I. Introduction
With proliferation of IoT technologies, smart devices are now closely connected to our life. Many of these devices such as smart phones, wearable devices and tablets greatly improve the quality of our life. In particular, wearable devices have become more and more popular in recent years [1]. There are diverse areas of applications developed for wearable devices [2] such as communications, entertainment, sport and lifestyle. Among these, lifestyle is considered as the dearest to our daily life, especially in a smart home environment.