Modeling an E1/TU12 mapper for SDH systems

The mapping problem of PDH signals into SDH systems is analyzed. Plesiochronous Digital Hierarchy (PDH) is a quasi-synchronous system used for multiplexing and transmission of voice(phone) and data, while Synchronous Digital Hierarchy (SDH) is a synchronous multiplexing system. Many differences beyond the synchronization make these standards difficult to integrate. We will present some of these problems and propose a method to help to understand and overcome such difficulties. An E1/TU12 mapper will be used as an example of the technique. The problem is analyzed by simulations using the object-oriented language Smalltalk (ST). ST was adopted because of its peculiar object model which makes development easy and fast.