Radio Coverage Research Articles

A Survey on STAR-RIS: Use Cases, Recent Advances, and Future Research Challenges

The recent development of metasurfaces, which may enable several use cases by modifying the propagation environment, is anticipated to substantially affect the performance of 6G wireless communications. Metasurface elements can produce passive sub-wavelength scattering to enable a smart radio environment. STAR-RIS, which refers to reconfigurable intelligent surfaces (RIS) that can transmit and reflect concurrently (STAR), is gaining popularity. In contrast to the widely studied RIS, which can only reflect the wireless signal and serve users on the same side as the transmitter, the STAR-RIS can reflect and refract (transmit), enabling 360-degree wireless coverage, thus serving users on both sides of the transmitter. This paper presents a comprehensive review of the STAR-RIS, focusing on the most recent schemes for diverse use cases in 6G networks, resource allocation, and performance evaluation. We begin by laying the foundation for RIS (passive, active, STAR-RIS), and then discuss the STAR-RIS protocols, advantages, and applications. In addition, we categorize the approaches within the domain of use scenarios, which include increasing coverage, enhancing physical layer security (PLS), maximizing sum rate, improving energy efficiency (EE), and reducing interference. Next, we will discuss the various strategies for resource allocation and measures for performance evaluation. We aimed to elaborate, compare, and evaluate the literature regarding setup, channel characteristics, methodology, and objectives. In conclusion, we examine this field’s open research problems and potential future prospects.

Adaptive real-time spectrum selection framework and handover decision algorithm (RSSF-HDA) for heterogeneous networks

Carrier aggregation (CA) is a technology introduced by the Long-Term Evolution-Advanced (LTE-A) system to increase user throughput by combining a selected number of component carriers (CCs). Its integration with heterogeneous networks enables the mobile user equipment to take advantage of increased throughput and radio coverage of various access technologies. However, due to the mobility of user equipment, these innovations have increased the likelihood of handoff scenarios, resulting in a high outage probability and low throughput. Handover is a crucial part of mobility management since it enables users to move from one cell to another while maintaining connections. However, no single access technique can provide seamless communication without interruption or delay. As a result, creating a suitable handover decision algorithm is necessary for ensuring high-quality service continuity and dependable user equipment access to the network at all times. An Adaptive Real-Time Spectrum Selection Framework and Handover Decision Algorithm (RSSF-HDA) with optimal resource allocation to the deployed system model is presented in this paper. This effort is geared toward preventing communication failure and improving system performance. It further positions the 4G LTE-A framework for inclusive coexistence with the current 5G New Radio enhanced Mobile Broadband (eMBB) use case scenario. The results of the simulation reveal that this method increases system performance in terms of Cell edge spectral efficiency and Handover success rate above 10% and 13%, respectively, when compared to Conventional Handover Decision Algorithm (Conv-HDA) and Multi-Influence Factor Handover Decision Algorithms (MIF-HDA).

Application of an Enhanced Whale Optimization Algorithm on Coverage Optimization of Sensor.

The wireless sensor network (WSN) is an essential technology of the Internet of Things (IoT) but has the problem of low coverage due to the uneven distribution of sensor nodes. This paper proposes a novel enhanced whale optimization algorithm (WOA), incorporating Lévy flight and a genetic algorithm optimization mechanism (WOA-LFGA). The Lévy flight technique bolsters the global search ability and convergence speed of the WOA, while the genetic optimization mechanism enhances its local search and random search capabilities. WOA-LFGA is tested with 29 mathematical optimization problems and a WSN coverage optimization model. Simulation results demonstrate that the improved algorithm is highly competitive compared with mainstream algorithms. Moreover, the practicality and the effectiveness of the improved algorithm in optimizing wireless sensor network coverage are confirmed.

A Multiple Mechanism Enhanced Arithmetic Optimization Algorithm for Numerical Problems.

The Arithmetic Optimization Algorithm (AOA) is a meta-heuristic algorithm inspired by mathematical operators, which may stagnate in the face of complex optimization issues. Therefore, the convergence and accuracy are reduced. In this paper, an AOA variant called ASFAOA is proposed by integrating a double-opposite learning mechanism, an adaptive spiral search strategy, an offset distribution estimation strategy, and a modified cosine acceleration function formula into the original AOA, aiming to improve the local exploitation and global exploration capability of the original AOA. In the proposed ASFAOA, a dual-opposite learning strategy is utilized to enhance population diversity by searching the problem space a lot better. The spiral search strategy of the tuna swarm optimization is introduced into the addition and subtraction strategy of AOA to enhance the AOA's ability to jump out of the local optimum. An offset distribution estimation strategy is employed to effectively utilize the dominant population information for guiding the correct individual evolution. In addition, an adaptive cosine acceleration function is proposed to perform a better balance between the exploitation and exploration capabilities of the AOA. To demonstrate the superiority of the proposed ASFAOA, two experiments are conducted using existing state-of-the-art algorithms. First, The CEC 2017 benchmark function was applied with the aim of evaluating the performance of ASFAOA on the test function through mean analysis, convergence analysis, stability analysis, Wilcoxon signed rank test, and Friedman's test. The proposed ASFAOA is then utilized to solve the wireless sensor coverage problem and its performance is illustrated by two sets of coverage problems with different dimensions. The results and discussion show that ASFAOA outperforms the original AOA and other comparison algorithms. Therefore, ASFAOA is considered as a useful technique for practical optimization problems.

Base Station Antenna Uptilt Optimization for Cellular-Connected Drone Corridors

Reliable wireless coverage in drone corridors is critical to enable a connected, safe, and secure airspace. To support beyond visual line of sight (BVLOS) operations of aerial vehicles in a drone corridor, cellular base stations (BSs) can serve as a convenient infrastructure as they are widely deployed to provide seamless wireless coverage. However, antennas in the existing cellular networks are down-tilted to optimally serve their ground users, which results in coverage holes at higher altitudes when they are used to serve drones. In this paper, we consider the use of additional uptilted antennas at each cellular BS and optimize the uptilt angle to maximize the wireless coverage probability across a given drone corridor. Through numerical results, we characterize the optimal value of the antenna uptilt angle for a given antenna pattern as well as the minimum/maximum altitudes of the drone corridor.

Multi-Active/Passive-IRS Enabled Wireless Information and Power Transfer: Active IRS Deployment and Performance Analysis

Intelligent reflecting surfaces (IRSs), active and/or passive, can be densely deployed in complex environments to significantly enhance wireless network coverage for both wireless information transfer (WIT) and wireless power transfer (WPT). In this letter, we study the downlink WIT/WPT from a multi-antenna base station to a single-antenna user over a multi-active/passive IRS (AIRS/PIRS)-enabled wireless link. In particular, we derive the location of the AIRS with those of the other PIRSs being fixed to maximize the received signal-to-noise ratio (SNR) and signal power at the user in the cases of WIT and WPT, respectively. The derived solutions reveal that the optimal AIRS deployment is generally different for WIT versus WPT due to the different roles of AIRS-induced amplification noise. Furthermore, both analytical and numerical results are provided to show the conditions under which the proposed AIRS deployment strategy yields superior performance to other baseline deployment strategies as well as the conventional all-PIRS enabled WIT/WPT.

Beyond Diagonal Reconfigurable Intelligent Surfaces: A Multi-Sector Mode Enabling Highly Directional Full-Space Wireless Coverage

Reconfigurable intelligent surface (RIS) has gained much traction due to its potential to manipulate the propagation environment via nearly-passive reconfigurable elements. In our previous work, we have analyzed and proposed a beyond diagonal RIS (BD-RIS) model, which is not limited to traditional diagonal phase shift matrices, to unify different RIS modes/architectures. In this paper, we create a new branch of BD-RIS supporting a multi-sector mode. A multi-sector BD-RIS is modeled as multiple antennas connected to a multi-port group-connected reconfigurable impedance network. More specifically, antennas are divided into <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> ≥ 2) sectors and arranged as a polygon prism with each sector covering 1/ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> space. Different from the recently introduced concept of intelligent omni-surface (or simultaneously transmitting and reflecting RIS), the multi-sector BD-RIS not only achieves a full-space coverage, but also has significant performance gains thanks to the highly directional beam of each sector. We derive the constraint of the multi-sector BD-RIS and the corresponding channel model taking into account the relationship between antenna beamwidth and gain. With the proposed model, we first derive the scaling law of the received signal power for a multi-sector BD-RIS-assisted single-user system. We then propose efficient beamforming design algorithms to maximize the sum-rate of the multi-sector BD-RIS-assisted multiuser system. Simulation results verify the effectiveness of the proposed design and demonstrate the performance enhancement of the proposed multi-sector BD-RIS.

Unmanned Aerial Vehicle (UAV) path planning and control assisted by Augmented Reality (AR): the case of indoor drones

Following the recent advances in Industry 4.0 and the upcoming Industry 5.0, the use of multiple UAVs for indoor tasks has risen, particularly in real-time remote monitoring, wireless coverage, and remote sensing. As a result, UAVs can be viewed as proactive problem solvers and can support Internet of Things (IoT) platforms by collecting and monitoring data cost-effectively and efficiently, leading to better decision-making. Moreover, sophisticated drone operations require specialised software and data processing abilities. However, the utilisation of drones has been mainly focused on outdoor environments, thus creating a literature gap regarding indoor navigation and operation. Therefore, the design and development of a method for remote planning and control of drones based on the utilisation of AR is presented in this paper. The proposed method is based on the utilisation of drones for remote monitoring. The suggested approach involves engineers designing a sequence of actions and transmitting them wirelessly to the drone, eliminating the need for human intervention. Thus, the proposed method contributes towards enabling engineers visualise the drone path with the use of Augmented Reality and provides the flexibility of adding multiple way points. The applicability of the developed framework is tested in a laboratory-based machine shop.

Secure Routing Protocols Comparison Analysis Between RNBR, SAA, A-UPK

The advent of wireless communications and the development of mobile devices have made great strides in the development of roaming communications. The MANET mobile network was developed with the ability for mobile devices to quickly self-configure and extend wireless coverage without infrastructure support. Security is one of the most important areas of research and plays a vital role in determining the success of personal and commercial telephone systems.Therefore, this study focuses on systematically examining MANET security and accountability issues and analyzing the performance of solutions proposed by three different design approaches to security systems.First, it provides an approach for identifying trusted nodes employing the proposed RNBR method for secure routing.it provides a Self-Assured Assessment (SAA) method to estimate node stability. Its main goal is to contribute to a self-assessment-based reliability assessment mechanism that provides a reliable and reliable pathway.it provides a new authentication method to prevent forgery attacks. It supports authentication mechanisms to prevent RF attacks and ensure secure routing development.The main Objective of this paper is compare to packet delivery Ratio ,Control Overhead, Packet Drop Ratio in different secure RNBR,SAA,A-UPK Routing Protocols in MANETS.

Optimal stratified placement of balloons and UAVs to support users’ coverage

Unmanned aerial vehicles (UAVs) base stations are a promising solution to provide better coverage to ground users. In this paper, balloons, UAVs and users are deployed to efficiently enhance users’ coverage. This paper studies three deployment problems: (i) placement of balloons to aid UAVs for wireless assistance, (ii) placement of UAVs to provide coverage to users, and (iii) a joint problem for successful deployment of balloons, UAVs, and connectivity to users. Firstly, an optimization problem is formulated to minimize the number and costs of balloons. Secondly, the goal is to minimize the number of UAVs, maximize the number of users’ connections, minimize the distance between users and UAVs, and minimize the UAVs’ deployment costs. Thirdly, a joint problem is also introduced to provide efficient wireless coverage. The problem is formulated as an integer linear program (ILP). An optimal algorithm is used to solve the optimization problem, however, the computational complexity of an optimal algorithm is high. Thus, a low-complexity greedy algorithm is also proposed. Simulation results show the efficiency of the proposed optimal and greedy algorithms.

Public Perception of Radio Coverage of Farmers/Fulani Herdsmen Conflict in Taraba State: Case Study of Taraba State Broadcasting Service, Jalingo, Nigeria

Farmers and herdsmen conflict was one of the many challenges that have thwarted harmony in most parts of Nigeria. Based on this, radio was always expected to be seen promoting unity and mutual respect through its programs. Therefore, at all times, broadcast media (radio) was expected to adopt a position aimed at dowsing the conflict and promoting mutual understanding and harmony. This research therefore, examined public perception of radio coverage of farmers and Fulani herdsmen conflict in Taraba State. The research focused on Taraba State Broadcasting service, Jalingo. The study was anchored on two theories: Agenda-Setting and Social Responsibility. A survey research design was adopted for the research. The sample size adopted was 400 respondents. The research used a questionnaire to gather data; an in-depth interview complemented it. The method of data analysis adopted was descriptive analysis. Findings showed that the media did not allocate much attention to the conflict, hence the lack of frequent coverage. Findings also showed no detailed dissemination of information about the crises. The research concluded that the broadcast media under study were not conscious of their society by being unprofessional in their coverage of the conflict and not adequately informing people about it. Therefore, the research recommended that broadcast media in Nigeria go beyond their cardinal functions and fully imbibe the practice of conflict reporting and management practice.

Circular Polarization Annular Leaky-Wave Antenna with Conical and Broadside Beams

In order to properly cover different scenarios, radiation patterns of antennas should be accordingly designed. However, most antennas are unable to provide either broadside beams or designable conical beams, which are the typically used radiation patterns for radio coverage, based on one single-structure format through adjusting parameters before fabrication. In this paper, a planar circular polarized (CP) annular leaky-wave antenna (LWA) is proposed, which is realized on an annular substrate-integrated waveguide (SIW). A broadside beam or a conical beam could be easily obtained through fabricating the LWA with different structural parameters. The operating frequency is 5.75 GHz. The LWA allows only the −1st spatial harmonic to radiate, while the fundamental wave and other spatial harmonics are suppressed in slow wave mode. In order to validate the design effectiveness, two examples for broadside beam and conical beam radiation are fabricated and measured. The measurement results show good agreement with the simulation results. The broadside beam LWA shows a gain of 9.75 dBic and the conical beam LWA with a beam angle of 13° has a gain of 7.93 dBic. The proposed LWA presents promising radiation performance and is a good candidate for wireless communication applications.

SNR Gain Evaluation in Narrowband IoT Uplink Data Transmission with Repetition Increment: A Simulation Approach

Deploying Internet of Things (IoT) on a large scale necessitates widespread network infrastructures supporting Machine Type Communication. Integrating IoT into cellular networks like LTE, known as Narrowband-IoT (NB-IoT), can fulfill this infrastructure need. Standard 3GPP Release 13 introduces NB-IoT's Repetition features, expanding radio transmission coverage while maintaining LTE performance. Focusing on uplink data traffic, this study examines NB-IoT's repetition mechanism, grid resource distribution, and NPUSCH performance through simulations. Results show that at SNR greater than -5 dB, maximum repetitions of 128 yield the highest BLER, while minimum repetitions of 2 result in the lowest. Quadrupling repetitions increases SNR by 5 dB, emphasizing repetition's role in error mitigation and uplink reliability, especially in challenging SNR conditions. For optimal throughput in SNR above -5 dB, maximum repetitions of 128 for NPUSCH format 1 are recommended. These findings underscore the importance of repetition in enhancing Narrowband IoT performance, offering insights for system optimization, where increasing the number of repetitions generally leads to higher SNR gain. The attained BLER and throughput values from Narrowband IoT simulations highlight the robustness of data transmission across varying channel conditions, affirming NB-IoT applicability to a wide range of IoT applications.

Sensor Topology Optimization in Dense IoT Environments by Applying Neural Network Configuration

In dense IoT deployments of wireless sensor networks (WSNs), sensor placement, coverage, connectivity, and energy constraints determine the overall network lifetime. In large-size WSNs, it is difficult to maintain a trade-off among these conflicting constraints and, thus, scaling is difficult. In the related research literature, various solutions are proposed that attempt to address near-optimal behavior in polynomial time, the majority of which relies on heuristics. In this paper, we formulate a topology control and lifetime extension problem regarding sensor placement, under coverage and energy constraints, and solve it by applying and testing several neural network configurations. To do so, the neural network dynamically proposes and handles sensor placement coordinates in a 2D plane, having the ultimate goal to extend network lifetime. Simulation results show that our proposed algorithm improves network lifetime, while maintaining communication and energy constraints, for medium- and large-scale deployments.

Títul Research on Wireless Network Coverage for Transformation and Upgrading of Exhibition Management with Artificial Intelligence Technology

Abstract The rapid development of artificial intelligence and modern communication technology provides a powerful opportunity to realize the transformation, upgrading and high-quality development of exhibition management. To solve the optimal coverage problem of wireless network in the exhibition area, a new generation of artificial intelligence algorithm is introduced to propose a novel method for solving the network coverage problem based on Harris Hawk optimization (HHO) algorithm. From the perspective of maximizing coverage and minimizing coverage redundancy, the multi-objective coverage optimization problem of wireless network nodes is optimally extracted into a function and solved using the improved HHO (IHHO) algorithm. Through the simulation of the wireless network coverage in the exhibition area, the experimental results show that the comprehensive evaluation index score of the optimization algorithm reaches 98.03%, which is higher than the traditional particle swarm optimizer (PSO) and the standard HHO. The proposed IHHO algorithm can be effectively applied to the network coverage problem and has a greater advantage over the traditional optimization methods in terms of improving node coverage, and has great practicality.

Energy consumption analytical modeling of NB-IoT devices for diverse IoT applications

Internet of things (IoT) has been employed in recent years across multiple disciplines in the Fifth Generation (5G) era. The low power consumption of the devices allows long battery lifetimes with increasing wireless coverage ranges. This paper presents a comprehensive power consumption model for battery lifetime estimation in narrowband IoT (NB-IoT), which is based on the user equipment (UE) state diagram and considers the extended discontinuous reception (eDRX) and power saving mode (PSM) mechanisms. This model has been used to simulate the effect of varying NB-IoT link parameters, covering a range of values defined in the specification, corresponding to a wide range of applications. Indeed, this study focuses on mathematical analysis of UE power consumption, mainly for NB-IoT communication applications. Repetitions, as defined in the standard, have also been considered in the analysis. Extensive simulations have been carried out to show the power of the proposed model, which provides accurate results for a wide variety of network parameters and let the network designer to select the most appropriated setup. They also show that the value of link parameters must be carefully selected to achieve a battery lifetime of more than a decade with a standard battery of 5 Wh capacity.

Integration of Optical and Free Space Optics Network Architecture for High-Speed Communication in Adverse Weather using suitable Optical Bands

Free Space Optics (FSO) is a highly viable solution for high-speed wireless communication and is widely preferred over radio frequency communication systems because of its faster data transmission, no regulatory requirements and highly secure long-range operations. However, the capacity and availability of FSO optical bands are a significant concern in varying atmospheric conditions. Our objective is to enhance network flexibility and expand wireless network coverage in adverse weather conditions by combining optical and FSO links using optical bands C, S, and O. The study analyzed the performance of a hybrid 4 channels FSO-WDM system with a 100GHz or 0.8 nm channel spacing under different conditions, including adverse weather and varying data rates. An attenuation of 0.25 dB/km was fixed, and the system's performance was analyzed up to 3 km. The results showed that as the data rate increased, the system's performance declined, and the O band was the best performer up to 25 Gbit/s. BER values were analyzed at different weather conditions using the Kim model, and the O band consistently outperformed the S and C bands. Eye diagrams were used to evaluate the signal quality, and the O band was shown to perform better than the other two bands, even in adverse weather conditions. Overall, the study suggests that FSO is a viable solution for high-speed wireless communication, particularly when using the O band.

Advanced Air Mobility Operation and Infrastructure for Sustainable Connected eVTOL Vehicle

Advanced air mobility (AAM) is an emerging sector in aviation aiming to offer secure, efficient, and eco-friendly transportation utilizing electric vertical takeoff and landing (eVTOL) aircraft. These vehicles are designed for short-haul flights, transporting passengers and cargo between urban centers, suburbs, and remote areas. As the number of flights is expected to rise significantly in congested metropolitan areas, there is a need for a digital ecosystem to support the AAM platform. This ecosystem requires seamless integration of air traffic management systems, ground control systems, and communication networks, enabling effective communication between AAM vehicles and ground systems to ensure safe and efficient operations. Consequently, the aviation industry is seeking to develop a new aerospace framework that promotes shared aerospace practices, ensuring the safety, sustainability, and efficiency of air traffic operations. However, the lack of adequate wireless coverage in congested cities and disconnected rural communities poses challenges for large-scale AAM deployments. In the immediate recovery phase, incorporating AAM with new air-to-ground connectivity presents difficulties such as overwhelming the terrestrial network with data requests, maintaining link reliability, and managing handover occurrences. Furthermore, managing eVTOL traffic in urban areas with congested airspace necessitates high levels of connectivity to support air routing information for eVTOL vehicles. This paper introduces a novel concept addressing future flight challenges and proposes a framework for integrating operations, infrastructure, connectivity, and ecosystems in future air mobility. Specifically, it includes a performance analysis to illustrate the impact of extensive AAM vehicle mobility on ground base station network infrastructure in urban environments. This work aims to pave the way for future air mobility by introducing a new vision for backbone infrastructure that supports safe and sustainable aviation through advanced communication technology.

A High-Reliable Wireless Sensor Network Coverage Scheme in Substations for the Power Internet of Things

With the construction of the Power Internet of Things (PIoT) in full swing as well as the development of wireless communication technology, the deployment of wireless sensor networks is the key to the intelligent transformation of power systems. This paper proposes an asymmetric double-layer wireless sensor network coverage scheme for the intelligent substation. We conducted field measurements in the substation to record the received power at different locations, which were compared with the prediction results of the simulation model established by Winprop to verify the effectiveness of the simulation method. Based on the simulation platform, two different simulation models of substation scenarios are built, including a 220 kV outdoor substation and a 110 kV GIS room. The coverage of received power and line-of-sight (LOS) transmission are analyzed for various nodes of different layers. Several node distribution planning methods are proposed and proven to be feasible according to the simulation results. The wireless coverage scheme can provide useful references for the implementation of PIoT in substations.

Unmanned aerial vehicle: a review and future directions

The use of unmanned aerial vehicles (UAVs) will be crucial in the next generation of wireless communications infrastructure. When compared to traditional ground-based solutions, it is expected that their use in a variety of communication-based applications will increase coverage and spectrum efficiency. In this paper, we provide a detailed review of all relevant research works as follows. This paper presents types of UAVs (e.g., wireless coverage, military, agriculture, medical applications, environment, and climate, and delivery and transportation), characteristics of UAVs (e.g., node density, altering system topology, node mobility, radio broadcasting mode, frequency band, localization, and power consumption and network lifetime), the application of UAVs (e.g., Multi-UAV cooperation, UAV-to-VANET collaborations, and UAV-to-ground tasks). Additionally, this paper reviews the routing protocols of UAVs (e.g., topology-based, position-based, heterogeneous, delay-tolerant networks (DTNs), swarm-Based, and cluster-based) and simulation tools (e.g., OMNeT++, AVENS, MATLAB, NS3, SUMO, and OPNET). The design and development of any new methods for UAVs may use this work as a guide and reference.