Joint channel estimation and fuzzy adaptive filter techniques in DS-UWB systems

In this paper, we propose a method that joints channel estimation and interference cancellation for direct-sequence ultra-wideband (DS-UWB) systems. For the channel estimation, we apply an expectation-maximization algorithm which adopts an iterative computation of maximum-likelihood parameter estimates, with a few number of iterations, the channel coefficient in each finger of Rake receiver can be efficiently estimated. A fuzzy step size LMS algorithm that adopts a variable step size for the interference cancellation is proposed in the multiuser transmission environment. To achieve a better performance, the joint of expectation-maximization (EM) algorithm and fuzzy adaptive filter is presented for the DS-UWB systems and the simulation result is investigated as well.