WO2012149810A1

WO2012149810A1 - Passive optical network system and downlink transmission method thereof

Info

Publication number: WO2012149810A1
Application number: PCT/CN2011/081226
Authority: WO
Inventors: 卫国; 程宁; 王峰
Original assignee: 华为技术有限公司
Priority date: 2011-10-25
Filing date: 2011-10-25
Publication date: 2012-11-08
Also published as: CN102439998A; CN102439998B

Abstract

Disclosed are a passive optical network system and a downlink transmission method thereof. The passive optical network system includes an optical line terminal, an optical distribution network and a plurality of optical network units, wherein the optical line terminal is used for sending a downlink multi-wavelength optical signal formed by the wave division multiplexing of a plurality of downlink optical signals with different wavelengths; and the optical distribution network includes a first stage optical splitter, a plurality of second stage optical splitters and a plurality of filtering modules, with the first stage optical splitter being used for dividing a path of downlink multi-wavelength signals sent from the optical line terminal into a plurality of paths of downlink multi-wavelength signals, and the plurality of filtering modules being used for performing filtering processing on the plurality of paths of downlink multi-wavelength optical signals to obtain a downlink single-wavelength optical signal with the wavelength thereof corresponding to the pathway central wavelength thereof, wherein the pathway central wavelengths of the plurality of filtering modules correspond to the plurality of downlink optical signals with different wavelengths respectively; and the second stage optical splitters being used for providing the downlink single-wavelength optical signals after optical splitting processing to the corresponding optical network units respectively.

Description

Passive optical network system and downlink transmission method thereof

The present invention relates to a passive optical network (PON) technology, and in particular to a passive optical network system and a downlink transmission method thereof. Background technique

The passive optical network system may include at least one optical line terminal (OLT), a plurality of optical network units (ONUs), and an optical distribution network (ODN). The OLT is connected to the plurality of ONUs in a point-to-multipoint manner through the ODN, and communicates with a plurality of ONUs in a Time Division Multiplexing (TDM) manner.

Passive optical networks have been developed to date and are widely used due to their low cost, maintenance schedule, and the ability to provide very high bandwidth. However, with the emergence of new services, the demand for bandwidth is increasing day by day, while the traditional P0N system adopts the TDM mechanism, and the service bandwidth is greatly limited. In order to meet the user's demand for bandwidth, it is necessary to upgrade the P0N, and the P0N upgrade means to replace or update the devices in the P0N, and this replacement or update requires a lot of cost, so how to maximize the utilization has been deployed. The P0N device reduces the cost of the P0N upgrade, and achieving a smooth upgrade becomes a problem that must be considered.

The deployed P0N devices include 0NU and 0DN. Usually, the equipment and operation and maintenance costs of these two parts account for more than 2/3 of the total cost. Therefore, how to maximize the use of deployed 0NU and 0DN devices during the upgrade process is especially important in the smooth upgrade process of P0N. The prior art solves the problem of maximizing the utilization of existing deployed devices by replacing the first-stage optical splitting device in the P0N with a hybrid splitter (Hybrid Splitter), and the prior art can only perform an overall upgrade of the P0N. , can not be flexibly upgraded according to the needs of specific users. Summary of the invention

The embodiment of the present invention provides a passive optical network system to solve the problem of flexible upgrade of the passive optical network. Meanwhile, the embodiment of the present invention further provides a downlink transmission method of the foregoing passive optical network system.

A passive optical network system, including an optical line terminal, an optical distribution network, and a plurality of optical network units, where the optical line terminal is connected to the plurality of optical network units through the optical distribution network; The optical line terminal is configured to send a downlink multi-wavelength optical signal, where the downlink multi-wavelength optical signal is formed by wavelength division multiplexing of a plurality of downlink optical signals of different wavelengths; the optical distribution network includes a first-stage optical splitter, a plurality of second-stage optical splitters and a plurality of filtering modules; the branching ports of the first-stage optical splitters are respectively connected to the plurality of second-level optical splitters, and the plurality of filtering modules are respectively coupled to the first-level optical splitter Between the branch port of the optical splitter and its corresponding second-stage optical splitter; the first-stage optical splitter is configured to split a downlink multi-wavelength signal sent by the optical line terminal into multiple downlink multi-wavelength signals; The module is configured to filter the multi-channel downlink multi-wavelength optical signal to obtain a downlink single-wavelength optical signal having a wavelength corresponding to a center wavelength of the channel, where A center wavelength channel filter module respectively corresponding to a plurality of different wavelengths of downstream optical signals; splitter for the second stage, after the single-wavelength optical signals downstream dividing light treatment are provided to a corresponding optical network unit.

A downlink transmission method of a passive optical network system according to an embodiment of the present invention includes: receiving a downlink multi-wavelength optical signal from an optical line terminal, where the downlink multi-wavelength optical signal is divided by a plurality of downlink optical signals of different wavelengths Reuse

Separating the downlink multi-wavelength optical signal to obtain a multi-channel downlink multi-wavelength signal; separately filtering the multi-channel downlink multi-wavelength optical signal to obtain a plurality of downlink single-wavelength optical signals of different wavelengths, wherein each downlink The single-wavelength optical signals respectively correspond to the downlink optical signals of one of the wavelengths of the downlink multi-wavelength optical signals; The passive optical network system and the downlink transmission method in the passive optical network system provided by the foregoing embodiments of the present invention can maximize the utilization of devices in the deployed passive optical network, thereby saving the upgrade cost of the passive optical network and improving Upgrade efficiency of passive optical networks. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings which are required in the embodiments or the description of the prior art will be described below. It is obvious that the drawings in the following description are merely The description of the prior art and some embodiments of the present invention can be obtained by those skilled in the art from the drawings without departing from the scope of the invention.

1 is a schematic structural diagram of a passive optical network system using a time division multiplexing mechanism; FIG. 2 is a schematic structural diagram of a passive optical network system according to an embodiment of the present invention; FIG. 3 is a schematic diagram of an embodiment of the present invention. Flow chart of a method for processing a downlink optical signal of a passive optical network;

4 is a schematic structural diagram of a method for processing a downlink optical signal of a passive optical network according to another embodiment of the present invention;

FIG. 5 is a flowchart of a method for processing a downlink optical signal of a passive optical network according to another embodiment of the present invention; FIG.

6 is a schematic structural diagram of a method for processing a downlink optical signal of a passive optical network according to a third embodiment of the present invention;

FIG. 7 is a flowchart of a method for processing a downlink optical signal of a passive optical network according to a third embodiment of the present invention. detailed description

FIG. 1 is a schematic diagram of a network architecture of a passive optical network (P0N) system using a time division multiplexing (TDM) mechanism. The passive optical network system may include an optical line terminal (0LT), an optical distribution network Network (ODN) and multiple optical network units (0NU).

The direction from the 0LT to the ONU is defined as a downlink direction, and the direction from the 0NU to the 0LT is defined as an uplink direction. In the downlink direction, the OLT broadcasts downlink data to the multiple ONUs by using a time division multiplexing manner, and each ONU receives only data carrying its own identifier; and in the uplink direction, the multiple ONUs use time division multiple access (TDMA, The Time Div is ion Mul t iplex ing Acces s) mode communicates with the OLT, and each ONU sends uplink data strictly according to the time slot allocated by the 0LT.

The passive optical network system may be a communication network system that does not require any active device to implement data distribution between the OLT and the ONU. For example, in a specific embodiment, the OLT and the ONU Data distribution between the two can be achieved by passive optical devices (such as optical splitters) in the 0DN. Moreover, the passive optical network system may be an asynchronous transmission mode passive optical network (ATM P0N) system or a broadband passive optical network (BP0N) system defined by the ITU-T G.983 standard, and an ITU-T G. 984 standard. A defined Gigabit Passive Optical Network (GP0N) system, an Ethernet Passive Optical Network (EP0N) defined by the IEEE 802. 3ah standard, or a next-generation passive optical network (NGA P0N, such as XGP0N or 10G EP0N, etc.). The entire contents of the various passive optical network systems defined by the above standards are incorporated herein by reference.

The 0LT is usually located at a central office (Centra l Offcece, CO), which can uniformly manage the plurality of ONUs and transmit data between the ONU and an upper layer network. Specifically, the OLT may serve as a medium between the ONU and the upper layer network (such as the Internet, a public switched telephone network), and forward data received from the upper layer network to the ONU, and The data received by the ONU is forwarded to the upper layer network. The specific configuration of the OLT may vary depending on the specific type of the passive optical network. For example, in an embodiment, the OLT may include an optical transmitter Tx and a receiver Rx. The downlink optical signal is sent to the ONU, and the receiver is configured to receive an uplink optical signal from the ONU, where the downlink optical signal and the uplink optical signal are transmitted by using the 0DN.

The ONU can be distributed in a user-side location (such as a customer premises). The 0NU The network device for communicating with the OLT and the user, in particular, the ONU may serve as a medium between the OLT and the user, for example, the ONU may receive from the OLT. The data is forwarded to the user, and data received from the user is forwarded to the OLT. It should be understood that the structure of the ONU is similar to the optical network terminal (ONT), so in the solution provided by the present application, the optical network unit and the optical network terminal can be interchanged.

The 0DN may be a data distribution system that may include fiber optics, optical couplers, beamsplitters, and/or other devices. In one embodiment, the optical fiber, optical coupler, optical splitter, and/or other device may be a passive optical device, in particular, the optical fiber, optical coupler, optical splitter, and/or other device may be Distributing the data signal between the 0LT and the ONU is a device that does not require power supply support. Additionally, in other embodiments, the 0DN may also include one or more processing devices, such as an optical amplifier or relay dev ice. In addition, the 0DN may specifically extend from the optical line terminal to the plurality of 0NUs, but may also be configured in any other point-to-multipoint structure.

For example, the data distribution is implemented by using a splitter. For the sake of reliability and operation and maintenance, the 0DN can be deployed in two-stage split mode, as shown in FIG. 1 . Taking the 0DN of 1:32 as an example, the 0DN may include a first-stage splitter with a split ratio of 1:4 and four second-stage splitters with a split ratio of 1:8, the first-stage splitter Each of the branch ports is correspondingly connected to the four second-stage optical splitters by optical fibers, and the respective branch ports of the second-stage optical splitters are respectively connected to the plurality of ONUs through the branch optical fibers. The data signal of the 0LT is divided into four channels by the first-stage splitter, and then divided into multiple channels by the second-stage splitter and transmitted to the respective ONUs. The first-stage optical splitter is disposed at an optical distribution frame (0DF, Opt ica l Di str ibut ion frame) that is closer to the central office for maintenance; and the second-stage optical splitter is deployed at the remote end. At the node (RN, Remote Node), the operation and maintenance cost of this part is high, and it often does not change after many years of deployment. 0NU devices are usually located in or near the user's home. Due to the large environmental differences, the operation and maintenance costs of this part are also high, and they often do not change after many years of deployment. In the PON system, the increase of bandwidth often leads to the change of the multiplexing mode. The TDM mode has achieved great success in the P0N. However, due to the limitation of the device, the higher rate TDM mode, especially in the burst mode. The bottleneck of the high-speed TDM method is increasingly apparent, and TDM P0N is difficult to cope with the development of P0N. Here, a new type of multiplexing method (WDM, Wavelength Divi s ion Mul t iplex ing) came into being.

The embodiment of the invention provides a novel passive optical network P0N system, which can greatly increase the bandwidth provided to users through the combined application of TDM and WDM. Specifically, the P0N system provided by the embodiment of the present invention may be based on the existing TDM P0N system, and the central office 0LT transmits a downlink multi-wavelength optical signal formed by wavelength division multiplexing of downlink optical signals of multiple different wavelengths. And grouping 0NUs (for example, 0NUs connected to the same second-stage optical splitter can be divided into one group), each set of 0NUs can respectively correspond to one downlink wavelength of the downlink multi-wavelength signal and between the same group of 0NUs The downlink wavelength channel is shared by the TDM mode, and different groups of ONUs respectively correspond to different downlink wavelengths and are multiplexed by WDM. In addition, the P0N system may further add a filtering module between the first-stage splitter and the second-stage splitter to filter out downlink optical signals belonging to other groups of the ONN in the downlink multi-wavelength signal, so that each The group ONU receives only the downlink optical signal corresponding to its downlink wavelength.

FIG. 2 is a schematic diagram of a network architecture of a passive optical network system according to an embodiment of the present invention. The passive optical network system includes an optical line terminal 0LT, an optical distribution network 0DN, and a plurality of optical network units 0NU, wherein the 0LT is connected to the plurality of 0NUs through the 0DN.

The optical line terminal OLT includes a plurality of optical transmitters ΤχΓΤχ4, a multiplexer 201, a duplexer 206, and an optical receiver Rx. Wherein, the duplexer has three ports. The plurality of optical transmitters Tx1_Tx4 are connected to one end of the multiplexer 201, the other end of the multiplexer 201 is connected to one of the duplexers 206, and the optical receiver Rx and the duplexer 206 The other port is connected, and the third port of duplexer 206 is connected to the 0DN. The optical transmitters ΤχΓΤχ4 have different transmission wavelengths for respectively transmitting downlink optical signals of different downstream wavelengths, and the multiplexer 201 is configured to transmit a plurality of downstream lights of the optical transmitters TxfTx4. The signal is subjected to wavelength division multiplexing processing to generate a downlink multi-wavelength optical signal, and the downlink multi-wavelength optical signal is output to the 0DN through the duplexer 206.

When upgrading the TDM P0N system to the TDM-WDM P0N system, the number of optical transmitters is first increased. In this embodiment, the number of optical transmitters is set to four. Therefore, the four optical transmitters Txl ^_ Tx4 is used to transmit 4 downlink optical signals with different downstream wavelengths. In addition, compared with the TDM P0N system shown in FIG. 1 , in the P0N system provided in this embodiment, the processing of the uplink optical signal by the 0LT may remain unchanged. Specifically, only one light is configured inside the 0LT. The receiver Rx is configured to receive an uplink optical signal transmitted by the plurality of ONUs and transmitted to the 0LT through the 0DN.

The optical distribution network 0DN may include a first stage splitter 202, a plurality of filtering modules 207, and a plurality of second stage beamsplitters 205. The common end of the first-stage optical splitter 202 is connected to the OLT through an optical fiber, and each of the branch ports is respectively connected to one of the filtering modules 207, and is further connected to a second-stage optical splitter 205 through an optical fiber. The common ports of the second-stage optical splitters 205 are respectively connected to different ONUs through optical fibers.

The filter module 207 can include an optical path redirection device 203 and a filter member 204. In a specific embodiment, the optical path redirection device 203 can be a three-port circulator 203, and the filter device 204 can be a reflective filter device, such as an FBG. (F iber Bragg Gra t ing , fiber Bragg grating). Each three-port circulator 203 has a port 1, a port 2 and a port 3, wherein port 1 is respectively connected to a corresponding branch port of the first-stage splitter 202, port 1 is connected to the FBG 204, and port 3 is connected to One of the second stage beamsplitters 205; that is, port 1 and port 3 of the three port circulator 203 are cascaded on the fibers between the first stage splitter 202 and the second stage splitter 205, respectively. The three-port circulator 203 can provide the downlink multi-wavelength optical signal input by the port 1 to the port 2 and output to the FBG 204, and provide the downlink optical signal input by the port 2 and filtered by the FBG 204 to be reflected to Port 3 is output to the corresponding ONU through the second stage splitter 205, and the upstream optical signal input by the port 3 is directly supplied to the port 1 and output to the 0LT through the first stage splitter. Moreover, in the 0DN, the FBGs 204 in the different filtering modules 207 may have different reflection channel center wavelengths, and the reflection channel center wavelength of each FBG 204 corresponds to the emission of one of the 0LT optical transmitters ΤχΓΤχ4, respectively. The wavelength, that is, the different FBGs 204, can reflect the downstream optical signals of the optical transmitters Txl_Tx4 corresponding to the transmitting wavelengths back to the three-port circulator 203, and filter out the downstream optical signals of the other optical transmitters Txl_Tx4.

In this embodiment, the 0DN of the branching ratio is 1:32, and the first-stage optical splitter 202 is configured to divide the downlink multi-wavelength optical signal transmitted by the 0LT into four downlink multi-wavelength optical signals; the three-port circulator 203 is configured to redirect each of the downlink multi-wavelength optical signals to the FBG 204, respectively; the FBG 204 is configured to reflect the downlink optical signals of the downlink multi-wavelength signal corresponding to the center wavelength of the reflective channel thereof. The three-port circulator 203 is configured to filter out the downstream optical signals of other wavelengths in the downlink multi-wavelength optical signal; the second-stage optical splitter 205 is configured to divide the downlink optical signal reflected by the FBG 204 into eight optical signals. The signal is passed to respective optical network units ONU that are coupled to the branch ports of the second stage splitter 205.

It can be seen that the passive optical network system provided in this embodiment can be equivalent to a plurality of TDM subsystems (each TDM PON subsystem can include a second-stage optical splitter 205 and a set of ONUs connected thereto) through the WDM mode. Stacked stacked PON (S tack PON) systems, and the same TDM P0N subsystem uses the same downstream wavelength channel, while different TDM P0N subsystems use different downstream wavelength channels. Since the stacked P0N system adopts multiple downlink wavelengths, it can upgrade the downlink bandwidth of the user, and meet the requirement of the user to generate bandwidth due to service diversification.

Compared with the TDM P0N system shown in FIG. 1 , the stacked P0N system architecture provided in this embodiment only requires that a plurality of optical transmitters Tx1 ^_ Tx4 of different transmission wavelengths be configured in the 0LT to transmit downlink multi-wavelength optical signals. The fiber connected to the branch port of the first-stage beam splitter 202 is coupled to the filtering module 207 to perform wavelength selection on the downlink multi-wavelength optical signal to meet the wavelength requirements of each downlink wavelength channel. Therefore, the stacked Ρ0Ν system provided in this embodiment can be smoothly upgraded from the TDM Ρ0Ν system shown in FIG. 1 without modifying the deployed TDM 子系统0Ν subsystem (including the main part of the 0DN and the user side). 0NU device), maximized use Existing PON devices have been deployed, which reduces the cost of P0N upgrades and improves the efficiency of P0N upgrades. Moreover, when the P0N upgrade is implemented by using the stacked P0N system architecture provided in this embodiment, since the first-stage optical splitter 202 does not need to be modified, the upgrade of each TDM P0N subsystem is independent of each other, so that it can be targeted only for one specific user. Or part of the TDM P0N subsystem is upgraded for flexible upgrades.

Based on the passive optical network system provided by the foregoing embodiment, the embodiment of the present invention further provides a downlink transmission method of the passive optical network, as shown in FIG. 3, including:

Step 301: The multiplexer 201 multiplexes the plurality of downlink optical signals of different wavelengths sent from the optical transmitters of the plurality of different transmitting wavelengths into one downlink multi-wavelength optical signal.

In this embodiment, in order to facilitate the description of the invention, it is assumed that the emission wavelengths of the plurality of optical transmitters are 1490 、, 1491. 6 nm, 1493. 2 and 1494. The optical transmitters can emit four downstream optical signals of 1490 GHz, 1491. 6 +1, 1493. 2 and 1494. 8 nm, respectively, correspondingly, the first stage optical splitter 202 and the second of the above 0DN The class splitters 205 are 1:4 and 1:8, respectively. It should be understood that, in practical applications, the number of channels of the downstream optical signal, the wavelength, and the branching ratio of the first-stage and second-stage optical splitters may be adjusted according to actual needs.

Step 302: The first-stage optical splitter 202 splits the downlink multi-wavelength optical signal to form multiple downlink multi-wavelength optical signals and respectively provide the three-port ring connected to each branch port of the first-stage optical splitter 202. 203.

The downlink multi-wavelength optical signal obtained after multiplexing is split by the first-stage optical splitter 202 having a split ratio of 1:4, and becomes a 4-channel downlink multi-wavelength optical signal, wherein the 4-channel downlink multi-wavelength optical signal The optical power can be the same.

Step 303: The three-port circulator 203 re-directs the downlink multi-wavelength optical signal received by the three-port circulator 203 and outputs it to the FBG 204.

The three-port circulator 203 has three ports, namely port 1, port 2, and port 3. The downlink multi-wavelength optical signal enters the three-port circulator 203 from the port 1, and is redirected. It is output to the FBG 204 via port 1.

Step 304: The FBG 204 filters the downlink multi-wavelength optical signal, and reflects the downlink optical signal of the downlink multi-wavelength optical signal corresponding to the center wavelength of the reflection channel of the FBG 204 back to the three-port circulator 203. .

Specifically, the FBG 204 filters the downlink multi-wavelength optical signals (including 1490 nm, 1491. 6 nm, 1493. 2 and 1494. 4 wavelengths) received by the FBG 204, and only retains the downlink multi-wavelength optical signals. A downstream optical signal of one wavelength reflects the single-wavelength downstream optical signal back to port 2 of the three-port circulator 203. The wavelengths of the downlink optical signals reflected by the different FBGs 204 are different. Therefore, the wavelengths of the three-port circulators 203 are respectively 1490, 1491. 6, 1493. 2 or 1494. Single wavelength downstream optical signal.

Step 305, the three-port circulator 203 redirects the received downlink optical signal and outputs it to the second-stage optical splitter 205.

The single-wavelength downstream optical signal separated by the FBG 204 is filtered by the port 2 of the three-port circulator 203 into the three-port circulator 203, and after being redirected, is output from the port 3 to the second-stage optical splitter 205.

Step 306, the second stage splitter 205 splits the downlink optical signal to form a plurality of downlink optical signals and respectively provide them to the respective 0NUs connected to the second stage splitter 205.

The single-wavelength downlink optical signal outputted by the three-port circulator 203 is split into two downlink optical signals by the second-stage optical splitter 205 having a split ratio of 1:8, wherein the wavelengths of the downstream optical signals are the same. And the optical power of each downstream optical signal can be the same. After being split, the eight downstream optical signals are respectively transmitted to eight 0NUs connected to the second-stage optical splitter 205, such as 0NU1 to 0NU8.

FIG. 4 is a schematic diagram of a network architecture of a passive optical network system according to another embodiment of the present invention. The passive optical network system can also be smoothly upgraded from the TDM P0N system shown in FIG.

The passive optical network system provided in this embodiment is similar to the passive optical network system shown in FIG. 2, and the main difference is that it is coupled between the first-stage optical splitter 402 and the second-stage optical splitter 406. The filter module 407 of the optical fiber is different in structure from the filter module 207 shown in FIG. 2.

In this embodiment, the optical path redirection device in the filtering module 407 may include a first duplexer 403 and a second duplexer 405, both of which have three ports, which are respectively recorded as ports 11, 12, and 13 And ports 21, 11, 23. The filter components in the filtering module 407 may be dual port narrowband filters 404, and the channel center wavelengths of the respective dual port narrowband filters 404 correspond to the emission wavelengths of one of the optical transmitters Txl_Tx4 of the 0LT, respectively. The port 11 of the first duplexer 403 is connected to the branch port of the first stage splitter 402; the port 13 of the first duplexer 403 is connected to the port 21 of the second duplexer 405; the dual port narrowband filter The two ports of the 404 are connected to the port 12 of the first duplexer 403 and the port 22 of the second duplexer 405, respectively; the port 23 of the second duplexer 405 is connected to the common terminal of the second stage splitter 406.

The first duplexer 403 is configured to redirect one of the downlink multi-wavelength optical signals output by the first-stage splitter 402 to the dual-port narrow-band filter 404; the dual-port narrow-band filter 404 is configured to the downlink multi-wavelength optical signal Filtering, after filtering, only retaining the downlink optical signal of the downlink multi-wavelength optical signal corresponding to the channel center wavelength of the dual-port narrowband filter 404, and filtering out the downstream optical signal of other wavelengths; the second duplexer 405 is configured to redirect the filtered downstream optical signal to the second stage splitter 405.

Based on the passive optical network system provided by the foregoing embodiment, the embodiment of the present invention further provides another downlink transmission method of the passive optical network. As shown in FIG. 5, the method includes:

Step 501: The multiplexer 401 multiplexes the plurality of downlink optical signals of different wavelengths sent from the optical transmitters of the plurality of different transmitting wavelengths into one downlink multi-wavelength optical signal.

Step 502: The first stage splitter 402 splits the downlink multi-wavelength optical signal to form a plurality of downlink multi-wavelength optical signals and respectively provide the first duplexer connected to each branch port of the first-stage splitter 402. 403.

Step 503: The first duplexer 403 redirects the downlink multi-wavelength optical signal received by the first duplexer 403 and outputs the signal to the dual port narrowband filter 404.

Step 504: The dual port narrowband filter 404 filters the downlink multi-wavelength optical signal. A downlink optical signal having a wavelength corresponding to a channel center wavelength of the dual port narrowband filter 404 in the downlink multi-wavelength optical signal is obtained.

Step 505: The second duplexer 405 redirects the filtered downlink optical signal and outputs the signal to the second stage splitter 406.

Step 506, the second stage splitter 406 splits the downlink optical signals and provides them to the respective 0NUs connected to the second stage splitters 406.

For specific details of the steps of this embodiment, refer to the passive optical network downlink transmission method embodiment shown in FIG. 3 above.

FIG. 6 is a schematic diagram of a network architecture of a passive optical network system according to a third embodiment of the present invention. The passive optical network system can also be smoothly upgraded from the TDM P0N system shown in FIG.

The passive optical network system provided in this embodiment is similar to the passive optical network system shown in FIG. 2, and the main difference is that the optical fiber coupled between the first-stage optical splitter 602 and the second-stage optical splitter 605 is filtered. Module 607 is structurally different from filter module 207 shown in FIG.

In this embodiment, the optical path redirection device in the filtering module 607 can be a four-port circulator 603, wherein the four-port circulator 603 has four ports, which are respectively recorded as port 1, port 2, and port 3. Port 4. The filter components in the filtering module 407 may be dual port narrowband filters 404, and the channel center wavelengths of the respective dual port narrowband filters 404 correspond to the emission wavelengths of one of the optical transmitters TxfTx4 of the 0LT, respectively. Wherein, the port 1 of the four-port circulator 603 is connected to the branch port of the first-stage splitter 602; the two ports of the dual-port narrow-band filter 604 are respectively connected to the port 2 and port 3 of the four-port circulator 603; The port 4 of the circulator is connected to the common end of the second stage splitter 406.

The four-port circulator 603 is configured to redirect one of the downlink multi-wavelength optical signals outputted by the first-stage splitter 602 to the dual-port filter 604; the dual-port narrow-band filter 604 is configured to filter the downlink multi-wavelength optical signal After filtering, only the downlink optical signal corresponding to the channel center wavelength of the dual port narrowband filter 604 in the downlink multi-wavelength optical signal is retained, and the downlink optical signal of other wavelengths is filtered out; and, the four-port circulator 603 Also used after filtering The downstream optical signal is redirected to the second stage splitter 605.

Based on the passive optical network system provided by the foregoing embodiment, the embodiment of the present invention further provides a downlink transmission method of the passive optical network. As shown in FIG. 7, the method includes:

Step 701: The multiplexer 601 multiplexes the plurality of downlink optical signals of different wavelengths sent from the optical transmitters of the plurality of different transmitting wavelengths into one downlink multi-wavelength optical signal.

Step 702: The first stage splitter 602 splits the downlink multi-wavelength optical signal to form multiple downlink multi-wavelength optical signals and respectively provide them to the four-port circulator 603 connected to each branch port of the first-stage splitter 602. .

Step 703, the four-port circulator 603 re-orients the received downlink multi-wavelength optical signal and outputs it to the dual-port narrowband filter 604.

Step 704: The dual port narrowband filter 604 filters the downlink multi-wavelength optical signal to obtain a downlink optical signal having a wavelength corresponding to a channel center wavelength of the dual port narrowband filter 604 in the downlink multi-wavelength optical signal.

Step 705: The four-port circulator 603 receives the filtered downlink optical signal, and redirects the downlink optical signal to the second-stage optical splitter 605.

Step 706, the second stage splitter 605 splits the downstream optical signals and provides them to the respective 0NUs connected to the second stage splitters 605, respectively.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus a necessary hardware platform, and of course, can also be implemented entirely by hardware. Based on such understanding, all or part of the technical solution of the present invention contributing to the background art may be embodied in the form of a software product, which may be stored in a storage medium such as a ROM/RAM, a magnetic disk, an optical disk, or the like. A number of instructions are included to cause a computer device (which may be a personal computer, server, or network device, etc.) to perform the methods described in various embodiments of the present invention or portions of the embodiments. The above is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope of the present disclosure. Alternatives are intended to be covered by the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

Rights request

A passive optical network system, comprising: an optical line terminal, an optical distribution network, and a plurality of optical network units; wherein the optical line terminal is connected to the plurality of optical network units through the optical distribution network;

The optical line terminal is configured to send a downlink multi-wavelength optical signal, and the one downlink multi-wavelength optical signal is formed by wavelength division multiplexing of a plurality of downlink optical signals of different wavelengths;

The optical distribution network includes a first-stage optical splitter, a plurality of second-stage optical splitters, and a plurality of filtering modules. The branch ports of the first-stage optical splitters are respectively connected to the plurality of second-level optical splitters. The plurality of filtering modules are respectively coupled between the branch port of the first stage splitter and the corresponding second stage splitter;

The first stage splitter is configured to split a downlink multi-wavelength signal sent by the optical line terminal into multiple downlink multi-wavelength signals;

The plurality of filtering modules are configured to filter the multi-channel downlink multi-wavelength optical signal to obtain a downlink single-wavelength optical signal whose wavelength corresponds to a center wavelength of the channel, where the channel center wavelengths of the plurality of filtering modules are respectively Corresponding to the plurality of different wavelengths of the downlink optical signals; the second-stage optical splitter is configured to separately provide the downlink single-wavelength optical signals to the corresponding optical network units after performing spectral processing.

2. The passive optical network system according to claim 1, wherein the filtering module comprises an optical path redirection device and a filter device;

The optical path redirection device is configured to output a downlink multi-wavelength optical signal output by the first-stage optical splitter to the filter device, and filter the downlink multi-wavelength optical signal by the filter device. The downlink single-wavelength optical signal is output to the second-stage optical splitter;

The filter component is configured to filter the downlink multi-wavelength optical signal entering the optical path redirection device to obtain the downlink single-wavelength optical signal.

3. The passive optical network system according to claim 2, wherein said optical path is reset The device is a three-port circulator, the filter device is a fiber Bragg grating; wherein the three-port circulator is for redirecting a downstream multi-wavelength optical signal entering from its first port to a second port and outputting to the fiber a Bragg grating, and redirecting the downstream single-wavelength optical signal reflected by the fiber Bragg grating and entering from the second port thereof to the third port and outputting to the second-stage optical splitter;

The fiber Bragg grating is configured to reflect an optical signal of the downlink multi-wavelength optical signal corresponding to a wavelength of a reflection channel of the filter module to a second port of the three-port circulator, and filter the Optical signals of other wavelengths in the downlink multi-wavelength optical signal.

The passive optical network system according to claim 3, wherein the first port and the third port of the three-port circulator are cascaded in the first-stage splitter and the second-stage splitter, respectively A second port of the three-port circulator is coupled to the fiber Bragg grating.

5. The passive optical network system of claim 2, wherein the optical path redirection device comprises a first duplexer and a second duplexer, the filter component being a dual port narrowband filter; The first duplexer is configured to redirect a downlink multi-wavelength optical signal output by the first-stage splitter to the dual-port narrowband filter, where the second duplexer is configured to filter the dual-port narrowband The downlink single-wavelength optical signal obtained after filtering is redirected to the second-stage optical splitter;

The dual port narrowband filter is configured to output an optical signal of a wavelength corresponding to a channel center wavelength of the filtering module in the downlink multi-wavelength optical signal to the second duplexer, and filter the downlink multi-wavelength Optical signals of other wavelengths in the optical signal.

6. The passive optical network system according to claim 5, wherein a first port of the first duplexer is connected to a branch port of the first stage splitter; a first duplexer The three ends are connected to the first port of the second duplexer; the two ports of the dual port narrowband filter are respectively connected to the second port of the first duplexer and the second port of the second duplexer; A third port of the tool is coupled to a common end of the second stage splitter.

7. The passive optical network system according to claim 2, wherein the optical path redirecting device is a four port circulator, and the filter device is a dual port narrow band filter;

The four-port circulator is configured to redirect a downlink multi-wavelength optical signal entering from the first port to the second port and output the signal to the dual-port narrowband filter, and filter the dual-port narrowband filter. The downlink single-wavelength optical signal obtained and entering from the third port is redirected to the fourth port and output to the second-stage optical splitter;

The dual port narrowband filter is configured to output an optical signal of the downlink multi-wavelength optical signal corresponding to a wavelength of a reflection channel of the filter module to a third port of the four-port circulator, and filter the The optical signals of other wavelengths in the downlink multi-wavelength optical signal are described.

8. The passive optical network system according to claim 7, wherein a first port of the four-port circulator is connected to a branch port of the first-stage optical splitter, and the dual-port narrow-band filter Two ports are respectively connected to the second port and the third port of the four-port circulator, and the fourth port of the four-port circulator is connected to the common end of the second-stage beam splitter.

A downlink transmission method for a passive optical network system, comprising: receiving a downlink multi-wavelength optical signal from an optical line terminal, wherein the downlink multi-wavelength optical signal is divided by a plurality of downlink optical signals of different wavelengths Reuse

Separating the downlink multi-wavelength optical signal to obtain a multi-channel downlink multi-wavelength signal; separately filtering the multi-channel downlink multi-wavelength optical signal to obtain a plurality of downlink single-wavelength optical signals of different wavelengths, wherein each downlink The single-wavelength optical signals respectively correspond to the downlink optical signals of one of the wavelengths of the downlink multi-tap long optical signal;

The downlink transmission method of the passive optical network system according to claim 9, wherein the multi-channel downlink multi-wavelength optical signal is separately filtered to obtain a plurality of downlink single-wavelength optical signals of different wavelengths, including :

Filtering the multi-channel downlink multi-wavelength optical signal by using a plurality of filtering modules, The channel center wavelengths of each of the filtering modules respectively correspond to the downlink optical signals of one of the wavelengths of the downlink multi-wavelength optical signals, and the channel center wavelengths of the different filtering modules are different.

The downlink transmission method of the passive optical network system according to claim 10, wherein the filtering module comprises an optical path reorienting device and a filter component, wherein the plurality of filtering modules respectively use the multipath The filtering process of the downlink multi-wavelength optical signal includes:

The optical path redirection device outputs one of the downlink multi-wavelength optical signals to the filter device;

The filter device filters the downlink multi-wavelength optical signal entering the optical path redirection device to obtain the downlink single-wavelength optical signal;

The optical path redirection device receives the downlink single-wavelength optical signal obtained after filtering by the filter component and outputs the signal to the optical splitter for spectral processing.

The downlink transmission method of the passive optical network system according to claim 10, wherein the filtering module comprises a three-port circulator and a fiber Bragg grating; wherein the plurality of filtering modules respectively use the plurality of filtering modules The filtering process of the downlink multi-wavelength optical signal includes:

The three-port circulator redirects a downstream multi-wavelength optical signal entering from its first port to a second port and outputs to the fiber Bragg grating;

The fiber Bragg grating reflects an optical signal of the downlink multi-wavelength optical signal corresponding to a wavelength of a center of the reflection channel of the filtering module back to a second port of the three-port circulator, and filters out the downlink Optical signals of other wavelengths in the wavelength optical signal;

The three-port circulator redirects the downstream single-wavelength optical signal reflected back from the fiber Bragg grating and entering from its second port to the third port and outputs it to the beam splitter for spectroscopic processing.

The downlink transmission method of the passive optical network system according to claim 10, wherein the filtering module comprises a first duplexer, a second duplexer, and a dual port narrowband filter; wherein the utilizing Filtering the plurality of downlink multi-wavelength optical signals by the plurality of filtering modules respectively includes:

The first duplexer is configured to redirect the downlink multi-wavelength optical signal it receives to the double Port narrowband filter;

The dual port narrowband filter outputs an optical signal of the downlink multi-wavelength optical signal corresponding to a channel center wavelength of the filtering module to the second duplexer, and filters the downlink multi-wavelength light Optical signals of other wavelengths in the signal;

The second duplexer redirects the downlink single-wavelength optical signal obtained after filtering the dual-port narrowband filter to the optical splitter for spectroscopic processing.

The downlink transmission method of the passive optical network system according to claim 10, wherein the filtering module comprises a four-port circulator and a dual-port narrow-band filter; wherein, the plurality of filtering modules are respectively used The filtering process of the multiple downlink multi-wavelength optical signals includes: the four-port circulator redirecting a downlink multi-wavelength optical signal entering from the first port to the second port;

The dual port narrowband filter outputs an optical signal of the downlink multi-wavelength optical signal corresponding to a channel center wavelength of the filtering module to a third port of the four-port circulator, and filters the downlink Optical signals of other wavelengths in a multi-wavelength optical signal;

The four-port circulator redirects the downlink single-wavelength optical signal obtained after filtering the dual-port narrowband filter and entering from the third port to the fourth port and outputs the optical splitter to the optical splitter for spectral processing.