I. Introduction
One of the main application areas for ambient intelligent systems is to sense objects of interest in the respective monitoring environment in a non-intrusive manner [2]. Human sensing is a concept that applies in a wide range of applications in ubiquitous computing [3]. For instance, automatically switching on and off a light based on human presence is a simple application of human sensing in a smart home. In general, the concept of human sensing can be classified into human presence detection, human counting, human localization, human tracking and human identification [2].