A practical method to mitigate severe clutter in signals received by wind profiler radar is proposed. It uses adaptive clutter suppression (ACS) for collected time series and the median filter for Doppler spectra consecutive in time. When the source of a clutter exists in or near the antenna main lobe, ACS cannot always mitigate the clutter sufficiently. The median filter for the Doppler spectra can reject the remnant of such severe clutter when its appearance in Doppler spectra is limited in time. Using a 1.3-GHz wind profiler radar, an experimental result for a severe clutter is shown.

This letter introduces an electronically reconfigurable 100-GHz band reflectarray (RA) utilizing a microfiber/liquid crystal composite. The unit cell design is analyzed through full-wave simulations, while experimental measurements elucidate the RA’s characteristics, including reflected power, steering range, and switching times. Results demonstrate that the proposed RA exhibits significant continuous beam steering capabilities, ranging from -40° to 40° at 100 GHz, with swift switching times of less than 230 ms. The maximum reflected power achieves -3.5 dB compared to a metal plate of the same size.

With the advent of the Internet and its close connection to people’s lives, web applications have become increasingly important. To ensure that the web application is secure, a web application firewall (WAF) detects and stops attacks that exploit application vulnerabilities in communication with server applications. However, these firewalls require continuous tuning by experts with in-depth knowledge of the technologies and services provided, which may become a major obstacle to the introduction of WAF. To resolve this problem, we developed two autoencoder-based models based on an unsupervised learning model that uses only normal requests, considering the implementation and operation costs. We then evaluated the performance of the two autoencoder-based models. The first model converts a hypertext transfer protocol (HTTP) request into ASCII codes and learns their relationship in a normal request using an autoencoder. The second model generates an array of word vectors using fastText and learns using a convolutional autoencoder, which solves the problem identified in the performance evaluation of the first model where the problem was that the simple conversion to ASCII codes was not enough to distinguish between normal and anomalous requests. The two models were evaluated using the HTTP DATASET CSIC2010 dataset. The AUC for the second model was approximately 0.94 while that for the first model was approximately 0.71. This means that the second model has higher accuracy despite being an unsupervised approach, one that does not require labeled anomalous requests, and can be applied with low costs.

A recent approach to expanding the coverage of 6G networks and enhancing disaster preparedness is the use of wireless networks based on unmanned aerial vehicles (UAVs), which can be positioned independent of ground conditions and provide line-of-sight communication with a high probability. In wireless communication using UAVs, propagation attenuation and interference vary significantly depending on UAV density and flight position. Therefore, understanding their quantitative effects on communication quality is crucial. Moreover, assuming the use of high-frequency bands, blockage also occurs; therefore, its impact must be evaluated. In this study, we evaluated the outage probability and throughput in millimeter-wave UAV wireless communication by varying UAV density and altitude using computer simulations. In particular, we clarify the effects of blockages specific to high-frequency bands on these performance criteria.

We proposed a phase accumulation to improve the SNR and accuracy on remote heartrate measurement based on multiple chirps mm-wave FMCW radar. However, specification of radar module has continued to be upgraded and it has become clear that increasing number of the accumulative phases may actually worsen the heartrate estimation accuracy, depending on subject and time of experiment. Therefore, this article proposes adaptive adjusting accumulative number of phases, for remote heartrate measurement based on mm-wave multiple chirps FMCW radar. The method adaptively adjusts accumulative number of phases of the received multiple chirps in each observation window according to a SNR criterion. Experimental result shows effect of the proposed method compared with single chirp and 32-phase accumulated cases, for eight subjects.

This study investigates the transmission performance of coded faster-than-Nyquist (FTN) signaling based on single-carrier with frequency-domain equalization in the presence of nonlinear distortion and multipath fading. In our performance evaluation, the effects of nonlinear distortion and channel coding were determined using a power amplifier model based on the Rapp model and turbo coding, respectively, which were incorporated into the frame error rate and throughput performance of FTN signaling. Moreover, we compared the performance of coded FTN and coded orthogonal frequency division multiplexing under the same transmission rate using computer simulations to verify the effectiveness of FTN signaling under nonlinear distortion and frequency selective fading.

The development and introduction of real-time remote control of robots using mobile NWs is expected. To realize this control, a network configuration in which the User Plane Function (UPF) and Mobile Edge Computing (MEC) are located near the Central Unit (CU) is considered. If traffic exceeds the processing capability of the UPF, there is the concern of congestion. In this paper, we propose and demonstrate a method for obtaining the uplink traffic volume from the CU and predicting the future traffic to switch the optical path and UPF before congestion occurs within the Mobile Backhaul (MBH) delay of 1ms.

In recent years, the demand for satellite communication has increased, and the realization of a higher capacity has become a challenge. However, the service area of each low-Earth orbital satellite changes constantly, requiring many satellites for continuous communication, which increases space debris and the risk of collision accidents. This paper proposes a multiple-input multiple-output transmission system using low-Earth orbit and quasi-zenith satellites that can expand the channel capacity while reducing the number of required satellites. Numerical simulations demonstrate a 50% increase in throughput or a quarter reduction in the number of satellites required to achieve the same performance.

Hollow-core photonic bandgap fibers exhibit nonlinear properties. In comparison with conventional silica-core optical fibers, we experimentally evaluate whether the hollow-core photonic bandgap fiber has extremely low nonlinearity compared with silica-core optical fibers in terms of stimulated Brillouin scattering and four-wave mixing. A low nonlinearity is useful for high-power optical transmission applications.

A challenging issue in continuous-variable quantum key distribution (CV-QKD) is the improvement in error correction efficiency because random number bits are encoded in a quadrature of faint optical pulses. Herein, we propose an error-control information reconciliation method for CV-QKD based on our recently proposed fixed-bit polar code. In the present scheme, unreliable bits are embedded in the prepared “fixed bits,” enabling the detection and reproduction of errors in these bits without error correction, effectively improving the error-correction efficiency. Numerical simulations demonstrate that the efficiency of the proposed scheme is 10% higher than that of polar code-based reconciliation without fixed bits.

Wireless channel emulator (WCE) allows site-specific evaluation of the wireless system with time- and cost-efficient and reproducible result. In addition to the conventional star topology between devices and a base station (BS), incorporating device-to-device communication (D2D) into WCE is essential. In this paper, the authors envision the concept and address the challenges of the two-layer grid-based channel emulation technique (2L-GBCE) to enable WCE in the D2D. The TV-CIR is synthesized from the pre-computed deterministic path parameters between two-layer grid structures representing both devices through interpolation. Performance is statistically evaluated in terms of average path gain, normalized delay spread, and Doppler spread profiles. The simulation was carried out at 5.25 GHz and the results qualitatively indicated the capability of the proposed emulating technique, as well as highlighting the effect of path clustering and grid size as challenges.

In this paper, we propose an inverse synthetic aperture radar (ISAR) imaging method using a millimeter wave (mmW) fast chirp modulation (FCM) multi-input and multi-output (MIMO) radar for drone detection. To obtain high-resolution ISAR images, the backprojection algorithm is adopted for the ISAR processing. This algorithm is suitable for ISAR imaging of a moving drone with an irregular motion. The measurement experiments were conducted using flying drones (DJI Phantom 3, DJI Mavic Pro and DJI Mavic Mini) in indoor situations to examine the effectiveness of our proposal. The measurement results demonstrated that the proposed method could generate the high-resolution ISAR images enough to recognize the approximate size and shape of each drone.

IEEE802.1Qbv (Time-aware Shaper: TAS) has recently been applied within user networks (NWs) for realizing factory automation and remote control. As mass customization matures, TAS is expected to extend its application coverage to not only user NWs but also wide-area NWs to enable real-time communication for remote control and cloud-based application use. However, designing a TAS schedule is an NP-hard problem, which becomes more difficult as the gate control list (GCL) hypercycle increases. In this paper, we propose a method to convert the transmission cycle of Talker to a different cycle time for TAS scheduling in a carrier NW. This results in a smaller GCL hypercycle in the carrier NW. Our evaluation experiments show that the GCL computation time of the proposed method is shorter. This paper contributes to the realization of TAS in the wide-area NW, which has not been discussed so far.

A novel 1-bit mechanically controlled reflectarray element features in high efficiency is proposed. The element is actuated by an electromagnet under ground plane thus opening via hole or slot is unnecessary. A locking system is designed to lock the steel patch in two different height, which can avoid high power consumption of electromagnet in either of the states. The mechanical performance is discussed in detail and the scattering characteristics of the element are experimentally and numerically validated. A 10×10 reflectarray antenna is modeled and its beam scanning ability is demonstrated through a MoM fullwave simulation.