Many countries face aging populations and declining birth rates, prompting exploration of information and communication technology (ICT)-driven solutions, including robotics. Japan’s Moonshot Project Goal 1 aims to develop cybernetic avatars (CAs) for a sustainable society where individuals maximize abilities and pursue diverse lifestyles. CAs go beyond teleoperated avatars by integrating ICT and robotics to enhance physical and cognitive functions, enabling teleoperators (TOs) to engage in social activities remotely. Stable teleoperation requires high communication quality, especially when network paths lack guaranteed bandwidth or quality of service (QoS). This paper proposes a CA reliability-ensuring platform with hybrid traffic management, comprising communication quality monitoring and visualization, jitter buffering, and dynamic path switching. The platform deploys called support node with these functions at several points in the end-to-end (E2E) network and in TO and CA devices. To evaluate the platform, a dual-arm robot (as CA) and control device were set up between two sites 70 km apart, with tests introducing quality degradation such as jitter and packet loss. In the E2E network, normal root mean square (RMS) of the difference of packet delay was 7.28 ms, calculated as a magnitude of jitter, while added jitter increased it to 20.87 ms. Using jitter buffering, the RMS was reduced to 0.84 ms. Dynamic path switching also stabilized teleoperation under packet loss, confirming the platform’s effectiveness.

Cybernetic avatars (CAs) are set to revolutionize society by enhancing human physical and cognitive capabilities through advanced ICT and robotics, as part of Japan's Moonshot Goal 1 project. CAs enable individuals to overcome physical and spatial limitations, facilitating participation in remote and collaborative activities. This effort is part of building a reliabilityensuring platform using Local 5G networks that guarantees seamless CA teleoperation. However, when numerous CAs operate concurrently, limited wireless communication capacity can significantly degrade service quality and fairness in resource allocation. To address this challenge, we propose a dynamic multilayer service area adjustment method that enhances fairness by dynamically adjusting coverage area boundaries in real time. This method optimizes resource block (RB) allocation efficiency, significantly improving fairness as measured by Jain's Fairness Index under varying network loads. Comparative performance evaluations using system-level simulations against the traditional fixed coverage service area method demonstrate that the dynamic approach effectively balances system throughput and resource utilization, offering a robust and adaptive solution for emerging Local 5G network deployments.

In this paper, we focus on a satellite-ground multi-casting scenario assisted by a free space optical (FSO) link, where multiple ground devices are requesting the same data packet from a satellite via the FSO link. Due to the extremely long link distance in satellite-ground communication, the coverage of an optical beam has been considerably enlarged. We aim at deploying the corresponding coverage benefits of the optimal beam in provisioning multicasting services to ground devices. At first, we characterize the achievable multicasting capacity for considered satellite-ground communication. Assuming the deployment of an optical beam can be switched between an activation mode and an idle mode, we formulate a multicasting throughput maximization problem under a maximum average power limit for the optical signal emission, via jointly optimizing the optical beam deployment and the activation slot scheduling. Both optical power bias and beam pointing direction will be optimized in the optical beam deployment design. For optimally solving the formulated nonconvex problem, we perform a two-fold problem reformulation and successfully convert the nonconvex problem to a convex one. The convex problem reformulation allows us to equivalently and optimally tackle the original problem via convex optimization tools. At last, in comparison with two benchmarks, we verify the optimality of our proposed design and illustrate the performance benefits of allowing idle operation mode and performing beam pointing design.

In order to fulfill the demand of increasing data transmission rate, usage of THz band is attracting much attention. To overcome the high propagation loss in THz band, access points (APs) are supposed to be densely placed. In order to control radio resource usage of APs as well as supporting applications that require device positioning, it is highly desirable that symbol timings of the APs are synchronized. In this paper, as an alternative approach to use a synchronization master, network synchronization nor the synchronization using global navigation satellite system (GNSS), over-the-air (OTA) peer AP synchronization is proposed, where a pair of peer APs adjusts their symbol timings according to measured time of arrival (ToA) of each other's signal. By performing the peer AP synchronization with other surrounding peer APs, a whole group of APs can form a synchronized cluster. The results of computer simulations show that the maximum symbol timing difference of APs can be kept less than 10 ps for the case that the symbol duration is 100 ps, with which centimeter level device positioning can be supported.

The adoption of wireless communication in various fields has created the needs for easy wireless network construction and optimal wireless system selection, considering the coexistence of multiple wireless systems. In this paper, we propose two main contributions: a database that describes indoor building information and a wireless estimation method that uses deep learning. The first contribution involves digitizing indoor building information and creating the database for the building information, while the second utilizes the database to operate a deep learning model called RadioResUNet, which predicts the radio signal strength (RSS) of a 2.4 GHz Wi-Fi system in complex indoor environments with multiple walls and obstacles. By leveraging the building information database, the deep learning-based radio estimation method enables the estimation of RSS for a given building configuration and the position of the access point (AP). This method also allows for radio prediction in a desired area in advance, even when updating the indoor building information in the database. It can save time and expense while ensuring ongoing wireless connectivity support by comprehending the wireless situation of the new indoor building configuration,

In this paper, the received power calculated using ray-tracing simulations is compared with measurement data obtained in a factory environment. In order to reduce the errors of the ray-tracing received power at sub-6 GHz frequencies due to the wavelength being larger than many objects, a novel method to adjust the power of reflected and diffracted waves based on the wavelength and the dimensions of the objects is proposed. Through cross-validation of the proposed method at 922 MHz and 4.85 GHz frequency bands, the median absolute error of the ray-tracing received power value could be reduced from 9.7 dB and 4.1 dB to 4.6 dB and 2.2 dB for each frequency band respectively.

The Internet of Things (IoT) has recently gained widespread adoption. In the context of IoT communications beyond 5G, both low latency and massive connectivity play an important role in mission-critical communication. To meet these requirements, a beyond 5G system utilizing configured grant (CG) and non-orthogonal multiple access (NOMA) is proposed, which reduces latency and increases the number of user equipment (UE) accommodated at gNodeB (gNB), respectively. Among the NOMA schemes, the power domain (PD) NOMA is considered to be one of the most promising methods because it has a lesser impact on 5G specifications. This paper aims to investigate the CG-PD-NOMA system with transmit diversity (TD) to enhance reliability for uplink communications. TD mitigates fading fluctuations that deteriorate the throughput of CG-PD-NOMA with successive interference cancellation (SIC). A computer simulation was conducted to assess the performance of the proposed CG-PD-NOMA system with TD. The results indicate that TD effectively decreases BLER and improves throughput by approximately 3%.

Although in-band full-duplex (IBFD) communication can theoretically double the spectral efficiency compared with conventional wireless communication technologies, it cannot be realized without reducing a high-power self-interference (SI) signal. Since the SI signal is affected by nonlinear distortion of radio-frequency (RF) circuits of its own terminal, cancellation systems capable of removing the nonlinear distorted SI have been actively developed. Detailed theoretical analysis based on the authors’ past literature shows that for IBFD using a nonlinear self-interference canceller, the symbol error rate is improved when the power amplifier has certain distortion characteristics rather than being ideally linearized. However, it is not yet known what amplifier characteristics are best for the IBFD system. In this study, we theoretically analyze the self-interference signal to clarify the optimum amplifier characteristics for the IBFD system. An optimization problem to obtain an optimum transfer function from theoretical analysis is formulated as an Rayleigh quotient with constraints, and we introduce a numerical technique to solve the optimization problem. By numerical experiments, we show that the SI cancellation performance, signal-to-interference-distortion-plus-noise ratio (SIDNR), and amplifier’s power efficiency are improved by the optimization.

Bridge inspection using drones has become considerably more attractive owing to the ability of drones to gather information safely in lesser time and at a lower cost than traditional inspection methods. However, one of the critical issues in drone-based bridge inspection is ensuring stable communication between the operation base and inspection drones. The inspection drone easily loses sight of the operation base because bridges have intricate structures. Therefore, this study developed a radio map-based flight planning method of autonomous repeater drones for bridge inspection in order to ensure stable communication. Based on the inspection scenario, the repeater drone needs to ensure the communication with a minimum movement even under position deviations caused by winds. First, we generated a three-dimensional radio map of the bridge. Then, under the assumption that the inspection drone adopted a predetermined path, we developed a path planning method for a repeater drone based on the radio map. Some path planning examples demonstrated that the generated path reduces the moving distance and is also robust against the position error, in addition to ensuring stable communication.

In order to measure the propagation channel characteristics in a factory environment, measurements were performed in the 2.4 GHz and 5.2 GHz bands to obtain the received power and delay spread at various locations. The received power at several fixed locations was recorded simultaneously to measure the long-term power fluctuations caused by the dynamic factory environment. Power fluctuations were also recorded from a receiver placed on an Automatic Guided Vehicle (AGV) which frequently moved around a fixed area within the factory. The probability distribution of the received power was compared with several distribution models, and results show that they can be modelled using the stable distribution. Furthermore, analysis of the relationship between delay spread and received power between several transmitter and receiver locations in the factory suggested that they are inversely correlated, where the delay spread increased when the received power decreased.

In-band full-duplex (IBFD) is a technique for transmitting and receiving signals simultaneously using the same frequency and time slot. Ideally, by adopting IBFD, the frequency utilization efficiency can be twice than that of the half-duplex. In this study, we focus on a full-duplex cellular (FDC) system, where the base station (BS) allows for the superimposition of downlink (DL) communications with other user equipment (UE) on the uplink (UL) communications and the superimposition of UL communications with other UE on DL communications by applying IBFD. The BS needs to identify the UE whose signals do not degrade DL communication quality in the FDC. Moreover, self-interference (SI) of the BS (i.e., interference when the transmitted signal interferes with its own received signal in IBFD) should not degrade the UL communication quality. This paper summarizes the system configuration and research and development items on the dynamic-duplex cellular system that is generally operated in half-duplex. It adaptively performs IBFD only for UEs whose signal does not interfere with other users. In addition, this paper summarizes the development of a monitoring system for the interference from UEs and the development of digital and analog SI canceller applicable to a BS. The developed BS can reduce SI by more than 35 dB in the RF and more than 20 dB in the digital parts.

Orthogonal precoded (OP)-orthogonal frequency-division multiplexing (OFDM) is an OFDM scheme with invertible precoding. As previously reported, slight redundancy in data transmission orthogonal precoding to efficiently suppress high out-of-band emission (OOBE) of traditional OFDM signals. On the other hand, precoding generally affects modulating symbols on all subcarriers, and thus, prevents classical channel estimation schemes based on pilot subcarriers. This study investigates a design to protect the pilot subcarriers in the OP-OFDM system and proposes an efficient semi-blind channel estimation method to reuse the redundancy of the precoding. Numerical experiments are conducted in the context of satisfying a strict spectral mask of 50 dB at band-edges by the OP-OFDM system with the pilot subcarriers. The experimental results show that the proposed method can estimate channel responses over all the subcarriers at a high accuracy equivalent to the counterpart on the pilot subcarriers.

This paper proposes a concept of large-scale emulation and evaluation environment of wireless communication systems. The environment can build radio nodes called virtual node by software in cyberspace and provide interaction among the virtual nodes and the reconfigurable physical radio devices that are connected to the environment from the outside. The environment therefore enables preliminary investigations and evaluations for the highly advanced and complicated wireless systems in the future. Moreover, in the radio interactive emulation, the radio propagation parameters based on the preliminary obtained models are suitably referred. The proposed wireless emulation environment enables wireless emulations required in the six typical wireless systems that are further developed and promoted in B5G/6G society. The paper shows evaluation and consideration of the fundamental performances for the proposed wireless emulation environment that includes numerical investigation for the interconnection performances between the virtual nodes and the reconfigurable physical radio devices, as well as fundamental operation for the wireless emulation with suitable visualization functions.

In recent years, the importance of pre-verifying the status of wireless communications has increased for designing offices. Because wireless communication is used for various purposes in offices, this technology has become a basic infrastructure for business. Therefore, when building a new office or renovating an office, verifying the impact on radio waves while designing the workspace is paramount. However, no highly accurate simulation tools for radio waves are available that can be easily used by office planners, who do not possess expert knowledge of radio waves. To address this challenge, we propose smart office planning system that can be linked to a radio wave emulation system that can verify radio wave propagation and communication behavior with high accuracy and can be easily used by office planners. This paper presents the results of a usability evaluation of a smart office planning system. As a result, users could easily set simulation scenario by preparing a general-purpose template option and could evaluate the state of wireless communication by using 2 visualization strategies: a three-dimensional visualization that simultaneously presents the three-dimensional structure of the office space, radio propagation, and communication behavior, and a two-dimensional visualization that visualizes problems affecting the quality of work. Moreover, in the future, by integrating the smart office planning system with the radio wave emulation system, office planners will presumably be able to verify the effects of workspace design on radio waves in advance, thereby reducing the man-hours required for office construction and ensuring adequate communication quality in the workspace.

In recent years, the number of Internet of Things (IoT) devices has been increasing. There is a growing demand for communications with high frequency utilization efficiency. Non-orthogonal multiple access (NOMA) is a promising scheme for realizing it. In this paper, we conduct evaluations in power domain NOMA in uplink channel (UL-PD-NOMA) using not only computer simulation but hardware experiment. In our simulations, four user equipments (UEs) send signals simultaneously. These UEs are assigned to the same time and frequency resource. To exploit the diversity effect of frequency selective fading, we propose repetition with cyclic frequency diversity (CFD) that is applied to UL-PD-NOMA system. The number of repetition transmission is set to two for any UE in the paper. At the BS, minimum mean square error based frequency domain equalization (MMSE-FDE) and successive interference cancellation (SIC) are performed to separate superimposed signals. As a result, at a carrier-to-noise ratio of 25 dB, the average block error rate (BLER) of four UEs is improved from 29.6% to 4.4% by using the proposed method in the hardware experiment. And we confirm that the repetition with CFD is effective to improve BLER in UL-PD-NOMA.

This article proposes a novel Airborne Internet of Things Network (AIN) system architecture for monitoring water quality, combining existing wireless technologies with the aid of a low altitude platform (LAP) to relay data over long distances in hilly terrain. The proposed system consists of water quality sensors, smart utility network (SUN) devices, long range (LoRa) wireless devices, an LAP air balloon, and Wi-Fi devices. A measurement campaign was conducted to assess the proposed system, focusing on the communication link reliability and the LAP stability and robustness. Several constraints, such as payload limit and safe weather conditions, were also highlighted for operating the LAP with extensive and reliable coverage. On the other hand, characterizing the wireless channel has become a crucial parameter for planning and deploying Internet of Things (IoT) applications. Accordingly, this work proposes a novel hybrid machine learning (ML)-based semi-empirical path loss (PL) model for LoRa wireless communication. The results validated the proposed system’s effectiveness, unique characteristics, and capability to monitor water quality in a harsh environment. Results also revealed a significant difference in packet delivery rate (PDR) for different gateway height and spreading factor (SF) configurations. For instance, switching SF7 to SF12 increased PDR by 28.7%. Meanwhile, increasing gateway height increased PDR by 29.2% for similar SF configurations. The evaluation also revealed that none of the established PL models are suitable to represent harsh tropical environments. Finally, the proposed model achieved nearly 90% prediction accuracy for testing samples and 95% accuracy for training and overall measurement samples, vastly outperforming conventional models.

Currently, in-band full-duplex (IBFD) has attracted much attention and has been researched for the beyond 5G systems. IBFD enables simultaneous operation of downlink (DL) and uplink (UL) communications at the same frequency and ideally doubles spectrum efficiency compared with the conventional half-duplex. In recent years, the dynamic-duplex cellular (DDC) system has been proposed to flexibly expand the system capacity with IBFD. However, previous studies of the DDC system were based on the LTE (Long-Term Evolution) system in the sub-6 GHz band. In this paper, we propose a 5G new radio-based DDC system to add UL communications to the DL subframes by considering the antenna directivity in the super high frequency (SHF) band.

Machine-to-machine (M2M) communication is an emerging communication paradigm, and it offers ubiquitous applications. Cellular M2M network has shown great potential. A well-established mobile cellular network seems to be the best option to provide connectivity for M2M communication, and this has attracted mobile network operators to host or deploy the M2M network on their existing infrastructure. However, one of the significant challenges to realize a cellular M2M network is its device density. In a cellular M2M network, millions of devices are connected to the mobile communication system in addition to the current mobile subscribers. The accommodation of a massive number of M2M devices would be a considerable burden for the mobile network system, as the signaling of M2M devices would cause channel congestion and undesirable signaling overheads due to mobility and session management. In this paper, we propose an efficient group-based mobility management mechanism for cellular M2M communication to mitigate the signaling cost for device mobility-related events.

Device-to-Device (D2D) communications in this paper refer to autonomous direct communications among end devices without central control. Wireless networks based on autonomous D2D communications are of resiliency feature. We developed a lifelog gathering system using such autonomous D2D communications towards elderly health monitoring in depopulated area, where creating wireless networks with coverage over entire area is costly. The developed system consists of three types of terminals, i.e., sensing terminal (s-terminal), delivering terminal (d-terminal), and gathering terminal (g-terminal). The s-terminal collects lifelog at objective’s house. The d-terminal can be placed in a moving car and it receives lifelog data when running within communication range of the objective’s house. Moreover, the lifelog is forwarded to the g-terminal when the d-terminal enters the communication range of facilities where the g-terminal is in operation. We conducted field experiments in a mountainous village. The measured results show that the developed system can successfully gather lifelog data even under non line-of-sight environments. Examples of observation from the gathered lifelog data are also presented.

To further improve spectral efficiency for current wireless communication systems, we propose a new lazy learning-based cancellation approach to suppress self-interference (SI) sent from a base station and enable in-band full-duplex (IBFD) transmissions in cellular networks. Differ from the existing IBFD systems based on traditional approaches, our proposal consists of two phases: an offline phase for database generation and an online phase for data transmission. In the offline phase, the output before a 0/1 decision is previously measured without the desired signal input and recorded to a database with self-defined feature vectors (FVs). In the online phase, for the same system architecture with the desired signal input, a suitable result is sought from the generated database with the help of a learning method and the use of FV; then, the result is assigned as a value of SI cancellation. Computer simulation results indicate that the proposed cancellation approaches can achieve about 134 dB SI suppression and thus enables the IBFD transmissions in the considered systems.

In this paper, we propose a novel efficient implementation of the optimal detector based on the minimum-mean-square-error criterion for orthogonally precoded orthogonal frequency-division multiplexing (OP-OFDM) systems. It enables the OP-OFDM to compensate for data rate loss reported in previous work with a reasonable receiver complexity. Numerical experiments show the proposed detector achieves outstanding error rate and throughput performances, and reduces the computational complexity by roughly 95 % from the conventional implementation in practical contexts where the OP-OFDM systems satisfy a strict spectral mask of 55 dB at band-edges.

It is expected that the highly-dense deployment of private fifth generation mobile communications system (5G) microcells will be further accelerated in order to meet the demands of a wide range of use cases in various environments. This motivates the need for spectrum sharing research in the mmWave spectrum. The use of array antennas in 5G systems opens the possibility for spectrum sharing in the angular domain in addition to the frequency domain. This paper investigates the use of compressive sensing (CS) to efficiently perform spectrum sensing over a wide bandwidth in the frequency and angular domains simultaneously using only a small number of compressed measurements. The CS problem is formulated using the Kronecker product of overcomplete dictionaries, where the overcomplete dictionary in the angular domain consists of frequency-dependent steering matrices. Modification of the Kronecker Orthogonal Matching Pursuit (Kron-OMP) algorithm is proposed, and group-sparsity is enforced over the frequency domain to improve detection of wideband signals. The effectiveness of the proposed approach for wideband spectrum sensing is confirmed through Monte Carlo simulation.

In this paper, a novel cancellation scheme named superposition cancellation technique is proposed by using a superposition modulation technique for the single carrier fullduplex (FD) system. The proposed scheme utilizes the features that a single carrier with the Nyquist filter has no inter-symbol interference (ISI) and the phase-shift keying (PSK) modulation symbol has a constant amplitude to perform the self-interference (SI) cancellation. The proposed scheme can be applied in combination with other conventional cancellation schemes. This means that the cancellation requirement for the conventional cancellation schemes can be mitigated. From the feasibility study with theoretical evaluation and computer simulations, the proposed scheme achieves about 40 dB SI cancellation.

IEEE 802.22 is a standardized WRAN (Wireless Regional Area Network) system that operates in TVWS (TV White Spaces) and aims to achieve an effective spectrum utilization. Since IEEE 802.22 offers excellent propagation characteristics in the UHF (Ultra High Frequency) band, it is expected to support a cost-effective wireless communication system in rural areas. To provide a long-distance wireless communication, it is important for the receiver design to compensate a multipath fading attributed to large differences in path lengths, while existing multipath fading channel profiles applicable to IEEE 802.22 has generalization and statistical limitations. To generally and stochastically reproduce the multipath propagation characteristics in an actual wide area environment, an algorithm to obtain a statistical channel model extracted from the field experiment data is required. In this study, we develop a novel channel modeling algorithm based on the conventional S-V (Saleh-Valenzuela) modeling algorithm that offers an approach to model and reproduce the multipath characteristics in an actual environment. The proposed channel modeling algorithm applies a dynamic GEV (Generalized Extreme Value) distribution fitting for the amplitude fluctuation of individual arrival cluster. We also evaluate the channel reproduction performance of the proposed algorithm by computer simulation using channel modeling factors calculated from the experiment result with a FE (Fading Emulator). As a result, by applying the proposed algorithm, the multipath fading characteristics measured in the experiment can be modeled, and its reproducibility is confirmed with regard to relative path power distribution, rms delay spread distribution, and BER characteristics.

The enhanced universal filtered-DFTs-OFDM (eUF-DFTs-OFDM) has been proposed for reducing the out-of-band emission (OOBE) drastically with low peak-to-average power ratio (PAPR). However, this scheme has high complexity due to the time-domain convolution of LPF. In this paper, we propose a new time-domain windowing function for the universal time-domain windowed-DFTs-OFDM (UTW-DFTs-OFDM) to reduce the OOBE with low PAPR and low implementation complexity by using a time response of the LPF for the eUF-DFTs-OFDM. The performance of the proposed time-domain window function is evaluated by simulation in terms of OOBE, PAPR, block error rate (BLER), and implementation complexity with the LTE uplink parameters. As a result, we achieve almost same performance as the eUF-DFTs-OFDM with the significant reduction of the number of multipliers used for wave-shaping.

IBFD (In-Band Full-Duplex) has attracted renewed attentions in recent years along with the improvement of self-interference cancellation technologies because IBFD can ideally double the system capacity. Although there have been various reports applying IBFD to the cellular system, some impair the compatibility with the conventional LTE (Long-Term Evolution) system and some are not evaluated in practical scenario such as a multi-cell environment. In this paper, we propose an advanced DDC (Dynamic-Duplex Cellular) system applying IBFD to all cells in a multi-cell environment. The proposed system suppresses inter-cell interferences among all cells and enhances the system capacity with proper scheduling and power control without information exchange among neighboring cells while maintaining compatibility with the conventional TD (Time division Duplex)-LTE system. Practicality of the proposed DDC system is also evaluated by computer simulation with regard to the enhancement of the user throughput.

Since IEEE 802.11af was standardized in 2013 as one of the standards for TVWS (TV white-spaces) communication, a variety of radio devices such as a high-power radio device al-lowing a transmission power of 1 W and a dongle-type com-pact radio device have been prototyped and demonstrated in field experiments. Meanwhile, since all the reported prototypes were limited to a single channel operation with a channel bandwidth of 6 MHz, achieved throughput was inferior to the commercialized WLAN (Wireless Local Area Network) systems with a channel bandwidth of 20 MHz or more. In this paper, to enhance the throughput of the IEEE 802.11af system, we de-sign and prototype a radio device based on IEEE 802.11af with a channel aggregation function. In addition, we evaluate fun-damental characteristics of the prototype radio device including radio performance and throughput.

Currently, the IAB (Integrated Access and Backhaul) system that offers effective relaying architecture between Donor and UEs (User Equipments) via Node has been discussed in 3GPP for various use cases including mobile relaying scenarios. For applying the IAB system to mobile systems, sub-6 GHz band is used for BL (Backhaul Link) to support wide coverage, and it is preferred to use the same frequency for both BL and AL (Access Link) due to the serious spectrum resource shortage below 6 GHz. However, since the frequency resource is divided into four links by the combination of BL/AL and UL/DL (Uplink/Downlink), system capacity of the sub-6GHz IAB system will be degraded. In this paper, we propose DDC (Dynamic full- Duplex Cellular)-IAB that applies IBFD (In-band Full-duplex) to the sub-6 GHz IAB system to enhance the system capacity. With the system level simulation in a multi-cell environment, the proposed DDC-IAB system improves UL UPT (User Perceived Throughput) between UE and Node and between UE and Donor by 90.2 % and 34.9 %, respectively, and also improves DL UPT between Donor and UE by 39.6 % compared to HD (Half-duplex)-IAB system.

The IEEE 802.22 system was standardized in 2011 as a fixed wireless communication system for regional area networks using TV white-spaces (TVWS). Due to its wide coverage area of 10-30 km, the IEEE 802.22 system is expected as a backbone wireless network system in developing countries as well as a public safety broadband communication system even in leading countries. This wide coverage enables a reduction of the number of base stations, resulting in the initial-cost saving compared to other communication systems. However, previously prototyped IEEE 802.22-based devices have not been deployed for social demonstrations, because there still have difficulties in cost and procurement due to the costly design such as FPGA-based baseband signal processing and specially customized RF components to comply with the strict spectrum limitations by some leading countries. In this paper, we prototype compact and lightweight IEEE 802.22-based radio equipment by applying mixed design using an FPGA and a DSP. Measured transmission spectrum conforms to Ofcom and FCC regulations with a transmit power of +30 dBm and +24 dBm, respectively. Also, measured receiver sensitivity achieves the requirement of the IEEE 802.22 system, and a maximal UDP throughput of 14.86 Mbit/s was obtained on the conditions of PHY mode 16 with a 6 MHz channel bandwidth and a 1/4 CP length.

In this paper, an enhanced universal filtered (UF)-DFT-spread-OFDM (eUF-DFTs-OFDM) is proposed. The conventional UF-DFTs-OFDM can drastically reduce the out-of-band emission (OOBE), which has been the problem of the conventional cyclic prefix (CP)-DFTs-OFDM. However, the conventional UF-DFTs-OFDM degrades the communication quality in long-delay multipath environment due to the frequency-domain ripples derived from extending the rise and fall time of the LPF corresponding to the guard interval (GI). On the contrary, the proposed eUF-DFTs-OFDM achieves significantly low OOBE and high communication quality even in the long-delay multi-path fading environment by applying the CP and the LPF with short rise and fall time. The advantages of the proposed eUF-DFTs-OFDM are discussed by simulating the characteristics of the OOBE, peak-to-average power ratio (PAPR) and block error rate (BLER) with the LTE uplink parameters. As a result, it is confirmed that the proposed eUF-DFTs-OFDM is capable of suppressing the OOBE at the channel edge by 40 dB compared to the conventional CP-DFTs-OFDM. Moreover, the proposed eUF-DFTs-OFDM can improve the ES/N0to achieve BLER= 10-3by about 2 dB for QPSK and 16QAM compared to the conventional UF-DFTs-OFDM. Especially for 64QAM, the proposed eUF-DFTs-OFDM can achieve BLER = 10-3at an ES/N0of 30 dB, even though BLER characteristics of the conventional UF-DFTs-OFDM results in error floor.

The 5G system requires flexible and ultrahigh-efficient spectrum usage, while spectrum efficiency is limited by using the conventional LTE and LTE-Advanced based on cyclic prefix-based orthogonal frequency division multiplexing (CP-OFDM) due to the high out-of-band emission (OOBE). Therefore, new-waveforms for reducing the OOBE are required to improve spectrum efficiency and the authors have proposed universal time-domain windowed OFDM (UTW-OFDM) as one of the new-waveforms for the 5G system. The UTW-OFDM has many advantages such as low-OOBE, low-complexity and high-compatibility with conventional CP-OFDM-based systems. In this paper, we developed a UTW converter enabling a proposed UTW-OFDM-based LTE-downlink (DL) system in real time. By applying the UTW converter to the off-the-shelf LTE-DL system, feasibility of the proposed UTW-OFDM is experimentally evaluated. The experimental results show that the UTW-OFDM suppresses power spectrum density at the channel-edge by about 20 dB and 18 dB for QPSK and 64QAM, respectively, without any throughput deterioration compared to the conventional CP-OFDM-based LTE-DL signal.

In this paper, we propose an enhanced universal filtered orthogonal frequency division multiplexing (eUF- OFDM) to achieve low out-of-band emission (OOBE) while maintaining high communication quality under the long-delay multipath fading environment by combinedly using a cyclic prefix (CP) and a filter with short-transition time. The proposed eUF- OFDM can suppress the OOBE at channel-edge by 25 dB compared to the conventional OFDM. Furthermore, the proposed eUFOFDM improves the signal-to-noise ratio (SNR) to achieve block-error-rate (BLER) = 10-3by 1.3 dB compared to the conventional UF-OFDM under the long- delay multipath fading mobile environment.

TV White Spaces (TVWS) technology allows wireless devices to opportunistically use locally-available TV channels enabled by a geolocation database. The UK regulator Ofcom has initiated a pilot of TVWS technology in the UK. This paper concerns a large- scale series of trials under that pilot. The purposes are to test aspects of white space technology, including the white space device and geolocation database interactions, the validity of the channel availability/powers calculations by the database and associated interference effects on primary services, and the performances of the white space devices, among others. An additional key purpose is to perform research investigations such as on aggregation of TVWS resources with conventional resources and also aggregation solely within TVWS, secondary coexistence issues and means to mitigate such issues, and primary coexistence issues under challenging deployment geometries, among others. This paper provides an update on the trials, giving an overview of their objectives and characteristics, some aspects that have been covered, and some early results and observations.

Utilization of the TV white-spaces (TVWS), which are spatially or temporally unused frequency in TV bands, is promising technology to alleviate spectrum resource shortage. Services using the TVWS have been already started in the U.S.A., and the TVWS pilot program has been performed and test operation of qualified white-spaces database (WSDB) has been started by the Ofcom in the U.K. Authors have developed TVWS LTE (Long Term Evolution) system with white-space devices (WSDs) licensed by the Ofcom and WSDB qualified by also the Ofcom, and participated in the pilot program performed in the U.K. In this paper, developed TVWS LTE system is summarized and field experiment of throughput measurement is performed in the London urban area is described. As a result of the field experiment, maximum downlink throughput of 45.4 Mbps in the FDD mode and 19.5 Mbps in the TDD mode were obtained under the condition of SISO with a signal bandwidth of 20 MHz. This is the first report on the field experiment of the TVWS LTE system aiming for practical use.

This paper performs the world's first IEEE 802.11af based Wireless Local Area Networks (WLAN) operating in TV White Space (TVWS) indoor experiment in the Ofcom TVWS pilot program of the UK. The prototype system consists of TVWS Database (WSDB), Registered Location Secure Server (RLSS), and two prototype hardware for an Access Point (AP) and a Station (STA). The developed WSDB qualified by Ofcom TVWS pilot program of the UK. The prototype hardware meets to the transmission spectrum regulation of the European Telecommunication Standards Institute (ETSI). By using the developed system, a trial indoor experiment performed in the building of the King's College London (KCL), Denmark Hill Campus in London, UK. The prototype system and the experiment results show an effectiveness of the IEEE 802.11af and indicate the way to the practical application.

An IEEE 802.11af indoor trial experiment has been conducted in the Ofcom pilot program of the United Kingdom. This paper describes an indoor propagation characterization and throughput estimation method using prototype devices based on the IEEE 802.11af standard. Since the IEEE 802.11af is recent technology for TV white space (TVWS) spectrum sharing, indoor propagation measurements at TVWS band for WLAN usage are very seldom in the previous researches. Path loss model parameters has been extracted for each line-of-sight (LoS) and non-LoS (NLoS) situation on the same floor. Also a fluctuation of measured path loss is analyzed using the log-normal and the extreme value distributions. A developed path loss model is useful for the location design of access points and the interference risk estimation for IEEE 802.11af devices. As another modeling, a throughput estimation model has been developed using the exponential distribution derived from the cumulative probability distribution (CDF) of measured throughputs. By combination of the developed path loss model and the throughput estimation model, throughput can be estimated as a function in each LoS and NLoS situation.

Cognitive radio technology, which enables an efficient use of spectrum, is expected as one of solutions for a spectrum shortage problem. Recently, spectrum sharing type cognitive radio technology in TV white-spaces has been actively promoted worldwide and technical specifications have been advanced in international standardization activities such as IEEE802.11af and IEEE802.22. These standardizing systems tend to secure more frequency channels for existing systems by simply converting their native frequency band to TV white-spaces for data traffic offload. As one of the simplest technologies to realize wireless communications in TV white-spaces, we proposed a frequency conversion system using a UHF converter. In this paper, we prototyped a tablet-type portable TV band device, which can communicate in TV band with IEEE802.11b/g-based communication systems by using the UHF converter. Also, physical features of our prototyped tablet terminal are summarized and the RF transmitter and receiver performance and spurious response are characterized.

DLNA devices, by definition, do not support remote connectivity. Even if attached to a LAN that is connected to the Internet, they can generally not be used to consume streamed or downloadable media. By providing a gateway in a mobile phone that exposes a 'remote Digital Media Server' on the LAN, content from different online sources can be made available on locally connected media renderers. Adding to this, the capabilities of the mobile phone can be used to publish presence information of the devices, for example to enable remote control of home appliances for energy management. This paper describes a demonstration of how Internet media services are delivered to devices in a personal network, using the mobile phone as a service control point.

In today's content delivery solutions, service delivery and control are still tightly coupled, a service typically being delivered to the same device that controls the session. We present a solution that was designed with the goal to decouple service control and delivery. Using our approach, multimedia streaming services can be delivered to off-the-shelf DLNA devices in visited networks. The service provider receives information about the remote media player and access environment via a mobile phone. Proximity technologies (e.g. barcodes, NFC) of the control device are used for the exchange of required credentials. This paper describes a typical scenario and our prototype implementation.