This paper outlines the basic principles of multiplex techniques for multimedia transmission over existing or upcoming mobile systems. After problem definition we evaluate the requirements for an additional layer. According to the two basic tasks, adaptation and multiplexing, this new layer is divided into two sub-layers. Existing multiplex techniques are discussed and a rather new method is presented with an appropriate decoding algorithm. For adaptation the principles are discussed and a special scheme is presented. A summary and an outlook to further strategies for multimedia transmission over error prone channels will conclude this paper.