I. Introduction
With the advances of electronics and communication technologies, IoT devices around us is increasing rapidly. As IoT-enabled devices can communicate and collaborate with each other, they can be used to realize smart house as a whole, where a number of IoT devices collaborate with each other to realize a better living space, not just as a collection of independent devices. For instance, air conditioner may collaborate with window, so that when an air conditioner is turned on, the window in the same room is closed to keep the indoor temperature. Such collaboration of IoT devices can further be extended to a city level, which we often refer to as smart city.