Javier Gozalvez
Editor-in-Chief
This issue of IEEE Vehicular Technology Magazine includes our second edition of the Special Issue on Recent Advances in Automated Driving technologies, and six open call papers covering topics related to road and aerial mobility as well as 6G technologies. I would like to thank Basilio (lead guest editor for this second edition), Ricardo, Yan, Shaobing, and Xudong for their hard work and their vigorous review and selection of the papers included in the special issue.
The first open call paper included in this issue addresses challenges encountered in the driving simulator cockpits widely used for developing and testing new automotive technologies. These cockpits are integrating virtual reality (VR) devices to improve immersion and visual realism. However, the use of VR devices can create dizziness due to mismatch between the fixed seat and the dynamic virtual graphics, and reduces the possibility to study drivers’ reactions because VR glasses cover the driver’s face. To overcome these challenges, the article “Toward Human-Centered Automated Driving: A Novel Spatiotemporal Vision Transformer-Enabled Head Tracker,” by Hu et al. [A1], proposes a vision-based driver head-tracking system to improve immersion and interaction. Accurately tracking the driver’s head pose is important for driver-automation collaboration, intelligent copilot, heads-up display, and other human-centered automated driving applications. The article presents a low-cost and markless head-tracking system that only requires a red, green, blue (RGB) camera. The planned system improves the accuracy of the driver’s head-pose estimation using a spatiotemporal vision transformer model that takes an image pair as the input instead of a single frame. The proposed model contains a spatial convolutional vision transformer and temporal transformer as well as an adaptive Kalman filter to handle error fluctuation of the head-pose estimation model.
The second open call paper focuses on advanced air mobility (AAM), also called urban air mobility, which is expected to transform how we move cargo and people in and around cities. The potential of AAM is attracting strong interest from both industry and research. However, there are still multiple technical challenges that need to be overcome before deploying AAM solutions. Namuduri et al. [A2] analyze the technology-readiness level of AAM solutions in the areas of communications, navigation, and surveillance in their article “Advanced Air Mobility: Research Directions for Communications, Navigation, and Surveillance.” The authors also identify and discuss open challenges and the future research directions for addressing them, with a focus on air corridor design, air-to-air communications, navigation, and collision-avoidance solutions.
The remaining four open call papers cover 6G or beyond-5G-related technologies. In “Time Reversal for 6G Spatiotemporal Focusing: Recent Experiments, Opportunities, and Challenges,” Alexandropoulos et al. [A3] revisit the time-reversal (TR) technique in the context of large-bandwidth 6G wireless communications, for example, for immersive applications including virtual and augmented reality. These applications require increasing data rates that advocate for the use of spectrum in the millimeter wave (mm-wave) band as well as the terahertz frequencies. Operating over these bands requires cost- and power-efficient radio-frequency front ends and multiantenna transceiver architectures as well as ultrawideband waveforms and computationally efficient signal processing schemes. TR is a computationally simple signal processing technique that was initially utilized for underwater wireless communications via acoustic signals, and that was considered for 5G and beyond because of its potential for realizing the benefits of massive multiple-input, multiple-output (MIMO) systems using only a single-antenna base station and simple reception processing circuitry at the mobile users. TR refers to the process of transmitting a received signal in a time reversed order, profiting from the time reversibility of the wireless channel when time-division duplexing is used. The article reviews first the state-of-the-art in TR-based wireless communications, and identifies requirements of TR for an efficient operation. The article also presents novel experimental results showcasing the high resolution spatiotemporal focusing capability of TR in a wide range of carrier frequencies with very different signal propagation characteristics, and showcase the potential of TR for realizing low complexity multiuser communications. The authors also analyze the key requirements for an efficient operation of TR and demonstrate the role of the available bandwidth and the number of transmit antennas on its performance. The article then discusses applications and opportunities with TR-based wireless communications, and identifies open challenges, research directions, and complementary technologies
In “Full-Duplex Massive Multiple-Input, Multiple-Output Architectures: Recent Advances, Applications, and Future Directions,” Alexandropoulos et al. [A4] present a unified, full-duplex (FD) massive MIMO transceiver architecture with analog and digital transmit and receive beamforming (BF) as well as analog and digital self-interference (SI) cancellation. FD MIMO architectures offer the potential for simultaneous uplink and downlink operations in the same frequency band but experience increasing interference between the transmitter and receiver as the number of antenna elements increases. The architecture proposed by the authors can jointly optimize BF and SI for various performance objectives and complexity requirements. The authors apply and evaluate the proposed architecture for fully digital and hybrid analog and digital BF operations as well as simultaneous communication of data and control signals. The conducted evaluation shows that the proposed architecture improves the spectral efficiency of FD communications for both small and large numbers of antennas. The authors conclude the article with a discussion of open challenges and future research directions for FD massive MIMO communications.
Euler et al. [A5] present an overview of technical, regulatory, spectrum, and standardization-related aspects of high-altitude platform stations as International Mobile Telecommunications (IMT) base stations (HIBSs) in “High-Altitude Platform Stations as International Mobile Telecommunications Base Stations: A Primer on HIBS.” HIBSs represent an airborne nonterrestrial network that utilizes the same frequency bands as ground-based 5G base stations. By using the same spectrum, HIBSs can extend the operator’s coverage area, operate with already-existing devices, and hence represent an attractive option for commercial adaptation. The authors evaluate at the system level the performance that can be achieved with a combined HIBS and terrestrial network, and discuss several directions for future research related to, for example, power consumption optimization and coordination and coexistence between HIBSs and terrestrial networks.
Finally, the article “Passive and Privacy-Preserving Human Localization: A Social Distancing Approach Using Commercial Millimeter-Wave Access Points,” by Devoti et al. [A6], presents a novel passive and privacy-preserving artificial intelligence-based human localization solution that relies on the directive transmission properties of mm-wave communications. The proposed system does not rely on dedicated wearable devices, applications, or active connections and does not require human intervention. The authors validate their approach through simulations, but also deployment-based experiments with commercial mm-wave devices in selected environments. The authors use the developed system for detecting social distance in the context of a pandemic, and the proof-of-concept results show a detection accuracy of social distance above 99%.
I hope you enjoy reading this issue. Please don’t hesitate to contact me if you have any comments, ideas, or proposals to improve IEEE Vehicular Technology Magazine.
[A1] Z. Hu, Y. Zhang, Y. Xing, Y. Zhao, D. Cao, and C. Lv, “Toward human-centered automated driving: A novel spatiotemporal vision transformer-enabled head tracker,” IEEE Veh. Technol. Mag., vol. 17, no. 4, pp. 57–64, 2022, doi: 10.1109/MVT.2021.3140047.
[A2] K. Namuduri, U.-C. Fiebig, D. W. Matolak, I. Guvenc, K. V. S. Hari, and H.-L. Määttänen, “Advanced air mobility: Research directions for communications, navigation, and surveillance,” IEEE Veh. Technol. Mag., vol. 17, no. 4, pp. 65–73, 2022, doi: 10.1109/MVT.2022.3194277.
[A3] G. C. Alexandropoulos et al., “Time reversal for 6G spatiotemporal focusing: Recent experiments, opportunities, and challenges,” IEEE Veh. Technol. Mag., vol. 17, no. 4, pp. 74–82, 2022, doi: 10.1109/MVT.2022.3196481.
[A4] G. C. Alexandropoulos, M. A. Islam, and B. Smida, “Full-duplex massive multiple-input, multiple-output architectures: Recent advances, applications, and future directions,” IEEE Veh. Technol. Mag., vol. 17, no. 4, pp. 83–91, 2022, doi: 10.1109/MVT.2022.3211689.
[A5] S. Euler, X. Lin, E. Tejedor, and E. Obregon, “High-altitude platform stations as international mobile telecommunications base stations: A primer on HIBS,” IEEE Veh. Technol. Mag., vol. 17, no. 4, pp. 92–100, 2022, doi: 10.1109/MVT.2022.3202004.
[A6] F. Devoti, V. Sciancalepore, and X. Costa-Perez, “Passive and privacy-preserving human localization: A social distancing approach using commercial millimeter-wave access points,” IEEE Veh. Technol. Mag., vol. 17, no. 4, pp. 101–109, 2022, doi: 10.1109/MVT.2022.3202025.
Digital Object Identifier 10.1109/MVT.2022.3221238