CN101707507B

CN101707507B - Multi-wavelength passive optical network system and protecting method thereof as well as multi-wavelength far-end nodes

Info

Publication number: CN101707507B
Application number: CN200910235891.8A
Authority: CN
Inventors: 张民; 刘磊; 王东昱; 陈雪; 张治国
Original assignee: Beijing University of Posts and Telecommunications
Current assignee: Beijing University of Posts and Telecommunications
Priority date: 2009-10-28
Filing date: 2009-10-28
Publication date: 2015-01-14
Anticipated expiration: 2029-10-28
Also published as: CN101707507A

Abstract

The invention provides a multi-wavelength passive optical network system and a protecting method thereof as well as multi-wavelength far-end nodes. The system comprises an optical line terminal, a plurality of multi-wavelength far-end nodes and a plurality of optical network unit groups, wherein the optical line terminal and the multi-wavelength far-end nodes form an annular network by an optical fiber, and an optical network unit group is connected to each multi-wavelength far-end node; different optical network unit groups adopt wavelength division multiplexing; optical network units in one optical network unit group multiplex a wavelength in a time division way, and the uplink wavelength and the downlink wavelength of the optical network unit group are equal. The optical line terminal comprises a first optical transmitting module, a second optical transmitting module, a first optical receiving module and a second optical receiving module, wherein the first optical transmitting module and the second optical transmitting module can transmit downlink signals along different directions, and the first optical receiving module and the second optical receiving module can receive uplink signals transmitted along different directions; and accordingly, when a network link generates failure, the annular network can still realize the receiving and the transmission of the signals in a place without failure after broken into two tree-shaped networks, thereby providing failure recovery at a telecommunication grade with lower cost.

Description

Multi-wavelength passive optical network system, its guard method and multi-wavelength distant-end node

Technical field

The present invention relates to optical communication field, particularly relate to a kind of multi-wavelength passive optical network (WDM-PON) system, its guard method and multi-wavelength distant-end node.

Background technology

EPON (Passive Optical Network, PON) is the desirable and long-range solution of the industry Access Network of generally acknowledging.Ethernet passive optical network (Ethernet Passive Optical Network, EPON) technology ripe also sizable application, the EPON (10GEPON) of 10Gb/s, multi-wavelength Ethernet passive optical network (Wavelength Division Multiplexed Ethernet Passive Optical Network, WDM-EPON), multi-wavelength and time division multiplexing (Wavelength Division Multiplexing andTime-Division Multiplexing, WDM-TDM) study hotspot that PON becomes broadband access network of future generation is mixed, 10GEPON inherits the flexibility of traditional TDM EPON and the feature such as technology is simple, but working mechanism does not have essence to change, lifting speed is only relied on to carry out spread bandwidth, network upgrade cost is higher.

EPON combines with WDM technology by WDM-EPON, realizes the up multiplexing of multiple optical network unit (Optical Network Unit, ONU), have a clear superiority in bandwidth sum network scalability in wavelength division multiple access mode.WDM-TDM mixing PON is a kind of mixed type multi-wavelength Ethernet Integrated access technology merging the technical advantages such as traditional TDM EPON and WDM-EPON.Compared with upper two kinds of new E PON technology, WDM-TDM mixing PON has taken into account network performance and cost, gets the attention.

Traditional PON structure mostly adopts point-to-multipoint tree topology.For this network topology structure; the Preservation tactics of the Preservation tactics that the measure improving network survivability mainly adopts the whole network to back up or the backup of subnetwork facility; above two kinds of modes all will back up key equipment (as optical line terminal OLT, optical fiber, optical branching device or WDM multiplexing demultiplexing device, crucial optical network unit ONU etc.); add system cost, also can reduce the fail safe of system simultaneously.Also have people's proposition ring topology to set up PON, but ring-shaped P ON structure under multi-wavelength condition and pretection switch method very few.

Fig. 1 shows the structural representation of the multi-wavelength passive optical network system of prior art.The multi-wavelength passive optical network system of the prior art adopts point-to-multipoint tree topology.For this network topology structure; the guard method of the Preservation tactics that the measure improving network survivability mainly adopts the whole network to back up or the backup of subnetwork facility; above two kinds of modes all will back up key equipment; as OLT, optical fiber, optical branching device or WDM multiplexing demultiplexing device, crucial ONU etc.; this guard method adopted; add system cost, also can reduce the fail safe of system simultaneously.As Fig. 1; in the multi-wavelength passive optical network system of the prior art; in OLT and ONU with resilient protection switching function, configure two cover transceivers, and the whole network backup is carried out to the PON link fiber between from OLT to independent ONU and Arrayed Waveguide Grating AWG equipment.Suppose that PON link 1 is as main transmission link, and PON link 2 is as backup transmission link, when the systems are operating normally, article two, PON link works simultaneously, in order to avoid on the receiving terminal of OLT and ONU, data on PON link 2 form interference to the data on another PON link 1, OLT and ONU receives only the data on PON link 1.

As Fig. 2; when the network optical device on PON link 1 or this link breaks down as the optical transceiver module of OLT, ONU, AWG; OLT sends pretection switch order; data on faulty link are switched on normal PON link 2; again find range and perform corresponding QoS and DBA coordination mechanism, wherein the control section of pretection switch bookkeeping is concentrated by OLT and is carried out.The guard method cost that the multi-wavelength passive optical network system of prior art adopts is high, and system redundancy is high.

Summary of the invention

The object of this invention is to provide a kind of multi-wavelength passive optical network (WDM-PON) system, its guard method and multi-wavelength distant-end node, needing to back up key equipment and the high technical problem of the protection cost that causes when protecting with the multi-wavelength passive optical network system solving prior art.

To achieve these goals, the invention provides a kind of multi-wavelength passive optical network system, comprise: optical line terminal, optical fiber, multiple multi-wavelength distant-end node, multiple optical network unit group, described optical line terminal and described multiple multi-wavelength distant-end node form ring network by described optical fiber, an optical network unit group is connected under described each multi-wavelength distant-end node, wavelength division multiplexing is adopted between different optical network unit groups, optical network unit time division multiplexing wavelength in a described optical network unit group, the up-downgoing wavelength of described optical network unit group is equal;

Described optical line terminal, comprises the first optical transmission module, the first Optical Receivers, the second optical transmission module and the second Optical Receivers;

When network link fault-free, one in described first optical transmission module and the second optical transmission module in running order, for by the multi-wavelength downstream signal of generation by described optical fiber along the optical network unit connected under predetermined direction is sent to described multi-wavelength distant-end node, one in described first Optical Receivers and the second Optical Receivers in running order, the upward signal that the optical network unit for receiving in described optical network unit group is sent along predetermined direction by corresponding multi-wavelength distant-end node;

When network link breaks down, described ring network fragments into the first tree network and the second tree network, described first, second optical transmission module and first, second Optical Receivers is all in running order, described first optical transmission module to be used for the multi-wavelength downstream signal of generation by described optical fiber along the optical network unit connected under first direction is sent to the multi-wavelength distant-end node of described first tree network, one in described first or second Optical Receivers for receiving the upward signal that the optical network unit in described first tree network is sent by corresponding multi-wavelength distant-end node along second direction, described second optical transmission module to be used for the multi-wavelength downstream signal of generation by described optical fiber along the optical network unit connected under second direction is sent to the multi-wavelength distant-end node of described second tree network, one in described first or second Optical Receivers for receiving the upward signal that the optical network unit in described second tree network is sent by corresponding multi-wavelength distant-end node along first direction, described first direction and second direction are clockwise or counterclockwise, described first direction is different with second direction,

Described each multi-wavelength distant-end node, for by road under the signal of predetermined wavelength in described multi-wavelength downstream signal to each optical network unit in described connected optical network unit group, the signal of other wavelength in described multi-wavelength downstream signal except the signal on described lower road is directly passed through, and the uplink signal transmissions sent by each optical network unit in connected optical network unit group is to described optical line terminal, under described each multi-wavelength distant-end node, the wavelength of the signal on road is corresponding with the wavelength of connected optical network unit group;

Described optical network unit, sends and the downstream signal on road under passing through connected multi-wavelength distant-end node for receiving described optical line terminal, and sends the upward signal of predetermined wavelength.

Preferably, described multi-wavelength passive optical network system, wherein,

Described first optical transmission module, for sending described downstream signal along first direction;

Described first Optical Receivers, for receiving the described upward signal sent along first direction;

Described second optical transmission module, for sending described downstream signal along second direction;

Described second Optical Receivers, for receiving the described upward signal sent along second direction.

Preferably, described multi-wavelength passive optical network system, wherein,

When network link fault-free, described first optical transmission module is in running order, for by the multi-wavelength downstream signal of generation along the optical network unit connected under first direction is sent to described multi-wavelength distant-end node, described first Optical Receivers is in running order, the upward signal that the optical network unit for receiving in described optical network unit group sends along first direction;

When network link breaks down, described first optical transmission module is used for by the multi-wavelength downstream signal of generation along the optical network unit connected under first direction is sent to the multi-wavelength distant-end node of described first tree network, the upward signal that the optical network unit that described second Optical Receivers is used for receiving in described first tree network along second direction is sent by corresponding multi-wavelength distant-end node; Described second optical transmission module is used for by the multi-wavelength downstream signal of generation along the optical network unit connected under second direction is sent to the multi-wavelength distant-end node of described second tree network, the upward signal that the optical network unit that described first Optical Receivers is used for receiving in described second tree network along first direction is sent by corresponding multi-wavelength distant-end node.

Preferably, described multi-wavelength passive optical network system, wherein, the up-downgoing wavelength of described each optical network unit group is identical, and the up-downgoing wavelength of described optical network unit group adopts time division duplex mechanism to send.

Preferably, described multi-wavelength passive optical network system, wherein,

Described multi-wavelength distant-end node comprises: grating coupler;

Described grating coupler, adopt the Mach-Zender interferometer structure of 2 × 2, comprising: the first direction coupler arranged respectively at two ends and second direction coupler and the first Fiber Bragg Grating FBG arranged respectively at upper underarm and the second Fiber Bragg Grating FBG;

First branch of first, second directional coupler described is connected to described ring network, and the second branch of first, second directional coupler described is connected with described optical network unit group;

First, second Fiber Bragg Grating FBG described is used for reflecting the signal of predetermined wavelength, the bragg wavelength of first, second Fiber Bragg Grating FBG described is equal, and the bragg wavelength of described Fiber Bragg Grating FBG is corresponding with the wavelength of connected optical network unit group.

Preferably, described multi-wavelength passive optical network system, wherein, described multi-wavelength distant-end node also comprises: Y shape splitter and splitter, first branch road of described Y shape splitter is connected with the second branch of described first direction coupler, second branch road of described Y shape splitter is connected with the second branch of described second direction coupler, 3rd branch road of described Y shape splitter is connected with one end of described splitter, the other end of described splitter has multiple interface, described splitter is connected by described multiple interface each optical network unit with corresponding optical network unit group.

Preferably, described multi-wavelength passive optical network system, wherein, described optical line terminal comprises:

Line switching control module, when making described ring network fragment into the first tree network and the second tree network for breaking down at network link, start optical transmission module not in running order in first, second optical transmission module described, and start Optical Receivers not in running order in first, second Optical Receivers described.

Preferably, described multi-wavelength passive optical network system, wherein, described line switching control module also comprises:

Abort situation judge module, for when network failure, according to the round-trip transmission time RTT mapping table pre-set, determines the position of breaking down;

Again range finder module, for according to the round-trip transmission time RTT mapping table that pre-sets, and described in the abort situation determined, described multi-wavelength distant-end node is found range again, and generates new round-trip transmission time RTT mapping table;

Time slot reallocation module, for according to described newly-generated round-trip transmission time RTT mapping table, redistributes the sending time slots of optical network unit, and notifies the transmitting time of described optical network unit according to the described sending time slots adjustment upward signal redistributed.

Preferably, described multi-wavelength passive optical network system, wherein, when described optical line terminal receives the operation maintenance management frame of optical network unit transmission, described optical line terminal determines that described network link there occurs fault.

Preferably, described multi-wavelength passive optical network system, wherein, described multi-wavelength distant-end node is 8, and a described optical network unit group comprises 8 optical network units.

Preferably, described multi-wavelength passive optical network system, wherein, described first direction is clockwise direction, and described second direction is counterclockwise; Or described first direction is that counterclockwise described second direction is clockwise direction.

On the other hand, provide a kind of guard method of multi-wavelength passive optical network system, wherein, comprising:

At down direction:

When network link fault-free, multi-wavelength distant-end node receives the multi-wavelength downstream signal that in optical line terminal, the first in running order optical transmission module or the second optical transmission module are sent along predetermined direction by optical fiber, and by road under the signal of predetermined wavelength in described multi-wavelength downstream signal to each optical network unit in connected optical network unit group, and the signal of other wavelength in described multi-wavelength downstream signal except the signal on described lower road is directly passed through, under described each multi-wavelength distant-end node, the wavelength of the signal on road is corresponding with the wavelength of connected optical network unit group,

When network link breaks down, ring network fragments into the first tree network and the second tree network, make described first optical transmission module and the second optical transmission module all in running order, the multi-wavelength distant-end node of described first tree network receives the multi-wavelength downstream signal that described first optical transmission module is sent along first direction by optical fiber, and each optical network unit in the optical network unit group that road under the signal of corresponding wavelength in described multi-wavelength downstream signal is connected to the multi-wavelength distant-end node of described first tree network, and the signal of other wavelength in described multi-wavelength downstream signal except the signal on described lower road is directly passed through, the multi-wavelength downstream signal that the second optical transmission module that the multi-wavelength distant-end node of described second tree network receives institute's optical line terminal is sent along second direction by optical fiber, by road under the signal of corresponding wavelength in described multi-wavelength downstream signal to each optical network unit in connected optical network unit group, and the signal of other wavelength in described multi-wavelength downstream signal except the signal on described lower road is directly passed through, described first direction and second direction are clockwise or counterclockwise, described first direction is different with second direction,

At up direction:

When network link fault-free, the upward signal that optical network unit in the optical network unit group that each reception in described multi-wavelength distant-end node connects is sent by time division multiplexed scheme, and described upward signal is sent to the first Optical Receivers in running order in described optical line terminal or the second Optical Receivers;

When network link breaks down, each multi-wavelength distant-end node in described first tree network receives the upward signal that the optical network unit in the optical network unit group connected is sent by time division multiplexed scheme, and described upward signal is sent to the first Optical Receivers or second Optical Receivers of described optical line terminal along described second direction; Each multi-wavelength distant-end node in described second tree network receives the upward signal that the optical network unit in the optical network unit group connected is sent by time division multiplexed scheme, and described upward signal is sent to the first Optical Receivers or second Optical Receivers of described optical line terminal along described first direction.

Preferably, described guard method, wherein, when network link fault-free, described first optical transmission module is by the multi-wavelength downstream signal of generation along the optical network unit connected under first direction is sent to described multi-wavelength distant-end node, and described first Optical Receivers receives the upward signal that the optical network unit in described optical network unit group sends along first direction;

When network link breaks down, described first optical transmission module by the multi-wavelength downstream signal of generation along the optical network unit connected under first direction is sent to the multi-wavelength distant-end node of described first tree network, the upward signal that the optical network unit that described second Optical Receivers receives in described first tree network along second direction is sent by corresponding multi-wavelength distant-end node; Described second optical transmission module by the multi-wavelength downstream signal of generation along the optical network unit connected under second direction is sent to the multi-wavelength distant-end node of described second tree network, the upward signal that the optical network unit that described first Optical Receivers receives in described second tree network along first direction is sent by corresponding multi-wavelength distant-end node.

Preferably, described guard method, wherein, the network link of ring network break down make described ring network fragment into the first tree network and the second tree network time, also comprise:

Described optical line terminal starts optical transmission module not in running order in first, second optical transmission module described, and starts Optical Receivers not in running order in first, second Optical Receivers described.

Preferably, described multi-wavelength passive optical network system, wherein, the up-downgoing wavelength of each optical network unit group is identical, and the up-downgoing wavelength of described optical network unit group adopts time division duplex mechanism to send.

Preferably; described guard method; wherein; at up direction; when the network link of ring network break down make described ring network fragment into the first tree network and the second tree network; the multi-wavelength distant-end node of described first tree network also comprises before receiving the upward signal that optical network unit in the optical network unit group connected sent by time division multiplexed scheme:

Described optical line terminal, according to the round-trip transmission time RTT mapping table pre-set, determines the position of breaking down;

Described optical line terminal according to the round-trip transmission time RTT mapping table pre-set, and described in the abort situation determined, described multi-wavelength distant-end node is found range again, and generates new round-trip transmission time RTT mapping table;

Described optical line terminal, according to described newly-generated RTT mapping table, redistributes the sending time slots of optical network unit, and notifies the transmitting time of described optical network unit according to the described sending time slots adjustment upward signal redistributed;

Described optical network unit sends upward signal according to the described sending time slots redistributed.

Preferably, described guard method, wherein, described upward signal and described downstream signal adopt time division duplex mechanism to send.

Preferably, described guard method, wherein,

Described multi-wavelength distant-end node comprises: grating coupler;

Preferably, described guard method, wherein,

At down direction:

When network link fault-free, the described downstream signal sent along described first direction is entered described grating coupler by the first branch of described first direction coupler by described first optical transmission module, described first, second Fiber Bragg Grating FBG reflects wavelength signals corresponding with described bragg wavelength in described downstream signal, and described reflected signal is entered connected optical network unit group by the second branch of described first direction coupler, the signal of other wavelength in described downstream signal leads directly to described first, second Fiber Bragg Grating FBG, and get back to described ring network from the first branch of described second direction coupler,

When network link breaks down, the described downstream signal that described first optical transmission module will send along described first direction, described grating coupler is entered by the first branch of described first direction coupler, described first, second Fiber Bragg Grating FBG reflects wavelength signals corresponding with described bragg wavelength in described downstream signal, and described reflected signal is entered connected optical network unit group by the second branch of described first direction coupler, the signal of other wavelength in described downstream signal leads directly to described first, second Fiber Bragg Grating FBG, and get back to described first tree network from the first branch of described second direction coupler, the described downstream signal that described second optical transmission module will send along described second direction, described grating coupler is entered by the first branch of described second direction coupler, described first, second Fiber Bragg Grating FBG reflects wavelength signals corresponding with described bragg wavelength in described downstream signal, and described reflected signal is entered connected optical network unit group by the second branch of described second direction coupler, the signal of other wavelength in described downstream signal leads directly to described first, second Fiber Bragg Grating FBG, and get back to described second tree network from the first branch of described first direction coupler,

At up direction:

When network link fault-free, the upward signal that described optical network unit sends enters grating coupler by the second branch of first, second directional coupler described, and after the reflection of first, second Fiber Bragg Grating FBG described, the first branch along first, second directional coupler described enters described ring network;

When network link breaks down, the upward signal that the optical network unit of described first tree network sends enters grating coupler by the second branch of described first direction coupler, and after the reflection of first, second Fiber Bragg Grating FBG described, the first branch along described first direction coupler enters described first tree network; The upward signal that the optical network unit of described second tree network sends enters grating coupler by the second branch of described second direction coupler, and after the reflection of first, second Fiber Bragg Grating FBG described, the first branch along described second direction coupler enters described second tree network.

Preferably; described guard method; wherein; described multi-wavelength distant-end node also comprises: Y shape splitter and splitter; first branch road of described Y shape splitter is connected with the second branch of described first direction coupler; second branch road of described Y shape splitter is connected with the second branch of described second direction coupler; 3rd branch road of described Y shape splitter is connected with one end of described splitter; the other end of described splitter has multiple interface, and described splitter is connected by described multiple interface each optical network unit with corresponding optical network unit group.

Preferably, described multi-wavelength passive optical network system, wherein, when described optical line terminal receives the operation maintenance management frame of optical network unit transmission, described optical line terminal determines that network link there occurs fault.

Another aspect, provides a kind of multi-wavelength distant-end node, wherein, comprising: grating coupler;

First, second directional coupler described comprises Liang Ge branch respectively;

First, second Fiber Bragg Grating FBG described is used for reflecting the signal of predetermined wavelength, and the bragg wavelength of first, second Fiber Bragg Grating FBG described is equal.

Technique effect of the present invention is:

The present invention is directed to the survivability problem of WDM-PON, TDM and WDM proposing a kind of endless belt tree-shaped mixes PON structure and pretection switch method thereof, wherein, optical line terminal and multiple multi-wavelength distant-end node form ring network by optical fiber, by first of downstream signal can be sent along different directions, second optical transmission module, and first of the downstream signal sent along different directions can be received, second optical transmission module, when losing efficacy as fibercuts or WDM distant-end node when breaking down in network, ring network splits into Liang Ge branch tree automatically, the transmitting-receiving of signal still can be realized for the place of not breaking down, thus carrier-class fault recovery can be provided with lower cost.

Accompanying drawing explanation

Fig. 1 is the structural representation of the multi-wavelength passive optical network system of prior art;

Fig. 2 is the protection schematic diagram of the multi-wavelength passive optical network system of prior art when breaking down;

Fig. 3 is the structural representation of the multi-wavelength passive optical network system of one embodiment of the invention;

Fig. 4 is in the multi-wavelength passive optical network system of the embodiment of the present invention, signal flow graph during network link fault-free;

Fig. 5 in the multi-wavelength passive optical network system shown in Fig. 4, signal flow graph when network link breaks down;

Fig. 6 in the multi-wavelength passive optical network system shown in Fig. 4, the structural representation of optical coupler in multi-wavelength distant-end node;

Fig. 7 is in the multi-wavelength passive optical network system of the embodiment of the present invention, the structural representation of optical line terminal;

Fig. 8 is in the multi-wavelength passive optical network system of the embodiment of the present invention, the structural representation of optical network unit.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly, describe the present invention below in conjunction with the accompanying drawings and the specific embodiments.

Fig. 3 is the structural representation of the multi-wavelength passive optical network system of one embodiment of the invention.As Fig. 3, the multi-wavelength passive optical network system of one embodiment of the invention comprises: optical line terminal OLT 301, optical fiber 302, multiple multi-wavelength distant-end node and WDM distant-end node 303, multiple optical network unit group 304, each optical network unit group comprises one or more optical network unit, optical line terminal and multiple multi-wavelength distant-end node form ring network by optical fiber, an optical network unit group is connected under each multi-wavelength distant-end node, wavelength division multiplexing is adopted between different optical network unit groups, optical network unit time division multiplexing in optical network unit group wavelength, the up-downgoing wavelength of optical network unit group is equal, wherein, optical line terminal, comprises the first optical transmission module, the second optical transmission module, the first Optical Receivers, the second Optical Receivers, when network link fault-free, one in described first optical transmission module and the second optical transmission module in running order, for by the multi-wavelength downstream signal of generation by described optical fiber along the optical network unit connected under predetermined direction is sent to described multi-wavelength distant-end node, one in described first Optical Receivers and the second Optical Receivers in running order, the upward signal that the optical network unit for receiving in described optical network unit group is sent along predetermined direction by corresponding multi-wavelength distant-end node, when network link breaks down, described ring network fragments into the first tree network and the second tree network, described first, second optical transmission module and first, second Optical Receivers is all in running order, described first optical transmission module to be used for the multi-wavelength downstream signal of generation by described optical fiber along the optical network unit connected under first direction is sent to the multi-wavelength distant-end node of described first tree network, one in described first or second Optical Receivers for receiving the upward signal that the optical network unit in described first tree network is sent by corresponding multi-wavelength distant-end node along second direction, described second optical transmission module to be used for the multi-wavelength downstream signal of generation by described optical fiber along the optical network unit connected under second direction is sent to the multi-wavelength distant-end node of described second tree network, one in described first or second Optical Receivers for receiving the upward signal that the optical network unit in described second tree network is sent by corresponding multi-wavelength distant-end node along first direction, described first direction and second direction are clockwise or counterclockwise, described first direction is different with second direction, described each multi-wavelength distant-end node, for by road under the signal of predetermined wavelength in described multi-wavelength downstream signal to each optical network unit in described connected optical network unit group, the signal of other wavelength in described multi-wavelength downstream signal except the signal on described lower road is directly passed through, and the uplink signal transmissions sent by each optical network unit in connected optical network unit group is to described optical line terminal, under described each multi-wavelength distant-end node, the wavelength of the signal on road is corresponding with the wavelength of connected optical network unit group, described optical network unit, sends and the downstream signal on road under passing through connected multi-wavelength distant-end node for receiving described optical line terminal, and sends the upward signal of predetermined wavelength.

Preferably, in many described multi-wavelength passive optical network systems of the embodiment of the present invention, first, second optical transmission module described can send downstream signal along different directions; First, second Optical Receivers described can receive upward signal along different directions; Like this when network link breaks down, when fragmenting into two tree networks, still realize the transmitting-receiving of the signal of OLT by above-mentioned two optical transmission modules and Optical Receivers in both direction, the signal of the optical network unit do not broken down is transmitted unaffected.

Preferably, in many described multi-wavelength passive optical network systems of the embodiment of the present invention, described first optical transmission module, for sending described downstream signal along first direction; Described first Optical Receivers, for receiving the described upward signal sent along first direction; Described second optical transmission module, for sending described downstream signal along second direction; Described second Optical Receivers, for receiving the described upward signal sent along second direction.

Preferably, in described multi-wavelength passive optical network system, during network link fault-free, described first optical transmission module is in running order, for by the multi-wavelength downstream signal of generation along the optical network unit connected under first direction is sent to described multi-wavelength distant-end node, described first Optical Receivers is in running order, the upward signal that the optical network unit for receiving in described optical network unit group sends along first direction;

The guard method of the wavelength passive optical network of the embodiment of the present invention, for when the multi-wavelength passive optical network system of the embodiment of the present invention breaks down, carries out pretection switch.The guard method of the multi-wavelength passive optical network system of this embodiment comprises:

At down direction:

At up direction:

Preferably, above-mentioned first direction is clockwise direction, and second direction is counterclockwise.

Preferably, above-mentioned first direction is that counterclockwise second direction is clockwise direction.

Preferably, above-mentioned upward signal and downstream signal adopt time division duplex mechanism to send.

The multi-wavelength passive optical network system of the embodiment of the present invention is endless belt tree, and its trunk becomes loop, OLT can in the clockwise of trunk loop and counterclockwise both direction receiving and transmitting signal.When network link fault-free normally works, OLT receives and dispatches clockwise or counterclockwise, and at each WDM distant-end node place of looped network, grating coupler carries out lower road to respective wavelength signal, and other wavelength signals lead directly to.Break down at network link, during as occurred that trunk optical fiber fracture or multi-wavelength distant-end node lost efficacy, original endless belt tree structure is split into Liang Ge branch tree, and OLT to support that Liang Ge branch sets, still can maintain the up-downgoing business for all ONU in two-way simultaneous transmitting-receiving.

When certain WDM distant-end node breaks down, original endless belt tree structure is split into Liang Ge branch tree, OLT is in two-way simultaneous transmitting-receiving to support that Liang Ge branch sets, and the business of the ONU only having fault WDM distant-end node to connect is affected, and can provide carrier-class fault recovery with lower cost.

Fig. 4 is in the multi-wavelength passive optical network system of the embodiment of the present invention, signal flow graph during network link fault-free.As Fig. 4, the multi-wavelength passive optical network system of another embodiment of the present invention comprises: an OLT 401,8 multi-wavelength distant-end nodes 402, ONU ₁to ONU ₆₄64 ONU 403; Wherein, multi-wavelength distant-end node comprises: grating coupler 404, Y shape splitter 405 and splitter 406.In this example, OLT sends out along the clockwise left receipts right side.The optical transmission module of OLT produces and comprises λ _d1to λ _d8the downstream signal of 8 wavelength.As Fig. 4, the network system of the embodiment of the present invention, at down direction, OLT receives and dispatches in the clockwise direction, at each WDM distant-end node place of looped network, grating coupler carries out lower road to the signal of predetermined wavelength, and other wavelength signals can lead directly to, exemplarily, be λ at first WDM distant-end node place wavelength _d1signal under road, wavelength is λ _d2to λ _d8signal lead directly to, continue to transfer to next WSM distant-end node; Arrived by Y shape splitter the ONU group be made up of 8 ONU by the wavelength signals on lower road, signal is broadcast to all ONU in this group along 1 × 8 splitter, each ONU obtains downlink service data by time division multiplexing (TDM) mechanism; Up direction, 8 ONU in same group obtain uplink chance by time-division multiplexing multiple access TDMA mechanism, and the ONU in same group uses identical wavelength, and it is λ that the ONU in first group of ONU that first WDM distant-end node is corresponding sends wavelength _u1signal; Upstream bandwidth is obtained by wavelength division multiple access WDM mechanism between different ONU groups.The signal of setting out on a journey of certain ONU is divided into two-way by Y shape splitter, enters trunk optical fiber ring respectively along clockwise and counterclockwise both direction; But in order to simplify the operation and avoid bidirectional ranging etc., only have clockwise upward signal to be received by OLT.In this example, the wavelength of upward signal that ONU group receives is identical with the wavelength of the upward signal of transmission, the ONU group of namely right i group, the wavelength X of its upward signal _ui=λ _di, i=1...N, N are the ONU group number comprised.

Fig. 5 is in the multi-wavelength passive optical network system of the embodiment of the present invention, signal flow graph when network link breaks down.As Fig. 5, when OLT detects that loop network link breaks down, during as detected that fibercuts or WDM distant-end node lost efficacy, the network system of the embodiment of the present invention, at down direction: looped network is divided into two parts: the first tree network and tree network branch road R and the second tree network and tree network branch road L.Line switching control module in OLT, the light starting backup sends and Optical Receivers, the Photoelectric Detection PD array operation of the dfb laser array namely backed up and backup.

In this example, using the first optical transmission module and the first Optical Receivers as key light transceiver module, when network link fault-free, start generation that the first optical transmission module carries out light signal to send and the first Optical Receivers carries out the reception of light signal, in this example, first optical transmission module sends downstream signal along clockwise direction, and be when normal non-fault, in order to simplify the operation and avoid bidirectional ranging etc., only have clockwise upward signal to be received by OLT, namely the first Optical Receivers receives only clockwise upward signal.Using the second optical transmission module and the second Optical Receivers as backup optical sending module and receiver module, when network link breaks down, start the second optical transmission module and receiver module, thus when network link breaks down, first, second optical transmission module is all in running order with first, second Optical Receivers, second optical transmission module is used for the transmission carrying out light signal in the counterclockwise direction, second Optical Receivers is used for the reception carrying out light signal in the counterclockwise direction, thus realizes the bidirectional transmit-receive of OLT.

In this example, optical transmission module be embodied as generation of and the laser array sending light signal as dfb laser array; Optical Receivers is embodied as receiving downstream signal and downstream signal being converted to the photoelectric detector PD array of the signal of telecommunication.Signal is sent to branch road R by the dfb laser array as the first optical transmission module, enters trunk optical fiber along clockwise direction, and corresponding wavelength, on WDM distant-end node Chu Xia road, sends to corresponding ONU.Signal is sent to branch road L by the dfb laser array as the backup of the second optical transmission module, enters trunk optical fiber in the counterclockwise direction, and corresponding wavelength, on WDM distant-end node Chu Xia road, is sent to corresponding ONU place; Up direction: OLT starts dfb laser array and the PD array operation of backup, and for the ONU on the first tree network and branch road R, start and receive counterclockwise, signal is by the PD array received of backup; ONU Signal reception mode on branch road L is constant, is namely still the upward signal sent by the ONU on the PD array of the first receiver module in the clockwise direction receiving branch L.OLT finds range again to the ONU on branch road L and branch road R simultaneously, and by mac frame instruction ONU according to new range finding, readjusts transmitting time.

In the system of this embodiment, when network link break down break down as fibercuts or ONU equipment time, the ONU failing to receive downstream signal is there will be in network, failing in network receives the ONU of downstream signal, along both direction transmit operation maintenance management (OAM) frame of looped network, prompting OLT system link occurs fault; Wherein, when fibercuts, OLT will can't detect the transmission that several groups of ONU trees do not have upward signal simultaneously, and several groups of ONU trees all do not receive downstream signal, and when certain ONU equipment breaks down, only this ONU does not receive downstream signal; New network topology is safeguarded, to each ONU report network trouble situation and new topological structure by mac frame; OAM frame in system is short frame, has the highest priority, can meet carrier class failure and recover requirement.In specific implementation, line switching control module comprises: abort situation judge module, for when network failure, according to the round-trip transmission time RTT mapping table pre-set, determines the position of breaking down; Again range finder module, for according to the round-trip transmission time RTT mapping table that pre-sets, and described in the abort situation determined, described multi-wavelength distant-end node is found range again, and generates new round-trip transmission time RTT mapping table; Time slot reallocation module, for according to described newly-generated round-trip transmission time RTT mapping table, redistributes the sending time slots of optical network unit, and notifies the transmitting time of described optical network unit according to the described sending time slots adjustment upward signal redistributed.

In this example, when a group in group transceiver of two in OLT breaks down, when such as, optical transmission module in one group of transceiver and/or Optical Receivers break down, still can maintain the up-downgoing business for all ONU.Such as, the first optical transmission module in first group of in running order when working properly transceiver breaks down and the first Optical Receivers is normal time, the second optical transmission module such as the second dfb laser array can be started by line switching module and send signal as signal source, downstream signal is being sent clockwise with the first optical transmission module, second optical transmission module is example sending downstream signal counterclockwise, after starting the second optical transmission module, OLT sends downstream signal in the counterclockwise direction, receive upward signal clockwise, now, OLT is equivalent to only receive and dispatch with one end, now the structure of looped network just becomes tree-like structure, still can maintain the up-downgoing business for all ONU.

Fig. 6 is the structural representation of grating coupler in the multi-wavelength distant-end node of one embodiment of the invention; As Fig. 6, the grating coupler of this embodiment adopts the Mach-Zender interferometer MZI structure of 2 × 2, comprise: the first direction coupler 601 arranged respectively at two ends and second direction coupler 602 and the first Fiber Bragg Grating FBG 603 and the second Fiber Bragg Grating FBG 604 arranged respectively at upper underarm, first, second Fiber Bragg Grating FBG is used for reflecting the signal of predetermined wavelength, the bragg wavelength of first, second Fiber Bragg Grating FBG described is equal, λ _brag1=λ _brag2, different grating couplers can reflect different wavelength signals according to its bragg wavelength, and the bragg wavelength of Fiber Bragg Grating FBG is corresponding with the wavelength of connected optical network unit group.In this embodiment, WDM distant-end node, except above-mentioned grating coupler, also comprises: Y shape splitter and 1 × 8 splitter.As Fig. 4, in the multi-wavelength passive optical network system of the embodiment of the present invention, first branch L1, L2 of first, second directional coupler above-mentioned is connected to ring network, second branch L3 of first direction coupler is connected with the second branch road L6 of Y shape splitter with the second branch L4 of the first branch road L5 of Y shape splitter, second direction coupler, 3rd branch road L7 of Y shape splitter is connected with one end of splitter, the other end of splitter has multiple interface, and splitter is connected by multiple interface each optical network unit with corresponding optical network unit group.

Time descending:

The signal that optical line terminal sends is by the first branch L1 i.e. first branch road of first direction coupler 601, enter WDM node, during by the first and second Fiber Bragg Grating FBGs, corresponding wavelength is entered first direction coupler 601 by reflection, corresponding optical network unit is transferred to downwards by the second branch L3 of first direction coupler, other signal directly enters second direction coupler 602 by the first and second Fiber Bragg Grating FBGs, comes back to looped network by the first branch L2 of second direction coupler 602, when breaking down, the WDM node belonging to tree-like branch road R normally works, belong to the WDM node of tree-like branch road L, signal will enter grating coupler in the counterclockwise direction, signal is by the first branch L2 of second direction coupler 602, enter WDM node, during by the first and second Fiber Bragg Grating FBGs, the signal of corresponding wavelength is entered second direction coupler by reflection, transmitted downwards by the second branch L4 of second direction coupler, other signals directly enter first direction coupler 601 by the first and second Fiber Bragg Grating FBGs, tree network is come back to by the first branch L1 of first direction coupler.

Time up:

The signal sent from ONU is divided into two-way by Y shape splitter, enters WDM distant-end node respectively from the second branch L3 of first direction coupler and these two branch roads of the second branch L4 of second direction coupler.During fault-free, the second branch along second direction coupler enters the signal of second direction coupler, is reflected by the first and second Fiber Bragg Grating FBGs, enters the first branch L2 of branch road second direction coupler, enters looped network along clockwise direction; The second branch L3 along first direction coupler enters the signal of first direction coupler, reflected by the first and second Fiber Bragg Grating FBGs, enter the first branch L1 of first direction coupler, enter ring network in the counterclockwise direction, in this example, for simplifying the operation and avoiding bidirectional ranging etc., clockwise signal of setting out on a journey is only had to be received by OLT.When breaking down, the operating state belonging to the grating coupler of the distant-end node of tree-like branch road L does not change; Belong to the part of tree-like branch road R, the signal only entering grating coupler from the second branch of first direction coupler could enter looped network in the counterclockwise direction, correctly could be received by OLT.

Fig. 7 is in the multi-wavelength passive optical network system of the embodiment of the present invention, the structural representation of optical line terminal OLT.As Fig. 7, OLT comprises: the first distributed feedback type semiconductor dfb laser array 701 as the first optical transmission module, the first photoelectric detector PD array 702 as the first smooth connection module, the second dfb laser array 703 as the second optical transmission module, the 2nd PD array 704, first optical multiplexer MUX1 705, first demodulation multiplexer DEMUX1 706, second optical multiplexer MUX2 707, the second demodulation multiplexer DEMUX2 708 as the second Optical Receivers, line switching control module 709.

Arrange two cover optical transmit-receive devices in OLT, first set optical transmit-receive device comprises: the first dfb laser array and the first photodetector array; Second cover optical transmit-receive device comprises: the second dfb laser array and the second photodetector array.

Line switching control module 709 in OLT, for controlling the operating state of two groups of transceivers, makes two groups of transceivers be connected with multi-wavelength distant-end node with the second remote node interface 712 by the first remote node interface 711.In this example, the first dfb laser array is connected with the optical fiber 3021 in looped network through coupler 714 with the 2nd PD array; Second dfb laser array is connected with the optical fiber 3022 in looped network through coupler 715 with a PD array; Each service adaptation module 713 in OLT is connected with Cross Connect equipment and handshaking module 710, handshaking module is connected with the 2nd PD array with the first Distributed Feedback Laser, the second Distributed Feedback Laser, a PD array respectively, is responsible for uplink and downlink signals and exchanges.

Under normal condition, first dfb laser array and a PD array are responsible for looped network signal in clockwise transmitting-receiving, control module controls the second dfb laser array and the 2nd PD array does not work, downstream signal enters looped network along clockwise direction by MUX1 input optical fibre 3021, upward signal is along clockwise with counterclockwise through optical fiber, wherein up along clockwise direction upward signal through the light-to-current inversion of a PD array, goes upward to backbone network by demodulation multiplexer DMUX2.

When there is fibercuts in OLT discovery system or distant-end node lost efficacy, system becomes two tree structures automatically, first tree network and the second tree network, be right tree network branch road R and left tree network branch road L in this embodiment, the control module simultaneously in OLT starts the second dfb laser array and the 2nd PD array operation.Now, the transmitting-receiving of branch of a network R light signal is realized by the first dfb laser array and the 2nd PD array; The transmitting-receiving of branch road L light signal is realized by the second dfb laser array and a PD array.Particularly, in descending process, the light signal that the first dfb laser array exports inputs branch road R by MUX1; The light signal that second dfb laser array exports, inputs branch road L through MUX2.In up process, the upward signal on branch road L, enters a PD array by DMUX2, realizes light-to-current inversion, by signal exchange device, get back to backbone network; Upward signal on branch road R, enters the 2nd PD array by DMUX1, completes light-to-current inversion, go upward to backbone network.Fig. 8 is in the multi-wavelength passive optical network system of the embodiment of the present invention, the structural representation of optical network unit.As Fig. 8, ONU comprise: the first laser LD1 801, first photoelectric detector PD1 802, second laser LD2 803, second photoelectric detector PD2 804, first passage switching controls module 805, second channel switching controls module 806, repeat in work connection device 807, service adaptation module 808.

Two cover transceivers are set in OLT: the first set transceiver comprising LD1 and PD1 and the comprise LD2 and PD2 second cover transceiver.OLT arranges the operating state of two groups of receiver equipment thereofs by passage bridge control module.LD1 and PD1 is connected with the working optical fibre 111 in looped network through coupler; LD2 and PD2 is connected with the working optical fibre 112 in looped network by coupler; Passage bridge control module in ONU is connected with LD1 and LD2, PD1 and PD2 respectively, when the transceiver of ONU breaks down, is responsible for the switching of signalling channel; Repeat in work connection device is connected with subscriber equipment by uni interface with service adaptation equipment, completes adaptation and the interconnection of up-downgoing different business data.

Under normal condition, LD1 and PD1 is responsible for the transmitting-receiving of ONU signal, LD2 and PD2 does not work, and the downlink data of ring network is by photoelectric detector 1, realize opto-electronic conversion, by repeat in work connection device and service adaptation equipment, different business datums is sent to different users; Uplink user data is by service adapter and repeat in work connection device, and the service adaptation of settling signal, goes upward to looped network by modulation LD1.

When ONU equipment breaks down, when OLT side can't detect the data of certain ONU in predetermined time length, judge that ONU transceiver breaks down, need to carry out pretection switch.OLT sends mac frame to ONU, and control channel switch device completes the switching of ONU transceiver, and be now responsible for the transmitting-receiving of ONU signal by LD2 and PD2, LD1 and PD1 does not work.

In an embodiment of the present invention, the transmitting-receiving of light signal is carried out in the clockwise direction for OLT under normal circumstances, namely, the transceiver started under normal circumstances is the transceiver realizing clockwise direction transmitting-receiving, but this is also not used in as restriction, other embodiments of the invention also can be that OLT carries out the transmitting-receiving of light signal in the counterclockwise direction under normal circumstances.

The system configuration that WDM and TDM that the present invention adopts combines; be conducive to smooth upgrade and the dilatation of system; utilize the characteristic of loop network, protection trunk optical fiber, improves the survivability of network; simultaneously due in common OLT device; all there is the transceiver of two covers, in the present invention, in time breaking down in looped network; can alternate device be utilized, the utilance of system equipment is provided.

The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims

1. a multi-wavelength passive optical network system, it is characterized in that, comprise: optical line terminal, optical fiber, multiple multi-wavelength distant-end node, multiple optical network unit group, described optical line terminal and described multiple multi-wavelength distant-end node form ring network by described optical fiber, an optical network unit group is connected under described each multi-wavelength distant-end node, wavelength division multiplexing is adopted between different optical network unit groups, optical network unit time division multiplexing wavelength in a described optical network unit group, the up-downgoing wavelength of described optical network unit group is equal;

When network link breaks down, described ring network fragments into the first tree network and the second tree network, described first, second optical transmission module and first, second Optical Receivers is all in running order, described first optical transmission module to be used for the multi-wavelength downstream signal of generation by described optical fiber along the optical network unit connected under first direction is sent to the multi-wavelength distant-end node of described first tree network, one in described first or second Optical Receivers for receiving the upward signal that the optical network unit in described first tree network is sent by corresponding multi-wavelength distant-end node along second direction, described second optical transmission module to be used for the multi-wavelength downstream signal of generation by described optical fiber along the optical network unit connected under second direction is sent to the multi-wavelength distant-end node of described second tree network, another upward signal sent by corresponding multi-wavelength distant-end node for receiving the optical network unit in described second tree network along first direction in described first or second Optical Receivers, described first direction and second direction are clockwise or counterclockwise, described first direction is different with second direction,

Described optical network unit, sends and the downstream signal on road under passing through connected multi-wavelength distant-end node for receiving described optical line terminal, and sends the upward signal of predetermined wavelength; Wherein

Described multi-wavelength distant-end node comprises: grating coupler;

2. multi-wavelength passive optical network system according to claim 1, is characterized in that,

3. multi-wavelength passive optical network system according to claim 2, is characterized in that,

4. multi-wavelength passive optical network system according to claim 1, is characterized in that, the up-downgoing wavelength of described each optical network unit group is identical, and the up-downgoing wavelength of described optical network unit group adopts time division duplex mechanism to send.

5. multi-wavelength passive optical network system according to claim 1, it is characterized in that, described multi-wavelength distant-end node also comprises: Y shape splitter and splitter, first branch road of described Y shape splitter is connected with the second branch of described first direction coupler, second branch road of described Y shape splitter is connected with the second branch of described second direction coupler, 3rd branch road of described Y shape splitter is connected with one end of described splitter, the other end of described splitter has multiple interface, described splitter is connected by described multiple interface each optical network unit with corresponding optical network unit group.

6. multi-wavelength passive optical network system according to claim 1, is characterized in that, described optical line terminal comprises:

7. multi-wavelength passive optical network system according to claim 6, is characterized in that, described line switching control module also comprises:

8. multi-wavelength passive optical network system according to claim 7, is characterized in that, when described optical line terminal receives the operation maintenance management frame of optical network unit transmission, described optical line terminal determines that described network link there occurs fault.

9. multi-wavelength passive optical network system according to claim 1, is characterized in that, described multi-wavelength distant-end node is 8, and a described optical network unit group comprises 8 optical network units.

10. multi-wavelength passive optical network system according to claim 1, is characterized in that, described first direction is clockwise direction, and described second direction is counterclockwise; Or described first direction is that counterclockwise described second direction is clockwise direction.

The guard method of multi-wavelength passive optical network system described in 11. 1 kinds of claims 1, is characterized in that, comprising:

At down direction:

When network link breaks down, ring network fragments into the first tree network and the second tree network, make described first optical transmission module and the second optical transmission module all in running order, the multi-wavelength distant-end node of described first tree network receives the multi-wavelength downstream signal that described first optical transmission module is sent along first direction by optical fiber, and each optical network unit in the optical network unit group that road under the signal of corresponding wavelength in described multi-wavelength downstream signal is connected to the multi-wavelength distant-end node of described first tree network, and the signal of other wavelength in described multi-wavelength downstream signal except the signal on described lower road is directly passed through, the multi-wavelength downstream signal that the second optical transmission module that the multi-wavelength distant-end node of described second tree network receives described optical line terminal is sent along second direction by optical fiber, by road under the signal of corresponding wavelength in described multi-wavelength downstream signal to each optical network unit in connected optical network unit group, and the signal of other wavelength in described multi-wavelength downstream signal except the signal on described lower road is directly passed through, described first direction and second direction are clockwise or counterclockwise, described first direction is different with second direction,

At up direction:

When network link breaks down, each multi-wavelength distant-end node in described first tree network receives the upward signal that the optical network unit in the optical network unit group connected is sent by time division multiplexed scheme, and described upward signal is sent in the first Optical Receivers of described optical line terminal or the second Optical Receivers along described second direction; Each multi-wavelength distant-end node in described second tree network receives the upward signal that the optical network unit in the optical network unit group connected is sent by time division multiplexed scheme, and by described upward signal along described first direction be sent in the first Optical Receivers of described optical line terminal or the second Optical Receivers another;

Described multi-wavelength distant-end node comprises: grating coupler;

12. guard methods according to claim 11, it is characterized in that, when network link fault-free, described first optical transmission module is by the multi-wavelength downstream signal of generation along the optical network unit connected under first direction is sent to described multi-wavelength distant-end node, and described first Optical Receivers receives the upward signal that the optical network unit in described optical network unit group sends along first direction;

13. guard methods according to claim 11, is characterized in that, the network link of ring network break down make described ring network fragment into the first tree network and the second tree network time, also comprise:

14. guard methods according to claim 11, is characterized in that, the up-downgoing wavelength of each optical network unit group is identical, and the up-downgoing wavelength of described optical network unit group adopts time division duplex mechanism to send.

15. guard methods according to claim 11; it is characterized in that; at up direction; when the network link of ring network break down make described ring network fragment into the first tree network and the second tree network; the multi-wavelength distant-end node of described first tree network also comprises before receiving the upward signal that optical network unit in the optical network unit group connected sent by time division multiplexed scheme:

16. guard methods according to claim 11, is characterized in that, described upward signal and described downstream signal adopt time division duplex mechanism to send.

17. guard methods according to claim 11, is characterized in that,

At down direction:

At up direction:

18. guard methods according to claim 17, it is characterized in that, described multi-wavelength distant-end node also comprises: Y shape splitter and splitter, first branch road of described Y shape splitter is connected with the second branch of described first direction coupler, second branch road of described Y shape splitter is connected with the second branch of described second direction coupler, 3rd branch road of described Y shape splitter is connected with one end of described splitter, the other end of described splitter has multiple interface, described splitter is connected by described multiple interface each optical network unit with corresponding optical network unit group.

19. guard methods according to claim 11, is characterized in that, when described optical line terminal receives the operation maintenance management frame of optical network unit transmission, described optical line terminal determines that network link there occurs fault.

20. guard methods according to claim 11, is characterized in that, described multi-wavelength distant-end node is 8, and a described optical network unit group comprises 8 optical network units.

21. guard methods according to claim 11, is characterized in that, described first direction is clockwise direction, and described second direction is counterclockwise; Or described first direction is that counterclockwise described second direction is clockwise direction.