Wireless Communication Techniques Research Articles

Reconfigurable Intelligent Surfaces Relying on Non-Diagonal Phase Shift Matrices

Reconfigurable intelligent surfaces (RIS) have been actively researched as a potential technique for future wireless communications, which intelligently ameliorate the signal propagation environment. In the conventional design, each RIS element configures and reflects its received signal independently of all other RIS elements, which results in a diagonal phase shift matrix. By contrast, we propose a novel RIS architecture, where the incident signal impinging on one element can be reflected from another element after an appropriate phase shift adjustment, which increases the flexibility in the design of RIS phase shifts, hence, potentially improving the system performance. The resultant RIS phase shift matrix also has off-diagonal elements, as opposed to the pure diagonal structure of the conventional design. Compared to the state-of-art fully-connected/group-connected RIS structures, our proposed RIS architecture has lower complexity, while attaining a higher channel gain than the group-connected RIS structure, and approaching that of the fully-connected RIS structure. We formulate and solve the problem of maximizing the achievable rate of our proposed RIS architecture by jointly optimizing the transmit beamforming and the non-diagonal phase shift matrix based on alternating optimization and semi-define relaxation (SDR) methods. Moreover, the closed-form expressions of the channel gain, the outage probability and bit error ratio (BER) are derived. Simulation results demonstrate that our proposed RIS architecture results in an improved performance in terms of the achievable rate compared to the conventional architecture, both in single-user as well as in multi-user scenarios.

Joint Security and Train Control Design in Blockchain-Empowered CBTC System

The communication-based train control (CBTC) system ensures the high efficiency and orderliness of trains and is widely used in urban rail transit networks. The adoption of wireless communication and network techniques makes the CBTC systems more vulnerable to cyber attacks. Identity authentication is an effective approach to improve system security. The existing identity authentication mechanisms in CBTC adopt a centralized key management system sensitive to single-point failures. To improve system security, in this article, we deploy a blockchain in CBTC systems. The client that runs the blockchain program not only acts as blockchain nodes to provide distributed key management for the CBTC system but they also work as a relay node to authenticate the communication between train control nodes in CBTC systems. Based on the blockchain-empowered distributed security scheme, the block producer selection and onboard blockchain client handoff decision problem are studied. With the objective to minimize the impact of the key updating process on CBTC system performance and keep the system security under a reasonable level, we formulate the block producer selection and onboard blockchain client handoff decision problem using the deep reinforcement learning approach. Extensive simulation results illustrate that the proposed blockchain-empowered security scheme can significantly improve the CBTC system security, and CBTC systems need to sacrifice part performance to ensure system security.

Iterative Pyramidal Filtering Method for Improved Signal Recognition in Radio Spectrograms

Spectrograms are an essential time-frequency representation tool that has been used to address several important problems in wireless communication systems. However, most existing techniques based on the processing of radio spectrograms require a relatively high Signal-to-Noise Ratio (SNR), performing poorly at low/moderate SNR. In this context, this letter proposes an iterative radio spectrogram filtering method based on a novel pyramidal convolution kernel. The obtained results demonstrate that the proposed technique improves the recognisability of signal components in radio spectrograms. Two illustrative examples are provided to show how this method helps to extend noticeably the SNR operational range of techniques for wireless communications based on the processing of radio spectrograms.

Spectral Efficiency Improvement Techniques in OFDM and UFMC

Abstract: This article describes about to analyse the spectral efficiency of different modulation techniques in OFDM and UFMC. UFMC is a multi-carrier modulation technique in fifth generation network (5G). In this paper, we review the different modulation techniques in 5G technology and motivate the need of UFMC technique in 5G wireless communication. In 4G OFDM modulation technique, some drawbacks like side band leakages, high Peak to Average Power ratio (PAPR) and spectrum utilization degrades the performance of the system. Another multi carrier technique called Filter Bank Multi carrier (FBMC) which is better than OFDM, have some issues in practical aspects. So by considering the above parameters a move to another technique called Universal Filtered Multi Carrier (UFMC) is used because of good spectrum usage. This paper also explains about the UFMC system model. Based on the Simulation results in MATLAB, the spectrum utilization of UFMC system is much better than OFDM system. Keywords: UFMC, OFDM, 5G, IFFT, FFT, DAC, ADC and Spectrum efficiency.

Industrial monitoring and control using LoRa communication

Monitoring and controlling industrial machinery is one of the best methods to prevent equipment breakdown. Industrial machines normally break down when the voltage or current goes low or high. With Industrial monitoring, we can ensure that the access is controlled, and the products are of higher quality. With this method, we can control access, improve productivity, and ensure high-quality results when manufacturing industrial products. In today's technological era, remote monitoring and control have become commonplace in industries using connectivity techniques such as ZigBee, RF,and Infrared. Due to their slow communication speeds, long distances, and weak data security, these wireless communication techniques are generally limited to simple applications. Additionally, they are easily affected by noise and bad weather conditions, such as snow, fog, and rain the present project proposes to use LoRa (long-range) technology to implement a new solution for the traditional monitoring and control of industrial applications using high-quality communication and high security.

Smart System Using Lora Technology to Connect Rural Areas Underserved By Existing Internet and Telecommunication Technologies

LoRa, Sigfox, and Narrowband-Internet of Things (NB-IoT) are some of the long-distance, low-power wireless communication technologies developed in the recent past. The proposed system consists of mainly nodes and a gateway as the fundamental system architecture. Nodes only communicate with the gateway individually and the gateway communicates with all the nodes separately and wirelessly. System in this proposed study, uses long range low power RF wireless communication technique for primary data communication, where an Internet connection will not be required for the communication between the gateway and the nodes. Any number of nodes can be paired with the gateway, and the gateway can individually communicate with each and every node. Furthermore, gateways have the ability of storing real-time data. Due to its unique design, the proposed system in this study, can achieve addressable, bidirectional, and continuous data communication even without the Internet connection. The bidirectional communication design of this proposed system facilitates real time and uninterrupted simultaneous handling of monitoring/sensor devices and controller devices without the need of a separate controlling system. As this system consists of those unique features, it is recommended to use in the rural areas underserved by current internet and telecommunication technologies. With the in-built option to get connected to the Internet, this system can be further expanded to an IoT based addressable data communication, processing, and visualization systems by eliminating the major technical problems in typical IoT systems such as interrupted communication and data losses during an Internet connection failure, power concerns and customization issues.

Physical insight into the terahertz polarization modulator by using Smith chart

Polarization modulation (PoM) provides an additional degree of freedom for the modulation of carrier waves and may be an alternative to conventional wireless communication techniques that use amplitude, frequency, and phase modulations. In this study, we proposed a metasurface-based modulator that transforms a linearly polarized wave into a circularly polarized wave in the terahertz range of 1.53 THz–1.57 THz. The polarization manipulation of the metasurface is analyzed using the Smith chart method, which builds a bridge between the metasurface pattern and its equivalent circuit impedance. We show the reflection/transmission coefficient and impedance of the metasurface in the Smith chart, providing clear physical images for the designers. According to the Smith chart analysis, we obtained a two-layer metasurface modulator with 90% efficiency for the transmitted field. All the results are validated from the simulation. The proposed Smith chart method opens a new design methodology of metasurface-based devices.

Challenges, Trends and Solutions for Communication Networks and Cyber-Security in Smart Grid

Abstract: Power grid is one of the most important manifestations of the modern civilization and the engine of it where it is described as a digestive system of the civil life. It is a structure has three main functions: generation, transmission lines, distribution. This concept was appropriate for a century. However, the beginning of the twenty-first century brought dramatic changes on different domains: media, human growth, economic, environmental, political, and technical etc. Smart grid is a sophisticated structure including cyber and physical bodies hence it reinforces the sustainability, the energy management, the capability of integration with microgrids, and exploiting the renewable energy resources. The quantum leap of smart grid is related to the advanced communication networks that deal with the cyber part. Moreover, the communication networks of smart grid offer attractive capabilities such as monitoring, control, and protection at the level of real time. The wireless communication techniques in integration frame are promised solution to compensate the requirements of smart grid designing such as wireless local area networks, worldwide interoperability for microwave access, long term evolution, and narrowband- internet of things. These technologies could provide high capacity, flexibility, low-cost maintenance for smart grid. However, the multi-interfaces in smart grid may exploit by persons or agencies to implement different types of cyber-attacks may lead to dangerous damage. This research paper reviews the up-to-date researches in the field of smart grid to handle the new trends and topics in one frame in order to offer integration vision in this vital section. It concentrates on the section of communication networks the mainstay of smart grid. This paper discusses the challenging and requirements of adopting the wireless communication technologies and delves deeply into literature review to devise and suggest solutions to compensate the impairments efficiently. Moreover, it explores the cyber security that representing the real defiant to implement the concept of smart grid safely.

Concealing RFID: Authentication using Cloud

Abstract: RFID (Radio Frequency Identification) has gone from unknown to well-known in recent years as it is frequently employed for security purposes. Because everyone's primary goal is to be safe, our project is heavily focused on security. Because everyone is concerned about data being leaked or misused, this project will ensure that security is increased and that RFID can be used safely. It is a wireless communication technique that allows computers to read the identity of electronic tags from a distance using computers. There are numerous advantages to RFID, but it also has certain disadvantages. This article use card/tag detection to ensure that RFID users are permitted. Radio frequency is the technology that allows smart labels to be attached to objects. As a result, even physical objects can take part in the computing process. It is gaining popularity as a result of its technological advancements and capacity to overcome line-of-sight issues. RFID has become commonplace in smart applications or IoT use cases such as smart education, smart housing, smart healthcare, and smart cities, to name a few. IoT, RFID, and a slew of other technologies and standards make it possible to connect the digital and physical worlds. When RFID technology is used to uniquely identify linked devices and things, it is critical to understand its utility in the authentication process as well as the security concerns that may arise. In wireless communication, RFID tags and RFID readers are used. Keywords: Radio frequency Identification ,smart IoT applications, Internet of Things, cloud-based remote RFID authentication

A Comprehensive Study of Past, Present, and Future of Spectrum Sharing and Information Embedding Techniques in Joint Wireless Communication and Radar Systems

Wireless spectrum is a limited resource, and the rapid increase in demand for wireless communication-based services is increasing day by day. Hence, maintaining a good quality of service, high data rate, and reliability is the need of the day. Thus, we need to apportion the available spectrum in an efficient manner. Dual-Function Radar and Communication (DFRC) is an emerging field and bears vital importance for both civil and military applications for the last few years. Since hybridization of wireless communication and radar designs provoke diverse challenges, e.g., interference mitigation, secure mobile communication, improved bit error rate (BER), and data rate enhancement without compromising the radar performance, this paper reviews the state-of-the-art developments in the spectrum shared between mobile communication and radars in terms of coexistence, collaboration, cognition, and cooperation. Compared to the existing surveys, we explore an open research issue on radar and mobile communication operating with mutual benefits based on collaboration in terms of spectrum sharing. Additionally, this paper provides important perspectives for future research of DFRC technology.

Design of metasurface-based polarization modulators by using Smith chart method

Polarization modulation (PoM) provides an additional degree of freedom for the modulation of carrier waves and may be an alternative to conventional wireless communication techniques that use amplitude, frequency, and phase modulations. Metasurfaces have provided unprecedented freedom for modulating the polarization state of electromagnetic waves. In this study, we introduce the Smith chart method to guide the design of metasurface-based modulator that transforms a linearly polarized wave into a circularly polarized wave. The proposed method bridges the metasurface pattern and its equivalent circuit impedance. We show that the parameter changes in the pattern can be directly displayed in the Smith chart, which provides clear physical image guidance to designers. According to the Smith chart analysis, we obtained a single-layer modulator with 50% efficiency and a three-layer modulator with 100% efficiency, all of which are verified using the full-wave simulation method. The Smith chart method will also be helpful in the design of other metasurface-based devices, such as metasurface absorbers.

Deep Learning-Aided OFDM-Based Generalized Optical Quadrature Spatial Modulation

In this paper, we propose an orthogonal frequency division multiplexing (OFDM)-based generalized optical quadrature spatial modulation (GOQSM) technique for multiple-input multiple-output optical wireless communication (MIMO-OWC) systems. Considering the error propagation and noise amplification effects when applying maximum likelihood and maximum ratio combining (ML-MRC)-based detection, we further propose a deep neural network (DNN)-aided detection for OFDM-based GOQSM systems. The proposed DNN-aided detection scheme performs the GOQSM detection in a joint manner, which can efficiently eliminate the adverse effects of both error propagation and noise amplification. The obtained simulation results successfully verify the superiority of the deep learning-aided OFDM-based GOQSM technique for high-speed MIMO-OWC systems.

Channel Measurement and Noise Estimation in FBMC/OQAM-Based IoT Networks

Channel measurement plays an important role in the emerging 5G-enabled Internet of Things (IoT) networks, which reflects the channel quality and link reliability. In this paper, we address the channel measurement for link reliability evaluation in filter-bank multicarrier with offset quadrature amplitude modulation- (FBMC/OQAM-) based IoT network, which is considered as a promising technique for future wireless communications. However, resulting from the imaginary interference and the noise correlation among subcarriers in FBMC/OQAM, the existing frequency correlation method cannot be directly applied in the FBMC/OQAM-based IoT network. In this study, the concept of the block repetition is applied in FBMC/OQAM. It is demonstrated that the noises among subcarriers are independent by the block repetition and linear combination, instead of correlated. On this basis, the classical frequency correlation method can be applied to achieve the channel measurement. Then, we also propose an advanced frequency correlation method to improve the accuracy of the channel measurement, by assuming channel frequency responses to be quasi-invariant for several successive subcarriers. Simulations are conducted to validate the proposed schemes.

Security in Internet of Things: A Review

Internet of Things (IoT) is the paramount virtual network that enables remote users to access connected multimedia devices. It has dragged the attention of the community because it encompasses real-world scenarios with implicit environs. Despite several beneficial aspects, IoT is surrounded by provocations for successful implementation, as data travels in different layers. One of the critical challenges is the security of the data in these layers. Researchers conducted numerous studies focused on the level of security at a single technique, creating loopholes to address the entire scenario of securing an IoT network. This study aims to comprehensively review current security issues, wireless communication techniques, and technologies for securing IoT. This work’s utmost significance is addressing all the security perspectives at a glance. For this purpose, research contributions from the previous years are investigated for better understanding. Some countermeasures and snags from security perspectives have also been analyzed in detail concerning the current industry trends. Blockchain, machine learning, fog, and edge computing are possible solutions to secure IoT. After studying these techniques and their immunity to attacks, machine learning can become a hope if incorporated with end-to-end security. This comprehensive review will provide adequate understanding and knowledge in defining security lines of action for the successful implementation of IoT.

Resource Allocation for Simultaneous Wireless Information and Power Transfer Systems: A Tutorial Overview

Over the last decade, simultaneous wireless information and power transfer (SWIPT) has become a practical and promising solution for connecting and recharging battery-limited devices due to significant advances in low-power electronics technology and wireless communications techniques. To realize the promised potentials, advanced resource allocation design plays a decisive role in revealing, understanding, and exploiting the intrinsic rate–energy tradeoff capitalizing on the dual use of radio frequency (RF) signals for wireless charging and communication. In this article, we provide a comprehensive tutorial overview of SWIPT from the perspective of resource allocation design. The fundamental concepts, system architectures, and RF energy harvesting (EH) models are introduced. In particular, three commonly adopted EH models, namely, the linear EH model, the nonlinear saturation EH model, and the nonlinear circuit-based EH model, are characterized and discussed. Then, for a typical wireless system setup, we establish a generalized resource allocation design framework that subsumes conventional resource allocation design problems as special cases. Subsequently, we elaborate on relevant tools from optimization theory and exploit them for solving representative resource allocation design problems for SWIPT systems with and without perfect channel state information (CSI) available at the transmitter, respectively. The associated technical challenges and insights are also highlighted. Furthermore, we discuss several promising and exciting future research directions for resource allocation design for SWIPT systems intertwined with cutting-edge communication technologies, such as intelligent reflecting surfaces, unmanned aerial vehicles, mobile edge computing, federated learning, and machine learning.

The Magic of Superposition: A Survey on Simultaneous Transmission Based Wireless Systems

In conventional communication systems, any interference between two communicating points is regarded as unwanted noise since it distorts the received signals. On the other hand, allowing simultaneous transmission and intentionally accepting the superposition of signals and even benefiting from it have been considered for a range of wireless applications. As prominent examples, NOMA, joint source-channel coding, and the computation codes are designed to exploit this scenario. They also inspired many other fundamental works from network coding to consensus algorithms. Especially, federated learning is an emerging technology that can be applied to distributed machine learning networks by allowing simultaneous transmission. Although various simultaneous transmission applications exist independently in the literature, their main contributions are all based on the same principle; <i>the superposition property</i>. In this survey, we aim to emphasize the connections between these studies and provide a guide for the readers on the wireless communication techniques that benefit from the superposition of signals. We classify the existing literature depending on their purpose and application area and present their contributions. The survey shows that simultaneous transmission can bring scalability, security, low-latency, low-complexity and energy efficiency for certain distributed wireless scenarios which are inevitable with the emerging wireless technologies.

A Survey on FEC Techniques for Industrial Wireless Communications

Industry 4.0 aims to digitize industrial processes entirely, and wireless technologies represent one of the enablers for scalable and flexible communications. However, the current standards and proprietary solutions do not meet the industry's tight requirements in fundamental use cases such as Factory Automation (FA). One of the key research challenges towards replacing wired fieldbuses with wireless links is the design of techniques that enable real-time and deterministic behavior when transmitting short packets. Forward Error Correction (FEC) techniques are critical to this objective, and coding/decoding algorithms must comply with reliability and low latency specifications. This paper surveys existing FEC techniques for short packet transmissions. Compared to other survey papers in the field, we propose several FEC candidate techniques specifically suitable for FA wireless systems. We explore four of these techniques, also examining hardware architecture proposals. The paper proposes a methodology to evaluate their latency and reliability performance. We finally discuss the lessons learned and challenges for future research.

A Review on Materials and Reconfigurable Antenna Techniques for Wireless Communications: 5G and IoT Applications

A Review on Materials and Reconfigurable Antenna Techniques for Wireless Communications: 5G and IoT Applications

Modeling of Leopard optimization based Node Localization Technique for Wireless Communication Networks

Wireless communication inculcates transfer of information not having any physical connection among two or more points. The significant operation of a sensor network becomes collecting and forwarding data to destiny. It is highly crucial to have an awareness regarding the place of collected data. This data is acquired by leveraging localization method in wireless sensor networks (WSNs). Localization is a way of determining the sensor nodes (SNs) location. Localization of SNs turns out to be an exciting research area, and several studies were performed till now. It is very favourable to model scalable, effectual, and low-cost localization systems for WSNs. This study develops a Leopard optimization based Node Localization Technique for Wireless Communication (LONLT-WC). The goal of the LONLT-WC model is to recognize the location of the nodes involved in the network. The LONLT-WC model involves the design of snow leopard optimization (SLO) algorithm, inspired from the characteristics of snow leopards. The presented LONLT-WC approach computes the unidentified location of the nodes utilizing anchor nodes in the network with the accomplishment of least error rate. The experimental analysis of the LONLT-WC model involves a series of simulations and the results highlighted the betterment of the presented technique.

Joint Optimization for RIS-Assisted Wireless Communications: From Physical and Electromagnetic Perspectives

Reconfigurable intelligent surfaces (RISs) are envisioned to be a disruptive wireless communication technique that is capable of reconfiguring the wireless propagation environment. In this paper, we study a free-space RIS-assisted multiple-input single-output (MISO) communication system in far-field operation. To maximize the received power from the physical and electromagnetic nature point of view, a comprehensive optimization, including beamforming of the transmitter, phase shifts of the RIS, orientation and position of the RIS is formulated and addressed. After exploiting the property of line-of-sight (LoS) links, we derive closed-form solutions of beamforming and phase shifts. For the non-trivial RIS position optimization problem in arbitrary three-dimensional space, a dimensional-reducing theory is proved. The simulation results show that the proposed closed-form beamforming and phase shifts approach the upper bound of the received power. The robustness of our proposed solutions in terms of the perturbation is also verified. Moreover, the RIS significantly enhances the performance of the mmWave/THz communication system.