CN105763284A

CN105763284A - Four-wave mixing-based TWDM-PON (Time and Wavelength Division Multiplexing-Passive Optical Network) local interconnection method

Info

Publication number: CN105763284A
Application number: CN201610203450.XA
Authority: CN
Inventors: 王宏祥; 王彦彦; 纪越峰
Original assignee: Beijing University of Posts and Telecommunications
Current assignee: Beijing University of Posts and Telecommunications
Priority date: 2016-04-01
Filing date: 2016-04-01
Publication date: 2016-07-13

Abstract

The invention discloses a research scheme for local ONU (Optical Network Unit) communication technology based on the TWDM-PON, which belongs to the technical field of passive optical networks (PON) in access networks. The mechanism that the traditional ONU communication is always forwarded by an OLT is changed, the structure at the OLT and the ONU in the TWDM-PON is not changed, an optical device is added at an ODN place, signal light and pumping light transmitted by the ONU pass through a high nonlinear fiber, multicast is realized through the four-wave mixing effects, multiple wavelengths are outputted, the multiple wavelengths are distributed to each ONU through a demultiplexer, local service information transmitted by the ONU is directly transmitted to other ONUs through the ODU place, forwarding through the OLT is not needed, and the bandwidth of an up link and a down link is greatly saved.

Description

A kind of local interconnected method of TWDM-PON based on four-wave mixing

Technical field

The present invention is that time-division wavelength-division is stacked multiplexing passive optical network (TWDM-PON, Time and Wavelength Division Multiplexing-Passive Optical Networks) in the research of local interconnection technique belong to EPON (PON, Passive Optical Network) technical field.

Background technology

Along with modern society is information-based and the sustained and rapid development of science and technology, various new business continue to bring out, especially cloud computing, the storage of big data and HD video application demand, making network bandwidth requirements present the trend of 11-fold increase in every 5 to 6 years, access network is faced with unprecedented bandwidth pressure.Intelligent acess has been increasingly becoming mainstream technology and the development trend in broadband access network market due to the transmission potentiality of ultra-wide.EPON (Passive Optical Networking, PON) it is the key technology solving optical access network " last one kilometer ", it it is the solution of the most attraction realizing FTTH, having become as one of hot technology that each telecom operators of the whole world pay close attention at present, Ye Shi operator implements " broadband speed-raising ", the technical foundation of " light entering and copper back " engineering.

PON product market is the most fiery, and the requirement to performances such as the high speed of PON product, low cost, extensive manufacturability, low-power consumption simultaneously improves further.Existing PON carries out smooth upgrade, and the cry breaking through optical access network key technology of future generation is more and more higher.For the capacity of optical access network is greatly improved, network carrying out smooth upgrade, the new period of NG-PON2 has been stepped in EPON development.

TWDM-PON follows from TDM-PON, and optical line terminal (OLT) is connected with all optical network units (ONU) still through optical branching device.From efficiency, owing to WDM-PON takes man-to-man static Wavelength Assignment, the dynamic wavelength of TWDM and bandwidth distribution to make its network utilization higher；From the perspective of technology, TWDM-PON technology need not change the ODN network being deployed at present on a large scale；From the point of view of the angle of agreement, TWDM-PON is closest to the TDM-PON the most extensively laid, and downward compatibility is good, so having obtained accreditation and the promotion of most of operator, equipment vendor and chip business.TWDM-PON was chosen to be unique developing direction of NG-PON2 in 2012 by International Standards Organization FSAN.Several frameworks of the TWDM-PON of current proposition have based on WDMA hybrid passive optical network (up WDM, descending TDM), also have based on TDMA hybrid passive optical network, also TDM over WDM hybrid passive optical network, WDM over TDM hybrid passive optical network.Being the conventional framework of a kind of TWDM-PON system shown in accompanying drawing 1, this framework is by the way of optical branching device and AWG three-stage cascade, it is simple to network expansion.On the emitter different wave length to be modulated the signal to of ONU, receive function by receiving signal to downstream wavelength, it is desirable to ONU has tunability, integrated tunable laser instrument, adjustable light wave-filter, high sensitivity photo-detector simultaneously.This network structure, can accordingly increase the number of AWG by increasing the output of optical branching device, it is possible to realize the network capacity extension, increase number of users.

Communication based on TWDM-PON system, for communication service, is divided into up-downgoing business and ONU local service, and in PON system, ONU local service must first go through OLT and does terminal, i.e. source ONU is sent to OLT, OLT and is handed down to purpose ONU again.This can expend the bandwidth resources of up-downgoing undoubtedly, therefore, we can consider to allow ONU can directly carry out local communication, need not do terminal by OLT again, to this, we can select the most newly-built local network to be coupled together by these ONU, it is specifically designed to the transmission of local service, but so can cause that whole network is more complicated, cost is the highest.Improvement based on existing PON is then more efficiently way.

The current research communicated about the local ONU in PON is also in the starting stage, researcher is had to propose the research of a lot of framework for EPON both at home and abroad, a kind of is ONU interconnection scheme based on FBG, increase a set of operation wavelength for each ONU and be made exclusively for the wavelength dedicated of local interconnection, and the wavelength reflection of local information will be carried to all ONU by FBG；It is also feedback scheme based on coupler, and uses CSMA/CD agreement as up multiple spot access scheme in MAC layer；Also have based on ring topology, the ethernet passive optical network system of offer Local Area Networking function.But the local communication protocol of these schemes is the most complicated, and these researchs are all based on time-multiplexed EPON, are not involved with the local interconnection technique of time-division wavelength-division stacking multiplex system.

Therefore, on the basis of not changing original TWDM-PON framework, by adding some passive optical signallings composition local multicast unit (LMU) at ODN so that network can support local communication, just can solve the problem that local exists mass communication.The present invention is namely based on and above present ONU this locality interconnection technique in a kind of TWDM-PON based on four-wave mixing.

Summary of the invention

In order to solve the problem that in TWDM-PON, local communication portfolio increases severely day by day, the present invention proposes a kind of novel PON framework of a kind of physically realizable support ONU this locality interconnection, and described scheme is as follows.

Do not change the structure at OLT and ONU in TWDM-PON, at ODN, add some passive optics composition local multicast unit (LMU) the local service information that ONU sends can be realized to be transmitted directly to other ONU by ODN, need not be again by the forwarding of OLT.

As shown in explanatory diagram accompanying drawing 2, the output of AWG at ODN, application coupler divides the signal into two-way, and uplink optical fibers of leading up to connects OLT, and a road enters local multicast unit, and wherein, local multicast unit includes circulator, wave filter, high non-optical fiber.

As shown in Figure 2, it is uplink and downlink communication business that the business transmission of whole system is divided into two parts, a part, and a part is local interworking service.In whole system structure, the transmission of original up-downgoing business is unaffected.Meanwhile, the local service between all ONU is by special wavelength dedicated transmission local service.

In local communication, first ONU is to the time window of OLT application local communication；Then, OLT, according to application information, gives ONU authorization message, receives the ONU of authorization message, sends wavelength dedicated.The wavelength signals carrying local service first passes through circulator, then filters this wavelength dedicated by wave filter, then enters high non-optical fiber after coupling pump light, four-wave mixing occurs.The signal that four-wave mixing generates enters into coupler by circulator, and then is sent to other ONU by AWG.The function that local multicast unit realizes is, the optical signal of one wavelength of input can export the optical signal of multiple different wave length, and the information that the optical signal inputted and export carries is identical, realization here is the multicast mechanism realized by four-wave mixing effect based on high non-optical fiber.Pump light (in view of PON as a kind of passive network, can obtain pump light from OLT) and flashlight can generate multiple wavelength carrying signal by FWM (four-wave mixing) effect.

Compared with prior art.It is an advantage of the current invention that:

The most do not change the integral layout of TWDM-PON, realize local ONU communication not by a newly-built LAN, which save a lot of resource.

2. have employed relatively simple passive optics and optical effect to realize wavelength multicast, there is quantitative mathematical relationship in the wavelength inputting and exporting, can obtain suitable wavelength by computational analysis.

The most really propose and solve the local interconnection problem in time-division wavelength-division stacking multiplex system, the local communication business of ONU, can directly transmit at ODN, terminal need not be done by OLT, save the bandwidth resources of uplink downlink.

Accompanying drawing explanation

Fig. 1: TWDM-PON system topological schematic diagram

Fig. 2: support the TWDM-PON fabric topology schematic diagram of this locality interconnection in the present invention

Detailed description of the invention

For making the object, technical solutions and advantages of the present invention clearer, below by specifically the present invention is described in further detail.The research of the local interconnection technique of the TWDM-PON of the embodiment of the present invention comprises the following steps:

Step 1: local signal sends.As shown in topological diagram 2, ONU sends local service, uplink service and local service by wavelength dedicated and passes through AWG by different wavelength, output at AWG, coupler divides the signal into two-way, and uplink optical fibers of leading up to is connected to OLT, and a road enters local multicast unit (LMU).

Step 2: local multicast unit produces multicast signal.As in figure 2 it is shown, local multicast unit is made up of circulator, wave filter, high non-optical fiber.By the signal of coupler output to local multicast unit, leach specialty wavelength by wave filter.The wavelength dedicated carrying local service exports paramount non-optical fiber together with pump light (exporting pump light from OLT), produces four-wave mixing effect, generates multicast signal, and send the ONU to other, complete local communication.

The content not being described in detail in this specification belongs to prior art known to professional and technical personnel in the field.

Obviously the foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all within the spirit and principles in the present invention, any amendment of being made, replacement etc., should be included in protection scope of the present invention.

Claims

1. local interconnection technique based on TWDM-PON, it is characterised in that comprise the steps:

In TWDM-PON system, change traditional ONU communication and forward this mechanism always by OLT, Optical process modules is added, it is possible to achieve the local service information that ONU sends is passed through can be straight at ODN at ODN Other ONU are given in sending and receiving, need not be again by the forwarding of OLT.And need not again build a LCN local communications network Network, thus reduce communications cost and complexity.

Local interconnection architecture the most according to claim 1, it is characterised in that:

At ODN in TWDM-PON, add wavelength signals and process, it is achieved single wavelength inputs, multi-wavelength Output, thus the information reaching ONU transmission is broadcast to other ONU, and then realize this locality interconnection.

Wavelength signals the most according to claim 2 processes, it is characterised in that:

At ODN, the upward signal of a road ONU, and the pump light source introduced from OLT side, jointly through too high Non-optical fiber, through four-wave mixing effect, output multi-channel optical signal, exports the ONU to other.

Four-wave mixing effect the most according to claim 3, it is characterised in that:

The effect of four-wave mixing based on high non-optical fiber, the multichannel wavelength light of generation all carries the letter that input light carries Number, and by calculating it is achieved that the reception wavelength of each road wavelength of output and ONU matches.