An integrated survey in Optical Networks: Concepts, Components and Problems

In optical networks, a connection is used to transmit data between source and destination nodes via lightpaths. The optical signal transmitted along a lightpath requires cross-connect switches (OXCs) and telecommunication carriers to switch high-speed optical signals in a fiber optic network. As a signal propagates from the source to the destination, the signal quality is continuously degraded by optical network components and impairments. Wavelength routing networks have two main problems: network design (fiber topology) and traffic requirements (traffic matrix). The network design problem is divided into lightpath topology design (LTD) and routing and wavelength assignment (RWA) problems. The RWA problem is more important for increasing the effectiveness of optical networks. The lightpath routing sub-problem requires determining the physical links for each lightpath that consist of optical channels. The wavelength assignment (WA) sub-problem requires determining the wavelength that each lightpath uses, i.e., assigning a wavelength to each lightpath in the logical topology such that wavelength restrictions are obeyed for each physical link. In this article, we discuss the important concepts of optical networks and the factors that affect in RWAs directly or indirectly.