CWDM is a low cost WDM transmission technology at the access level of man .It is based on the use of wavelength division switching, such as some telecommunications and data services, such as sonnet /SDH, atm, fiber channel, in layman’s terms, modulates many different signals through the fiber to the other end, and then demodulates many different models on the other end. CWDM is to realize flexible and transparent access to optical fiber network by using coarse wavelength division multiplexing technology recombination. Optical fiber resources and network costs are greatly saved. It solves two problems, namely short optical fiber and transparent transmission of multiple services.
CWDM single-fiber two-way equipment can transmit 4-wave services through a single optical fiber, which is a very important function point. A single-fiber one-way device can even transmit 8-wave traffic through a single fiber. These functions are mainly applied in the metropolitan area network convergence and access layer, and can meet the needs of network construction and business development in a short time.
It can be done through optical transceivers, also known as coarse wavelength division multiplexers, where optical resources are saved by connecting different wavelengths of optical signals through optical cables. CWDM is widely used in the field of education and network, because it is a network connection solution, very economical and efficient.
CWDM achieves very low cost with very high access bandwidth. It is suitable for various popular network structures, such as point-to-point, Ethernet, SONET ring, especially for communication applications with high bandwidth and dense access points, as well as short distance transportation.
CWDM has six specific application directions. Firstly, it is used for network expansion and upgrading. Because any input light wavelength can be converted to a fixed itu-cwdm output light wavelength, realizing the simultaneous transmission of up to a dozen optical signals in a single fiber, so the transmission capacity and utilization rate of optical fiber are greatly expanded. The time and cost of laying fiber optic cables are greatly reduced, and new services are opened without affecting existing ones.
Second, it is used for model conversion, which can realize arbitrary conversion of single-mode light wave and various single-mode and multi-mode light wave, and is suitable for various complex network situations.
Third, it can complete the mixed transmission of all kinds of signals. It is suitable for upgrading SDH, ATM, Ethernet and fiber channel equipment in the rate of 10Mb/s ~ 2.5gb /s, as well as mixed transmission of digital and analog signals in one optical fiber, as well as long-distance line relay and analog signal transmission.
Fourth, it can complete wavelength conversion, which can convert one CWDM wavelength to another wavelength at will, and the transmission distance is very long, which can reach several hundred kilometers. It can also convert any wavelength of single-mode and multi-mode light wave to CW /DM wavelength.
Fifth, it is used for optical relay, which can increase the transmission distance by connecting several CWDM in series, and extend the distance to hundreds of kilometers.
Sixth, security networking: because CWDM can be composed of a number of optical fiber in a single pair of virtual optical network (OPN) isolated from each other on the physical channel, make the network completely free from all software viruses and hackers attack, its security is much higher than the general VPN, in the government, public security, Banks and other public areas is very popular.
In some telecom fiber optic cable resources are insufficient, but the business growth is rapid, and the need for fiber optic cable capacity expansion is not convenient, CWDM can provide several times the existing transmission capacity bandwidth to achieve the two-way convergence of multiple services between two points, compared with traditional DWDM has better cost performance.
CWDM capacity expansion process is very simple, to increase the capacity of optical cable 8 times, just add a pair of CWDM equipment at both ends. Moreover, the business interruption time is very short in the process of capacity expansion. After the capacity expansion is completed, the smooth transition of the business is realized and the original business is not affected by anything.
CWDM can be used to distinguish different users by wavelength and meet the specified bandwidth required by customers, so as to make operators more convenient to provide wavelength rental services. At present, CWDM provides a variety of interface rates below 2.5g, which can meet the rate requirements of different users and improve the actual transmission capacity of optical fiber.
CWDM can adapt to a variety of network complex environment, from the core bureau to the transmission of different services between multiple branches, to the convergence and client access network construction. CWDM access to transmission of multiple data services can achieve non-interference, and can make the customer’s business transmission reliable and secure guarantee. CWDM forms a passive optical network with EPON or APON and connects with DISLAM to realize the integration of various services, providing many good practical solutions for fiber to building users (FTTH).
In order to implement point-to-multipoint applications in optical networks, we need a large number of optical fibers to form a star topology. Based on the shortage of fiber resources, we can use a light path through each branch needs to transmit data, by defining wavelength to distinguish between the user and the business in advance, in various business nodes using CWDM multiplexing equipment, multiplexing equipment and terminal points in each region multiplexing transmission of the business and the business of transmission can be realized up and down. This method can be used to solve the transmission of different services between the central node and multiple branch nodes, thus implementing the logical star structure with a simple physical light path.