Dense Wavelength Division Multiplexing (DWDM)
Dense Wavelength Division Multiplexing (DWDM) is a combination of a group of optical wavelengths that can be transmitted with a single fiber. This is a laser technology used to increase bandwidth on existing fiber backbone networks. More precisely, the technique is to multiplex the close spectral spacing of a single fiber carrier in a designated fiber in order to utilize the achievable transmission performance (for example, to achieve the smallest degree of dispersion or attenuation). In this way, under a given information transmission capacity, the total number of optical fibers required can be reduced.
DWDM can combine and transmit different wavelengths in the same fiber. To ensure effectiveness, one fiber is converted into multiple virtual fibers. Therefore, if you plan to reuse 8 optical fiber carriers (OC), that is, transmit 8 signals in one optical fiber, the transmission capacity will be increased from 2.5Gb / s to 20Gb / s. Data was collected in March 2013. Due to the use of DWDM technology, a single fiber can transmit more than 150 beams of different wavelengths at the same time, and the maximum speed of each beam can reach a transmission rate of 10Gb / s. As manufacturers add more channels to each fiber, terabit transmission speeds are just around the corner.
A key advantage of DWDM is that its protocol and transmission speed are not related. Networks based on DWDM can use IP protocol, ATM, SONET / SDH, Ethernet protocol to transmit data, and process data traffic between 100Mb / s and 2.5Gb / s. In this way, DWDM-based networks can transmit different types of data traffic at different speeds on a laser channel. From a QoS (Quality Service) perspective, DWDM-based networks quickly respond to customer bandwidth requirements and protocol changes in a low-cost manner.
Advantages of integrated dense wavelength division multiplexing system:
1.The combiner and demultiplexer of the integrated DWDM system are used separately at the sending end and the receiving end, namely: only the combiner at the sending end, only the demultiplexer at the receiving end, and both the receiving end and the sending end are removed OTU conversion equipment (this part costs more)? Therefore, investment in DWDM system equipment can be saved by more than 60%.
2. The integrated DWDM system uses only passive components (such as multiplexer or demultiplexer) at the receiving end and the sending end. Telecom operators can order directly from the device manufacturers to reduce the supply link and lower the cost, thereby saving equipment costs.
3. The open DWDM network management system is responsible for: OTM (mainly OTU), OADM, OXC, EDFA monitoring, and its equipment investment accounts for about 20% of the total investment of the DWDM system; while the integrated DWDM system does not require OTM equipment, its The network management is only responsible for the monitoring of OADM, OXC, EDFA. More manufacturers can be introduced to compete. The network management cost can be reduced by about half compared with the open DWDM network management.
4. Because the combined wave / demultiplexing device of the integrated DWDM system is a passive device, it is convenient to provide multiple services and multi-rate interfaces, as long as the wavelength of the optical terminal of the service end equipment meets G. The 692 standard can be accessed by any service such as PDH, SDH, POS (IP), ATM, etc., and supports 8M, 10M, 34M, 100M, 155M, 622M, 1G, 2.5G, 10G and other rates of PDH and SDH , ATM and IP Ethernet? Avoid the open DWDM system due to OTU, and can only use the SDH, ATM or IP Ethernet equipment of the purchased DWDM system that has determined the optical wavelength (1310nm, 1550nm) and transmission rate? It is simply impossible to use other interfaces.
5. If the laser device modules of optical transmission equipment such as SDH and IP routers are uniformly designed as pins with standard geometric dimensions, the interface is standardized, which is easy to maintain and plug, and the connection is reliable. In this way, the maintenance personnel can freely replace the laser head of a specific color wavelength according to the wavelength requirements of the integrated DWDM system, which provides convenient conditions for the failure maintenance of the laser head and avoids the drawbacks that the manufacturer must replace the whole board before. High maintenance costs.
6. Color wavelength light sources are currently only slightly more expensive than ordinary 1310nm and 1550nm wavelength light sources. For example, 2.5G rate color wavelength light sources are currently more than 3,000 yuan more expensive, but when connected to an integrated DWDM system, they can make The cost of the cost system is reduced by nearly 10 times, and with the large-scale application of color wavelength light sources, its price will be close to that of ordinary light sources.
7. The integrated DWDM equipment is simple in structure and smaller in size, only about one-fifth of the space occupied by the open DWDM, saving machine room resources.
In summary, the integrated DWDM system should be used in a large number of DWDM transmission systems, and gradually replace the dominant position of the open DWDM system. Considering that there are a large number of optical transmission equipment with ordinary light sources currently in use on the network, it is recommended that integrated and open compatible hybrid DWDM can be used, which has protected the previous investment.
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