Explore the vast range of titles available.

Wireless sensor networks and nodes are faced with severe constraints in power capacity and lifespan, especially in harsh and cold environments. Electromagnetic radiation energy harvesters serve as a promising alternative power source for sensor nodes. However, the power output from reported energy harvesters remains limited, emphasizing the critical need to reduce power consumption in sensor nodes. Here, a miniaturized, low‐voltage, low‐power active frequency selective surface solution is proposed for backscatter communication under ice. It is designed for the 2.4 GHz wireless band and can operate under extreme conditions, such as sub‐ice environments, requiring only a 3.3 V control voltage and consuming approximately 0.3 μW $\\upmu\\text{W}$of energy. Experimental results in sub‐ice scenarios demonstrate its reliable reflection control characteristics, making it particularly suitable for backscatter communication nodes in wireless sensor networks deployed in harsh environments. Here, a miniaturized, low‐voltage, low‐power active frequency selective surface solution is proposed for backscatter communication under ice.

Nowadays, Unmanned Aerial Vehicles (UAVs) are widely used in heterogeneous contexts and, thanks to a continuous technological evolution, are going to be used for several applications such as, for example, Beyond Visual Line of Sight (BVLOS) operations. Since in BVLOS flights the UAV and the ground control center may not have a direct visibility with each other, a robust communication system is needed to provide reliable connectivity. Although a cellular (4G/5G) network is the current best candidate to enable BVLOS applications, there are still some limitations to overcome, as 4G (LTE) and 5G (NR) cellular networks are natively designed for terrestrial use. In this paper, we first investigate current cellular communication limitations for UAV-based applications, in particular taking into account both results available in the literature, as well as experimental performance campaigns. Then , a viable solution for mitigating these drawbacks exploiting selective on-board antennas is proposed, whose performance is experimentally investigated with a preliminary prototypical architecture.

The fourth generation （4G） mobile communication systems are offering service worldwide steadily. Although 4G systems could be loaded with much more services and data than previous systems, there is still a dramatic gap between the people＇s practical requirements and what can be offered by the 4G technologies. Consequently, the research and development for the fifth generation （5G） systems have already been started. This article presents an overview of potential network architecture and highlights several promising techniques which could be employed in the future 5G systems. These techniques include non-orthogonal multiple access （NOMA）, massive multiple input and multiple output （MIMO）, cooperative communications and network coding, full duplex （FD）, device-to-device （D2D） communications, millimeter wave communications, automated network organization, cognitive radio （CR）, and green communications. The state-of-art and implementation issue of these techniques are also addressed.

Dedicated short-range communication (DSRC) and 4G-LTE are two widely used candidate schemes for Connected Vehicle (CV) applications. It is thus of great necessity to compare these two most viable communication standards and clarify which one can meet the requirements of most V2X scenarios with respect to road safety, traffic efficiency, and infotainment. To the best of our knowledge, almost all the existing studies on comparing the feasibility of DRSC or LTE in V2X applications use software-based simulations, which may not represent realistic constraints. In this paper, a Connected Vehicle test-bed is established, which integrates the DSRC roadside units, 4G-LTE cellular communication stations, and vehicular on-board terminals. Three Connected Vehicle application scenarios are set as Collision Avoidance, Traffic Text Message Broadcast, and Multimedia File Download, respectively. A software tool is developed to record GPS positions/velocities of the test vehicles and record certain wireless communication performance indicators. The experiments have been carried out under different conditions. According to our results, 4G-LTE is more preferred for the nonsafety applications, such as traffic information transmission, file download, or Internet accessing, which does not necessarily require the high-speed real-time communication, while for the safety applications, such as Collision Avoidance or electronic traffic sign, DSRC outperforms the 4G-LTE.

This article presents an optimal pilot pattern for the data‐aided channel estimation (DACE) scheme for both single‐input single‐output (SISO) and multiple‐input multiple‐output orthogonal frequency division multiplexing (MIMO‐OFDM) wireless systems. The research evaluates the performance of the DACE scheme using different comb‐type pilot patterns for both least square (LS) and linear minimum mean square error (LMMSE) channel estimators. In this regard, it is found that pilot spacing significantly influences system performance. Inserting pilot symbols in consecutive subcarriers cannot compensate for increased pilot spacing. Hence, the solution to this problem is to place pilot symbols at appropriate locations within the given spectrum. Moreover, data symbols which are reliably detected at the receiver are used as additional pilot signals to further enhance system performance. However, reliable data symbols need to be determined carefully because wrong detection results in severe performance degradation. In this respect, the proposed comb‐type pilot pattern using a single pilot subcarrier extracts the maximum number of reliable data symbols for the DACE scheme, improves channel estimation accuracy, and provides bandwidth optimization for MIMO‐OFDM systems. Furthermore, it outperforms all other pilot patterns in terms of system mean square error (MSE) and bit‐error‐rate (BER) performance. This article presents an optimal comb‐type pilot pattern for the data‐aided channel estimation (DACE) scheme for both single‐input single‐output (SISO) and multiple‐input multiple‐output orthogonal frequency division multiplexing (MIMO‐OFDM) wireless systems. The research evaluates the performance of the DACE scheme using different comb‐type pilot patterns for both least square (LS) and linear minimum mean square error (LMMSE) channel estimators.

In recent years, the development and standardization of 5G networks have received extensive attention. 3GPP officially confirmed that Service-Based Architecture (SBA) is the unified infrastructure of the 5G core network (5GC). The Service-Based Interface (SBI) is an important part of the SBA for interaction between network function services within the 5GC. The fifth generation mobile network will support a range of use cases and requirements that are completely different from traditional 4G networks, such as providing a high level of authentication mechanisms. This paper is organized as follows: First, we compare the difference between 4G authentication and 5G authentication in three aspects including the 4G architecture, authentication process, and communication protocol stack, then implement the simulation environment, and finally evaluate the performance by comparing the delay.

Due to the explosive growth of communication devices and vehicles, the ever‐increasing communication data traffic is a challenge for mobile communication in the Internet of Vehicles (IoV). A practical solution is to offload the traffic from cellular networks to Wireless Local Area Network (WLAN), that is, WiFi, where the spectrum is license‐free. However, the coordination of unlicensed spectrum severely reduces the utilization rate on the spectrum. In this case, unlicensed networks assisted access is proposed to facilitate long‐term evolution technology in unlicensed spectrum (LTE‐U). To improve the data rate for LTE‐U and WLAN users, an allocation optimization scheme for the resources of the licensed and unlicensed spectrum is proposed. Accordingly, the data rate of LTE‐U users and WLAN users can be maximized by adjusting the transmit power and the frequency occupancy time ratio of the unlicensed spectrum for the small cell and WLAN users. Numerical results show that the proposed hybrid LTE networks with WLAN can improve the communication efficiency for the served users. We propose unlicensed networks assisted access to facilitate long‐term evolution technology in unlicensed spectrum (LTE‐U). To improve the data rate for LTE‐U and WLAN users, we propose an allocation optimization scheme for the resources of the licensed and unlicensed spectrum. Accordingly, the data rate of LTE‐U users and WLAN users can be maximized by adjusting the transmit power and the frequency occupancy time ratio of the unlicensed spectrum for the small cell and WLAN users.

The conventional way to monitor the vibration signals of aircraft engines is to use wired communication sensors to transmit and collect the signals on a fixed platform on the ground. The signal acquisition equipment of wired communication technology has various drawbacks, resulting in the inability to collect vibration signals when the object under test is in real operating conditions. Based on previous studies, this research team uses a 2.4G wireless transmission scheme to realize short-distance wireless transmission of aero-engine vibration signals, and a 4G cellular communication scheme to realize long-distance wireless transmission of aero-engine vibration signals. The acquired signals are displayed and monitored using the tool developed in LabVIEW2022. The designed tool is successfully applied in the engineering practice of engine maintenance, realizing the remote real-time monitoring of the engine operation status, shortening the monitoring cycle of the equipment from hourly to real-time level, and greatly facilitating the technical support work of engineers and technicians.

The Digital sub-band system is an indispensable technology for the development of modern society, which has a wide range of applications. This work is particularly concerned with developing applications for modulation techniques used in mobile communication. Based on MATLAB, this paper compared the modulation and demodulation of 2ASK, 2FSK, 2PSK, and QPSK horizontally and analysed the practical and theoretical error rates. With the constellation maps of 16QAM, 32QAM, 64QAM, and 256QAM, the relationship between the error rate and the signal-to-noise ratio was studied. In binary modulation systems, 2PSK has the best noise resistance and requires 6dB less SNR than 2ASK when employing the same demodulation approach. In addition, this paper outlined the technologies and modulation standards employed in the development of 1G-4G. To make the comparison clearer, the advantage, disadvantages, and modulation comparisons among 1G-5G are displayed. The analysis and research of digital sub-band modulation technology is the basis for developing new technology in the future.

Cellular developments encourage the integration of both 4G, Wi-Fi, and 5G network technologies into one device; an antenna is a tool that can be used to support the integration of these networks. A microstrip antenna is an antenna that is small, light, thin, easy to fabricate, and can be used in long ranges. In this paper, a microstrip antenna is designed on a printed circuit board (PCB) with a permittivity of 4.3 and a thickness of 1.6 mm. This research aims to design a microstrip antenna that is capable of working on 4G (2.3 GHz), Wi-Fi (2.4 GHz), and 5G 3.5 GHZ) frequencies in one antenna. The microstrip antenna is designed on a Printed Circuit Board (PCB) with a permittivity of 4.3 and a thickness of 1.6 mm, rectangular shaped patches, and each patch is connected using a bridging method. Next, the antenna is simulated using CST Suite 2021 software. Simulation results at frequencies of 2.3 GHz, 2.4 GHz, and 3.5 GHz produce return losses of -23.70, -22.87, and -20.60, VSWR values of 1, respectively. .13, 1.15, and 1.20, the bandwidth values are 6.27%, 3.84%, and 5.84%, respectively, and the gain values are 4.69 dBi, 8.53 dBi, and 3.49 dBi.