  Hyperloop is a sonic-speed train transporting passengers and freights in a
vacuum tube without friction or air resistance. Two essential communications in
such vehicles are central control connection and real-time dispatching, also an
optional data connection for passengers is welcome. The high mobility of
Hyperloop imposes a severe impact on the performance of wireless communication
links. Therefore, designing a new wireless communication system is necessary to
cope with the challenges. Motivated by the importance of doppler spreading,
this paper focuses on the characterizations of the wireless channel in
Hyperloop and then analyzes the performance degradation of the radio link.
Afterward, a comprehensive overview of the present railway communication
technologies as potential solutions for the Hyperloop project and a detailed
discussion of their cons and pros are provided. It is shown that current
communication technologies are not satisfactory for this scenario. Finally,
this paper concludes the key points that need to be considered in future
railway communications systems in order to overcome the Hyperloop communication
challenges. So, we open up a new issue that Hyperloop communications require
designing a novel method or improving the existing technologies or a
combination of different techniques (some of these techniques are mentioned).
