I. Introduction
According to statistics, fall accidents have become the second leading cause of unintentional injuries[1]. Most fall-related deaths occur in people over the age of 65, so fall has become one of the important factors endangering the elderly. Facing the increasing global aging problem, developing a set of portable, accurate, and real-time fall detection system has extremely important economic and social value. In fact, over the past few decades, people have been creating new technologies to realize more effective human behavior perception and analysis. The traditional technical methods mainly include the following ways: computer vision [5], infrared technology [6] and special sensor technology [7]. However, most of these methods need to deploy expensive additional devices, and there may be a risk of divulging customer privacy. Some traditional detection methods require wearables and are thus not user-friendly.