1 Introduction
A smart mobile device expands its role as a gateway for personal pervasive services. It will form a PAN-scale sensor rich environment with diverse wearable or space-embedded sensors, for example, e-watch, sensing garments, and textile electrodes in bed sheets [18], [23]. As a common platform, a mobile device will accommodate various personal context-aware applications, for example, dietary monitoring, life assistant [28], and elderly support [29]. The applications monitor user contexts continuously [16], and provide highly proactive and situational services. The context monitoring often requires multistep complex processing across the mobile and sensor devices (e.g., for a “running” context, acceleration sensing on multiple body-worn sensors, FFT-based feature extraction, and classifying the features through a decision tree [17]).