Wireless Services Research Articles

AN IMPROVED PARTICLE SWARM OPTIMIZATION ALGORITHM FOR SPECTRUM ALLOCATION IN COGNITIVE RADIO NETWORKS

The seriousness of the spectrum scarcity has increased dramatically due to the rapid increase of wireless services. The key enabling technology that can be viewed as a novel approach for utilizing the spectrum more efficiently is known as Cognitive Radio. Therefore, assigning the spectrum opportunistically to the unlicensed users without interfering with the licensed users, concurrently with maximizing the spectrum utilization is addressed as a major challenge problem in cognitive radio networks. In this paper, an improved metaheuristic optimization algorithm has been proposed to solve this problem that contingent on a graph coloring model. The proposed approach is a hybrid algorithm composed of a Particle Swarm Optimization algorithm with Random Neighborhood Search. The key objective function is maximizing the spectrum utilization in the cognitive radio networks with the subjected constraints. MATLAB R2021a was used for conducting the simulation. The proposed hybrid algorithm improved the system utilization by 1.23% compared to Particle Swarm Optimization algorithm, 5.57% compared to Random Neighborhood Search, 7.9% compared to Color Sensitive Graph Coloring algorithm, and 27.33% compared to Greedy algorithm. Moreover, the system performance was evaluated with various deployment scenarios of the primary users, secondary users, and channels for investigating the impact of varying these parameters on the system performance.

Optimization of UAV 3D trajectory in a post-disaster area using dual energy-aware bandits

In a post-disaster area, Unmanned Aerial Vehicles (UAVs) are considered one of the most effective ways to provide emergency wireless communication services. In this letter, we investigate the UAV-based emergency wireless communication network for a post-disaster area. Our optimization problem aims to optimize the UAV 3D flight trajectory to maximize the number of visited ground users during the flight round. Then, a dual-cost-aware multi-armed bandit algorithm is adopted to tackle this problem under the limited available energy for both the UAV and ground users. Finally, simulation results show that the proposed algorithm could solve the optimization problem and maximize the achievable throughput under these constraints.

Address direction finding of ZigBee devices

Statement of problem. The active use of wireless technologies requires the development of means of monitoring devices and data transmission networks and, in particular, ZigBee wireless personal networks. Therefore, the detection and localization of working ZigBee devices is an urgent task of radio monitoring services. Correlation-interferometric direction finders based on two-channel radio receiving equipment cyclically connected to various pairs of elements of a multi-element antenna system can serve as a tool for bearing radio signals. For the direction finding of packet radio signals, the direction finder accumulates time samples from different antenna pairs over long time intervals; joint processing of these data allows determining the direction of arrival of radio signals. An obstacle to the direction finding of ZigBee devices is the fact that many similar devices can simultaneously operate in the same frequency range, generating a chaotic alternation of packets in the air. As a consequence, the accumulation of information from a specific ZigBee device for different antenna pairs of the direction finder becomes problematically. Purpose of the work is to develop a method for joint identification and bearing of detected devices of ZigBee networks. Results. the presented method of address bearing is implemented on the basis of the mobile direction finder ARTICLE-M, used to search for and locate unauthorized sources of radio emissions, and allows detecting signals of the 802.15.4 standard, identifying personal network devices, as well as forming estimates of directions to these sources of radio emissions. Practical importance. the use of address bearing of ZigBee network devices increases the functionality of existing radio monitoring equipment, and also allows the localization of unauthorized radio sources masquerading as Internet of Things devices.

Implementation of dynamic selective location in new radio communication services of the 5th generation based on the «vehicle connected to everything» technology

Problem statement. The principle of operation of dynamic selective positioning in fifth generation (5G) networks is especially relevant in the “vehicle connected to everything” (V2X) technology used in the automotive communication system, which includes types of communication that occur between one “vehicle” object and objects such as "infrastructure", "network", "pedestrian" or "device". To achieve high accuracy in V2X services, it is necessary to provide stable and uninterrupted connection, coverage with a minimum number of available communication points and wide bandwidth. Lack of line of sight is one of the major challenges in achieving accurate positioning in many locations, such as urban environments, tunnels, and underground parking lots. Today, the development of potential solutions to provide new users of the V2X service with high positioning accuracy is an urgent task for promising versions of the 5th generation mobile communication technology, which is being formed by the 3rd Generation Partnership Project (3GPP) consortium. Target. Introduce a new selective positioning method based on the dispersion of adjacent signal arrival times for dynamic switching between RAT-dependent methods and GNSS positioning methods. Results. Promising solutions have been explored to provide NR V2X users with long-term and highly accurate positioning. A selective positioning method is shown to dynamically switch between GNSS and DL-TDOA measurements based on the location of V2X users and improve the accuracy of the collected measurements using a MAP-based criterion to evaluate performance gains by combining measurements from different technologies in services. NR V2X. The proposed hybrid methods were evaluated using system-level simulations, the results of which demonstrated that the proposed algorithms can achieve position errors ≤ 3 m with an availability of approximately 76% compared to the 51 and 58% availability obtained using only GNSS measurements. or DL-TDOA, respectively. It is shown that in order to improve the tail of the distribution of user positioning errors by more than 56%, it is necessary to apply the deployment of roadside communication units. Practical significance. The implementation of the selective positioning method based on the dispersion of adjacent times of signal arrivals makes it possible to improve the accuracy of determining the location of a moving object in networks built on the basis of V2X technology. Thus, the developed solution helps to ensure stable data transmission with minimal interference due to dynamic switching between different detection methods.

The Security in Optical Wireless Communication: A Survey

With the demand for economical and high-speed wireless services, Optical Wireless Communication (OWC) has attracted increasing attention in both research and the market. In the past decades, numerous optical-related techniques (e.g., LEDs, displays, cameras) and systems (e.g., VLC, LiFi, LiDAR) have been invented. OWC techniques, which are considered as a competitive mechanics in next-generation networks as an alternative to RF approaches, offer 10,000 times more bandwidth than conventional radio frequency (RF)-based wireless techniques (e.g., WiFi, LoRa, Bluetooth, LTE), as well as tremendous spatial reuse potential with even less interference. Because optical communications have a limited wavelength and travel in the line of sight (LoS) manner, the OWC is commonly thought as a secure wireless approach to confine light transmissions within physical bounds. However, in the real world, it is completely untrue. The privacy leakages and security risks broadly exist in the optical-related wireless applications including OWC networks. These threats and weaknesses have recently been the subject of several initial studies. However, they lack systematic analysis and are isolated. This survey first presents a general workflow of OWC systems, which consists of three stages: before signal emission (BSE), during signal propagation (DSP), and after signal receiving (ASV). For each stage, related risks are reviewed. Then, we summarize existing attacks in optical-related wireless applications and corresponding counter-attack solutions. Finally, we outline the future trends for improving OWC security.

Resource Sharing and Trading of Blockchain Radio Access Networks: Architecture and Prototype Design

Recently, blockchain radio access network (B-RAN) arises as an innovative paradigm for the sixth-generation (6G) wireless communications to build cooperative trust, aggregate wireless resources, and schedule inter-and intra-network tasks among independent network entities. It establishes an open platform based on blockchain to provide diverse wireless services and applications, such as radio access, Internet of Things (IoT), and mobile edge computing, via trusted interactions with enhanced security and efficiency. As a distinctive feature, B-RAN enables secure and efficient resource sharing and trading by aggregating, pooling, and coordinating resources from multiple resource hosts and owners across subnetworks. Therefore, an implementable architecture along with various functional modules shall be delicately designed. This work aims to establish a unified architecture with enhanced efficiency, security, compatibility, and flexibility for resource sharing and trading in B-RAN. Specifically, we develop a six-layer architecture that incorporates a number of novel features such as enhanced blockchain structures, secure interaction methods, efficient service mechanisms, and scalable transaction patterns. We design a number of pluggable functional modules in each layer to support diverse functions, services, and applications of resource sharing and trading. At last, we implement a practical prototype based on the layered architecture for resource-limited devices. Multiple experiments are presented to verify the performance of the proposed architecture from different aspects.

Detection and analysis of Wi-Fi signals for address direction finding

Statement of problem. The active use of wireless technologies requires the development of radio equipment that monitors devices and data transmission networks and, in particular, wireless local area networks of the 802.11 standard (Wi-Fi). The need to identify unauthorized access points and subscriber devices of these networks, including their bearing and localization, is an urgent task of radio monitoring services. Correlation-interferometric direction finders based on a two-channel radio receiving equipment cyclically connected to various pairs of elements of a multi-element antenna system are an effective tool for bearing radio signals. For the direction finding of packet radio signals, direction finders accumulate time samples from different antenna pairs over long time intervals; joint processing of these data allows determining the direction of arrival of radio signals. However, in the frequency range of transmission of signals of the IEEE 802.11 standard, many sources carry out parallel transmission of information in the time-sharing mode, therefore, the direct accumulation of samples entails mixing and combining data generated by different sources. This causes gross bearing errors and requires the development of new ways of joint identification and bearing of packet radio signals. The purpose of the work is to propose a method for determining the identification features of access points and subscriber devices of Wi-Fi networks, which allows combining fragments of data samples when bearing radio sources. Results. The presented method of address bearing, focused on signals of the 802.11 standard, allows detecting OFDM signals, identifying access points and subscriber devices of the local network and forming an estimate of the direction to these sources of radio emissions. Practical importance. The use of address bearing of Wi-Fi network devices increases the functionality of existing analyzers. The presented method of address bearing is implemented based on the mobile direction finder ARTICLE-M [1], which is used in search and localization systems of unauthorized sources of radio emissions.

Multi-Relay Cognitive Network With Anti-Fragile Relay Communication for Intelligent Transportation System Under Aggregated Interference

The rapid development and continuous innovation of wireless services have led to a boom in the number and types of smart terminals. The huge amount of data that deep learning needs to calculate relies on the continuous improvement of hardware devices to solve. Therefore, the realization of intelligent transportation system(ITS) has become the general trend. The increase in the number of Internet of Things devices and the changes in the location of vehicles in the Internet of Vehicles(IOV) system have put forward higher requirements for the reliability and effectiveness of information transmission and the effective use of spectrum resources. Aiming at the influence and elimination of aggregated interference in intelligent transportation system, an anti-fragile communication algorithm is proposed to improve the reliability of signal transmission. At the same time, the outage probability of energy harvesting and cognitive radio technology enhanced with relay cooperative transmission under cognitive wireless network system with the aggregate interference can be deduced in detail. Finally, the correctness of theoretical analysis and the reliability of the proposed anti-fragile communication algorithms are verified by simulation experiments.

Sustainable Wireless Services With UAV Swarms Tailored to Renewable Energy Sources

Unmanned Aerial Vehicle (UAV) swarms are often required in off-grid scenarios, such as disaster-struck, war-torn or rural areas, where the UAVs have no access to the power grid and instead rely on renewable energy. Considering a main battery fed from two renewable sources, wind and solar, we scale such a system based on the financial budget, environmental characteristics, and seasonal variations. Interestingly, the source of energy is correlated with the energy expenditure of the UAVs, since strong winds cause UAV hovering to become increasingly energy-hungry. The aim is to maximize the cost efficiency of coverage at a particular location, which is a combinatorial optimization problem for dimensioning of the multivariate energy generation system under non-convex criteria. We have devised a customized algorithm by lowering the processing complexity and reducing the solution space through sampling. Evaluation is done with condensed real-world data on wind, solar energy, and traffic load per unit area, driven by vendor-provided prices. The implementation was tested in four locations, with varying wind or solar intensity. The best results were achieved in locations with mild wind presence and strong solar irradiation, while locations with strong winds and low solar intensity require higher Caital Expenditure (CAPEX) allocation.

Low-Profile Compact Tri-Band Multimode Reconfigurable Antenna Using Characteristic Mode Analysis

A low-profile compact tri-band (2.45/3.5/5.8 GHz) reconfigurable antenna with versatile radiation modes is proposed for portable wireless communication in this paper. The characteristic mode analysis method is used to explain the antenna’s operating principles and reduces the dimension. The antenna primarily comprises a patch radiator with T-shaped cuts, meander-slot defected ground, and shorting pins, resulting in three frequency bands with different radiation patterns. The antenna features a compact volume of 0.24λ0 × 0.24λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.026λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free-space wavelength of 2.45 GHz) and exhibits omnidirectional radiations at 2.45 and 5.8 GHz and unidirectional radiations at 3.5 GHz. In addition, the operating bands can be tuned by applying different DC biases to the varactors. The antenna is fabricated, and the measured results agree reasonably well with the simulations. The miniaturized tri-band antenna can be potentially used in portable wireless services and intelligent transport devices.

Unit middleware for implementation of human–machine interconnection intelligent ecology construction

General speech recognition models require large capacity and strong computing power. Based on small capacity and low computing power to realize speech analysis and semantic recognition is a research area with great challenges for constructing intelligent ecology of the Internet of Things. For this purpose, we set up the unit middleware for the implementation of human–machine interconnection, namely human–machine interaction based on phonetics and semantics control for constructing intelligent ecology of the Internet of Things. First, through calculation, theoretical derivation and verification we present a kind of novel deep hybrid intelligent algorithm, which has realized speech analysis and semantic recognition. Second, it is to establish unit middleware using the embedded chip as the core on the motherboard. Third, it is to develop the important auxiliary tools writer-burner and cross-compiler. Fourth, it is to prune procedures and system, download, burn and write the algorithms and codes into the unit middleware and cross-compile. Fifth, it is to expand the functions of the motherboard, provide more components and interfaces, for example including RFID(Radio Frequency Identification, RFID), ZigBee, Wi-Fi, GPRS(General Packet Radio Services, GPRS), RS-232 serial port, USB(Universal Serial Bus, USB) interfaces and so on. Sixth, we take advantage of algorithms, software and hardware to make machines "understand" human speech and "think" and "comprehend" human intentions so as to implement human–machine interconnection, which further structure the intelligent ecology of the Internet of Things. At last, the experimental results denote that the unit middleware have very good effect, fast recognition speed, high accuracy and good stability, consequently realizing the intelligent ecology construction of the Internet of Things.

Performance analysis of pulse shaping rectangular pulse through frequency selective fading transmission channel in OFDM system

- Long Term Evolution or LTE is a fourth generation (4G) cellular network technology that uses OFDM as its multiplexing technique for fast and effective wireless communication services. OFDM uses the concept of orthogonality for bandwidth efficiency by multiplexing overlapping subcarriers. But in its implementation, this system will have problems in the transmission channel. In addition, OFDM has the major drawback of being susceptible to frequency offset between the transmitter and receiver. This offset frequency will cause the orthogonal character built in the OFDM system to experience a decrease in performance. This decrease in performance is due to the occurrence of ICI. To overcome this, a method is needed to improve system performance. The method used in this research is Rectangular Pulse. Therefore, this research is made to combine the advantages of OFDM and pulse shaping and is expected to produce a superior system and can contribute to the improvement of 4G-LTE implementation. The approach method in this research applies a quantitative descriptive approach to analyze system performance and in this research uses the simulation method as a reference to obtain research data using the Matlab application.

QoS-Aware Precoding in Downlink Massive MIMO LEO Satellite Communications

Satellite communications (SATCOM) are essential parts of future wireless networks and are moving towards standardization in 6G. Low Earth Orbit (LEO) SATCOM show significant performance gain in global wireless access services, due to their minor path loss and short propagation delay, compared with other SATCOM counterparts. A quality of service (QoS)-aware precoding design is presented in this work to enhance the performance of massive multiple-input multiple-output (MIMO) LEO SATCOM. In particular, we set up a multi-objective optimization problem to balance the system energy efficiency (EE) and the percentage of users achieving their QoS requirements. An efficient algorithm is developed for obtaining the precoding vectors. Numerical results show that the proposed algorithm leads to a larger percentage of users achieving their QoS requirements and brings improvements in EE performance, compared with conventional approaches.

AirTouch Communications’ Innovative Disclosure: “Proportionate Financial Data”

ABSTRACT This note relates and discusses the financial reporting innovation in the 1990s by AirTouch Communications, Inc., a wireless telephone service provider. The innovation was intended to show the parent company’s proportionate ownership share of its subsidiaries’ and joint ventures’ operations, restating key figures from the income statement and operating cash flow. The author corresponded with AirTouch’s then chief financial officer (CFO) for an explanation of the reasoning behind the innovation. Another issue that this note addresses is the opinion given by the audit firm on supplemental disclosures that depart from GAAP.

Framing Issues: Public Participation in Canadian Wireless Spectrum Consultations

Background: A descriptive statistical analysis was performed on Innovation, Science and Economic Development Canada’s (ISED) spectrum consultations from 2008 to 2021, along with a qualitative case study of the 2019 consultation on the 3500 MHz band. Analysis: The statistical analysis evinces the dominance of corporate participation in spectrum consultations, particularly by large wireless service providers. This article examines the relationship between the complicated technical framing of spectrum management issues and the corresponding lack of public participation. Conclusions and implications: To address the lack of public participation in spectrum management, the article proposes an adaptation of the Broadcasting and Telecommunications Legislative Review Panel’s recommendation for a public interest committee for ISED’s consultation process.

The Diverse Technology of MANETs: A Survey of Applications and Challenges

In recent years, mobile ad hoc networks (MANETs) have shown much potential in providing wireless network solutions for a variety of situations. MANETs are made up of a variety of devices (both mobile and internet of things (IoT)) which form a wireless network that provides wireless network functionality and cloud services and can be used to provide wireless services to devices in areas where fixed infrastructure is not accessible. Although it is not necessary for a node to be connected to fixed wireless or cellular infrastructure for the network, even a single node connected to infrastructure opens up a wide range of new research opportunities and applications. Due to the variety of compatible devices, MANETs are the perfect technology for a wide variety of scenarios, such as: military, search and rescue operations, and more. Our contribution is a complete survey of the applications of MANETs, which to our knowledge has not been previously documented. This survey will discuss the industries MANETs are used in (e.g. education, smart city, etc.), the benefits and services they can provide users, and will also explore the challenges this technology still experiences

Automatic Recognition of Beam Attachment for Massive MIMO System in Densely Distributed Renewable Energy Resources

Several large-scale and distributed systems such as renewable energy systems (RESs) require ubiquitous and reliable communication. RESs are designed to provide efficient power management and improve both energy production and consumption. Decision making in RESs heavily depends on real-time communication. Fifth and sixth-generation (5G, 6G) wireless networks promise to deliver significant communication advantages to RESs including ultra-low latency, high throughput and improved coverage. However, the communication behavior in RESs is categorized as unpredictable due to aspects such as system flexibility and equipment heterogeneity. This may affect the stability of the entire RES, which results in further issues such as signal reliability and degraded coverage. Therefore, precise identification of user equipment’s (UE) location greatly improves the sustainability of 5G and 6G wireless services. In this work, we propose a novel low-complexity technique to automatically recognize UE locations in an area of interest. The approach aims at providing precise identification of UE with minimum memory and feature requirements. We use the lazy learning approach to build a prediction model to construct beam-attachment maps. We then train the model to provide distributed intelligent models to automatically recognize beam-attachment indexes. We compare the proposed approach with instance-based techniques to measure its ability at predicting beam-attachment maps. The results show that the proposed model has the ability to provide an accurate prediction with respect to the beam-attachment index (around 100%) with minimal complexity.

Design and Implementation of Vehicle Tracking System with GPS

Abstract: An efficient vehicle tracking system is designed and implemented for tracking the movement of any equipped vehicle from any location at any time. The proposed system made good use of a popular technology that combines a Smartphone application with a microcontroller. This will be easy to make and inexpensive compared to others. The designed in-vehicle device works using Global Positioning System (GPS) and Global system for mobile communication / General Packet Radio Service (GSM/GPRS) technology that is one of the most common ways for vehicle tracking. The device is embedded inside a vehicle whose position is to be determined and tracked in real-time. A microcontroller is used to control the GPS and GSM/GPRS modules. The vehicle tracking system uses the GPS module to get geographic coordinates at regular time intervals. The GSM/GPRS module is used to transmit and update the vehicle location to a database. A Smartphone application is also developed for continuously monitoring the vehicle location. The Google Maps API is used to display the vehicle on the map in the Smartphone application. Thus, users will be able to continuously monitor a moving vehicle on demand using the Smartphone application and determine the estimated distance and time for the vehicle to arrive at a given destination

In Case You Haven't Heard…

TracFone Wireless, a leading prepaid, no‐contract mobile service provider, and part of the portfolio of Verizon Communications Inc., is bringing back flip phones for Mental Health Awareness Month, the news release service, Business Wire, reported. Beginning May 18 and running for a limited time only, TracFone will offer a flip phone and wireless service bundle exclusively at Walmart.com to encourage customers to unplug and reconnect. Smartphones are a necessity for nearly everyone, but flip phones are having another moment in the sun with a whole new generation. According to a McKinsey Health Institute survey, Gen Zers and millennials are more likely than other generations to indicate that social media affects their mental health. These younger generations are prioritizing their mental wellness by reducing screen time and temporarily putting their smartphones away. What was once considered a kitschy throwback, flip phones have now become a new path to wellness for those who need a break from the screen and still want the security and connection of a mobile phone. The hashtag #BringBackFlipPhones has been gaining traction — the buzzy phrase has over 46.9 million views on TikTok alone — and the “old‐school” phones are becoming more relevant to Gen Z than ever before, according to Business Wire.

Grid-connected solar-powered cellular base-stations in Kuwait

Recently, the number of mobile subscribers, wireless services and applications have witnessed tremendous growth in the fourth and fifth generations (4G and 5G) cellular networks. In turn, the number of base-stations (BSs) has increased rapidly for wider ubiquitous networking; however, powering BSs has become a major issue for wireless service providers. Most BSs are either grid-connected, which are powered via fossil fuels-dependent power plants, or are off-grid, and operated via diesel generators. Hence, BSs are responsible for carbon dioxide (CO2) emissions. Intuitively, utilizing photovoltaic (PV) solar energy has posed itself as an alternative “green” renewable energy source. This paper studies utilizing PV solar power to energize on-grid (G) cellular BSs in Kuwait, and selling excess PV energy back to the grid to minimize the total cost over the BS operational lifetime. To this end, an on-grid electrical system is designed to power a 4G/5G cellular BS at an urban cell-site. Various electric system configurations are modeled, simulated, and optimized via the HOMER software, while incorporating PV panels, a diesel generator (DG), and/or a battery bank (BB). Comparisons are conducted in terms of net present cost (NPC), CO2 emissions, energy sold, and required system area. The simulation results revealed that the on-grid system configurations yield significantly lower NPC than their off-grid counterpart systems and the PV-G system configuration is the most economical. However, it cannot guarantee system autonomy in power outage scenarios, as it does not contain energy storage devices. Alternatively, the PV-BB-G system configuration is shown to be more reliable than the PV-G configuration, but at the expense of marginally higher NPC. Also, utilizing a dual-axis tracker has been shown to further reduce the NPC and CO2 emissions. In general, increasing the sell-back price effectively reduces the NPC and CO2 emissions, and increases energy sold, however, entails greater system area.