This paper describes the benefits of frequency-dependent signal input power control in ultra-wideband wavelength-division multiplexed (UWB-WDM) transmission using only distributed Raman amplification (DRA). We evaluate the transmission performance of both backward pumping and bidirectional pumping configurations, and show that a significant improvement in signal-to-noise ratio (SNR) and total throughput is obtained in backward pumping, while the improvements are much smaller in bidirectional pumping.

The radiated immunity test methods for in-vehicle equipment with wiring harnesses are specified by manufacturers or international standards. These test methods require high-power amplifiers to satisfy the specified electric field strength. A proximity radiation test method using antenna scanning is proposed to reduce the transmitting power. The effect of the electric field radiated by the conventional and proposed methods on the harnesses is evaluated using a long wire antenna. The proposed method is shown to be an effective pretest method for the conventional test.

As sensor nodes that constitute a wireless sensor network are battery-powered, it is essential to extend their life. Wireless mesh network, one type of wireless sensor network, require routing and must consider power consumption. However, existing methods that are based on the shortest paths are insufficient to reduce power consumption. In this study, we propose a routing method that considers the maximum flow problem. Experimental results show that the proposed method increased the time until a node that runs out of battery first occurs.

Sign language and hearing aids are among the most widely used communication support methods for individuals with hearing impairments. However, these methods present certain limitations: sign language can only be used between people who understand it, and hearing aids can cause discomfort when worn. To address these issues, we propose and implement a system that displays the direction of arrival of speech, speech recognition results, and speaker recognition results on augmented reality (AR) glasses. We also evaluate its effectiveness through user studies and evaluation experiments.

Adaptive video streaming using Moving Picture Experts Group dynamic adaptive streaming over Hypertext Transfer Protocol (MPEG-DASH) enables adaptive bitrate (ABR) control based on network conditions. Network conditions can be estimated based on the network throughput or playback buffer level. However, the conventional proportional-derivative (PD)-based ABR algorithm that considers both network throughput and playback buffer level can degrade the quality of experience (QoE) when the available bandwidth of each user fluctuates. This study proposes an ABR algorithm that combines multiple bitrate selection methods using PD control and buffer-based throughput estimation, considering buffer-level fluctuations to achieve a stable bitrate and buffer-level control. Simulations confirm that the proposed algorithm improves QoE under multi-user and throughput-varying conditions and does not negatively impact another ABR algorithm in a heterogeneous environment.

The primary objective of this letter is to identify the optimal relay positions theoretically for one-way relay protocols. Account is taken of the signal propagation scenario typically experienced by the communication systems utilizing unmanned aerial vehicles (UAVs). This letter focuses on a relay network using UAVs, where it is necessary to consider the geometric network configuration including the relay location most suitable to the surrounding environment. This letter assumes the Decode-and-Forward (DF), Lossy Forward (LF), and Adaptive Decode-and-Forward (ADF) protocols in the one-way UAV relay network having Source, Destination, and Relay nodes, and derive theoretically their outage probabilities. Results of numerical calculations are presented to demonstrate the optimal positions in several propagation environments.

We develop and evaluate the TransportPCE-based controller for transport networks with fiber cross connects (FXCs) in addition to ROADMs for the first time. FXC-only-path provisioning is completed in 1433 msec, significantly quicker than ROADM paths.

As quantum computing technology continues to advance, Shor’s quantum algorithm poses a significant threat to mainstream cryptographic methods, including RSA and elliptic curve cryptography. Consequently, post-quantum cryptography (PQC) has emerged as an inevitable trend for the future. Among PQC approaches, lattice-based cryptography and hash-based cryptography have already been standardized, while code-based cryptography remains a candidate for standardization. In light of these developments, this study proposes a Code-based Butterfly Key Expansion (CBKE) mechanism, built on code-based cryptography principles. The proposed method enables a registration authority (RA) to expand an original code-based caterpillar public key into a code-based cocoon public key, achieving anonymity for entities other than the RA. Subsequently, a certificate authority further expands the code-based cocoon public key into a code-based butterfly public key, which is then embedded in a pseudonymous certificate as the public key for the end entity. This approach ensures anonymity for both the RA and other entities. To enhance computational efficiency, the study proposes a random invertible matrix generation algorithm with a time complexity of O(n). This algorithm achieves high efficiency and anonymity without increasing the key length, thereby addressing the computational demands of the proposed method effectively.