The design of future communication systems with high throughput demands will become a critical task, especially when sophisticated channel coding schemes have to be applied. LDPC codes are one of the most promising candidates because of their outstanding communications performance. One major problem for a decoder hardware realization is the huge design space composed of many interrelated parameters which enforces drastic design trade-offs. Another important issue is the need for flexibility of such systems. In this paper we illuminate this design space with special emphasis on the strong interrelations of theses parameters. Three design studies are presented to highlight the effects on a generic architecture if some parameters are constraint by a given standard, given technology, and given area constraints.