Title: Basic Study on FSK Transmission Using Convolutional Code in Terahertz Band

Abstract:Terahertz-band wireless transmission enables high-speed communication due to its ultra-wide transmission bandwidth. However, significant propagation losses in the terahertz range make long-distance transmission challenging. Additionally, the development of high-efficiency signal generators, filters, and power amplifiers remains a critical issue for the realization of terahertz communication. In this study, we conducted terahertz transmission experiments under the assumption that the system is power-limited rather than bandwidth-limited. We focused on frequency shift keying (FSK), one of the constant-envelope modulations favorable for power amplification. Furthermore, since forward error correction (FEC) has not been well investigated in terahertz communication experiments, we examined the application of convolutional codes as FEC in this study. We conducted wireless transmission experiments at a carrier frequency of 289.44 GHz and analyzed the results. The experiments demonstrated that the maximum error-free transmission distance for 0.5 Gbit/s of data bits was as far as 1.5 meters when using convolutional code with block interleaver and soft decision.

Title: Fundamental Experiments on Modulation Schemes and Forward Error Correction in Terahertz Communication

Abstract:In this paper, we evaluate the BER characteristics of the linear modulation schemes BPSK, QPSK, and 16QAM, which are relatively easy to implement and resistant to noise and interference in THz communications system with limited transmission power. Additionally, we investigate the improvement in BER by introducing convolutional codes (CC) as forward error correction (FEC). Through simulations and experiments, we assess the BER of each modulation scheme and analyze in detail how much the BER can be improved with the use of CC. The experimental results in THz communications demonstrate that the transmission distance for achieving a BER of 10-2 extends by 1.5, 1.2, and 0.4 meters for BPSK, QPSK, and 16QAM, respectively, when CC is applied, with the input power of -1 dBm. These results provide fundamental data that are expected to contribute to the selection of optimal modulation schemes and error correction methods in future THz communication systems.

Title:Development and Basic Characteristics Verification of Hardware Wireless Link Emulator for Large-scale Wireless Emulation

Abstract:In the B5G era, the increasing number of radio devices will exacerbate radio resource shortages and frequency utilization inefficiency. To address these, new wireless access and frequency-sharing technologies are being developed. However, these technologies require testing in actual environments for practical use, which are time-consuming and costly. Testing with real radio devices is also challenging for ensuring reproducibility due to environmental changes. Additionally, large-scale wireless systems pose significant challenges in equipment procurement and operation. To overcome these hurdles, a new concept for a radio emulation system is expected. This paper describes the design and development of the hardware wireless link emulator (HWLE) that consists of a link emulator and an analog-to-digital/digital-to-analog interface for evaluating actual radio devices with supporting up to 256 × 256 links. In addition, this paper evaluates processing delay, dynamic range, and multipath fading characteristics of the HWLE and verifies its performance in comparison to a commercial fading emulator.

Title:Beyond 5G Testbed Environment employing the Large-Scale Wireless Emulator enabling the Layer Management Technology

Abstract:This paper proposes the radio system evaluation environment employing the wireless emulation technology that enables effective and critical evaluations of the advanced and diversified radio systems in Beyond 5G era. The employed wireless emulation technology can reduce the evaluation costs by realizing the large-scale wireless emulator environment where radio interactions among the assumed radio devices are suitably calculated and evaluated. The paper reports on those evaluations by assuming both virtual nodes and reconfigurable radio devices. Furthermore, the paper proposes a concept of layer management technology that is considered as one of the advanced control schemes on the wireless emulator, and reports on the fundamental characteristics of the deployed layer management.

Title:Long-range C2 Link Experiment in 169 MHz Band with Engine-Powered UAV Flying Above the Sea

Abstract:This paper presents an experiment on long-range command-and-telemetry link in 169 MHz band with engine-powered fixed-wing unmanned aerial vehicle (UAV), assuming to apply to the wide observation of coastal areas, where mobile phones are hardly available. In the experiment, we confirmed a direct link from ground station to the UAV with the distance of about 10 km. However, we also found a problem to overcome, which is on the onboard noise.

Title:Terrestrial Mobile Testbed Enhancement employing the Reconfigurable Evaluation Environment for the Non-Terrestrial Networks toward B5G Systems

Abstract:This paper proposes an enhancement for the B5G mobile testbed environment that enables evaluations of the non-terrestrial networks (NTNs) -based systems. In the proposed evaluation environment, harmonizations with NTN and the terrestrial mobile systems are realized by using the reconfigurable testbed facilities that are constructed to evaluate the future possible advancement on the current L5G compliant mobile systems. The proposed NTN harmonized B5G mobile system provides an expanded C-Plane functions by exploiting the NTN's inherent advantages of service continuity, ubiquity and scalability thereby further enhances the performances of the conventional terrestrial mobile systems. This paper also reports on the experimental results that are obtained on the NICT developed B5G/IoT testbed with high reliability and high elasticity. The experimental results confirm that the proposed NTN harmonized B5G mobile systems provide system performance of both throughput and RTT equivalent to the conventional terrestrial mobile systems without serious degradation owing to such assumed expanded C-Plane functions.

Title:Multi-Layer Resource Management Strategies for Cybernetic Avatars in Dynamic Local 5G Environments

Abstract:In Japan, research and development aimed at realizing a Cybernetic Avatar (CA) society is progressing under the Moonshot Goal 1 project. CAs are technologies that extend human physical and cognitive capabilities, enabling remote activities and offering a new means for anyone to participate in social activities. However, when a large number of CAs operate simultaneously, service quality is impaired due to limited wireless communication capacity. To address this issue, this study proposes a wireless resource management scheme in a dynamic Local 5G network environment. This scheme manages the available service areas for each CA service in a multi-layer structure and adaptively downgrades the service levels of some CAs when communication demands exceed the available capacity. This approach ensures that, in scenarios where communication resources are strained due to a high number of CAs, service levels can be effectively adjusted based on the CAs' situations and operations, maintaining the overall service quality at a higher level. Simulations demonstrate that the proposed scheme improves the proportion of CAs meeting the desired quality of service by 60 percentage points, compared to the conventional Proportional Fair Scheduling (PFS)-based resource management scheme. These results indicate that even under limited resource conditions, it is possible to maintain high service quality.