Full-duplex cellular (FDC), which incorporates inband full-duplex (IBFD) into a cellular system, is a candidate scheme to enhance the spectral efficiency of the mobile communication system. To realize FDC, it is necessary to reduce self-interference (SI) and control inter-user interference (IUI) by appropriate user scheduling. Many researchers have studied various technologies to overcome them, but there are few studies to demonstrate the effectiveness of IBFD with actual equipment, which works in real time. In this paper, we develop a 5G-based real-time FDC prototype, which has functions of digital SI cancellation, collecting IUI information, and flexibly changing user scheduling in real time. In addition, this system can transmit and receive arbitrary data using 5G signals even in FD operation. We evaluate its fundamental effectiveness by experiment and show that IBFD can nearly double the UL and DL throughput.

In this paper, we show that there is an excellent possibility that 5G can be operated as a spectrum-sharing system in the 15 GHz band of the frequency range 3 (FR3). First, we consider how much spectrum resource can be secured in the 15 GHz band and show that it can ensure a 550 MHz bandwidth in many places and a 190–510 MHz bandwidth in urban areas. Next, we propose a phase noise model for the 15 GHz band, evaluate the block error rate characteristics of various sub carrier spacings (SCSs) using link-level simulation, and show no effect of phase noise if the SCS is 30 kHz or more. Finally, the interference immunity of the 5G new radio is evaluated, and it is found that the required SIR is approximately 10 dB and that each 5G base station could achieve coverage of approximately 700 m in radius.

This paper first summarizes the specifications of standardized wireless personal area networks (WPANs) and wireless local-area networks (WLANs) using the 60 GHz band, for example IEEE 802.15.3c and 802.11ad standards, and the significance of the standardization, together with the standardization transition of third-generation partnership project (3GPP)-based public wireless communication systems and other radio systems in the 2010s. The concept of a virtual community network (VCN) using a millimeter-wave wireless communication system in the 6G era is then proposed based on the 3GPP-based orthogonal frequency-division multiple access (OFDMA) system. Moreover, by using a latest propagation characteristics model of the 60-GHz propagation characteristics in 3GPP, we evaluated the block error rate (BLER) performance of the proposed VCN by changing the parameters of the physical layer such as the subcarrier spacing (SCS) through computer simulation. The results showed that a transmission distance of 5 m per terminal could be achieved even with a low-gain antenna, demonstrating the feasibility of a VCN based on the high-density installation of many terminals in a room.

Full-duplex cellular (FDC) system, which introduces in-band full-duplex (IBFD) to the cellular system, has been paid attention to for increasing spectral efficiency in 5G and 6G systems. IBFD causes new interferences, such as self-interference (SI), because uplink (UL) and downlink (DL) communications are performed simultaneously on the same frequency resources; however, if the new interferences problem can be overcome, IBFD can ideally improve spectral efficiency up to twice that of half-duplex (HD) system. Many SI cancellations have been proposed; however, to the best of our knowledge, there has been no study of digital SI cancellation for application of IBFD to the 5G system by taking into account the 5G signal configuration and the impact on the performance of low-density parity-check (LDPC) code. In this paper, we propose a digital SI cancellation for applying to the 5G-based orthogonal frequency division multiplexing (OFDM) signal. First, we propose a demodulation reference signal (DMRS) configuration to improve the estimation accuracy of the SI channel. Second, the noise power estimation scheme using the proposed DMRS configuration is also proposed for decoding 5G adopted LDPC. Finally, the proposed scheme is evaluated by computer simulations, and we found that the communication quality in IBFD operation becomes equivalent to that in HD operation by applying the proposed digital SI cancellation.

In-band full-duplex (IBFD), which ideally leads to a doubling of spectral efficiency, has been attracting much attention as a promising technology for the beyond 5G and 6G cellular systems. As a method for introducing IBFD to cellular systems, the dynamic duplex cellular (DDC) system has been proposed. In the DDC system, IBFD is applied if it does not degrade the quality of existing half-duplex (HD) communications. However, the conventional DDC system has not established sufficient improvement of user throughput due to the residual self-interference (SI) at the base station (BS). In this paper, we propose a DDC system with distributed receive-only base stations based on the concept of distributed antenna systems to reduce the impact of the SI. In the proposed system, the radio unit (RU) of the BS is separated into transmit-only RU (TRU) and receive-only RU (RRU), and the TRU and multiple RRUs are spatially distributed in the cell. The effectiveness by the proposed system is evaluated by computer simulation in the single-cell environment.

This paper proposes an inter-user interference (IUI) reduction scheme applying successive interference cancellation (SIC) to expand the in-band full-duplex (IBFD)-applicable area in the dynamic-duplex cellular (DDC) system. If the received power of the IUI is stronger than that of the desired signal at the user equipment for downlink communication (DL-UE), the IUI component is firstly demodulated and decoded in the proposed scheme. Then, a replica signal of the IUI is generated. Finally, we can obtain the IUI-reduced desired signal by subtracting the replica signal of the IUI from the received signal. By applying the proposed scheme to the DDC system, the IBFD-applicable area can be expanded. The proposed scheme is evaluated by the link-level and the system-level simulations to show the IUI reduction and the IBFD-applicable area expansion performances. From the evaluation results, it is found that the IBFD-inapplicable area can reduce from 33.9% to 8.0%, namely the IBFD-applicable area can expand by 25.9%, by applying the proposed scheme to the DL-UE.

In this study, the topic model was applied to specify the topics of the discussions in community disaster risk management workshops in Kunigami village, Okinawa, Japan. 20 topics were extracted from the text data of the workshop discussions held at 8 communities in the village. Not only the issues on natural hazards, but also the issues on local factors and mitigation activities were specified.

Safety and general versatility are necessary for robots to perform various tasks in human living area. There are tendon based manipulators with nonlinear springs as a manipulator for the requirement. Tension distribution which converts from joint space to tendon space are necessary to control such tendon mechanisms. A conventional tension distribution method using pseudo inverse matrix or inverse matrix of jacobian can not consider tension limits. On the other hand, advantages of structures utilizing bilogical extremities attract much attention. In this paper, we focus on an advantage of musculoskeletal model which contributes to simple algebraic calculation when deriving tension commands. And we develop a tension distribution method which can consider tension limits for musculoskeletal model of biological extremities. Its effectiveness as a part of whole control system is verified by simulations.