The application of hyper-wideband is required by 6G sub-THz wireless communication, to enable it provide a peak data rate of up to hundreds of Gbps. However, simultaneously achieving a large bandwidth and high signal quality at the receiver remains a challenge owing to a various hardware non-idealities; hence, additional signal processing techniques are necessary to compensate for these issues. Although conventional analog circuits for the signal compensation cause extra power consumption and hardware implementation complexity, the digital-domain signal compensation technique at the receiver modem exploits both the low power consumption per computation and side-information provided by a sub-THz communication system. In this paper, we propose a digital-domain signal compensation method comprising a compensation filter and parameter estimation, achieving both hyper-wideband and high signal quality. Numerical evaluations were conducted with hyper-wideband and high signal quality scenarios, and the performance of the proposed method was further demonstrated with the spectrum variability of sub-THz systems.

This paper presents novel ultrareliable and low-latency communication (URLLC) techniques for URLLC services, such as Tactile Internet services. Among typical use cases of URLLC services are teleoperation, immersive virtual reality, cooperative automated driving, and so on. In such URLLC services, new kinds of traffic such as haptic information including kinesthetic information and tactile information need to be delivered in addition to high-quality video and audio traffic in traditional multimedia services. Furthermore, such a variety of traffic has various characteristics in terms of packet sizes and data rates with a variety of requirements of latency and reliability. Furthermore, some traffic may occur in a sporadic manner but requires reliable delivery of packets of medium to large sizes within a low latency, which is not supported by current state-of-the-art wireless communication systems and is very challenging for future wireless communication systems. Thus, to meet such a variety of tight traffic requirements in a wireless communication system, novel technologies from the physical layer to the network layer need to be devised. In this paper, some novel physical layer technologies such as waveform multiplexing, multiple-access scheme, channel code design, synchronization, and full-duplex transmission for spectrally efficient URLLC are introduced. In addition, a novel performance evaluation approach, which combines a ray-tracing tool and system-level simulation, is suggested for evaluating the performance of the proposed schemes. Simulation results show the feasibility of the proposed schemes providing realistic URLLC services in realistic geographical environments, which encourages further efforts to substantiate the proposed work.

Light-field imaging and holographic imaging are currently the two mostly investigated 3-D imaging technologies because of their potentials to create the viewing environment conforming to a natural viewing condition. The basic optical geometries for image display in these imaging are not different from that of integral photography. The images in the two type of imaging are a set of different view images. These images are arranged as a 2-D point image array, and each point image is expanded with a certain angle to form a viewing zone. The differences between the two types of imaging are the number of point images in the array and the physical entities forming the images. Holographic imaging has many more point images than light-field imaging, and each image in the array consists of coherent right rays from different positions of an object. In light-field imaging, an array of pixels represents a direction view of the object. Despite these differences, they share the same goal of providing a continuous parallax to viewers and require display panels of almost the same characteristics. It is expected that in the future these two imaging techniques will be integrated into the same flat panel along with the plane image.

Three-dimensional imaging is still not in the full commercial stage, but its application is widening due to its capability of creating real-world-like environments. This capability is especially important in realizing reality communication and telepresence operations in medical and unreachable places. For these applications, technologies for interacting with objects in the 3-D image should also be developed. The widespread use of 3-D images is expected in near future, but before that, problems of minimizing physical stresses, especially eye fatigue, should be solved for 3-D imaging. Currently, expected solutions to the problems are electroholography and super multiview methods. These two methods work at different principles, but they both can provide the continuous parallax as in the real-world scenes/objects. Electroholography can also provide focusable depth information to the viewers, though its viewing zone angle is limited. For the super multiview, it is not apparent that it can provide the focusable depth information, but it can provide more comfortable viewing condition than the holography because of its wider viewing zone angle.