An iterative channel estimation and interference cancellation procedure with partial decoupling of observation for coded transmission

We propose a new iterative channel estimation and symbol detection procedure for multipath fading channels and a coded packet oriented transmission system by using a training sequence and decoded data. The general block coded communication system and the general block coded CDMA system are considered. The channel estimation corresponds to the pseudo-inverse type. For every symbol, the detection takes into account just the part of the observation which contains the considered symbol and has length corresponding to the channel memory length. The previous part of the observation is excluded from the total observation for making the channel estimation for this symbol. Thus there are as many symbol detections as channel estimates. Using the modified pseudo-inverse channel estimation has reduced the complexity. For the feedback loop, the soft or hard decision of the channel decoder output is employed. An application of this procedure to the UMTS-TDD system shows that an important performance improvement is obtained.