DWDM系统中OSNR的定义以及设计参考WDMNetworkdesign.pdf

WDM Network Design Date: Feb 7, 2003 By Tony Antony, Ashwin Gumaste. 1. Introduction to Optical Design 2. Factors That Affect System Design 3. Effect of Chromatic Dispersion on Transmission Length and Induced Power Penalty 4. Design of a Point-to-Point Link Based on Q-Factor and OSNR 5. Calculation of Q-Factor from OSNR 6. Margin Requirements 7. Design Using Chromatic Dispersion Compensation 8. OSNR and Dispersion-Based Design 9. Frequency Chirp 10. Effects of FWM and XPM on Long-Haul Design 11. PMD in Long-Haul Design 12. Examples 13. Summary 14. References Introduction to Optical Design A network planner needs to optimize the various electrical and optical parameters to ensure smooth operations of a wavelength division multiplexing (WDM) network. Whether the network topology is that of a point-to-point link, a ring, or a mesh, system design inherently can be considered to be of two separate parts: optical system design and electrical or higher-layer system design. To the networking world, the optical layer (WDM layer) appears as a barren physical layer whose function is to transport raw bits at a high bit rate with negligible loss. Most conventional network layer planners do not care about the heuristics of the optical layer. However, such lapses can often be catastrophic. Until the bit rate and the transmission distance is under some bounded constraint (for example, small networks), it is often not important to consider the optical parameters. However, as the bit rate increases and transmission length increases, these optical parameters have the capability of playing truant in the network. A network planner must consider the affecting parameters and build a network that accommodates the impairments caused by the optical parameters. This chapter explores some of the design constraints involved in the WDM network design. Consider an optical si