WDM signals contain multiple wavelength channels, which are multiplexed in a single optical fiber. Each wavelength channel carries an independent traffic flow.
If only one wavelength of optical signal is transmitted in a fiber, the cost is expensive compared with the cost of optical fiber. If multiple wavelengths of optical signals are transmitted in a single optical fiber, and these optical signals do not interfere with each other, then the cost is saved and the transmission bandwidth is increased. At present, WDM technology is to transmit multiple wavelength optical signals in one fiber. The optical signal of each wavelength represents a channel. Multiple channels transmit data in a single fiber at the same time, which is the multiplexing of a fiber.
OADM realizes the function of traditional electric SDH add / drop multiplexing in the optical domain, and it has transparency. It can process signals of any format and rate, which is superior to the electric ADM (add drop multiplexer) used in SDH network.
The explanation inserted here means going on the road and going down the road.
On the road means that a new wavelength channel is added to the optical signal entering the optical add / drop multiplexer, which is multiplexed with other channels into the optical fiber.
Downlink means that one wavelength channel is removed from the optical signal entering the optical add / drop multiplexer, and other irrelevant channels pass through the optical add / drop multiplexer directly. Note: the downlink channel is directly transferred to the equipment for service processing, not truncation.
Optical communication has the characteristics of large bandwidth, high reliability and low cost. The rapid development of optical communication system and optical network brings new revolution to the information age.
The application of OADM node in optical network makes the routing operation in the ring not affected by the type and rate of transmission signal, thus realizing the transparency of local network and laying the foundation for providing end-to-end wavelength service. That is to say, users can carry information of any form and rate on a certain wavelength according to their own needs, and the network can route it to the destination through the wavelength identification route.
OADM is one of the key devices in WDM optical network. Its function is to selectively receive and transmit some wavelength channels from the transmission optical path, without affecting the transmission of other wavelength channels. In other words, OADM realizes the function of traditional SDH add / drop multiplexer in time domain in optical domain, and has transparency, and can process signals of any format and rate, which is superior to electric ADM.
According to the different network design, service requirements and resource configuration, the optical network has certain requirements for the OADM nodes used in it, mainly focusing on the performance requirements, which are embodied in the following aspects: reconfigurability, scalability, transparency and multi-channel processing capacity.
Main parameters of OADM
Channel interval, channel bandwidth, center wavelength, channel isolation, wavelength temperature stability, channel differential loss uniformity.
Technology category editing
The core device of OADM node is optical filter device, which selects the wavelength to be up / down and realizes wavelength routing. At present, the mature filters used in OADM include acousto-optic tunable filter, volume grating, arrayed waveguide grating (AWG), fiber Bragg grating (FBG), multilayer dielectric film and so on.
According to the flexibility of upper and lower wavelengths, OADM can be divided into fixed wavelength OADM, semi reconfigurable OADM and fully reconfigurable OADM. From the practical application, fixed wavelength OADM and semi reconfigurable OADM can be applied in the system, but it is still difficult to realize the fully reconfigurable OADM which can go up and down any wavelength channel in large network nodes.
In terms of the implementation of OADM, it mainly includes two categories: wave splitter with optical switch array and fiber Bragg grating with optical switch.
OADM has low insertion loss and improves networking capability. It can be said that OADM develops the WDM system from the initial point-to-point connection to the point to multipoint and multipoint to multipoint connection, making the DWDM system more flexible and convenient when applied in the local network, greatly reducing the construction cost of metropolitan WDM, and finally becoming an indispensable key device in the future optical network.
Application of OADM in local network
The local network is concerned about how to reduce the cost of network construction and improve the operation ability. Therefore, when the OADM system is applied in the local network, it should develop towards the direction of low cost and high cost performance. On the basis of the original OADM, combined with the characteristics of metropolitan area, the adjustable OTU and C / DWDM integration features are introduced, which greatly reduces the network construction and maintenance costs, and further optimizes the metropolitan wavelength division.
The construction and operation cost of transmission network is a big problem in the current development. Only the technology that can meet the needs of development and greatly reduce the cost will have the market and vitality. Metropolitan WDM designed by OADM has the characteristics of large capacity, multi service, low cost, scalable and manageable, and has become an important means of local network transmission solutions. The emergence of adjustable OTU and other technologies has brought a new mode of Ge service transmission. Combined with the flexible design of C / DWDM integration, the network construction cost is greatly reduced, and it will be widely used with the development of data services.
1. WDM equipment data service transmission network solution
In the construction of man / LAN, the important backbone nodes are usually selected in the core layer of the network to construct the OADM ring network. As the core network of the highest layer, it is an integrated optical transmission platform for voice and data services, which plays a crucial role in the transmission, scheduling and aggregation of services.
a. Ring networking is adopted instead of optical fiber direct drive, which saves a lot of valuable man / local fiber resources.
b. The system is flexible and scalable. It supports services of various rates and signal formats, and provides transparent service scheduling based on wavelength. In the later stage, the new service only needs to increase the wavelength without affecting the original wavelength, which greatly enhances the market competitiveness of the network.
c. The number of upper and lower wavelengths in the initial stage of the system can be planned according to the actual demand, and the later expansion and upgrading are convenient. The maximum system bandwidth can be up to 800g, which can protect the construction investment of operators to the greatest extent.
d. The network node has strong expansibility and provides multiple services and multi rate interfaces. It can access STM-1 / 4 / 16 / 64, Fe, Ge / 10GE, POS, ATM, FC, FICON, ESCON, DVB and 10m ~ 2.5G arbitrary rate services.
e. For large granular service convergence, such as 4 × STM-1 / 4 / 16, 2 / 8 × Ge, 8 × any convergence, etc.
f. It can provide multiple protection functions on the optical layer for important data services such as GE and 10GE, which is more efficient than the traditional dual home protection.
2. Metro / local network data transmission solution
OADM core network not only solves data transmission, but also carries voice services of SDH rings under metro / local transmission network. In addition, convergence processing is provided for large granular services (such as 155m dedicated line service) in man / LAN, which can efficiently utilize channel resources. For important data services, two fiber two-way channel sharing protection and 1 + 1 optical channel protection can be provided on the optical layer.
3. Metro / local network data transmission solution
In order to transfer data service in OADM ring network, we can change the usual dual home Ge service planning into single ownership, save the expensive long-distance ports on the data equipment, and provide various optical layer protection functions (MS level) for the service, which is more efficient and faster (second level) than the traditional data dual home protection.
4. Metro / local network data transmission solution
OADM ring network provides a data transmission solution for building large local network. Due to the equipment conditions of data network and the problems of optical cable resources, the core routing and switch data services may be interconnected by single home Ge, and can not form a loop. Through OADM group ring network, it can provide various protection methods based on optical layer, which provides reliable guarantee for the safe transmission of services. In addition, OADM technology can also solve the long-distance transmission of data services across cities.
If you need anything, you can contact HTF Zoey.
contact：support@htfuture.com
Skype：sales5_ 1909，WeChat：1663502502
