I. Introduction
Smart mobile devices have been the pivot for personal services. Many diverse sensors around the mobile device will enable highly proactive services with the help of a lot of personal context-aware applications, e.g., u-Trainer, dietary monitoring, and health monitoring. In such PAN-scale sensor-rich environments, mobile devices will serve as the common computing platform which accommodates diverse wearable sensors or nearby space-embedded sensors, e.g., e-watch, sensing garments, and textile electrodes in bed sheets. Then a mobile device will usually run multiple context-aware applications at a time which mainly focus on continuous monitoring of users' context with diverse sensors [19]. The context monitoring often requires multi-step and complex processing over multiple devices at the same time, e.g., for a ‘running’ context, sensing of body-worn accelerometers, filtering, FFT-based feature extraction, and classifying the features through a decision tree [20].