The fundamental framework for today's digital communication systems is given by the information theoretical considerations of Shannon. It was soon discovered that due to the constraints of real world applications a joint design of the different components of the communication system, e.g., source coding, channel coding, and modulation, is benficial if not essential. A breakthrough in closely approaching
the information theoretical limits at a moderate and manageable complexity has been the discovery of Turbo decoding for concatenated channel codes. The underlying Turbo principle of exchanging statistically independent extrinsic information between components has been extended to other concatenations of receiver elements. In this thesis the concatenation of demodulation of higher order modulations and channel decoding, called bit-interleaved coded modulation with iterative decoding (BICM-ID), as well as the concatenation of channel decoding and soft decision source decoding, known as iterative source-channel decoding (ISCD), are investigated. To jointly exploit the inevitable redundancy in all three considered components in one Turbo process the novel Turbo DeCodulation (TDeC) scheme is developed.