When we choose the fiber optic devices for our fiber optic networks, cost is necessary factor that we have to consider, almost all the consumers want good quality and affordable products for their network, but there is a point we need to know that is not reasonable to judge which costs of system or technology is more expensive only by the fiber optic devices. Therefore, this page will focus on DWDM system and SDH networks.
The fact that channel spacing’s and frequency stability of CWDM results that EDFAs could not be utilized. As though the DWDM can. The DWDM EDFA Booster amplifier (shown as the figure) is a cost efficient solution for DWMD fiber optic link amplification which operates at the transmission side of the link. SDH EDFA Booster Amplifier is designed for the SDH applications which installed after the optical transmitter to increase transmission distance for single wavelength optical module system.
As we know, the fiber optic module is integrated EDFA, it is divided into optoelectronic integrated EDFA and optical gain module, which has the characteristics of small size, low power consumption and easy to use. Can be installed in various systems easily according to users requirements, such as SDH frame, CATV machine box and DWDM system chassis. In fact, it is the specific infrastructure not only in DWDM system but also SDH networks. Although DWDM EDFA is more expensive than SDH EDFA from the diagram, can we say that the cost we need for DWDM system application is more expensive? No, the answer is negative.
DWDM are technologies that improve the capability of optical cable in carrying data by multiplexing many channels of wavelengths, and SDH are technologies that are used as a buffer interfacing layer for higher layers access the huge capability of Optical transmission system. DWDM is multiple signal transmit over a single fiber called DWDM or Different frequencies (colors/wavelengths/lambdas) for different connections over the single fibre. Full featured DWDM equipment can comprise the same range of cards as SDH. They can support fully configurable cross connect features. DWDM technology provides very high bandwidth long haul inter-connect links. Let’s say in microwave or fiber of point to point terms, SDH equipment is used when you need to connect several site/clients towards star topology. It is conventional TDM based and traffic is dropped and collected in SDH and rerouted towards desired point destination in form of electrical or light signals. Where as DWDM is mostly used at the core and is of fiber, traffic gathered from different equipments (SDH or others) and transported over fiber for analyzing billing or interpretation.
Due to the different characteristics between DWDM and SDH and then they cannot be compared logically. A DWDM ring may be equivalent to 40 SDH rings. But we can compare two rings of different capacities. Well, the only cost savings we will notice is that on the same fiber, we will be able to send multiple lambdas (SDH equipments / routers), using DWDM. SDH costs will be the same and you will add DWDM systems costs, maybe tens or hundreds of thousands of dollars and it all depends on the complexity. If you do not use DWDM, you will have to install more fibers for each SDH link. Well, fiber installation costs are high and they depend on the distance and geography. If the operators could transport the data using only SDH which would imply bigger costs for fiber infrastructure, more power consumption. In fact, there are also so many other elements in the network that for monitoring the network, more workers would be needed, they are both in monitoring and field intervention. Except this, DWDM systems are usually more reliable than SDH. So maybe the cost of maintenance would be cheaper. However, you need to keep in mind that DWDM systems amplification can save the use of many SDH repeaters or regenerator. In a word, if you wonder that which infrastructure costs are more reasonable, judge not only by the devices’cost, you need a combination of various factors to have a decision.