This article aims to propose a novel approach for unobtrusive vital sign acquisition based on contactless measurements in the context of Ambient Assisted Living-AAL. We focus on the utilization of baseband Ultra-Wide Band (UWB)-Sensors for distinctive preprocessing by using refractive index and dielectric constant (or complex permittivity) of multidimensional materials, complex permittivity of body tissues and feature-extraction methods for the recognition of vital signs hidden within multidimensional reflection datasets. The method of calculating the refractive index and dielectric constant of multidimensional material is based on sampling the deflection and the loss of electromagnetic waves in the experimented multilayer material. After a brief description of the application context, coherent user demands and the importance of robust data acquisition as a precondition for the achievement of prediagnosis functionality, physical fundamentals and the applied principles of spatial and temporal data mining are described. Preliminary experiments prove relevance of the proposed solutions and prepare final tests in a real world scenario.