Motion characteristics
Mobility is the communication that keeps the object in a moving state, so it must be wireless communication, or a combination of wireless communication and wired communication. The propagation conditions of radio waves are complicated. Because moving objects may move in various environments, electromagnetic waves will produce reflection, refraction, diffraction, Doppler effect and other phenomena in the propagation process, resulting in multipath interference, signal propagation delay and broadening.
The noise and interference are serious. In urban environment, automobile spark noise, all kinds of industrial noise, intermodulation interference, adjacent channel interference and co-frequency interference between mobile users, etc. The system and network structure are complex. It is a multi-user communication system and network, and users must not interfere with each other and work in harmony.