In our previous cognition, WIFI was only used for surfing the Internet. In other words, the only thing that allows us to surf the Internet is the electromagnetic wave signal, which does not have the same perceptual computing ability as the equipment. It seems a bit impossible to let the WIFI signal on the Internet detect the state of the human body like a camera or AI wearable device. However, as we said just now, WIFI signals are electromagnetic waves, and so are light, radio, microwave, infrared and ultraviolet rays. Since some "brothers and sisters" who are also electromagnetic waves can do it, why can't you do WIFI?

Therefore, scientists and professors with sudden inspiration have studied the technical realization of using WIFI signals to detect people's falls and breathing. This arduous scientific and technological research is the result of the joint efforts of our Peking University professor Boya, who has been deeply involved in this field for more than 20 years, and Zhang Daqing, an academician of the European Academy of Sciences. Wit-readers looked at the data and said, of course, this is not an open-minded idea. It belongs to the technical category of pervasive computing, and the research direction that falls in the perception layer is called ubiquitous perception. And the technical concept of pervasive computing, as early as 30 years ago, Mark weiser, Mark? Yaser, the chief scientist of Xerox PARC Research Center and the father of pervasive computing, talked about this point forward-looking in his classic article.

This time, Professor Zhang Daqing's team used WiFi signals to magically identify people's falling behavior under normal and natural indoor living conditions. At present, in academic circles, the identification technology of continuous behavior is the first in the world. In addition, WIFI wireless signals can not only detect falls in real time, but also sense physiological parameters such as breathing, heartbeat and sleep state. This can stimulate the imagination. Every scene in our life-whether it is home, office, car, hotel, hospital, warehouse and other crowded places-should be used.

From a technical point of view, taking the wireless sensing paper published on UbiComp on October 20 16 as an example, Zhang Daqing and others introduced the Fresnel zone model derived from optics into the field of wireless sensing, revealing the mechanism of when WiFi signals can detect people's breathing. Fresnel zone is a concept derived from optical theory, which means that a series of concentric ellipses focus on two points where devices (such as WiFi signal transmitters and receivers) send and receive signals.

It is the basic model based on Fresnel zone that allows scientists to further consider the reflection characteristics of electromagnetic waves and the frequency diversity of WiFi signals, so that the expanded model can capture the tiny movements of human bodies at the sub-wavelength level, thus laying a theoretical foundation for sensing the millimeter-scale behavior of human bodies with WiFi signals. It can be said that this ubiquitous computing technology, which uses WIFI to detect people around it, gets rid of the traditional manual operation and the conventional Internet of Things operation that uses remote control and other devices to adjust the wind speed and intensity of air conditioning fans. In other words, it just pushes the current level of Internet of Things to a new height.

Of course, pervasive computing is not an independent technology, but a cross-cutting technology, involving the realization of artificial intelligence technology and Internet of Things technology. If we think that the well-known era of artificial intelligence has arrived, then there may be an unknown era, that is, the era of pervasive computing has also arrived. Wit guests welcome you to the new world, whether we have already felt it or not. Oh, by the way, pervasive computing was originally designed to let us enjoy ubiquitous computing unconsciously. Before we realized it, a new era had arrived.