This paper presents a novel QoE provisioning system with micropayment for Voice of Internet Protocol (VoIP) and video streaming services (QmV²). QmV² leverages Software Defined Networking (SDN) to provide guaranteed QoE and the distributed ledger IOTA technology micropayment. More specifically, QmV²’s SDN controller has an innovative QoE calculation mechanism utilizing Mean Opinion Score (MOS) that considers service flow monitoring parameters, including packet loss rate and delay. Upon a QoE request and receiving the IOTA payment, QmV² can provide the requested QoE for the service flow. We have implemented and evaluated QmV² using the POX SDN controller, the network emulator Mininet-WiFi with VoIP and video streaming. The results confirm QmV² delivers satisfactory user experiences (i.e., aligned with the guaranteed MOS values) for VoIP and video streaming applications with the confirmed IOTA payment.

A slot timing detection method as realized by a detector and a comparator in a TDD-operated RF relay device causes timing detection errors due to received signal power fluctuations caused by fading. Here, we clarify the timing detection errors by simulating such a timing detection method using the DL received signal and the UL received signal in a relay device for various fading characteristics. When the CDL-A model is used and the moving speed is 5km/h, the timing detection error using the DL received signal exceeds 16.7μsec, which is the OFDM symbol length, and the BER of the UE degrades significantly, while the error is within 1μsec using the UL signal.

The Quasi-Zenith Satellite System, nicknamed Michibiki, broadcasts not only navigation signals but also messages to improve its accuracy. On the other hand, the European navigation satellite system, Galileo, has also begun broadcasting messages to improve accuracy. Both broadcast messages in Compact SSR format to improve accuracy, but the actual message format differs greatly between them. The differences between them are summarized here. In addition, with the created message decoders as open source and software-defined radio, both signals are actually received, and the augmented information are compared in this letter.

The “virtualized terminal” system which uses an OFDM waveform spanning 4.8GHz bandwidth passing through terahertz and millimeter-wave bands has been studied towards the Beyond 5G. This paper studied the effect of the “2-stage nonlinearity” caused by two amplifiers at both of those bands. This study also evaluated two baseband circuits for the OFDM signal generation: one that generates a 4.8GHz OFDM signal in a single batch, and another one that divides the 4.8GHz into 400MHz sub-bands and generates OFDM signal for each sub-band. The results of the evaluation that assumed the phase noise, fading, and 2-stage nonlinearity showed there was little degradation by the 2-stage nonlinearity or sub-band division.

We are developing a system that augments user accessibility by integrating various facial recognition engines across multiple enterprises, thereby facilitating the widespread adoption of facial recognition technology within societal structures. In this system, homomorphic encryption is employed to mitigate the risk of data leakage during facial recognition. However, the use of homomorphic encryption in facial recognition significantly increases latency, making it challenging to meet practical response time requirements. We experimentally evaluated the impact of adopting homomorphic encryption on the response time. The evaluation revealed that the number of registrants per facial recognition engine should be “< 120”. Additionally, we evaluated a clustering strategy for reducing the response time to the level of practical application.

Low-complexity coherent detection using self-interference of aggregated optical orthogonal frequency division multiplexing (O-OFDM) subcarriers is proposed. Self-interference among the aggregated O-OFDM subcarriers is employed to recover their relative phase relationships through the variation in the obtained power spectra. The differences in a few preselected principal spectral components are successfully demonstrated based on the phase states of four O-OFDM subcarriers modulated via quadrature phase shift keying (QPSK). We experimentally verified self-interference and bit error rate reaches 10^-3. The number of bits available in the proposed method increases with the number of subcarriers, gradually approaching that in QPSK beyond OOK.

We have proposed an ICN-based Wireless Sensor Network (ICSN), which enables multiple IoT services within a single sensor network. Previous research focused on reducing power consumption in sensor nodes and load balancing at service provisioning points. However, the presence of malicious sensor nodes generating fraudulent data poses challenges. If IoT services retrieve and use such illicit data, it can lead to disruptions and malfunctions. We propose a novel authentication mechanism for new sensor nodes in environments with multiple IoT services to address this. We have implemented and conducted experiments using Cefore to evaluate the effectiveness of this mechanism.

Resource pooling is an important fairness concept for multi-path congestion control. Practical congestion control (PCON) in Named-Data networking (NDN) is common congestion control in NDN. Previously, we showed that PCON cannot fully achieve resource pooling fairness due to the lack of design policy. In this paper, to improve the fairness of PCON, we introduce our proposed AQM enhancement for PCON and newly propose a suppression method to excessive window reduction caused by simultaneous congestions on multiple paths. Furthermore, we propose a flow-aware traffic steering technique for balancing congestion inspired by a MPTCP’s design policy. The combination of these techniques dramatically improves fairness among consumers and quickly brings us achieving closer to the complete resource pooling state. Specifically, the overall throughput among users was improved, and then fairness index became quite high, i.e. 0.998.

It seems to be reasonable that various IoT services are deployed over the IoT platforms with commonalities for these services. One of these platforms is CCN with Network Initiative And Traffic Control (C-NAT) which has been proposed by the authors. C-NAT intends to be operated over the Internet. However, this operation causes to increase in the processing delay at interworking points by multiple buffer copies. As the first step to solve this problem, this paper proposes that C-NAT is operated over the data link layer to reduce the processing delay. It indicates the advantages of this proposal by queuing analysis. It also describes operational sequences in this proposal.

BBR has been proposed as congestion-based congestion control by Google. It was originally designed to operate around optimal operating point where maximum throughput is obtained without incurring increase of roundtrip delay. In this paper, with simple analysis and detailed simulation results, we show that BBR increases its delivery rate even though BBR flows sharing the same bottleneck link fully utilize available bandwidth. From simple analysis results, we propose a new BBR delivery rate calculation algorithm which regulates delivery rate moderately, BMR. Our simulation results show that our proposed BMR operates around the optimal operating point.

This study focuses on a digital signage and image sensor-based visible light communication system in which the transmitter side modulates data signals on the signage image, and the receiver side detects and demodulates the data signals from the captured images. In the conventional studies, the detection and demodulation of the data signals are processed independently. This paper proposes a novel algorithm that simultaneously processes the data signal detection and demodulation by applying object detection DNN (Deep Neural Network). Using pseudo received images with blur and noise, it is shown that the proposed method achieves much higher detection and demodulation performance than a template matching-based detection and threshold-based demodulation method.

This study proposes the suppression of the azimuth ambiguity with high azimuth resolution and signal-to-noise ratio in an image captured at a low pulse repetition frequency for the detection of ships on the ocean with wide swath by spaceborne synthetic aperture radar (SAR). The proposed scheme can reduce the azimuth ambiguity by processing the two images divided in the Doppler frequency region, which selects pixels with smaller values between the two images and derives their gains. After evaluating the proposed scheme, we discovered that azimuth ambiguity can be suppressed, and the expected swath of the observed image is equivalent to five times that of the conventional SAR image. The proposed scheme improved the signal-to-azimuth ambiguity power ratio by 27.7 dB.

The realization of low-latency mobile edge services is expected to be realized by placing edge sites closer to users and shortening the transmission distance from user terminals. This requires construction of Radio Access Network (RAN), Core Network (CN) and a physical/logical network. In order to provide on-demand Mobile Edge Computing (MEC) service tailored to the user’s demands, these should be constructed quickly without service interruption. In this paper, we propose a network control method that works in combination with an existing network protocol running on a simple optical network that simplifies optical path construction in the End-to-End section.

In this paper, we investigate the change in received power at the access point when the sensor terminal is submerged in water by electromagnetic field simulation, aiming to realize an underpass flooding monitoring system using IoT wireless access technology and obtaining design guidelines for such a system. In particular, since the relative permittivity and electrical conductivity of muddy water are unknown, simulations were performed by changing these parameters. As a result, it was confirmed that the received power decreased by approximately 5dB when the bottom of the antenna was submerged and by approximately 20dB when the antenna feed point was submerged.

Radio over fiber (RoF) is attracting much attention as one way to realize high frequency bands (above about 10GHz) systems. A fixed wavelength allocation beamforming scheme has been proposed to attain the desired link budget in such systems. However, this beamforming performance is degraded with massive antenna elements, because of increasing the phase error due to chromatic dispersion. Therefore, we propose a novel beam control method for the scheme, that implements beamforming initially with just a few antenna elements negligible beamforming deterioration. In this letter, the proposed method characteristics is evaluated, and the effects of suppressing beamforming deterioration and improving beamforming gain are shown.

In this letter, we propose a Received Signal Strength Indicator (RSSI)-based indoor localization method using two-step extreme gradient boosting (XGBoost). The proposed two-step XGBoost leverages one of the location coordinates (x or y) as a feature to enhance the estimation accuracy. Simulation examples confirm that the proposed two-step XGBoost approach could improve the estimation accuracy while maintaining low computational complexity.

This paper proposes an active-time-reduction technique of base stations for energy reduction using terminal position information estimated from wireless-communication signals. Although high-frequency wireless communication system requires dense deployment of base stations, the system is enabled to detect terminal position from communication signals. The proposed technique was evaluated using a formula car as an example of a high-speed mobility environment. The results indicate the base-station-active time decreased by about 59%without any degradation in transmission performance, suggesting that the proposed technique can reduce power consumption of base stations.