An iterative channel estimation algorithm and receiver structures based on Turbo principle were proposed for estimating channel parameters in a TH-UWB system under the realistic UWB channel model from IEEE 802.15. In each iteration

the soft-output of decoder is fed back to the channel estimation module

and used as the prior information

which means no training sequences are used. The performance of the proposed iterative channel estimation algorithm in UWB dense multipath channels is evaluated. The numerical results show that the new algorithm can efficiently estimate channel parameters

and moreover

can efficiently track the time-variant of the channel.