The fingerprint technique is used as an indoor localization method. This study uses a CNN-based indoor fingerprint localization method. The estimation accuracy of CNN improves as the number of AP information (AP identifiers and received signal strength indicator) increases. However, gathering AP information is time-consuming and costly. The problem can be solved using UD (AP information users measured). However, the UD measuring method does not know the user’s exact location. Therefore, it is essential to choose UD that is accurately estimate and use it for CNN training. In this study, we propose a method for selecting UDs that makes use of the RSSI similarity between AP information and UD.

Arbitral control of reflection direction of a reflectarray for the mobile communication system is a key technology to amplify the coverage area. Here, we examined the correlation between the tilt and rotational angles of the reflection wave acquired by a reflectarray. Simulation results showed that changing the reflection rotation angle up to 75° reduces the radar cross section (RCS) by only a few dBsm. Furthermore, the maximum scanning angle up to ±60° was achieved by appropriate design of a reflectarrray. The reflection characteristics of the reflectarray will pave the way for the design guideline for a wide-angle reflectarray.

This work provides an optimization method for route selection and control-inputs for multihop networked control systems (MH-NCS) considering the communication delay and link reliability. In a multihop network, the higher number of multihops, the more reliable the communication, while the longer the communication delay. Considering the above facts, this study proposes to compute the routing and control-inputs based on a model predictive control (MPC) method. Simulation results show that the proposed method can efficiently work in the MH-NCS with link failures.

We report a single-layer frequency selective dual band reflectarray operated at 28 and 39GHz simultaneously. The reflectarray consists of cross dipole and spiral elements aligned on the surface of a substrate and dual band frequency selective surfaces aligned on the rear side. We aligned the cross dipole and spiral elements that can control the reflection direction at 28 and 39GHz aligned on the same plane of the substrate, resulting in a simultaneous dual-band control of the reflection direction up to ±30° independently. Furthermore, the dual band reflectarray showed higher transmittance at frequencies except for the target frequencies, indicating the reflectarray function only at 28 and 39GHz and does not interfere with the other communication bands.

Electromagnetic analysis (EMA) attacks are a type of side-channel attacks that can be performed without opening or modifying a cryptographic module. In this study, we propose a detection method for the measurement of side-channel information, which is performed at the preliminary stage of the analysis of the target device as a countermeasure against EMA attacks performed near integrated circuits (ICs) with cryptographic modules. The presence of an electromagnetic (EM) field probe is detected by analyzing the sampling background noise around the IC using an analog-to-digital converter (ADC) inside the IC and by observing any changes in the EM environment. The proposed method can effectively detect a probe placed 5 cm from the IC package.

This study investigates the effectiveness of a low-complexity blockage mitigation method employing information about the antenna height and user position in consideration of antenna directivity in millimeter-wave (mmWave) communications. The feature of the proposed approach is that the base station (BS) selection is efficiently realized by using the theoretical throughput expressed by static parameters, such as the antenna height and user position. A beamforming (BF) approximation model is applied to the radiation pattern, specifically in this study, to reflect the influence of antenna directivity on performance evaluation. The effectiveness of the proposed method is demonstrated with parameters of the blocker density and carrier frequency via computer simulations.

This paper presents a method to eliminate the phase difference ambiguity in angle of arrival (AOA) estimation using the radio-frequency-based interferometric monopulse technique. In order to uniquely determine the AOA, we utilize four directivities which are formed by using selected elements with the same weight function as the AOA estimation. We investigate the AOA estimation accuracy for the direction of the incoming wave from a high elevation angle and in multi-path propagation environments using a three-dimensional fading emulator. The results show that the proposed method is valid for complex propagation environments.

In this study, the characteristics of a wideband, low-profile, double-shell Halo antenna is investigated. The Halo antenna is a horizontally polarized antenna with a small diameter and a relative bandwidth of about 4%, which corresponds to a narrow bandwidth characteristic. Therefore, as a conventional broadband method, it is possible to increase the bandwidth of the Halo antenna while maintaining the antenna diameter by loading parasitic elements vertically above and below. However, the disadvantage of this method is that the antenna height increases owing to vertical stacking of the elements. In this study, a double-shell structure with the parasitic elements placed inside the Halo antenna is used to achieve a relative bandwidth of 9.3% while maintaining the antenna height and diameter.