Subspace-Based Blind Channel Identification for Orthogonal Modulation

We consider blind channel estimation for orthogonal modulation and its variants - which include pulse position modulation (PPM) and frequency shift keying (FSK). While equalization of this modulation format has been given some attention by the research community, little attention has been paid to techniques for (blind) channel estimation in systems employing orthogonal modulation. We extend classical subspace-based blind techniques in a way that is suitable for use with orthogonal modulation. Unlike classical subspace-based blind channel estimators, however, our scheme does not require oversampling and/or multiple sensors. After introducing the system model, we present the proposed method of channel estimation, and include conditions under which the scheme is valid. We conclude with several simulations.