The growing demand in wireless communication systems for multimedia services requires the use of multi-carrier transmission schemes with high transmission rates. Orthogonal Frequency Division Multiplexing (OFDM) offers high data rates with a high spectral eficiency and low multi-path distortion.

In order to obtain high spectral eficiencies, multilevel modulation with non-constant
amplitude is needed and therefore coherent detection is generally used, which requires an accurate channel estimator to track the channel fading process. Accurate channel estimation in OFDM systems can be a dificult task, especially under extreme conditions of time variation and frequency selectivity. Iterative techniques are a good solution, both in fast and slow fading environments becouse they require less pilot overhead. In addition Iterative channel estimation can take advantage of the information provided by an iterative decoding process such as the ones used to decoded Bit Interleaved coded Modulation (BICM) and Turbo-Codes. Joint iterative channel estimation and decoding can significantly reduce the complexity of receiver and maintaining a high level of performance.