength division multiplexing passive optical networks. Different wavelength schemes need to use different types of filters to adapt them to 10G passive. The coexistence of optical networks. Once the type of filter is determined, the selection of other passive light guide modules is relatively simple, because WDM couplers, wavelength selective couplers, and wavelength selective routers, although their names and functions are different, they all use The same kind of filters, their position and related connections are shown in Figure 7. Among them, the selection of the arrayed waveguide grating is related to the planning of the wavelength of the wavelength division multiplexed passive optical network. If the up-and-down light is in the C-band, the AWG can be made and selected simply, as long as the AWG is temperature-dependent (the general choice of AWG does not require temperature control, it should be independent of ambient temperature) and the choice of AWG wavelength interval (eg , 50GHz or 100GHz); If the upstream light is in the C-band and the downstream light is in the L-band, the AWG is slightly more complicated to make and select, but there are now dual-band AWG devices available, generally C-band and L-band wavelength spacing. Should be synchronized. The position and connection of the arrayed waveguide grating is shown in Figure 7. It is located next to the splitter and its universal port is connected to the wavelength selective combiner, each of which is connected to its corresponding wavelength selective router. It should be noted that in the process of forming a coexistence network, the first thing to look at is the wavelength division multiplexing passive optical network coexisting with the 10G passive optical network, and then the wavelength planning of the wavelength division multiplexing passive optical network. Selecting the corresponding filter and the arrayed waveguide grating, the wavelength division multiplexing coupler composed of the filter, the wavelength selective coupler and the passive optical module of the wavelength selective router, and the arrayed waveguide grating according to the position shown in FIG. Connected with the interface method, a new wavelength division multiplexing passive optical network and a 10G passive optical network coexistence system are generated. It can be seen that the wavelength selection router is added in the embodiment of the present invention, so that the branch fiber is not selective to the TDM-ONU or the WDM-ONU, and the ONU selects it, that is, what PON signal is transmitted by the ONU. With this coexistence system, for a diverse and rapidly changing user environment, operators only need to make a transformation to the ODN before they can change their ONU according to the user's needs. To meet the bandwidth requirements from a few megabits to a gigabit or from a few hundred megabytes to several megabits, this saves operators a lot of time and investment, enabling operators to quickly adapt to diverse and rapidly changing application scenarios. In summary, through the above embodiments, TDM-PON and WDM-PON can coexist, low-end users can continue to use their TDM-PON facilities, and high-end users can configure WDM-PON facilities. For example, the user needs to upgrade, and only need to replace the ONU whose ONU is WDM-PON; after the high-end user moves away, the new user is a low-end user, then only need to replace the ONU whose ONU is TDM-PON. . In this way, the problem that the point-to-point network is incompatible with the original network when using the point-to-point network and the wavelength division multiplexing PON when upgrading the original time division multiplexed PON in the related art is solved, and the network compatibility is enhanced. Sexuality improves the user experience. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

A passive optical network comprising a wavelength selective coupler, a beam splitter, an arrayed waveguide grating AWG, and a plurality of wavelength selective routers, wherein the wavelength selective coupler is coupled to the optical splitter and the AWG, The splitter and the AWG are respectively connected to each of the wavelength selective routers, and each of the wavelength selective routers is connected to a branch fiber and a time division multiplexed optical network unit TDM-ONU or a wavelength division multiplexed optical network unit WDM - ONU connection; the wavelength selection router is configured to set a downlink signal of the time division multiplexed optical line terminal TDM-OLT from the optical splitter and a downlink signal of the wavelength division multiplexed optical line terminal WDM-OLT from the AWG Coupling and transmitting to the branch fiber connected to the wavelength selective router; and transmitting an uplink signal in the branch fiber connected to the WDM-ONU to the AWG, to be connected to the TDM-ONU An uplink signal is transmitted to the beam splitter in the branch fiber.

2. The passive optical network according to claim 1, wherein the passive optical network further comprises a wavelength division multiplexing coupler, wherein the wavelength division multiplexing coupler and the TDM-OLT and the a WDM-OLT is connected and connected to the wavelength selective coupler through a primary kilofiber;

The wavelength division multiplexing coupler is configured to couple the downlink signal of the TDM-OLT and the downlink signal of the WDM-OLT into the primary kilometer fiber; and separate from the uplink signal of the primary kilofiber The uplink signal of the TDM-ONU is transmitted to the TDM-OLT, and the uplink signal of the WDM-ONU is separated and transmitted to the WDM-OLT;

The wavelength selective coupler is configured to transmit a downlink signal of the WDM-OLT from the downlink signal of the primary kilo-fiber to the AWG, and separate a downlink signal of the TDM-OLT to the optical split And coupling an uplink signal of the TDM-ONU from the optical splitter to an uplink signal of the WDM-ONU from the AWG and transmitting the uplink signal to the primary kilofiber.

3. The passive optical network according to claim 2, wherein

The AWG, configured to direct a downstream signal of the WDM-OLT from the wavelength selective coupler to its wavelength to a corresponding one of the wavelength selective routers; and to the WDM-ONU from the wavelength selective router The upstream signal is directed to the wavelength selective coupler.

The passive optical network according to claim 3, wherein the number of channels of the AWG is the same as the number of the branched fibers.

5. The passive optical network of claim 2, wherein one or more of the wavelength division multiplexing coupler, the wavelength selector, and the wavelength selective router are optical filters.

6. The passive optical network according to claim 5, wherein the optical filter is a thin film filter or a fiber Bragg grating sensor.

7. The passive optical network according to claim 5, wherein the optical filter is one of the following: a thin film sideband filter, a single window wideband filter, and a dual window wideband filter.

8. The passive optical network according to claim 1, wherein

The TDM-ONU is configured to select a downlink signal of the TDM-OLT from a downlink signal of the branch fiber; and transmit an uplink signal of the TDM-ONU to the wavelength selective router by using the branch fiber ;

The WDM-ONU is configured to select a downlink signal that receives the WDM-OLT from a downlink signal of the branch fiber; and transmit an uplink signal of the WDM-ONU to the wavelength selective router by using the branch fiber .

9. A method of transmitting a signal in a passive optical network according to any one of claims 1 to 8, comprising the following steps:

The downlink signal of the primary kilo-fiber is separated by the wavelength selective coupler to transmit the downlink signal of the WDM-OLT to the AWG, and the wavelength of the downlink signal of the WDM-OLT is directed to the corresponding wavelength. Selecting a router, and transmitting the branch fiber to the WDM-ONU connected thereto;

And transmitting, by the wavelength selective coupler, a downlink signal of the TDM-OLT to the optical splitter, and transmitting, by the wavelength selective router, the downlink signal to the branch fiber. TDM-ONU.

10. A method of transmitting a signal in a passive optical network according to any one of claims 1 to 8, comprising the following steps:

The uplink signal of the WDM-ONU is transmitted to the AWG through the wavelength selection router via the branch fiber connected to the WDM-ONU. The uplink signal of the TDM-ONU is transmitted to the optical splitter through the wavelength selective router via the branch fiber connected to the TDM-ONU;

An uplink signal from the WDM-ONU of the AWG and an uplink signal from the TDM-ONU of the optical splitter are coupled via the wavelength selective coupler and transmitted to the primary kilo-fiber.