Transportation needs to be in constant communication with the

outside world. Take cars for example. The position is calculated

using satellites, music is provided through radio waves and the

internet is accessed via mobile networks. All these forms of

communication allow cars to perform complex tasks and

become autonomous. A new mode of transportation with a lot of

potential is the Hyperloop, whereby a vehicle, or pod, levitates

and travels through near-vacuum tubes. As a result, these pods

can transport people and cargo at speeds of 1000 km/h. The

Hyperloop pod also requires a constant connection to

infrastructure, internet and control center. Therefore, like any

other mode of transportation, the Hyperloop requires an

appropriate communication system. Delft Hyperloop and

Globalinternet joined forces to investigate the challenges and

alternatives to achieve this.

Communication in transportation has two important functions: comfort and safety.

The communication network allows the pod and its passengers to be connected

to the internet. This greatly improves the passenger experience during the trip.

Communication is also used to exchange data between the pod, infrastructure

and control center. Information concerning location and speed is shared and

used to guide the Hyperloop pods. A reliable communication system enables

stable guidance of the pod and thus improves the safety of all passengers.

A communication system requires that certain system characteristics are met in

order to function properly. The most important system requirements are:

• Bandwidth: The rise of smartphones and the Internet of Things has

significantly increased the number of devices connected to the internet.

This article was first published in Hyperloop Connected, a platform built by the Delft Hyperloop with the aim to maximally

contribute to the development of Hyperloop technology by sharing the knowledge acquired while working on a

Hyperloop team. For more information, visit: http://hyperloopconnected.org/

Communications in a

near-vacuum environment. Hyperloop Communication System

Enough bandwidth should be available for Hyperloop communication to

facilitate all these devices.

• Data rate: The internet demand of passengers grows every year. To provide a

comfortable experience, a sufficient internet speed is necessary. Keeping the

growth rate in mind, a minimal data rate of 300 Mbit/s is required.

• Latency: In communication systems there is always a delay between sending

out a signal and receiving the response. If the delay becomes too large

communications are less effective, and the safety is reduced. Therefore, a

maximum latency of 50 milliseconds is set for critical services (Sniady & Soler,

2013).

Challenges

The communication system of the Hyperloop shares similarities to other modes of

transportation. However, the Hyperloop encounters some new challenges mainly due

to the unique characteristics such as the steel tube, low pressure and high speeds. The

design of the Hyperloop communication system needs to overcome these challenges

to provide a reliable and high-speed connection between the Hyperloop pod and

infrastructure. A brief overview of the challenges faced is given below.

1. Tube: The Hyperloop tube forms a unique environment. The thick tube is made

of steel preventing the use of wireless communication. Moreover, the near-

vacuum environment makes maintenance more difficult.

2. Handover: The Hyperloop pod requires a constant connection to the

infrastructure. Due to the mobile nature of the pod, the connection sometimes

needs to be transferred to a new part of the tube. This transfer is called a

handover. The Hyperloop travels at speeds over 1000 km/h which makes

handovers frequent. The Hyperloop communication networks needs to ensure

reliable handovers to create a constant connection with the outside world.

3. Doppler effect: One of the phenomena present when travelling at high relative

velocity is a shift in frequency. This phenomenon, called the Doppler effect,

needs to be addressed for Hyperloop communications.

Communication Technologies The requirements and challenges of the Hyperloop communication system have

been identified. Different technologies can be used to overcome the challenges and

meet the requirements. These technologies make use of several parts of the

electromagnetic spectrum. The electromagnetic spectrum is shown in Figure 1. Radio

waves are traditionally part of communication systems such as GPS and phone

networks. However, due to the lack of available bandwidth and low data rate, radio

waves are not considered for next generation communication systems. Therefore,

other parts of the electromagnetic spectrum are looked at.

The millimeter wave band offers much more bandwidth and allows for high-speed

connections. The main drawback of using millimeter waves is the lower range

compared to radio waves. Another drawback is the inability to penetrate materials

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such as concrete.

The optical spectrum is another possible option. This spectrum includes ultraviolet,

infrared and visible light. Optical communication has an almost infinite bandwidth

and data rates of 100 Gbps can be reached (Tsonev et al., 2015). Atmospheric

effects heavily influence the optical spectrum due to attenuation and therefore limit

the range.

Design of the communication system

Communication between the Hyperloop pod and tube takes place inside a near-

vacuum environment. These unique conditions alongside the system requirements

Figure 1: Electromagnetic spectrum

Figure 2: Overview of the optical wireless communication system in the Hyperloop

make optical wireless communication the preferred communication technology to

use. Methods such as Light Fidelity, or Li-Fi, and Free Space Optical Communication,

or FSOC, are suitable for use because the atmospheric losses in the tube are minimal.

Li-Fi is a communication system which rapidly modulates the intensity of LEDs to

transfer data at high speeds. FSOC uses the modulation of laser tracking beam to

establish a long-range and high-speed connection.

The tracking beams are unable to provide a long-distance connection due to the

small size of the tube. Therefore, Li-Fi is chosen over FSOC for the pod to infrastructure

communication.

A schematic overview of the Hyperloop communication system is shown in Figure 2.

Internet and control data is sent via fiber optic cables to Hyperloop base stations

located along the tube. At regular intervals, the cables enter the tube. An LED

transmits the signal to the Hyperloop pod moving at 1000 km/h. A traditional Wi-Fi

router enables internet access for all the passengers.

Conclusion The Hyperloop communication system provides both safety and passenger comfort.

But the communication aspect is made more difficult by internal and external

challenges. Using combined wired-wireless communication system and optical

wireless solutions, a reliable and high-speed communication system is created.

Optical wireless communication provides low-latency communication with almost

unlimited bandwidth. However, some aspects that have not yet been evaluated to a

high enough degree require more research. The range of optical communication is

limited which increases the frequency of handovers. By implementing a system with

visible light and a system with infrared, the range is increased. Moreover, the two

systems working independently incorporate redundancy into the design.

Handovers are an integral part of every mobile communication system. The increased

range of infrared Li-Fi systems lowers the frequency of these handovers. Nonetheless,

the issue of handovers remains one of the biggest challenges of the communication

system. An in-depth review of computing power, frequency and handover protocols

is required for the implementation of the Hyperloop.

Collaboration with Globalinternet

The Hyperloop communication system is designed in collaboration with

Globalinternet. Globalinternet provides innovative communication and internet

solutions worldwide. Delft Hyperloop and Globalinternet both investigated the system

requirements and challenges for Hyperloop communication. Both parties sat together

to combine their finding into the requirements and challenges as presented in the

article. The next step in the collaboration was a brainstorm session to come up with

different solutions. By bundling the knowledge of Globalinternet and Delft Hyperloop,

a concept design for the Hyperloop communication system was proposed. We look

back at a very pleasant collaboration with a lot of enthusiasm from both parties!

For more information about Globalinternet, please visit: https://www.globalinter.net

Sniady, A. & Soler, J. (2013). Performance of lte in high speed railway scenarios.

Tsonev, D., Videv, S., & Haas, H. (2015). Towards a 100 gb/s visible light wireless access

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