Tera Hertz Communication For Vehicular Networks

Mahmoud Elkholy 37-2400 Omar Youssef 37-5566

The Faculty of Information Engineering and Technology, The German University in Cairo

Cairo, Egypt February 24-2020

Outline:

» Introduction and Background

» Advantages and Disadvantages of THz

» Vehicular Communications

» Types of Vehicular Communications

» Benefits

» Challenges and Limitations

» Conclusion

» References

• The following figure shows how the THz band is located in the electromagnetic spectrum.

• THz frequencies are between the microwaves band and the infrared waves.

• It ranges from 0.1 THz to 10 THz.

THz Band

Why the need for THZ ?

Wireless data rates are expected to be around 10Gbps or even more within the upcoming decade. The realization of such high data rates is unlikely with the currently licensed bands in the spectrum. Therefore, it is clear that such high rates could only be achieved by employing more bandwidth. The large amount of spectrum available beyond 275 GHz makes this frequency range attractive for a new generation of wireless communication systems.

Advantages:

• Higher Bandwidth

• Higher Security

• Increased Capacity

• Less Interference

Disadvantages:

• High Path Loss

• Large Antenna Arrays needed

• New Coding Schemes

• New Modulation Techniques

Channel Modelling in THZ:

• The TeraHertz band has shown high wave extinction due to molecular absorption

• The total attenuation that an EM wave suffers from due to molecular absorption when traveling over a distance d is given by :

l𝐴l (𝑓, d) = exp[𝛼molec (𝑓,𝑇K,𝑝)d]

where, “𝛼molec” is the molecular absorption coefficient which depends on the fraction of water in the air, “𝑇K” is temperature in kelvin , “d” is the distance travelled , “f” is frequency of the wave , “A” is the amplitude.

Vehicular Communications

THz band communication can be used in advanced vehicular communication networks. Vehicular communications has been one of the main fields of research in the last years due to the rising developments of smart cities and smart cars. The automotive industry is evolving towards connected and autonomous vehicles that offer many benefits, such as improved safety, less traffic congestion, less environmental impacts and lower capital expenditure. A key enabler of this evolution is vehicle-to-everything (V2X) communication.

Levels of Car Automation:

» Vehicular Communications can be divided in 3 parts:

• Vehicle-to-vehicle (V2V)

• Vehicle-to-infrastructure (V2I)

• In-car communications

Vehicle-to-vehicle (V2V):

• It is where neighboring/cooperating vehicles share perceptual data with each other using THz bands for high-rate and low-latency communication.

• The shared data can be used to create a satellite view of the surrounding traffic.

• Each vehicle can use the shared data to extend its perception range, which enables it to reveal hidden objects ahead or in its blind spots and therefore avoid collision with other vehicles.

Vehicle-to-infrastructure (V2I):

• The infrastructure or roadside units (RSUs) gather sensing data about the vehicles and the surrounding traffic. The sensed data can be used to provide real-time maps of the environment.

• These maps can be used by the transportation control system for congestion avoidance, general warnings and overall traffic efficiency improvement.

• The infrastructure can also be used to provide high-rate Internet access to vehicles for autonomous driving and services such as media download and video streaming.

In-car communications:

• Communication among the component systems of

the vehicles is via THz bands instead of low-rate technologies such as Bluetooth

• THz bands can provide ultra-high rate and short range in-car communication for autonomous driving systems

-Example: Monitoring of car functions.

» Benefits of V2X Communication:

• Transportation Safety

• Traffic Efficiencies

• Infrastructure Savings

• Smart Green Environments

» Challenges and Limitations:

• Internet Protocols: Existing internet protocols (TCP/UDP) showed poor performance in Inter-Vehicle Communication (IVC). New transport protocols are proposed and need to be developed such as Vehicular Transport Protocol (VTP) and Mobile Control Transport Protocol (MCTP).

» Security: To avoid any system manipulation high security protocols should be considered, in addition privacy of users needs to be protected from any unauthorized access.

• Safety: Vehicular communication systems safety is the highest priority since it deals with human life. Any malfunction in IVC system may cause a threat to involved people

• Growth: Only few cars now are equipped with vehicular communications system due to long life time of existing cars so the growth of the equipped cars will be slow. Therefore the equipped cars should be satisfying for the consumer.

» Conclusion:

The connected car market is already a mainstream reality. It is leveraging cellular connectivity to provide telematics, connectivity and improved use experience. The vision to go beyond cellular connectivity towards V2X communication is also becoming a reality.

» References:

• Mumtaz, S., Miquel Jornet, J., Aulin, J., Gerstacker, W. H., Dong, X., & Ai, B. (2017). Terahertz Communication for Vehicular Networks. IEEE Transactions on Vehicular Technology, 66(7), 5617–5625.

• Qualcomm, “5G NR based C-V2X”; https://www.qualcomm.com/media/documents/files/5g-nr-based-c-v2x-presentation. pdf, accessed 3 Mar. 2019.