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In this paper, a millimeter-wave (mmWave) 5G communication prototype composed of a phased-array antenna and a transceiver is proposed. The prototype involves a custom-manufactured planar active phased array antenna featuring linear polarization, which incorporates a beamforming integrated circuit (BFIC) comprising an $8\times 8$ -element planar array. The 27 GHz transceiver is a prototype fabricated with off-the-shelf components and designed to downconvert/upconvert signals from 3.5 GHz to 27 GHz. Additionally, a 3GPP-inspired gNodeB based on the FR2 5G signal, which introduces a phase tracking reference signal (PT-RS) and implements a phase noise cancellation (PNC) algorithm in the user equipment (UE) node, was emulated. A measurement campaign in an indoor scenario, including validation using commercial equipment and a comparison with a passive antenna for the Q-PSK and 16-QAM modulation schemes has been carried out. We provide several key performance indicators (KPIs) including throughput, EVM, and BLER, to demonstrate the statistical performance of the proposed prototype. The obtained results support that the integration of a phased-array antenna is a promising technology for the future of wireless communications.

Broadband over Power Line (BPL) technologies are a successful solution for setting up communication networks in domestic environments. Several standards such as ITU-T G.hn and IEEE 1901 have evolved over the years, and commercial solutions based on them are currently available. However, most existing BPL technologies have not been designed to perform in Low Voltage (LV) access power distribution networks, so there is a need to adapt to the specificities of the communications channel found there. To accommodate the attainable performances of BPL technologies to the access segment of the grid, a communications prototype has been developed that injects custom BPL waveforms with different physical layer configurations and then measures performance. This prototype is an instrumental part of a process to define the most suitable physical layer parameters of Smart Grid BPL devices (namely, next generation BPL smart meters). In the absence of such a prototype, it is not feasible to obtain a proper characterization of the LV grid, as devices capable of producing OFDM (Orthogonal Frequency Division Multiplexing) modulations (typical of BPL technologies) with a varied set of adjustable features, and prepared to connect to the LV access grid, are not available in the market. The prototype is being used to carry out a measurement campaign in Iberdrola’s LV grid in Spain. This paper shows how the prototype has been field validated and derives initial conclusions to drive the future of BPL in LV access grids for Smart Metering and other Smart Grids applications.

With new services emerging in fifth generation (5G)-advanced, the evolution in duplex modes plays an important role to meet more stringent requirements for both downlink (DL) and uplink (UL) transmissions. In this paper, sub-band full duplex (SBFD) at base station (BS) is studied as an attainable evolution of the traditional time division duplex (TDD). Both user equipment (UE) transparent SBFD and UE perceptive SBFD are proposed and studied to serve different types of UEs. To tackle the interference introduced by SBFD, a model including both BS self-interference and cross-link interference (CLI) is presented as a first step, and new interference management schemes are proposed. Three approaches to mitigate BS self-interference, namely the passive suppression, analog interference cancellation and digital interference cancellation are analyzed. A new framework for CLI management is illustrated along with enhancements for interference identification, spatial domain interference coordination and power domain adjustment. To validate the feasibility and performance of the proposed SBFD methods under indoor and dense urban scenarios, system-level simulations (SLSs) are carried out and a proof-of-concept (PoC) is developed for the purpose of obtaining experimental results.

Recently, reconfigurable intelligent surfaces (RISs) are considered as a strong candidate for next generation wireless technologies, thanks to its advantage of being able to configure the wireless propagation environment in a cost-effective and energy-efficient way. Many literature study the theoretical aspects of RIS-assisted communication while prototyping and field trials are relatively scarce. A key step towards the standardization and commercialization of RISs is to complete comprehensive field trials in cellular networks, such as the 5th generation (5G) network. There are several typical deployment scenarios in 5G networks such as indoors, outdoors and mixed indoors and outdoors, where RISs can provide coverage to weak reception areas, enhance transmission robustness, fix coverage holes and increase the maximum available data rate. In this paper, a variety types of RIS prototypes are fabricated and tested with off-the-shelf 5G user equipments (UEs) in 5G networks to validate the performance gain introduced by RISs to typical deployment scenarios of 5G at different working frequencies. Some system-level simulations are also conducted for several typical scenarios to be used as a baseline to compare to the trial results, where all parameters are selected according to 5G standards. The experimental results confirm the feasibility and effectiveness of RISs to solve coverage issues and improve received signal qualities in 5G networks across different frequency ranges.

During the design and development of a reliable transceiver, its performance and robustness are evaluated using channel models that simulate the propagation channel characteristics in a real-world environment. In the case of wide-area communication systems in rural areas such as those based on TV white spaces, long delay multipath fading is one of the dominant factors impairing communication quality, and it is important to apply realistic multipath fading channel models in various application scenarios. Therefore, it is necessary to develop channel measurement and modeling systems that adaptively obtain channel factors and reflect multipath propagation characteristics in various wide-area communication environments. In this study, we developed a flexible channel measurement and modeling prototype applicable to mobile IEEE 802.22-based wide-area communication systems, which can be simply implemented by using programmable hardware and software. The prototype includes a new channel modeling framework that applies an improved double exponential slope model to extract the essential factors of multipath propagation characteristics. To validate the developed prototype, a fading emulator is applied to it to measure the raw data used for modeling. As a result, the multipath fading characteristics measured with the prototype were successfully modeled and reproduced by the proposed channel modeling framework with a high fitness of root mean square delay spread distribution. The derived bit error rate characteristics agreed better with the simulation results compared to the conventional channel model.

In wireless communications, higher transmission power enables higher coverage or higher data rate. However, due to hardware limitations, achieving high power efficiency becomes challenging. The main issue is that at high power region close to power amplifier (PA) saturation point the highly non-linear response of the PA leads to significant spectral regrowth. In such a case, waveforms with inherently good spectral containment allow for more spectral degradation and can be seen as the most effective solution for the problem. In this study, a fifth-generation new radio (5G NR) user equipment (UE) transmit power is improved by utilizing fast-convolution filtered orthogonal-frequency-division-multiplexing (FC-F-OFDM) waveform, which has an excellent spectral containment performance. A novel method is proposed for improving the peak-to-average-power ratio (PAPR) of FC-F-OFDM waveform, based on applying clipping before FC processing and allocating the clipping noise that stems from the applied clipping, over not only on active band, but a wider band consisting of both the in-band and guard-band regions. An accurate transmitter chain simulator including a measured memory-polynomial model of a practical PA is used to evaluate a wide set of different subcarrier spacings and channel bandwidths. Then, to validate the numerical results, a software-defined radio (SDR) based testbed is created and the modeled PA is used in this testbed. Weighted overlap-and-add (WOLA) based OFDM, also with clipping, is used as a reference in both the numerical evaluations and in measurements. For both waveforms, the transmitted signal quality, out-of-band emissions, and maximum PA output powers are measured under 5G NR specifications and results for different subcarrier spacings and channel bandwidths are provided to prove the benefits and robustness of the presented FC-F-OFDM approach.

The Internet of medical things is an emerging information network technology, which can realize the automatic identification, monitoring and management of personnel, medical equipment, medicines, etc. through this network, and is an effective means to reduce medical errors and improve work efficiency. This article first studies the theory and method of health information and sports information collection, that is, the temperature sensor and the acceleration sensor are used to collect human body temperature and exercise steps, respectively, and then estimate the human health and sports. Second, the prototype system of health and sports information collection system is realized the system is divided into two parts: terminal node and client information management system. Finally, a component collaborative modeling and data analysis method for Internet of medical things is proposed. This method constructs different types of components according to different functions of the Internet of Things equipment, and designs a set of communication mechanisms between the components based on the Internet of Things network communication characteristics, and uses visual methods to model. The experimental results verify that the method of collecting and analyzing human motion information using a motion information collection system is feasible. Multiple methods should be integrated to obtain as much information as possible to make the human motion analysis more scientific and reasonable.

The use of drones or UAVs (unmanned aerial vehicles) for commercial or leisure purposes is increasingly common in our society. However, UAVs can also be used for other purposes that may compromise the privacy and safety of the population. For this reason, it has become necessary to enable the monitoring and identification of UAVs through a radio system with a license to avoid unwanted interferences. This article proposes the AIS (Automatic Identification System) as an alternative to monitor drone activities in near-real time. To do this, a prototype has been designed and integrated in an amateur UAV unit, enabling the transmission of UAV parameters through this system. AIS density testing has been carried out in selected zones of Gran Canaria (Spain), demonstrating the compatibility between the canonical usage of the AIS for vessels and its new proposed purpose for amateur UAVs.

One of the key enablers of future wireless communications is constituted by massive multiple-input multiple-output (MIMO) systems, which can improve the spectral efficiency by orders of magnitude. In existing massive MIMO systems, however, conventional phased arrays are used for beamforming. This method results in excessive power consumption and high hardware costs. Recently, reconfigurable intelligent surface (RIS) has been considered as one of the revolutionary technologies to enable energy-efficient and smart wireless communications, which is a two-dimensional structure with a large number of passive elements. In this paper, we develop a new type of high-gain yet low-cost RIS that bears 256 elements. The proposed RIS combines the functions of phase shift and radiation together on an electromagnetic surface, where positive intrinsic-negative (PIN) diodes are used to realize 2-bit phase shifting for beamforming. This radical design forms the basis for the world's first wireless communication prototype using RIS having 256 two-bit elements. The prototype consists of modular hardware and flexible software that encompass the following: the hosts for parameter setting and data exchange, the universal software radio peripherals (USRPs) for baseband and radio frequency (RF) signal processing, as well as the RIS for signal transmission and reception. Our performance evaluation confirms the feasibility and efficiency of RISs in wireless communications. We show that, at 2.3 GHz, the proposed RIS can achieve a 21.7 dBi antenna gain. At the millimeter wave (mmWave) frequency, that is, 28.5 GHz, it attains a 19.1 dBi antenna gain. Furthermore, it has been shown that the RIS-based wireless communication prototype developed is capable of significantly reducing the power consumption.

Due to the increasing popularity of multimedia social networks (MSNs), the ability to mine users' interests in different contexts on such networks is crucial in recommendation systems. It is, however, challenging to mine users' current preferences based on session on MSNs. In this study, we propose a novel recommendation algorithm based on both social situation analytics and collaborative filtering for session-based recommendation. Specifically, the algorithm predicts the rating for target users based on their nearest neighbors and historical behaviors. First, for the purpose of mining users' current intentions, the session-level behavioral sequences of target user are analyzed based on SocialSitu (t). Then, the recommended contents are generated for target users based on their behaviors and perceived session-based intentions and identity. We evaluate the performance of the proposed algorithm using real-world social media dataset from Shareteches. Findings demonstrate that our algorithm outperforms two classical algorithms and a state-of-the-art method.