Two Blind Adaptive Mobile Receivers in Time-Hopping PAM UWB Impulse Radio System

Abstract

This paper deals with the design of blind mobile station (MS) receiver for time-hopping (TH) ultrawide-band (UWB) impulse radio (IR) system employing antipodal pulse amplitude modulation (PAM). In the presence of multipath fading channel, batch-mode minimum output energy (MOE) receiver, as well as a blind channel estimator, is first developed. To reduce the computational complexity, we propose two blind adaptive algorithms to determine the weight vector of the MS receiver. The rational of the algorithms premises on iteratively maximizing the minimum possible receiver's output energy. The first (indirect) approach is derived by first developing an adaptive blind channel estimator, then the updated channel impulse response (IR) is used to calculate the MS receiver's weight vector. Meanwhile the second (direct) method jointly and iteratively optimizes the weight vector and channel IR to improve system performance. Simulation results demonstrate convergence of both algorithms.Moreover, the algorithms are shown to be robust to multiuser interference (MUI) and near-far problems.