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We have undertaken an R&D project in the "advanced 5G" era that aims at accommodating various types of communication involving current and emerging services with different data flow-level quality requirements. In this paper, the objectives and the technologies of the project are presented. We propose an architecture based on a virtualized radio access network (vRAN) that enables adaptive resource control of radio, computation and transport links, and RAN function placement in accordance with spatially changing communication demands. The topics under study that are essential for realizing the advanced 5G network are as follows: (a) blockage prediction, new radio access technologies (RATs) and their implementations with software-defined radio (SDR) for nano-area using the millimeter wave band, (b) adaptive interference and resource control, integration of radio and optical resource control, highly efficient optical transport link control, adaptive RAN function replacement, and service estimation per data flow for adaptive RAN. These research topics are essential to the realization of the advanced 5G network and will become the entrance to the Beyond5G/6G system.

Advanced 5G around 2025 is expected to support various services with a combination of different quality requirements including data rate, latency, and error rate. To satisfy the quality requirements, we proposed adaptive placement of base station functions in a radio access network (RAN). When traffic congestion occurs on the transport link, the quality requirements cannot be satisfied. To avoid congestion on the transport link, one approach is to formulate a constraint on the transport link capacity based on predicted user traffic. Then, function placement is determined under the constraint. However, the predicted value of user traffic has errors, because user traffic changes in a random manner. In addition, traffic on the transport link is changed by function placement even if the same user traffic occurs. In this paper, we propose a control method for the constraint on the transport link by feedback loop. Our method calculates the constraint by considering both feedback of prediction error of the user traffic and the next base station function placement. We evaluated the proposed method by performing simulations. The result shows that our method can determine base station function placement without congestion on the transport link caused by the constraint when the user traffic changes dynamically.

The future 5G system is expected to support an additional diverse range of services with performance targets of low latency, high reliability, and high capacity. We have proposed an adaptive radio access network (RAN) system to support communication services called the advanced 5G system. The RAN slice is defined as a logical network able to provide a variety of services separately in a RAN. In adaptive RAN, an efficient slice admission control (SAC) scheme for RAN slices is required. Recently, research on applying a machine learning (ML) to facilitate efficient slice resource management and SAC in 5G RAN slicing environments has been discussed. However, the training time for the existing SAC scheme based on the Deep Reinforcement Learning Framework (DRLF) takes too long to achieve an acceptable level of performance. Since it takes a long time to learn, it is difficult to guarantee sufficient performance in the early phase of the operating period. In this paper, we propose a SAC based on an ensemble learning method (ELM) to reduce learning time and improve performance for the adaptive RAN. Our evaluation with ELM for the improved utilization of resource blocks (RBs) shows that the proposed approach outperforms the other approaches.

We started a new research project in the “advanced 5G” era that aims at accommodating various types of communications involving current and emerging services with different data flow-level quality requirements. In this paper, the objectives and the technical aspects of the research project are introduced. We propose an architecture based on a virtualized radio access network (vRAN) that enables adaptive control of equipment resources and location of functions in the vRAN environment in accordance with spatially and temporally changing communication demands. The seven planned research items that are essential for realizing the advanced 5G network are listed as follows: blockage prediction, new radio access technologies (RATs) and their implementations with software-defined radio (SDR), adaptive interference and resource control, integration of radio and fiber resource control, highly efficient access transmission control, adaptive placement of BS functions, and quality aware traffic pattern prediction.

The future 5th generation (5G) mobile communication system will be required to support diverse services. Because of the difficulty in addressing the requirements of all these services using the same physical network, “network slicing,” which provides a customized logical network corresponding to service requirements, has recently attracted a great deal of attention. In the radio access network (RAN), the appropriate locations of base station functionalities to meet service requirements and achieve efficient network operation differ according to service type. Therefore, we have proposed a novel RAN slicing architecture, which has logical networks (slices) that choose an appropriate functional split option and its placement, to adjust to providing any service. This architecture achieves high flexibility and large scalability by employing a software-defined network and network function virtualization. A prototype is then developed based on the proposed architecture employing a unified controller of open-source software. It can construct slices for three service types: enhanced mobile broadband, ultra-reliable and low-latency communication, and massive machine-type communication, with flexibly located functionalities. In this paper, an experimental evaluation, considering the points of bandwidth consumption in midhaul, the impact of midhaul delay, communication latency, and isolation among slices, shows that the slices have specific performance benefits for each service type and also to achieve efficient network operation. This suggests that the proposed architecture is able to construct slices in a single infrastructure with different features according to the services required and to accommodate various services efficiently.

In the context of 5G mobile networks, various types of services need to be supported. Network slicing is key to enabling a diverse range of services to be accommodated in the same physical network by providing a customized logical network. In a radio access network (RAN), the placement of RAN functions can be customized for each slice in order to satisfy service requirements. In this paper, we propose a RAN slicing architecture which has multiple sets of functional splits and function placement in one cell. For better resource efficiency with the proposed architecture, resource allocation should be updated by RAN controller at a specific interval. We propose a resource allocation method for the architecture which maintains isolation between slices while taking the fulfillment of the Service Level Agreement (SLA) into consideration. The results show that the proposed method guarantees isolation between slices and keeps the probability of SLA fulfillment close to that of the conventional method.

In this paper, we mainly evaluate a proof-of-concept (PoC) for a cost-efficient virtualized, functional splits 2 and 5 enabled TDM-PON based Cloud Radio Access Network (CRAN) using M-CORD. In doing so, we first present a novel M-CORD based prototype for the virtualized CRAN (vCRAN) in LTE systems. We then evaluate the PoC under ideal fronthauls for the vCRAN by assessing the feasibility of the TDM-PON system and virtualization of CRAN itself as a cost-efficient solution as well as the impact of fronthaul delay and packet loss using both TCP and UDP traffic with the 3GPP functional splits 2 and 5. Finally, we compare the evaluation results with both splits, and overall, it is found that split 5 shows better throughput performances than split 2. More specifically under ideal fronthauls, with virtualized BBUs, the throughput improvement is significant for TCP as compared to UDP, which are about 30%-40% and 40%-45% higher in mean throughputs respectively in the downlink and uplink with split 5 than that with split 2. Further, unlike split 2, the mean throughput with split 5 is neither affected by the TDM-PON system nor deviated considerably with the fronthaul delay and packet loss.

Efficiency is one of the most important parameters in a microwave power transfer system. We proposed a wireless charging system for an electric truck via microwaves. Here we studied the antenna absorption efficiency of a finite receiving array antenna and the beam efficiency between a transmitting and receiving array antenna using finite-difference time-domain (FDTD) simulations. The antenna absorption efficiency of a finite receiving array antenna reaches 95.1% with a matched optimum load and the beam efficiency reaches 99.9% using a Gaussian beam with an optimum focal point.

Non-leak energy technology is essential for high power system in microwave power transmission (MPT). MPT mainly consists of a transmitting antenna and a receiving antenna, and we focus on the receiving antenna. Non-leak energy system requires the receiving antenna to receive all the energy which reaches the antenna surface. It is known that the receiving efficiency of an infinite dipole array antenna with reflector becomes 100% analytically under the matching condition by the induced electromotive force (EMF) method. In this paper, the matching condition is discussed by using finite difference time domain (FDTD) method simulation. The radiation impedance is analyzed to satisfy the matching condition. In case that the load impedance is complex conjugate of the radiation impedance, the receiving efficiency reaches 99.9%. In addition, the reflection of the transient state is discussed.

Tributyltin is ubiquitous in the environment and an endocrine disruptor for many wildlife species. However, minimal information is available regarding the effect of this chemical on bone formation. When tributyltin chloride (TBT) (1mg/kg body weight) was administered subcutaneously to pregnant mice at 10, 12, and 14 days post coitus (dpc), fetuses at 17.5 days post coitus revealed the inhibition of calcification of supraoccipital bone. In contrast, 1mg/kg body weight monobutyltin trichloride (MBT) did not affect the fetal skeleton. Therefore, we examined the effects of TBT and its metabolites (dibutyltin dichloride, DBT, and MBT) on bone metabolism using rat calvarial osteoblast-like cells (ROB cells). The viability of ROB cells was not affected by the exposure of the cells to 10(-10) to 10(-7)M TBT. However, TBT reduced the activity of alkaline phosphatase (ALPase) and the rate of deposition of calcium of ROB cells. In addition, the expression levels of mRNA for ALPase and osteocalcin, which are markers of osteoblastic differentiation, were depressed by the treatment with TBT. TBT inhibited ALPase activity and the deposition of calcium to a greater extent than did DBT. MBT had no effect on the osteoblast differentiation of ROB cells. Tributyltin is known to inhibit the activity of aromatase. However, the aromatase inhibitor aminoglutethimide did not reproduce the inhibitory effects of TBT on osteoblast differentiation. Our findings indicate that TBT might have critical effects on the formation of bone both in vivo and in vitro although its action mechanism is not clarified.

It is possible that the flavonoids that are found in many foods might have a protective effect against osteoclastic activity. However, little information is available about the effects of flavonoids on osteoblastogenesis. Therefore, we investigated the effects of quercetin, a flavonoid, on the metabolism of rat calvarial osteoblast-like cells (ROB cells) in culture. The proliferation of cells was markedly inhibited upon exposure of cells to quercetin at 5 x 10(-6) to 1 x 10(-5) M. Quercetin at 1 x 10(-5) M did not induce apoptosis in ROB cells but arrested cells at the G1 phase of the cell cycle. In addition, quercetin stimulated the expression of mRNA for p21(waf1/cip1), which inhibits the activity of cyclin-dependent kinases, and inhibited the phosphorylation of histone H1. Furthermore, after cells had ceased to proliferate, quercetin reduced the activity of alkaline phosphatase, the level of expression of mRNA for osteocalcin, the rate of deposition of Ca(2+), and the formation of mineralized nodules, all of which are markers of osteoblast differentiation. These findings indicate that quercetin inhibits the proliferation, differentiation, and mineralization of osteoblastic cells.

Holographic data storage (HDS) is a promising technology that has huge capacity. A multiplexing method plays a significant role in increasing the data capacity. Various multiplexing methods have been researched so far. In this paper, we proposed shift-peristrophic multiplexing using spherical reference wave and experimentally verified that this method is efficiently increase the data capacity. A series of holograms was recorded with shift multiplexing and rotating recording material with the axis of rotation being perpendicular to the material's surface. This method can realize more than 1 Tbits/inch 2 data density recording. Furthermore if we maximize the performance of a recording medium, several TB per disk capacity would be available.

Holographic data storage (HDS) is a next-generation optical storage that uses the principles of holography. The multiplex holographic recording method is an important factor that affects the recording capacity of this storage. Various multiplex recording methods have been proposed so far. In this study, we focus on shift multiplexing with spherical waves and propose a method of shift multiplex recording that combines the peristrophic multiplexed recording. Simulation and experimental verification shows that the proposed method is effective in principle.

Along with the wider use of high-speed information networks and multimedia, it is increasingly necessary to have higher-density and higher-transfer-rate storage devices. Therefore, research and development into holographic memories with three-dimensional storage areas is being carried out to realize next-generation large-capacity memories. The mainstream in the world is the angle multiplexing method, however, its beam position control is quite severe. In such situation, we study about shift multiplexing method because it costs not much and its control is easier than the angle multiplexing. In this experiment, we examined shift selectivity of track direction, radial direction and vertical direction of the medium. As a result, combining these different kinds of selectivity, we found a possible multiplexing way to achieve several tera bits per inch square density recording.

Alkylphenols are endocrine disruptors that show estrogen-like effects in various wildlife species. However, little information is available about the action of these chemicals on bone metabolism. We investigated the effects of alkylphenols, such as nonylphenol (NP) and octylphenol (OP), on the formation of bone using several culture systems for osteoclasts and osteoblasts, as well as in vivo experiments. NP and OP dose-dependently inhibited the formation of tartrate-resistant acid phosphatase-positive multinucleated cells (osteoclasts) in cocultures of mouse spleen cells or mouse bone marrow cells with ST2 cells. However, β-estradiol at 10 −9 M to 10 −6 M did not affect this process. In contrast, neither compound affected the proliferation and differentiation of rat calvarial osteoblast-like cells (ROB cells). When NP or OP (0.1 mg/kg body weight) was administered subcutaneously to pregnant mice at 10 days, 12 days and 14 days post-coitus, fetuses at 17.5 days post-coitus showed stimulation of sternebrae bone calcification. Our findings suggest that alkylphenols have critical effects on the formation of bone by non-estrogenic effects.