CN205305047U - Optical mixer, based on DOCSIS3. 0's up link system - Google Patents

Abstract

The utility model provides an optical mixer and use the up link system based on DOCSIS3.0 of this optical mixer, can avoid using the customization wavelength the laser instrument the too high problem of bringing of cost for the up link practical value of system improves greatly more than the DOCSIS3.0, an optical mixer, and it includes spectrometer and light matrix switch, the input of spectrometer with light matrix switch's one end communication is connected, the automatically controlled the control unit that is connected with of light matrix switch, the control unit control light matrix switch the light path break -make and light matrix switch with the connection of spectrometer, based on DOCSIS3.0's up link system include cable modem, RFoG optical node, go upward the optical receiver, cable modem end system, optical mixer.

Description

Optical mixer, up-line system based on DOCSIS3.0

Technical field

This utility model relates to radio and television two-way communication field, particularly relates to optical mixer, up-line system based on DOCSIS3.0.

Background technology

DOCSIS(DataOverCableServiceInterfaceSpecifications, data over cable service interface specification), it is an international standard formulated by wire cable normal structure CableLabs, its excellent QoS(QualityofService, service quality) spoken approvingly of in the industry. The nucleus equipment of DOCSIS is CMTS(CableModemTerminalSystems cable modem termination system) and CM(CableModem cable modem), CMTS is the local side apparatus of DOCSIS system, and CM is the terminal unit of DOCSIS system. In general CMTS is installed in machine room, and CM is installed in user side (being typically mounted in user family). Between CMTS to CM, bidirectional communication link is divided into downlink and up-link, and downlink refers to the link from CMTS to CM, otherwise is up-link.

Along with light entering and copper back constantly advances, optical node constantly refines, and optical node constantly advances to user side, quantity is continuously increased, and causes that trunk optical fiber demand is continuously increased, and the up light of machine room is received and is also continuously increased. Receiving and the Cost Problems of backbone optical cable to solve up light, RFOG(RFoverGlass in recent years, optical fiber radio frequency transmits) technology is widely applied, and makes " up optical-fiber network " can adopt the tree structure similar with " descending optical-fiber network ". RFOG is SCTE(SocietyofCableTelevisionEngineers American Cable TV IEEE) technical specification formulating, the up light emission module in RFOG optical node can open and close laser instrument according to the uplink transmission power of CM. In the DOCSIS2.0 epoch, its upper and lower provisional capital is single channel, down going channel is called DS, data feedback channel is called US, it is TDM(time division multiplex that upward signal controls technology main flow), that is in the same time, " in the broadcast domain of same CMTS " only one of which CM at most launches signal, means that the up optical sender of only one of which optical node at most in the same time is in work.Thus being easy to use optical mixer to become a road to deliver to machine room the fiber mix from multiple optical nodes, the up light inside machine room is received quantity and is also greatly reduced, and cost substantially reduces. Fig. 1 is the typical case's application in DOCSIS2.0 up-link of the RFOG optical node.

Supporting that the DOCSIS3.0 equipment of multichannel binding technology is popularized rapidly in recent years, DOCSIS3.0 device bandwidth is greatly increased, and supports that the CMTS Typical Disposition of DOCSIS3.0 is 16 descending RF passages (radio-frequency channel), has the downlink bandwidth of 800MBPS; 4 up RF passages, have the upstream bandwidth of 160MBPS. But DOCSIS3.0 specification makes RFOG Technique Popularizing there occurs a difficult problem, in order to improve communication bandwidth, DOCSIS3.0 employs channel bundled technology, allow " in the broadcast domain of same CMTS " multiple up radio-frequency channels concurrent, although each passage still uses TDM technology, but works alone mutually between these radio-frequency channels. This means have multiple CM to launch signal in " in the same time ", if it is simultaneously luminous to use the model of Fig. 2 to will result in multiple RFOG optical node simultaneously. Although those CM launched frequencies on radio frequency are separated simultaneously, it radio-frequency channel is frequency division multiplexing, but the optical maser wavelength after being modulated by RFOG optical node is truly had and is probably identical, and they arrive the same up smooth time receiving of machine room, and error code just creates at once simultaneously. Here it is the OBI(OpticalBeatInterference optical beat interference that people often says in the industry) phenomenon.

OBI is owing to two wavelength restrainting laser get too close to, the interference produced after convergence, it it is a kind of common light interference phenomenon, the problem of co-channel interference of its similar radio frequency link, the light interference phenomenon that same frequency is found through experiments will cause link SNR(SignalNoiseRatio signal to noise ratio) serious deterioration, and then cause a large amount of error code.

Solving the simplest way of OBI problem is the laser instrument allowing each optical node use customization wavelength. If notification number is the laser instrument using customization wavelength in 204131651U Chinese utility model patent, the optical return signal producing different wave length transmits minimizing OBI problem, it is possible to avoid the overlap of optical wavelength completely. But this can cause that optical node cost steeply rises, add maintenance also inconvenience, so this kind of scheme practical value is very low.

Utility model content

To the problems referred to above, this utility model provides a kind of optical mixer and applies the up-line system based on DOCSIS3.0 of this optical mixer, the problem that can avoid the high cost using the laser instrument customizing wavelength to bring, up-link practical value is greatly improved, the optical beat interference of the up-link of above-mentioned DOCSIS3.0 system above can also be eliminated simultaneously.

A kind of optical mixer, it is characterized in that: include beam splitter and optical matrix switch, the input of described beam splitter is connected with an end communication of described optical matrix switch, described optical matrix switch has electricly connected control unit, and described control unit controls the light path break-make of described optical matrix switch and the connection of described optical matrix switch and described beam splitter.

A kind of up-line system based on DOCSIS3.0, including what be connected:

Cable modem, for uploading through data feedback channel after the ethernet signal from user side is converted to radiofrequency signal;

RFoG optical node, for uploading after the radiofrequency signal from described cable modem is converted into optical signal;

Up optical receiver, in the future from the beginning the optical signal of described RFoG optical node upload after being converted into radiofrequency signal;

Cable modem termination system, is converted into ethernet signal for the radiofrequency signal of described up optical receiver from the beginning in future and is sent to Metropolitan Area Network (MAN);

It is characterized in that:

It is provided with the optical mixer described in claim 1 between described up optical receiver and described RFoG optical node, described optical mixer includes beam splitter and optical matrix switch, the input of described beam splitter is connected with one end of described optical matrix switch, each beam splitter is connected to a described up optical receiver, the receiving terminal of described up optical receiver is connected with the outfan communication of described beam splitter, one end of described RFOG optical node is connected with the other end communication of described optical matrix switch, described optical matrix switch has electricly connected control unit, described control unit controls the light path break-make of described optical matrix switch, and the connection of described optical matrix switch and described beam splitter, the radiofrequency signal of described cable modem is controlled in different data feedback channels by described control unit, described control unit carrys out detection signal-to-noise ratio by reading the information in the snmp protocol uploading link.

Further, described RFOG optical node adopts Distributed Feedback Laser.

The utility model has the advantages that:

Optical mixer in this utility model, it does not have electrooptical device so that device cost reduces, low in energy consumption, it is possible to using in adverse circumstances, the scope of application is more extensive; Optical mixer of the present utility model is applied in the up-link of DOCSIS system, the optical beat interference of the up-link of DOCSIS system can be eliminated, the laser instrument of customization wavelength need not be used to produce the optical signal of different wave length simultaneously, avoid the significant cost using the optical node of customization wavelength to bring, up-link cost is reduced, bringing facility to equipment operation maintenance, the practical value of the up-link of DOCSIS system is also greatly improved simultaneously; The up-link of DOCSIS system of the present utility model keeps optical-fiber network to be tree structure, it is possible to save substantial amounts of optical cable, thus reducing cost.

Accompanying drawing explanation

Fig. 1 is existing RFoG optical node application schematic diagram in DOCSIS2.0 up-link;

Fig. 2 is existing RFoG optical node application schematic diagram in DOCSIS3.0 up-link;

Fig. 3 is the wavelength of transmitted light test tables of data of the RFoG optical node in this utility model embodiment;

Fig. 4 is the cohersive and integrated data table of OBI bunch in this utility model embodiment;

Fig. 5 is the tables of data after the mixed reorganization in this utility model embodiment;

The structural representation under there are 2 delivery outlets, 32 input port situations of Fig. 6 optical mixer of the present utility model;

Fig. 7 is the application schematic diagram of the up-link of the DOCSIS3.0 system of utility model;

Fig. 8 is the schematic block diagram of the up-link of the DOCSIS3.0 system of utility model.

Detailed description of the invention

In present embodiment, the up-link of optical mixer of the present utility model, DOCSIS system is specifically described in the situation based on DOCSIS3.0 technology, the CMTS Typical Disposition of support DOCSIS3.0 is 16 descending RF passages, there is the downlink bandwidth of 800MBPS, 4 up RF passage US1, US2, US3, US4, have the upstream bandwidth of 160MBPS.

Optical mixer 1 of the present utility model includes beam splitter 6 and optical matrix switch 7, the input 8 of beam splitter 6 is connected with an end communication of optical matrix switch 7, optical matrix switch 7 has electricly connected control unit 10, see Fig. 6, in the present embodiment, beam splitter 6 is provided with two, Fig. 6 is shown as light output A and light output B, therefore the optical mixer 1 in the present embodiment is an optical mixer with 2 delivery outlets, 32 input ports.

Seeing Fig. 7, Fig. 8, the up-link of the DOCSIS3.0 system of the present embodiment contains optical mixer 1, up optical receiver 2, RFoG optical node 3, modulation /demodulation terminal system 4, cable modem 5, control unit 10.

In the present embodiment, RFOG optical node adopts Distributed Feedback Laser, two Distributed Feedback Laser (DistributedFeedbackLaser, i.e. distributed feedback laser) wavelength difference less than 0.2nm time the OBI obvious effect to signal to noise ratio, the present embodiment contains 32 RFoG optical nodes, Fig. 3 is the wavelength of transmitted light data of 32 RFoG optical nodes, and wavelength of transmitted light data have pressed wavelength sequence;

The form of Fig. 3 also analyzes the RFoG optical node ID that can produce OBI and combines (being called OBI bunch), it is possible to find there be multiple OBI bunch of existence.

See Fig. 7, Fig. 8, the up-link of DOCSIS3.0 system is from cable modem 5 to the signal transmission link of cable modem termination system 4, ethernet signal from user side is converted to radiofrequency signal by cable modem 5, between RFoG optical node and cable modem 5, upstream radio-frequency signal and downlink radio-frequency signal employ frequency multiplexing technique, uplink and downlink signals transmits in same cable and does not interfere with each other, upstream radio-frequency signal is uploaded through data feedback channel, upstream radio-frequency signal is changed into optical signal and sends by RFoG optical node, optical signal from RFoG optical node 3 is gone back to radiofrequency signal by up optical receiver 2 again, upstream radio-frequency signal is converted into ethernet signal and is sent to Metropolitan Area Network (MAN) by last cable modem termination system 4. the signal conversion of up-link is 5 State Transferring: Ethernet-radio frequency-light-radio frequency-Ethernet.

In the up-link of the DOCSIS3.0 system of the present embodiment, optical mixer 1 is arranged between up optical receiver 2 and RFoG optical node 3, each beam splitter 6 is connected to a up optical receiver 2, the receiving terminal of up optical receiver is connected with outfan 9 communication of beam splitter, one end of RFOG optical node 3 is connected with the other end communication of optical matrix switch 7, optical matrix switch 7 has electricly connected control unit 10, control unit 10 controls the light path break-make of optical matrix switch 7 and the connection of optical matrix switch 7 and beam splitter 6, the radiofrequency signal of cable modem 5 can be controlled in different data feedback channels by control unit 10, the information that control unit can be uploaded by reading in the snmp protocol of link carrys out detection signal-to-noise ratio.

The Distributed Feedback Laser of RFoG optical node is controlled by the upward signal of cable modem 5, and in the uplink, when cable modem 5 launches radiofrequency signal, RFoG optical node is just luminous; Input optical fibre order, when just powering on, can be accessed by optical mixer 1, say, that input port 1 ~ 16 is mixed into light output A, and input port 17 ~ 32 is mixed into light output B. Now due to the impact of OBI phenomenon, the up signal to noise ratio having some CM is very poor.

In order to solve OBI problem, the method needing to adopt the optical beat interference of the up-link eliminating DOCSIS system of the present utility model, the topological structure between cable modem and RFoG optical node can be obtained, in units of RFoG optical node, control the data feedback channel of cable modem, detect signal to noise ratio change when RFoG optical node uploads optical signal by control unit and determine the optical node combination that will produce optical beat interference; The RFoG optical node sorting and grouping that will produce optical beat interference builds OBI bunch;Each OBI bunch is assigned in different data feedback channels.

Cable modem termination system is CableModemTerminalSystems, represents hereafter abbreviated with CMTS; Cable modem is CableModem, represents hereafter abbreviated with CM; Optical beat interference is OpticalBeatInterference, represents hereafter abbreviated with OBI.

Method in the optical beat interference of the up-link eliminating DOCSIS3.0 system of the present utility model adopting utility model, first carry out preparation process, concrete: eliminate OBI: control all CM by control unit and be all limited in data feedback channel US1, but uploading bandwidth can only use 1/4th, but OBI no longer exists, all CM can without packet loss communication, all of CM is operated in US1, then will cause the waste of other 3 data feedback channels, inefficiency, preparation process 1 is to facilitate subsequent control.

Detection can produce optical beat interference RFoG optical node and build OBI bunch specifically include following steps:

Step (1): obtain the topological structure between CM and RFoG optical node, close matrix switch input port one by one by control unit and obtain the topological structure between CM and RFoG optical node. concrete operations are: recover after being closed 5 seconds matrix switch input port, close matrix switch input port and can cause the CM communication disruption of association, by packet loss statistics and these CM inventories of channel utilization index parameter acquiring from the management information of CMTS, thus the topological structure obtained between all CM and optical mixer input port, owing to RFoG optical node and optical mixer input port are one to one, and then obtain the topological structure between CM and optical node, owing to RFoG optical node and CM are many-to-one relations, firstly the need of the corresponding relation determining CM and optical node, control unit is facilitated to be controlled by CM in different data feedback channels, RFoG optical node is not affected by control, RFoG optical node finds that CM has radio frequency up, turn on laser instrument to launch, therefore it is control CM to data feedback channel that control unit 10 controls RFoG optical node reality in data feedback channel, the uplink channel descriptor controlling cable modem is the data feedback channel controlling RFoG light joint, complete preparation process 1, start to control the data feedback channel of CM after preparation process 2 in units of optical node, each optical node can select US passage (optional US1, US2, US3, US4)

Step (2): create one OBI bunch as current OBI bunch by control unit 10, selects data feedback channel US1 as current data feedback channel, selects a RFoG optical node add in current OBI bunch and control in current data feedback channel US1;

Step (3): control unit 10 selects next RFoG optical node as current optical node and to control in another data feedback channel US2, respectively with current OBI bunch in arbitrary RFoG optical node upload by the infomation detection signal to noise ratio in reading snmp protocol simultaneously;

Step (4): signal to noise ratio deterioration illustrates that two RFoG optical nodes exist OBI if detecting, then add in current OBI bunch by control unit by current RFoG optical node and control in current up logical US1 road, otherwise current optical node is not dealt with;

Step (5): repeat step (3), step (4), detect all RFoG optical nodes successively, obtain the whole RFoG optical nodes in current OBI bunch;

Step (6): after obtaining the whole RFoG optical nodes in current OBI bunch, removes the whole RFoG optical nodes current OBI bunch by control unit 10 from all RFoG optical nodes;

Step (7): repeat step (2)-step (6) on the basis of the remaining RFoG optical node of step (6), until all RFoG optical nodes are marked as the member of different OBI bunch, obtain all OBI bunch and the RFoG optical node that comprises.

The RFoG optical node that can be produced OBI by detection is combined and builds OBI bunch, the cohersive and integrated data of OBI bunch obtained is shown in Fig. 4, 32 RFoG optical nodes form 7 OBI bunch altogether, each OBI bunch is assigned in different data feedback channels and uploads, the RFoG optical node that OBI can occur would not be uploaded simultaneously cause OBI problem, the laser instrument of customization wavelength need not be used to produce the optical signal of different wave length simultaneously, avoid the significant cost using the optical node of customization wavelength to bring, facility is brought to equipment operation maintenance, in addition also using whole data feedback channel, without the ability to communicate reducing system.

See Fig. 4,3rd bunch has 12 RFoG optical nodes, DOCSIS3.0 system in this utility model has 4 data feedback channels US1, US2, US3, US4, according to static equilibrium requirement, 32 RFoG optical nodes need to be evenly distributed in each data feedback channel, if it is just excessively crowded to be limited in a data feedback channel by the member of the 3rd bunch, it is impossible to meet the requirement of static equilibrium.

Four, OBI bunch of splitting and reorganizing: in order to meet the requirement of static equilibrium, before OBI bunch is assigned in different data feedback channels, by control unit OBI bunch split and recombinate, static unbalanced for avoiding RFoG optical node in arbitrary OBI bunch too much to cause so that the RFoG optical node quantity in different data feedback channels tends to balanced.

During distribution, it meets distributive condition:

(1), when having a RFoG optical node, b mixing group, e data feedback channel, when meeting a and can be divided exactly by b, there is in each mixing group a/b RFoG optical node, otherwise, d more than the a/b=c, then the 1-d mixing group there is c+1 RFoG optical node, the d+1-b mixing group has c RFoG optical node.

(2), when b is less than or equal to e, each OBI bunch of maximum distribution are in b data feedback channel, if the RFoG optical node distribution of OBI bunch is in different data feedback channels, the RFoG optical node distributed in same OBI bunch in different data feedback channels must simultaneously meet the mixing group belonging to different; When b is more than e, each OBI bunch of maximum distribution are in e data feedback channel, if the RFoG optical node distribution of OBI bunch is in different data feedback channels, the RFoG optical node distributed in same OBI bunch in different data feedback channels must simultaneously meet the mixing group belonging to different.

(3) after, distributing when one of them OBI bunch, more than the member in other data feedback channels z of RFoG optical node in one of them data feedback channel, then just first z RFoG light joint in next one OBI bunch is assigned in other data feedback channels when next OBI bunch of distribution.

Adopting two beam splitters to constitute two mixing groups in the present embodiment, be respectively used to upload, when having two beam splitters and 32 RFoG optical nodes in the present embodiment, the splitting and reorganizing principle of OBI bunch is as follows:

1, each mixing group must distribute 16 nodes.

2, each OBI bunch of maximum distribution are in 2 data feedback channels, if distribution is in two data feedback channels, must belong to different mixing groups.

3,32 node mean allocation in 4 data feedback channels as far as possible.

RFoG optical node in each OBI bunch is equally divided into two groups as far as possible, then these group's average marks are sent in 2 mixing groups, then the group in mixing group is controlled in different data feedback channels, it is made to meet each OBI bunch of maximum distribution of process in 2 data feedback channels, if distribution is in two data feedback channels, must belong to different mixing groups, meet 32 node mean allocation in 4 data feedback channels as far as possible as far as possible, if there is OBI bunch of only one of which member, can in data feedback channel arbitrary disposition, play flexible allotment effect, allocation result is shown in Fig. 5, by OBI bunch of splitting and reorganizing, it is deployed in 4 data feedback channel passages, each passage is made to distribute 8 RFoG light joints.And forming two mixing group A, B, each mixing group comprises 16 members, can avoid OBI in mixing group.

Shown in Fig. 6 is the application of the optical mixer mixing the RFoG optical node after splitting in Fig. 5 in DOCSIS3.0 environment, optical mixer adopts two uplink optical fibers to machine room, also two up optical receiver correspondences are had to receive in machine room, the signal of telecommunication after reception delivers to CMTS after being merged by electricity blender, signal from RFoG optical node can carry out packet fully according to the node number in Fig. 6 and just can work well, it is to avoid the generation of OBI phenomenon.

If certain OBI bunch more than 16 members, then certain US needs to hold unnecessary 8 optical nodes and produce crowded certainly, and this situation load balancing cannot perform to optimum. Control unit is able to detect that this situation, can in time provide replacing RFoG optical node, Renewal process needs to disconnect the network service of single RFoG optical node, need operation with caution, it is likely to need to retest the performance of system after replacing, so needing in the time period construction that terminal use can accept.

In current this area, this utility model is also applied for DOCSIS3.1 standard, and DOCSIS3.1 standard can make application prospect of the present utility model wider, because DOCSIS3.1 supports higher upstream bandwidth. OBI bunch excessive causes the crowded problem of the RFoG optical node of single data feedback channel, and the single data feedback channel of DOCSIS3.1 has bigger bandwidth, and this will make congested problem seem less serious.

The beam splitter quantity of optical mixer can be arranged according to practical situation, thus adjusting the output quantity of optical mixer, the optical mixer of 2 tunnel outputs in the above-described embodiments, if certain OBI bunch more than 16 members, then certain data feedback channel needs to hold unnecessary 8 optical nodes and produce crowded certainly. If adopting 4 beam splitters, optical mixer expanding to 4 road light and exports, congested problem has not just existed. And each bunch may be divided into 4 groups (be not less than 4 members bunch), each group is positioned at different US and different mixing groups. RFoG optical node sorting technique is identical with the optical mixer that 2 tunnels export with OBI bunch of splitting and reorganizing principle with OBI bunch of construction method.

Claims (3)

1. an optical mixer, it is characterized in that: include beam splitter and optical matrix switch, the input of described beam splitter is connected with an end communication of described optical matrix switch, described optical matrix switch has electricly connected control unit, and described control unit controls the light path break-make of described optical matrix switch and the connection of described optical matrix switch and described beam splitter.

2. based on a up-line system of DOCSIS3.0, including what be connected:

Cable modem, for uploading through data feedback channel after the ethernet signal from user side is converted to radiofrequency signal;

RFoG optical node, for uploading after the radiofrequency signal from described cable modem is converted into optical signal;

Up optical receiver, in the future from the beginning the optical signal of described RFoG optical node upload after being converted into radiofrequency signal;

Cable modem termination system, is converted into ethernet signal for the radiofrequency signal of described up optical receiver from the beginning in future and is sent to Metropolitan Area Network (MAN);

It is characterized in that:

It is provided with the optical mixer described in claim 1 between described up optical receiver and described RFoG optical node, described optical mixer includes beam splitter and optical matrix switch, the input of described beam splitter is connected with one end of described optical matrix switch, each beam splitter is connected to a described up optical receiver, the receiving terminal of described up optical receiver is connected with the outfan communication of described beam splitter, one end of described RFOG optical node is connected with the other end communication of described optical matrix switch, described optical matrix switch has electricly connected control unit, described control unit controls the light path break-make of described optical matrix switch, and the connection of described optical matrix switch and described beam splitter, the radiofrequency signal of described cable modem is controlled in different data feedback channels by described control unit, described control unit carrys out detection signal-to-noise ratio by reading the information in the snmp protocol uploading link.

3. a kind of up-line system based on DOCSIS3.0 according to claim 2, it is characterised in that: described RFOG optical node adopts Distributed Feedback Laser.