I. Introduction
Blind equalization and source separation is a wide field of research. Initiated by the works of Sato [2], many authors have followed, e.g., Godard [3], Jutten and Herault [4], Treichler and Agee [5], Shalvi and Weinstein [6], Cardoso [7], and Comon [8]. Many solutions are tied to the optimization of certain cost functions (also known as contrasts [8]), e.g., cumulant-based methods [7], mixed second-order/fourth-order methods, augmentations with independence constraints (related to finding beamformers to all sources) [9], characteristic function-based techniques [10], [11], etc. An overview of blind source separation techniques and blind equalization can be found in [12]–[14].