Sdh Access Equipment, Network Interface And Intelligent Multiplexing

Against the background of the application of Synchronous Digital Hierarchy (SDH), the paper mainly discusses the design principles and chief techniques of an Add-Drop Multiplexer (ADM), one of the SDH equipments.Firstly the basic principles of SDH are simply introduced. And the basic functions of ADM are described, based on which a macro design project is set up. The key technologies of SDH such as asynchronous mapping, pointer processing, Virtual Concatenation (Vcat) and Link Capacity Adjustment Scheme (LCAS) are applied in this system with which the primary block signal E1 and Ethernet data can be accessed through SDH network together.Secondly the principles of every subsystem are discussed in detail. The technologies of asynchronous mapping, pointer processing and Ethernet over SDH are deeply studied. The modules of overhead processing, mapping and multiplexing and Ethernet over SDH are designed.Finally the technique of intelligent multiplexing is explained, which includes LCAS and auto protection switching (APS).Because the system is designed in modules, and some highly integrated special purpose chip are used, the structure of the system is very concise and the management is very convenient.