Wireless Terminals Research Articles

Multifunctional Frequency Selective Absorber Enabling FR1 and FR2 5G OTA Tests in a Hybrid Reverberation Chamber

Due to the special advantages of the reverberation chamber (RC), it has been recognized as a standardized over-the-air (OTA) testing methodology by the cellular telecommunications industry association (CTIA). Currently, OTA tests of the fifth-generation (5G) wireless terminals are usually performed in different testing environments, e.g., in a reverberation chamber for fast isotropic tests in the sub-6 GHz frequency band, and in an anechoic chamber for directional tests in the millimeter-wave (mm-wave) frequency band, which are inconvenient and costly. In this work, two multi-functional frequency selective absorbers (FSAs) are designed to realize absorption in the 5G mm-wave band and reflection/transmission in the sub-6 GHz band. By loading the FSAs to the RC, an integrated testing environment for 5G terminals can be established. Namely, a quasi-anechoic environment in the mm-wave band and a reverberation environment in the sub-6 GHz band can be simultaneously achieved in the RC loaded with the proposed FSAs. Experimental and simulated results are presented to demonstrate the effectiveness of the proposed scheme.

An Active SearchTime Tuning Model Based on the Optimally Weighted LightGBM Algorithm

A proactive search time adjustment model based on the optimally weighted LightGBM algorithm was studied in this paper for the problem of large delay fluctuations in 5G distribution terminals leading to protection blocking. The model used historical data on delay fluctuations of wireless communication terminals and feature variables such as temperature and date and time as inputs to predict delays and dynamically adjust equipment parameters. First, the original feature variables were pre-processed via feature engineering, then the data were fitted together with the historical delay data by the LightGBM algorithm. And the final weighted combination was used to adjust the predicted values in combination with the real-time monitoring delay of the terminal, finally realizing the high-precision prediction of 5G terminal delay. The results show that the proposed method can effectively achieve delay prediction and has higher prediction accuracy than random forest regression and XGBoost algorithms.

Improvements for Uplink Long Term Evolution (UL-LTE) in Heterogeneous Network using Dynamic Spectrum Allocation Technique

Several interference mitigation strategies can be used in LTE networks to meet the consumers' increasing need for faster data speeds. Dynamic Spectrum Allocation (DSA), which maintains spectrum in a converged radio system and distributes it across all participating radio terminals, is one of the most promising solutions. However, the fundamental obstacle to achieving increased network capacities is increased inter-cell interference. The aim of this paper is to analyse the effectiveness of a newly proposed DSA technique by comparing its bit error rate (BER) and throughput (TP) with a typical uplink LTE configuration. To maximise throughput in a heterogeneous network, the suggested DSA technique utilises the Nash Bargaining Solution (NBS) scheme, a cooperative game theory that could correlate with the bit error rate. The software tool GNU Radio, which offers signal-processing blocks to develop softwaredefined radios and signal-processing systems, was used to create the setups. After the simulations were performed, the BER values were recorded and compared, while the TP values were established and computed appropriately. According to the results, the uplink (UL-LTE) architecture with DSA has an improved TP and a lower BER value. As a result, spectral efficiency can also be improved.

A Novel MEMS Capacitor with a Side Wall for High Tuning Ranges

These days, the market of wireless communications has developed dramatically. Thus, demand increased with respect to wireless communication terminals that consume less power. Consequently, integration technology for passive elements and circuit module development with respect to ‘Radio frequency systems’ using ‘Micro electro mechanical system’ is becoming a focused topic. Many researchers focused various perspectives in this field. The development of ultra-low operating voltage elements is required in voltage-tunable MEMS-type capacitors, but development for satisfying demands has not occurred. Among many studies, a capacitor with a high tuning range using carrier beams has been proposed by Barki-Kassem and others in 2006. In the proposed study, a high tuning range was generated using a carrier beam when the voltage was applied, passing through the pull-in point and exceeding the controllable range. However, these carrier beams are relatively inefficient because these are applied only in one location and not in several air gaps. Therefore, this study dealt with the optimization of a new MEMS capacitor concept, such as using a total of four beams and by applying a side wall instead of a single carrier beam compared to the previous study. Therefore, in this study, further steps were applied to existing research findings to optimize a new concept MEMS capacitor by applying the side wall instead of a carrier beam. The side wall is the same as the one used in the four-beam example.

A Compact Dual-Band MIMO Antenna for Sub-6 GHz 5G Terminals

In this paper, a dual-band multiple-input-multiple-output (MIMO) antenna is proposed for fifth-generation (5G) wireless communication terminals. The measured -10 dB impedance bandwidths of 380 MHz (3.34–3.72 GHz) and 560 MHz (4.57–5.13 GHz) can cover the 3.4–3.6 GHz and 4.8–5 GHz 5G bands. The single antenna element of this proposed MIMO is composed of an F-shaped feed strip and an inverted L-shaped radiation strip. A defected ground structure is employed to obtain a good isolation performance, whereby the measured isolation between the antenna elements is observed to be larger than 23 dB. The measured total radiation efficiencies at 3.5 GHz and 4.9 GHz are 76.65% and 71.93%, respectively. Besides, the calculated envelope correlation coefficients (ECC) are less than 0.00125 and 0.01164 at the low-frequency and high-frequency bands, respectively. Furthermore, the specific absorption ratio (SAR) analysis of the antenna verifies that it qualifies for 5G terminals.

5G meets satellite: Non‐terrestrial network architecture and 3GPP

SummaryWith 3GPP Release‐17, global 5G standards now support non‐terrestrial mobile networks comprising radio access network, terminals, and core network. This enables multi‐vendor interoperability as well as interoperability with 3GPP‐compliant 5G systems. This paper describes the key features enabling the NG‐RAN architecture defined for 5G to support non‐terrestrial networks. Starting from a general overview of NG‐RAN and of the new paradigms of NTN, we introduce the NTN functionality in NG‐RAN specifications with respect to feeder link switchover, cell handling, terminal registration, and OAM aspects. We also discuss different scenarios combining satellite access with 3GPP‐defined core networks. We also describe some further enhancements expected to be seen in the next 3GPP release (Rel‐18). We believe current and upcoming 3GPP work for NTN represents a solid basis on which 5G satellite networks can be built in the upcoming future.

Hybrid RIS and DMA Assisted Multiuser MIMO Uplink Transmission With Electromagnetic Exposure Constraints

In the fifth-generation and beyond era, reconfigurable intelligent surface (RIS) and dynamic metasurface antennas (DMAs) are emerging metamaterials keeping up with the demand for high-quality wireless communication services, which promote the diversification of portable wireless terminals. However, along with the rapid expansion of wireless devices, the electromagnetic (EM) radiation increases unceasingly and inevitably affects public health, which requires a limited exposure level in the transmission design. To reduce the EM radiation and preserve the quality of communication service, we investigate the spectral efficiency (SE) maximization with EM constraints for uplink transmission in hybrid RIS and DMA assisted multiuser multiple-input multiple-output systems. Specifically, alternating optimization is adopted to optimize the transmit covariance, RIS phase shift, and DMA weight matrices. We first figure out the water-filling solutions of transmit covariance matrices with given RIS and DMA parameters. Then, the RIS phase shift matrix is optimized via the weighted minimum mean square error, block coordinate descent and minorization-maximization methods. Furthermore, we solve the unconstrainted DMA weight matrix optimization problem in closed form and then design the DMA weight matrix to approach this performance under DMA constraints. Numerical results confirm the effectiveness of the EM aware SE maximization transmission scheme over the conventional baselines.

Chinese Online Language Dissemination from the Perspective of Mobile Information System

The emergence of new media technology will inevitably bring new changes to people's daily communication. The development and change of society supports the development and change of language. Language networks are created and developed along with Internet applications. It is a new variant of the traditional language adapted to the new media environment of the Internet Age. With the increasing popularity and importance of network media, network language has received extensive attention and research on local languages. This paper analyzes and investigates the dissemination of Chinese Internet language from the perspective of mobile information system. On the basis of researching and proposing the mobile information system model, the structure of the system is deeply analyzed, and the key characteristics and technologies of various fields are discussed. Wireless mobile terminal wireless Internet access technology, portable intelligent terminal mobile application development technology, and local database technology are very suitable for Chinese network analysis and research to reduce wireless connections, and the effective range is from 50 feet to 1000 feet. The article uses the communication theories and methods of linguistics, cultural studies, network neologism generation, and communication characteristics analysis. It uses students as examples to explore their online neologism use and dyslexia and their problem-solving strategies for obstacles. The results show that 50% of the students can accept the new words on the Internet very well, and 30% of the students do not understand it.

Improved Multi-Channel Multi-Interface Routing Protocol for Wireless Mesh Networks

In recent years, Wireless Mesh Networks (WMN) are emerging as a potential technology to enhance the ability and availability of wireless networks. WMN consists of wireless mesh routers and terminals connected by wireless multi-hop communication. Besides, in WMN, each wireless node owns many interfaces, and each interface operates on many channels. However, effectively using multiple orthogonal channels and multiple interfaces to increase the performance of WMN and decrease the radio link transmission interference is of significant challenge. In this paper, we consider routing issues in WMN. Then, we proposed an on-demand routing protocol, adaptive multi-channel multi-interface operation, improved from the AODV protocol. This protocol is capable of effectively managing communication in the WMN and limited effects of co-channel interference. The simulation results on NS2 show that our proposed protocol improves throughput, delay and packet delivery rate compared to existing traditional protocols.

A Planar Low-Profile Meander Antenna Design for Wireless Terminal Achieving Low RF Interference and High Isolation in Multi-Antenna Systems

In this article, a meander line internal antenna used for wireless terminal is proposed. The current of this antenna is mostly distributed on the antenna radiator itself, rather than on the main board of the wireless device. As a result, the chance of having radio-frequency (RF) interference issues, which usually result in receiver desensitization in wireless radios, can be significantly reduced. The antenna has good radiation performance in the vertical polarization with a low physical profile, compared with the existing antenna designs for typical wireless terminals. The antenna has efficiency similar to the monopole antenna with much less reference/ground plane dependence, achieving lower RF interference, which is demonstrated by the noise coupling measurements in a predefined digital clock - antenna configuration. Furthermore, the mutual coupling (i.e., isolation) between two such antennas is studied and the envelope correlation coefficient between the two antennas is found to be low. A router assembled with the two proposed antennas is tested, and the total isotropic sensitivity is found lower compared with monopole antennas, due to the characteristics of low RF interference and high isolation of the proposed antenna.

Radio Frequency Fingerprint-Based DSRC Intelligent Vehicle Networking Identification Mechanism in High Mobility Environment

In recent years, Dedicated Short-Range Communication (DSRC) vehicle interconnection technology has achieved mature development and broad applications, which is the key Vehicle to Everything (V2X) technology to realize transport intelligence. However, the openness of wireless transmission and the mobility of wireless terminals cause the identification mechanism of the DSRC system to face serious security threats. A radio frequency fingerprint (RFF)-based identification method can better resist the identity attack and spoofing by extracting the hardware characteristics formed by the differences of electronic components to authenticate different devices. Therefore, in this paper a novel RFF identification mechanism is proposed for IEEE 802.11p protocol-based DSRC intelligent vehicle networking devices suitable for a high mobility environment, in which the preamble field features of physical layer frames are extracted as device fingerprints, and the random forest algorithm and sequential detection method are used to distinguish and authenticate different devices. The experiment and simulation results demonstrate that the identification accuracy rates of the eight DSRC modules in the low-speed LOS and NLOS experimental states and up to 70 km/h high-speed simulations all exceed 99%, illustrating that this method has important application value in the field of identity authentication of V2X devices in high-speed scenarios.

Anonymous Traceability Protocol Based on Group Signature for Blockchain

In blockchain technology, data are stored on decentralized nodes and public to each node in the blockchain network. Hence, the focus of privacy protection in the blockchain guarantees the anonymity of transactions such that attackers cannot attain the users’ personal information through data analysis. Among the existing privacy protection technologies, the scheme based on group signature has good anonymity, but the existing scheme exists a large number of operations that are difficult to apply to wireless terminals. In this paper, using the powerful offloading capability of edge computing, we propose a blockchain node traceable identity privacy technology scheme based on threshold group signature, and the scheme greatly reduces the computing burden of nodes while achieving node privacy protection.

Wireless Position Method for Indoor Personnel Based on Improved Neural Network by Chaotic Whale Optimization Algorithm

The positioning accuracy of the indoor personnel positioning system is low, which cannot meet the needs of an intelligent transformer substation. Therefore, a wireless positioning method for indoor personnel based on the Elman neural network (ENN) using chaotic whale optimization algorithm (CWOA) was proposed. Firstly, a certain number of sample fingerprint databases were collected by wireless terminals in the wireless network on indoor personnel. Secondly, CWOA was used to optimize the weights and self-connected feedback gain factor of the ENN. Thirdly, the fingerprint database was used to train and test the optimized ENN, and the position algorithm model of the neural network was established. Finally, the real-time position was achieved with the neural network location algorithm model through the fingerprint data of the position point collected by the wireless terminal. The results show that the average position error of this indoor wireless positioning method is 1.24 m; ENN position algorithm by the CWOA has a stronger global search ability and is more suitable for the application in the time-varying indoor environment.

Evaluating the Comprehensive Performance of 5G Base Station: A Hybrid MCDM Model Based on Bayesian Best-Worst Method and DQ-GRA Technique

In recent years, 5G technology has rapidly developed, which is widely used in medical, transportation, energy, and other fields. As the core equipment of the 5G network, 5G base stations provide wireless coverage and realize wireless signal transmission between wired communication networks and wireless terminals. However, as the scale of 5G base stations gradually increases, problems such as poor user experience and insufficient coverage area frequently occur. Hence, it is necessary to evaluate the comprehensive performance of 5G base stations, so as to clarify the problems existing in the construction of base stations. First, the performance evaluation index system is constructed from the perspectives of operational performance, financial performance, environmental impact, and social influence. Then, a novel hybrid multicriteria decision-making (MCDM) model based on the Bayesian best-worst method (BBWM) and difference-quotient gray relational analysis (DQ-GRA) technique is adopted. Finally, sixteen 5G base stations are taken as examples for analysis. The result shows that the signal coverage area and per capita input cost are the most important indicators greatly affecting the overall performance of the 5G base station. Compared with the two other MCDM models, the proposed hybrid MCDM model has good applicability and effectiveness for performance evaluation of 5G base stations.

A Concept for a Cloud-Driven Controller for Wireless Sensors in IoT Devices

The paper presents an optimization algorithm applied to a cloud-driven controller for wireless sensors in Internet of Things (IoT) devices. The experiment investigates operational duty cycle control and energy management of a wireless sensor node device powered by prediction from global solar irradiance in the environment. Rapid increases in the development and growth of smart technologies is placing greater demands on optimizing computing power. The study attempted to manage and optimize wireless terminals using methods to adjust work cycles and planning. The study's contribution is a simulated wireless environmental IoT sensor node and cloud controller implemented in Matlab. The simulation examined energy management and optimization, supplemented by prediction from data measured at different locations in the period 2016–2019. The experiment investigated suitable modes of operation of the device according to data updates in the cloud. The controller was based on the following parameters: state of energy storage, number of failures relative to correctly performed device cycles, and predicted values for charging energy storage from the cloud.

A Primer on Software Defined Radios

The commercial success of cellular phone systems during the late 1980s and early 1990 years heralded the wireless revolution that became apparent at the turn of the 21st century and has led the modern society to a highly interconnected world where ubiquitous connectivity and mobility are enabled by powerful wireless terminals. Software defined radio (SDR) technology has played a major role in accelerating the pace at which wireless capabilities have advanced, in particular over the past 15 years, and SDRs are now at the core of modern wireless communication systems. In this paper we give an overview of SDRs that includes a discussion of drivers and technologies that have contributed to their continuous advancement, and presents the theory needed to understand the architecture and operation of current SDRs. We also review the choices for SDR platforms and the programming options that are currently available for SDR research, development, and teaching, and present case studies illustrating SDR use. Our hope is that the paper will be useful as a reference to wireless researchers and developers working in the industry or in academic settings on further advancing and refining the capabilities of wireless systems.

Experimental Demonstration of Delay-Bounded Wireless Network Based on Precise Time Synchronization

Low latency and reliable information transfer are highly demanded in fifth generation (5G) and beyond 5G wireless communications. A novel delay-bounded wireless media access control (MAC) protocol called Carrier Sense Multiple Access with Arbitration Point (CSMA/AP) was established to strictly ensure the upper boundary of communication delay. CSMA/AP enables collision-free and delay-bounded communications with a simple arbitration mechanism exploiting the precise time synchronization achieved by Wireless Two-Way Interferometry (Wi-Wi). Experimental demonstration and proving the feasibility in wireless environments are among the most critical steps before any further discussion of CSMA/AP and extension to various applications can take in place. In this work described in this paper, we experimentally demonstrated the fundamental principles of CSMA/AP by constructing a star-topology wireless network using software-defined radio terminals combined with precise time synchronization devices. We show that CSMA/AP was successfully operated, even with dynamic changes of the spatial position of the terminal or the capability to accommodate mobility, thanks to the real-time adaption to the dynamically changing environment by Wi-Wi. We also experimentally confirmed that the proposed CSMA/AP principle cannot be executed without Wi-Wi, which validates the importance of precise time synchronization. This study paves the way toward realizing delay-bounded wireless communications for future low-latency and highly reliable critical applications.

UE Reporting Uncertainty Analysis in Radiated Two-Stage MIMO Measurements

Over-the-air (OTA) performance evaluations of wireless terminals need to be accurate and consistent. The radiated two-stage (RTS) method is a promising solution for the 5G multiple-input and multiple-output (MIMO) OTA test because of its advantages in cost and efficiency. However, the accuracy of the RTS method has not been theoretically investigated. In this article, an uncertainty analysis on the throughput performance using the RTS method with regard to the reporting errors in the device under test (DUT) reporting system is presented. A mathematical model of the RTS method is constructed and error factors are introduced. Based on the analysis, the reporting errors in the DUT antenna pattern measurement are eliminated using the proposed RTS implementation in the final throughput evaluations. In other words, the RTS method is free of the effects of the DUT reporting errors, contributing to the accuracy and consistency of the test. An example DUT was tested to demonstrate the impact of the reporting errors and validate that the reporting errors are eliminated in the proposed RTS implementation. The theoretical proof of the accuracy of the RTS method helps further develop the method for 5G MIMO OTA testing.

StegoFrameOrder-MAC Layer Covert Network Channel for Wireless IEEE 802.11 Networks.

The proposed StegoFrameOrder (SFO) method enables the transmission of covert data in wireless computer networks exploiting non-deterministic algorithms of medium access (such as the distributed coordination function), especially in IEEE 802.11 networks. Such a covert channel enables the possibility of leaking crucial information outside secured network in a manner that is difficult to detect. The SFO method embeds hidden bits of information in the relative order of frames transmitted by wireless terminals operating on the same radio channel. The paper presents an idea of this covert channel, its implementation, and possible variants. The paper also discusses implementing the SFO method in a real environment and the experiments performed in the real-world scenario.

Anonymous Traceability protocol based on Group Signature for Blockchain

In blockchain technology, data are stored on decentralized nodes and public to each node in the blockchain network. Hence, the focus of privacy protection in the blockchain guarantees the anonymity of transactions such that attackers cannot attain the users’ personal information through data analysis. Among the existing privacy protection technologies, the scheme based on group signature has good anonymity, but the existing scheme exists a large number of operations that are difficult to apply to wireless terminals. In this paper, using the powerful offloading capability of edge computing, we propose a blockchain node traceable identity privacy technology scheme based on threshold group signature, and the scheme greatly reduces the computing burden of nodes while achieving node privacy protection.