Abstract
High-speed rail (HSR) communication has always been an attractive research topic with the continuous progress of transportation systems and communication technologies. Recently, Hyperloop has emerged as a candidate for very high-speed transportation systems. Because of its outstanding potential, Hyperloop can usher in a new transportation era with several attractive features. Developing suitable communication system solutions is crucial to bring this promising technology closer to reality. In addition, the Hyperloop communication system is essential to support monitoring-and-controlling services and deliver communication services inside its capsules/pods. Throughout this article, we overview Hyperloop technology and discuss its general characterization to recognize and estimate its relative position among the current HSR communication systems. Then, we investigate different attributes of the communication system, including network architecture, quality-of-service (QoS) requirements, and critical challenges to implement a reliable communication system. With the high speed of the capsule/pod and the system's unique structure, severe Doppler effect and frequent handover may considerably affect the operation of the communication system. Because Hyperloop is a recent development, it is necessary to study the existing HSR communication technologies to determine whether they can establish robust communication links for the Hyperloop system and deliver data with the required QoS. Furthermore, we provide technical details of the current HSR technologies and related research. Subsequently, we present the recent advances in the Hyperloop communication system with classification depending on whether it is a radio-, network-, antenna-, or software-based solution. Finally, we propose future research directions that can promote an improved communication performance.