Modelling the problematic coexistence of two communication technologies in smart vehicles
Daejeon, November 2019
Though complementary, the two available communication protocols for autonomous cars can easily interfere with each other and among themselves.
Automobiles have evolved to become autonomous driving vehicles with wireless connectivity and a myriad of features. However, as of today, smart vehicles can only employ two communication technologies that coexist in a small portion of the spectrum of available frequencies. To prevent communication problems caused by interference between vehicles operating at very similar frequencies, a research team from Electronics and Telecommunications Research Institute (ETRI) developed a detailed mathematical model to analyze various test cases and fill a current knowledge gap.
Modern cars have become very capable smart mobile systems that provide automated driving, entertainment, and traffic information to make the experience of driving safer and more productive and enjoyable. These features rely on the successful communication between the cars, and between the car and mobile devices, cellular towers, and other infrastructures. However, cars are currently only allowed to communicate over a small range of frequencies around 5.9 GHz. Two main protocols have been developed and tested for this communication, long-term evolution (LTE), also known as 4G, which is commonly used in smartphones; and Wireless Access in Vehicular Environments (WAVE), which was specifically developed for vehicles communicating while driving at high speed.
These two protocols are complementary and cover each other’s limitations. However, this comes at a price. “Signal interference occurs when different communication technologies coexist in the same service band,” explains Dr. Yoo Seung Song, the leading researcher. “This motivated our research group to identify and analyze the resulting frequency-interference problems.” Although the interference that occurs when two transmissions are carried out at very similar frequencies (“adjacent channel interference”) is a widely studied topic among virtually all existing communication technologies, no studies focusing on the potentially problematic coexistence of LTE and WAVE had been published.
To account for this, the ETRI researchers recently published a paper in ETRI Journal presenting a detailed mathematical model that was used to analyze various real-life test scenarios for vehicles interfering with each other while employing various combinations of WAVE and LTE (including WAVE-to-WAVE and LTE-to-LTE cases). In this model, a vehicle, called the “victim”, suffers from interference caused by the transmitted signals of another vehicle, called the “aggressor”. Their approach covers all possible combinations of LTE and WAVE for cases in which the victim wants to communicate with another vehicle or with a structure (such as a cellular tower).
Using this model, the researchers determined the minimum requirements for vehicles to maintain successful communication using the two protocols under different conditions, such as the communication environment, transmitted power, and most importantly, the distance from the victim to the aggressor and from the victim to its target. Based on these factors, they also determined the maximum transmission rates possible, which is a key parameter when developing applications and communication systems for vehicles.
“In the future, autonomous vehicles will provide various services through different communication technologies. Without frequency interference, the stability of autonomous vehicles will be greatly improved. In addition, car users will be able to enjoy various Internet services seamlessly.”
states Dr. Song.
The results of this study will hopefully be of great use to other researchers and engineers developing communication systems and applications to improve our experience and increase our safety when using autonomous vehicles.
Reference
Name of author: Yoo Seung Song, Shin Kyung Lee, Jeong Woo Lee, Do Wook Kang, and Kyoung Wook Min
Affiliation: Artificial Intelligence Research Laboratory, Electronics and Telecommunications Research Institute
About Dr. Yoo Seung Song
Yoo Seung Song has devoted many years to electrical engineering; he received a BS degree in this area from Changwon National University, Korea in 1996 and MS and PhD degrees in electrical and computer engineering from Wichita State University, USA in 1998 and 2001, respectively. He worked in the Media Lab. for Samsung Electronics in Korea before joining the Electronics and Telecommunications Research Institute in Daejeon in 2005. Since then, his work has focused on next-generation wireless LAN, WAVE, intelligent transport systems, and vehicle communications, with multiple publications on these topics in ETRI journal.
Media contact:
Yoo Seung Song’s email: yssong00@etri.re.kr
