Multi-user MIMO systems enable high capacity transmission. A base station, however, needs accurate channel state information (CSI). In time-varying environments, the CSI may be outdated at the actual transmission time. One of the solutions to this issue is channel prediction. The authors have proposed the prediction method using FISTA, a compressive sensing technique, for OFDM systems in a millimeter-wave band. Unfortunately, in realistic multipath environments, the prediction performance of the proposed technique degrades. In this letter, we examine the prediction performance in wider OFDM systems. It will be shown that FISTA reveals excellent performance in a sufficiently wide band case.

Demand for positioning services such as object tracking systems and navigation systems is increasing. The current Wi-Fi positioning system uses the algorithm using mainly the signal strength. However, the signal strength is susceptible to multipath propagation, thus the ranging error generally large. The IEEE802.11mc specifies the fine timing measurement (FTM) protocol based on round trip time (RTT). As of now, few commercial products support the FTM function. The objective of this letter is to evaluate the accuracy of the Wi-Fi FTM using the actual devices and to perform one-dimensional positioning by a simple algorithm. In the one-dimensional positioning, average positioning accuracy is 0.10m in outdoor and 0.23m in indoor.

In the 5^th generation mobile communication system, introduction of small cells using low-height base station is being examined. Small cells are installed in urban street cell environments where mobiles are densely populated. Therefore, actual measurement and complicated modeling of radio wave propagation are necessary to grasp the propagation characteristics. In this paper, a simple propagation delay estimation method is proposed. In the proposed method, neural network using urban area structure parameters is applied. It is shown that the propagation delay time can be easily estimated by the proposed method without considering moving objects and trees.

In future wireless communication systems, massive multiple-input multiple-output (MIMO) is attracting attention for improving transmission rate. However, there is an issue that a large scale of hardware is needed due to massive numbers of antennas, transmitters, receivers, A/D and D/A convertors in massive MIMO. In this study, we propose a method to realize a virtual massive array with only one receiver by changing the beam pattern and performing A/D conversion at high speed within one symbol. The basic performance and effectiveness of the proposed method is demonstrated via a computer simulation.

In this report, we show the critical condition of the slope angle between orbits in InSAR (interferometric synthetic aperture radar) analysis. InSAR analysis, where the phase difference between two SAR observation data is measured, has been used for terrain height monitoring, and ground deformation detection, for example. However, InSAR data observed from nonparallel orbits degrades the performance of analysis. In the case of repeat-pass InSAR using airborne SAR, it is difficult to realize sufficiently parallel orbits. The purpose of this report is to formulate the nonparallel component of repeat-pass InSAR using an airborne SAR system and clarify the limitation of its parallel assumption. Then, we show the critical slope angle for use in InSAR analysis.

Adverse effect of pulse disturbances on the communication quality is investigated experimentally on in-vehicle Ethernet (1000BASE-T1, IEEE 802.3bp). Common- and differential-mode pulse disturbances were injected into communication cables by a method referring to the coupling network described in IEC 62228-5. As a result, it was revealed that steep change of differential signal due to pulse disturbance degrades the communication quality at a specific pulse width.

In this letter, an initial verification results of a bandwidth tunable power amplifier in Ku-band designed by the hybrid semiconductor integrated circuit (HySIC) concept is reported. A GaAs monolithic microwave integrated circuit (MMIC) and a Si radio frequency integrated circuit (RFIC) were utilized as the HySIC configuration in the circuit design. For the purpose of initial confirmation of this design validity, the GaAs and Si chips were fabricated and packaged onto the copper tungsten plate with gold plating. As measured results, the lower cut-off frequency was changed from 9.8GHz to 11.9GHz, resulting in the bandwidth tunability in Ku-band.

The purpose of this paper is to estimate emotions for music pieces with lyrics. We investigate whether four emotions (happy, sad, angry and relaxed) can be accurately estimated by obtained bio-signals of subjects during music listening by analyzing them with convolutional neural network. Questionnaire responses by subjects are used as the correct labels, and the four emotions are classified by each and combined. The results of the analysis show that the accuracies of the both classification methods highly exceed the chance level. It suggests the possibility of emotion estimation for music listeners by bio-signals.

Blockchain is a distributed ledger technology for recording transactions. To guarantee the immutability of the blocks, miners need a lot of computational resources for generating blocks (mining). Since mining is conducted distributedly by many miners, chain forks can occur in the blockchain. In this paper, we investigate the effects of miners’ locations, the size of the mining pool (MP), and the network structure on the selection rate of blocks generated by the MP when chain forks occur through simulations.

The importance of real-time and data-driven notification has been growing for social services and Intelligent Transporting System (ITS). As an advanced version of Pub/Sub systems, publish-process-subscribe systems with MEC (Multi-access Edge Computing), where published messages are spooled and processed on edge servers, have been proposed. In this paper, we present a topic-based publish-process-subscribe system that allows a topic to be managed on multiple edge servers so that messages are processed near publishers and transferred to subscribers immediately. However, managing each topic on numerous edge servers can cause exhaustion of storage resources on edge servers. We introduce a simple topic allocation method on edge servers to discuss the problem. Experiments show the feasibility of our proposed system.

“Person Re-identification” technology has attracted more attention because of the proliferation of surveillance cameras and the increased awareness of crime prevention. However, there are various problems. One of them is that the same person is likely to be recognized erroneously as a different person due to the differences in persons’ appearance. Therefore, in this paper, we propose a method of hard positive mining to achieve better performance in identifying the same person images that are difficult to identify as the same person. The evaluation results using MARS dataset show that the CMS by applying the proposed hard positive mining is higher than the existing method of CNN with temporal pooling. It suggests that it is effective to apply hard positive mining in MARS dataset.

This letter proposes a rate control for robust data transmissions utilizing multiple access points (APs) combined with packet-level forward error correction (FEC). Beacon frames received from multiple APs are used to select an appropriate set of PHY and FEC rates to be employed for uplink transmissions, which is based on a machine-learning technique. With computer simulations, we show that the proposed rate control achieves the required reliability while significantly reducing the occupancy period of the shared channel.

In this paper, we investigate to estimate the subjective video quality of mobile users in a real situation of daily life. We conduct an experiment to collect bio-signals and sensor data from three subjects for a week as well as their contexts by questionnaire, and machine learning algorithms including Random Forest and k-Nearest Neighbor are applied for the estimation. The experimental results show that the subjective video quality is estimated accurately by Random Forest, while the contribution of users’ context is not confirmed. It suggests that the subjective video quality can be well estimated by bio-signals and sensor data of mobile users in a real situation.

In rolling-shutter (RS) optical camera communication (OCC), as the ratio of the exposure time to the symbol length increases, it becomes difficult to achieve error-free transmission due to inter-symbol interference. In this study, to increase the symbol rate, symbol decision based on spatial luminance distribution is adapted for RS OCC. When the symbol rate increases and the ratio is close to 1, it is difficult to achieve error-free transmission by conventional symbol decision based on pixel value. However, even when the ratio increases up to 1, error-free transmission is achieved by the symbol decision based on spatial luminance distribution.

We propose a correction formula using the percentage of area occupied by buildings, α, for a path model in the urban macrocell environment defined in ITU-R M.2135 based on measurements performed in Japan for below 6 GHz for 5G. Based on analysis, the regression results of the correction formula in which S, the median of the difference between the measured path loss and that of the reference path model is proportional to α, is better than when S is proportional to the logarithm of α.

In general, a millimeter-wave component, such as a waveguide, is made of metal, therefore, it is heavy weight and expensive. In this development, a W-band waveguide based on an additive manufacturing with an electroless plating was demonstrated. We confirmed that the performance of the transmission is approximately -2dB in 75-110 GHz on a 50mm long WR-10 waveguide.

In manufacturing fields such as factories, multiple wireless communication systems often operate in the same area simultaneously. Moreover, it is known that industrial equipment emits electromagnetic noise over channels for wireless communications [1]. In order to ensure reliable communications under such an environment, monitoring radio wave environments specific to each manufacturing field and finding channels and timing which enable stable communications are required. The authors have studied technologies to efficiently analyze a large amount of monitoring data including signals which show unknown spectrum such as wide band electromagnetic noise [2,3]. This paper proposes performing machine learning using cepstrum vectors as features to grasp types of noise and signals from data measured under environments in which electromagnetic noise and communication signals coexist. By using this features, the authors demonstrate that reduction of computational loads and improvement of detection accuracy can be expected.

This paper proposes a backbone network resource optimization algorithm for video communications of teleconferencing that use edge computing. In the current video communication architecture, the key component, the multi-point control unit (MCU), is deployed in the central cloud server, and its bandwidth consumption in the backbone network becomes huge as the video resolution and the frequency of use increase. By using edge computing, MCU can be deployed at the entrance node of the backbone network. This can reduce the bandwidth consumption of the backbone network. However, the edge deployment and routing (EDR) problem, which is classified as NP-hard, should be solved to achieve sufficient bandwidth reduction. To solve the EDR problem within a feasible time, we propose a divide and merge algorithm using the linear programming approach. We demonstrate that, with our algorithm, bandwidth consumption using edge computing is reduced by approximately 30% compared to the current architecture on a world-wide network.

Biological information monitoring systems are widely used to obtain and monitor the vital signs of patients in hospitals. However, the current system mainly uses the 420-450MHz band, making it difficult to manage channel switching, adding and removing equipment and so on, unless you are an expert in wireless communications. There is also the problem of having to carry a transmitter that is the same size as a small terminal. Therefore, we proposed a textile antenna using the 5.2GHz band as a replacement for the system’s transmitter antenna. In this paper, we report the antenna characteristics of the transmitter antenna designed by the authors when it is attached to the human body, the received power results of the transmitter power by analyzing the textile antenna in a simulated real-world environment model.

In this paper, we consider the reversibility problem in the class of quasi-cyclic (QC) codes Q over F_q of length nℓ and index ℓ generated by unfolding cyclic codes C over F_qℓ of length n. We prove a necessary and sufficient condition on C that ensures the reversibility of Q. Using computer search, we offer some good reversible QC codes that are generated by unfolding cyclic codes.

The millimeter-wave band is being focused as a frequency band in which high-speed and large-capacity communication can be realized, and various approaches for practical use have been made. In this paper, we studied the attenuation characteristics of the 45 GHz with the moisture contents and thickness of snow, which had never been studied and is expecting to be used in next-generation train communication systems and 5G. The characteristics are also compared with ones of 60 GHz which can be used for new Wi-Fi standard (IEEE 802.11ad). As the result, it is found that when snow accretes to the surface of the antenna radome, the attenuation increases as the moisture content increases and we can not neglect the influence on wireless communication using millimeter-waves.