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In recent years, wireless communication has experienced a massive shift from a single service (i.e., voice) to an interconnected web of networks. Although many techniques have been developed improving the offered services to mobile users, still the demand for high-quality services cannot be reached. Therefore, this paper proposes a joint non-orthogonal multiple access (NOMA)-enabled optimization framework for small-cell network (SCNet) by utilizing the concepts of multi-objective problem. In particular, the transmit power of base station (BS) in each small-cell simultaneously optimizes to maximize the sum-capacity and total energy efficiency (EE) of SCNet. The multi-objective optimization problem is formulated as non-convex subject to several practical constraints, i.e., individual quality of service requirement, maximum power budget of small-cell BS, and efficient decoding of superimposed signal using successive interference cancellation. Based on the nature of the problem, the optimal solutions are provided using sequential quadratic programming, and Karush-Kuhn-Tucker approaches. The obtained results show significant performance gains over conventional orthogonal multiple access technique in terms of sum-capacity and total EE.

A new wireless era beckons, giving rise to novel communication techniques to support the services and demands foreseen for the coming decades. One such revolutionizing technique intended to enable the Internet of Things (IoT) is backscatter communication. Simply employing backscatter communication may not be enough to efficiently connect the massive number of devices in the IoT network. To achieve this feat, non-orthogonal multiple access (NOMA) techniques have been merged with backscatter communications. Although NOMA-enabled backscatter communication is expected to significantly improve the low-powered IoT system, the benefits come with several challenges. In this article, we show that NOMA-enabled backscatter communication has the potential to connect a large number of IoT devices in a battery-free manner. To begin, this article provides the basics on backscatter communication and NOMA techniques. Next, a taxonomy and gap analysis of the studies on backscatter communication is provided. Then novel use cases for NOMA-enabled backscatter communication are detailed, and a case study for smart farming using the overall data rate of backscatter sensor devices employing power-domain NOMA is presented. Finally, we discuss some interesting and potential research challenges to the realization of massive IoT networks using NOMA-enabled backscatter communication.

openaire: EC/H2020/825496/EU//5G-MOBIX Vehicular communication is gradually evolving from the rudimentary data exchange techniques to innovative, efficient, and large-scale communication platform. The future vehicular networks aim to offer new services and achieve massive connectivity with the aid of advanced wireless communication techniques. In this regard, one of the emerging paradigms is non-orthogonal multiple access (NOMA) which holds the promise to meet the resource-intensive demands of future networks. Due to this reason, the applications of NOMA are being investigated by the researcher of academia and industry alike. This article aims to build on the state-of-the-art by providing a novel multiobjective optimization framework for vehicle-to-infrastructure (V2I) communications. Specifically, this work aims to improve upon the sum-rate and energy efficiency of uplink NOMA-enabled V2I communications. The formulated problem is based on the tradeoff between sum-rate and total transmit power while maintaining the quality of service (QoS) requirements of the network. To provide a reliable solution, a multiobjective optimization framework has been proposed by applying the weighted-sum method and handle joint metrics of sum-rate maximization and total transmit power minimization. Extensive simulations have been performed to validate the superiority of the proposed framework against conventional benchmark techniques. The results clearly indicate that the proposed framework is feasible for NOMA-enabled V2I communication and can be scaled up for practical implementation.

Simultaneous wireless information and power transfer (SWIPT) has recently gathered much research interest from both academia and industry as a key enabler of energy harvesting Internet-of-things (IoT) networks. Due to a number of growing use cases of such networks, it is important to study their performance limits from the perspective of physical layer security (PLS). With this intent, this work aims to provide a novel analysis of the ergodic secrecy capacity of a SWIPT system is provided for Rician and Nakagami-m faded communication links. For a realistic evaluation of the system, the imperfections of channel estimations for different receiver designs of the SWIPT-based IoT systems have been taken into account. Subsequently, the closedform expressions of the ergodic secrecy capacities for the considered scenario are provided and, then, validated through extensive simulations. The results indicate that an error ceiling appears due to imperfect channel estimation at high values of signal-to-noise ratio (SNR). More importantly, the secrecy capacity under different channel conditions stops increasing beyond a certain limit, despite an increase of the main link SNR. The in-depth analysis of secrecy-energy trade-off has also been performed and a comparison has been provided for imperfect and perfect channel estimation cases. As part of the continuous evolution of IoT networks, the results provided in this work can help in identifying the secrecy limits of IoT networks in the presence of multiple eavesdroppers., IoT Network, Eavesdroppers, Nakagami-m fading, Physical layer security, Rician fading, SWIPT

Backscatter communication offers a reliable and energy-efficient alternative to conventional radio systems. With the additional capability of wireless power transmission, the backscatter tags can work in a completely battery-less manner. Due to these exciting features, the researchers from academia and industry are extensively investigating its utility as an enabler of massive Internet of Things (IoT) networks. However, before reaping the benefits of ambient backscatter communications, it is necessary to evaluate its feasibility and operability for large scale networks. To do so, this research paper provides an empirical study of the real city wide deployment of monostatic wireless powered backscatter tags in Helsinki region. The coverage and outage performance has been assessed for both indoor and outdoor conditions using a sophisticated 3D ray tracing simulations. Whereby, the indoor scenario consists of several story buildings with low and high loss materials. Moreover, an indepth evaluation of energy shortage at backscatter tags has also been provided which sheds the light on the importance of wireless power transmission for such networks. The results provided here would be helpful in upscaling the practical deployment of backscatter tags.

Research efforts in vehicular communication networks have been driven by the need to achieve high data rates for value-added services and safety applications. The proliferation of billions of connected devices along with their ever growing data demands can potentially cause severe congestion in vehicular networks unless effective solutions are developed. In this context, the multiuser interference encountered in vehicular ad hoc networks is a major performance bottleneck. The interference among vehicles needs to be harnessed to meet the high data rate requirements of heterogeneous vehicular communication networks. This work proposes a novel paradigm of interference-aided vehicular networks in which the interference signals are exploited for communication-related operations such as message flooding, energy harvesting, channel estimation, signal alignment, and link security. We also highlight the technical and socio-economic challenges that must be addressed for successful implementation of interference- aided vehicular communication networks.

Device-to-Device (D2D) communication has emerged as a promising technology for optimizing spectral efficiency in future cellular networks. D2D takes advantage of the proximity of communicating devices for efficient utilization of available resources, improving data rates, reducing latency, and increasing system capacity. The research community is actively investigating the D2D paradigm to realize its full potential and enable its smooth integration into the future cellular system architecture. Existing surveys on this paradigm largely focus on interference and resource management. We review recently proposed solutions in over explored and under explored areas in D2D. These solutions include protocols, algorithms, and architectures in D2D. Furthermore, we provide new insights on open issues in these areas. Finally, we discuss potential future research directions.

Machine learning is a rapidly evolving paradigm that has the potential to bring intelligence and automation to low-powered devices. In parallel, there have been considerable improvements in the ambient backscatter communications due to high research interest over the last few years. The combination of these two technologies is inevitable which would eventually pave the way for intelligent Internet-of-things (IoT) in 6G wireless networks. There are several use cases for machine learning-enabled ambient backscatter networks that range from healthcare network, industrial automation, and smart farming. Besides this, it would also be helpful in enabling services like ultra-reliable and low-latency communications (uRLLC), massive machine-type communications (mMTC), and enhanced mobile broadband (eMBB). Also, machine learning techniques can help backscatter communications overcome its limiting factors. The information-driven machine learning does not require the need of a tractable scientific model as the models can be prepared to deal with channel imperfections and equipment flaws in backscatter communications. Particularly, with the use of reinforcement learning approaches, the performance of backscatter devices can be further improved. On-going examinations have likewise demonstrated that machine learning methodologies can be used to protect backscatter devices to enhance their ability to handle security and privacy vulnerabilities. These previously mentioned propositions alongside the ease-of-use of machine learning techniques inspire us to investigate the feasibility of machine learning-based methodologies for backscatter communications. To do such, we start this chapter by talking about the basics and different flavors of machine learning. This includes supervised learning, unsupervised learning, and reinforcement learning. We also shed light on the deep learning models like artificial neural networks (ANN) and deep Q-learning and discuss the hardware requirements of machine learning models. Then, we go on to describe some of the potential uses of machine learning in ambient backscatter communications. In the subsequent sections, we provide a detailed analysis of reinforcement learning for wireless-powered ambient backscatter devices and give some insightful results along with relevant discussion. In the end, we present some concluding remarks and highlight some future research directions.

The research efforts on cellular vehicle-to-everything (V2X) communications are gaining momentum with each passing year. It is considered as a paradigm-altering approach to connect a large number of vehicles with minimal cost of deployment and maintenance. This article aims to further push the state-of-the-art of cellular V2X communications by providing an optimization framework for wireless charging, power allocation, and resource block assignment. Specifically, we design a network model where roadside objects use wireless power from RF signals of electric vehicles for charging and information processing. Moreover, due to the resource-constraint nature of cellular V2X, the power allocation and resource block assignment are performed to efficiently use the resources. The proposed optimization framework shows an improvement in terms of the overall energy efficiency of the network when compared with the baseline technique. The performance gains of the proposed solution clearly demonstrate its feasibility and utility for cellular V2X communications., Comment: Energy efficiency, Resource block assignment, Vehicle-to-everything (V2X) communications, Wireless power transfer

Ambient backscatter communications is an emerging paradigm and a key enabler for pervasive connectivity of low-powered wireless devices. It is primarily beneficial in the Internet of things (IoT) and the situations where computing and connectivity capabilities expand to sensors and miniature devices that exchange data on a low power budget. The premise of the ambient backscatter communication is to build a network of devices capable of operating in a battery-free manner by means of smart networking, radio frequency (RF) energy harvesting and power management at the granularity of individual bits and instructions. Due to this innovation in communication methods, it is essential to investigate the performance of these devices under practical constraints. To do so, this article formulates a model for wireless-powered ambient backscatter devices and derives a closed-form expression of outage probability under Rayleigh fading. Based on this expression, the article provides the power-splitting factor that balances the tradeoff between energy harvesting and achievable data rate. Our results also shed light on the complex interplay of a power-splitting factor, amount of harvested energy, and the achievable data rates., 11 Pages, 7 Figures

Machine-to-machine (M2M) communication is emerging as a new paradigm to realize the concept of smart cities. In this chapter, we provide a comprehensive introduction to M2M communications, discuss its applications, and highlight its critical challenges. The chapter also provides a discussion of the energy harvesting techniques and their importance in modern wireless communication systems. Here, we mainly focus on RF energy harvesting due to its dual use in energy harvesting and information transfer. Next, a detailed discussion on recent trends of physical layer security (PLS) is presented. Using this basic knowledge of PLS and RF energy harvesting, we analyze the secrecy performance of an M2M communication system under the imperfect knowledge of wireless channel state. Later, the chapter provides a comparison of two jamming techniques, namely, full duplex (FD) jamming and dedicated jamming. It is shown that the dedicated jamming performs better than the FD jamming at the cost of introducing an additional node with additional power requirements. The results also show that by increasing the energy harvesting duration of devices, the FD destination-assisted jamming can also perform very close to dedicated jamming.

Physical layer security (PLS) has been extensively explored as an alternative to conventional cryptographic schemes for securing wireless links. Many studies have shown that the cooperation between the legitimate nodes of a network can significantly enhance their secret communications performance, relative to the noncooperative case. Motivated by the importance of this class of PLS systems, this paper provides a comprehensive survey of the recent works on cooperative relaying and jamming techniques for securing wireless transmissions against eavesdropping nodes, which attempt to intercept the transmissions. First, it provides a in-depth overview of various secure relaying strategies and schemes. Next, a review of recently proposed solutions for cooperative jamming techniques is provided with an emphasis on power allocation and beamforming techniques. Then, the latest developments in hybrid techniques, which use both cooperative relaying and jamming, are elaborated. Finally, several key challenges in the domain of cooperative security are presented along with an extensive discussion on the applications of cooperative security in key enablers for 5G communications, such as nonorthogonal multiple access, device-to-device communications, and massive multiple-input multiple-output systems. peerReviewed

With the ubiquitous use of smartphones and other connected pieces of equipment, the number of devices connected to the Internet is exponentially growing. This will test the efficiency of the envisioned 5G network architectures for data acquisition and its storage. It is a common observation that the communication between smart devices is typically influenced by their social relationship. This suggests that the theory of social networks can be leveraged to improve the quality of service for such communication links. In fact, the social networking concepts of centrality and community have been investigated for an efficient realization of novel wireless network architectures. This work provides a comprehensive introduction to social networks and reviews the recent literature on the application of social networks in wireless communications. The potential challenges in communication network design are also highlighted, for a successful implementation of social networking strategies. Finally, some future directions are discussed for the application of social networking strategies to emerging wireless technologies such as non-orthogonal multiple access and visible light communications.

Physical layer security (PLS) has been shown to hold promise as a new paradigm for securing wireless links. In contrast with the conventional cryptographic techniques, PLS methods exploit the random fading in wireless channels to provide link security. As the channel dynamics prevent a constant rate of secure communications between the legitimate terminals, the outage probability of the achievable secrecy rate is used as a measure of the secrecy performance. This work investigates the secrecy outage probability of a simultaneous wireless information and power transfer (SWIPT) system, which operates in the presence of multiple eavesdroppers that also have the energy harvesting capability. The loss in secrecy performance due to eavesdropper collusion, i.e., information sharing between the eavesdroppers to decode the secret message, is also analyzed. We derive closed-form expressions for the secrecy outage probability for Nakagami-$m$ fading on the links and imperfect channel estimation at the receivers. Our analysis considers different combinations of the separated and the integrated SWIPT receiver architectures at the receivers. Numerical results are provided to validate our analysis., Comment: 15 pages, 7 figures, journal paper

Wireless communication is shaping the future of seamless and reliable connectivity of billions of devices. The communication sector in Qatar is mainly driven by rising demand of higher data rates and uninterrupted connectivity of wireless devices. Wireless fidelity (Wi-Fi), cellular telephone and computer interface devices (e.g. Bluetooth) are a few of the commonly used applications for wireless distribution of information in Qatar. According to analysts, strong growth of Islamic banking, increase in IT consolidation and increased adoption of mobility solutions are some of the key contributors to the growth of digital infrastructure in Qatar. Modernization of legacy infrastructure is another focal point of government of Qatar to enable e-government initiative in rural areas and Tier II/ III cities of Qatar which has long term effects in various domains such as health, electricity, water, heat, communication and trade. Considering this exponential rise of wireless communication in Qatar, a great deal of research is being done from the perspective of secure deployment of new wireless networks. There is also a growing demand to develop more energy-efficient communication techniques to reduce the consumption of fossil fuel without compromising the quality of experience of users. This is also beneficial for solving economic issues that cellular operators are faced with the ever growing number of users. Moreover, with the upcoming FIFA world cup in 2022, millions of dollars are being spent to enhance the capacity and security of existing and upcoming communication networks. However, with greater connectivity and ultimate functionality come several important challenges. The first challenge is the security of data or more specifically who has access to the data. The broadcast nature of wireless channels implies that the transmitted information signals are also received by nodes other than the intended receiver, which results in the leakage of information. Encryption techniques at higher layers are used to secure transmitted information. However, the high computational complexity of these cryptographic techniques consumes significant amount of energy. Moreover, secure secret key management and distribution via an authenticated third party is typically required for these techniques, which may not be realizable in a dense wireless networks. Therefore, a considerable amount of work has recently been devoted to information-theoretic physical layer security (PLS) as a secure communication technique which exploits the characteristics of wireless channels, such as fading, noise, and interferences. The varying nature of these factors causes randomness in the wireless channel which can be exploited to achieve security. The transmission of secret messages takes place when the receiver»s channel experiences less fading than the eavesdropper»s channel, otherwise transmission remains suspended. The second concern is regarding the limited lifetime of wireless devices, especially when massive amount of data needs to be collected and transferred across the network. This challenge can be addressed by innovative means of powering, and for small energy limited devices, this implies the use of energy harvesting (EH) techniques. In this context, the transfer of data and power over a common electromagnetic (EM) wave has gained significant research interest over the past decade. The technique which merges wireless information transfer (WIT) with wireless power transmission (WPT) is commonly termed as simultaneous wireless information and power transfer (SWIPT). However, SWIPT systems cannot be supported using conventional design of transmitter and receiver. To address this issue, two broad categories of receiver architectures have been proposed in SWIPT literature i.e. separated and integrated architecture. In separated receiver architecture, the information decoder and energy harvester act as dedicated and separate units. This although not only increases the cost of receiver but also increases the complexity of the hardware. In contrast, the integrated receiver architecture jointly processes the information and energy using a unified circuitry for both. This architecture reduces the cost and hardware complexity Our work attempts to address the aforementioned issues by evaluating secrecy performance and proposing practical secrecy enhancement scheme in EH wireless devices. In particular, we investigate PLS in SWIPT systems in the presence of multiple eavesdroppers. The secrecy performance of the SWIPT system is analyzed for Rician faded communication links. The security performance is analyzed for imperfect channel estimation, and both separated and integrated receiver architectures for the SWIPT system. We derive closed-form expressions of the secrecy outage probability and the ergodic secrecy rate for the considered scenario and validate the derived analytical expressions through extensive simulations. Our results reveal that an error floor appears due to channel estimation errors at high values of signal to noise ratio (SNR); such that outage probability cannot be further minimized despite an increase in the SNR of the main link. Moreover, the results show that largest secrecy rate can be achieved when the legitimate receiver is equipped with separated SWIPT receiver architecture and the eavesdroppers have an integrated SWIPT receiver architecture. It is also demonstrated that the power splitting factor at both legitimate receiver and at eavesdroppers play a prominent role in determining the secrecy performance of SWIPT. We prove that a larger power splitting factor is required to ensure link security for poor channel estimation. Finally, our work discusses transmit antenna selection and baseline antenna selection schemes to improve security. Therein, it is shown that transmit antenna selection outperforms baseline antenna selection. The results provided in this work can be readily used to evaluate the secrecy performance of SWIPT systems operating in the presence of multiple eavesdroppers.

Device-to-device (D2D) communications has recently gathered significant research interest due to its efficient utilization of already depleting wireless spectrum. In this article, we considered a scenario where D2D users communicate in the presence of cellular users in an overlay network setup. In order to analyze the revenue of service providers in monetary terms, the paper provides exact expressions of operator profit for both D2D and cellular users. More specifically, we take into account different network parameters including user density, transmit power and channel variations to understand their impact on the total revenue of the operator. Finally, we derive the balancing value of frequency partitioning factor and provide relevant discussion on the analytical expression. Our findings show that D2D communications outperform the conventional cellular communications in terms of revenue generation capability. Our results have been verified by performing extensive simulations.

Energy harvesting relays are predicted to play a pivotal role in large scale networks. This paper evaluates the secrecy performance of a system that employs a two-way decode-and-forward relay assisting transmission between two nodes. The relay has RF energy harvesting capability and it can receive energy from the RF signal and the transmission of the system can be overheard by an eavesdropper. More specifically, we derive an exact expression for the interception probability when the main and wiretap links experience generalized κ-μ fading. The impacts of the power- splitting factor at the relay and the fading parameters on the secrecy performance of the considered system are also assessed. Numerical and simulation results are presented to verify the derived results.

This paper investigates the information theoretic secrecy for different combinations of Rayeligh, Weibull and Hoyt fading channels. The considered communication model employs distinct channel conditions at legitimate and eavesdropping links. This scenario is deemed to be practical when the legitimate receiver and eavesdropper are placed far from each other and experience completely different type of channel fading conditions. Hence, this paper provides four scenarios when main (legitimate)/ wiretap (eavesdropping) channel undergo Weibull/Rayleigh fading, Rayleigh/Weibull fading, Weibull/Hoyt fading and Hoyt/Weibull fading. Closed-form expressions for the secrecy outage probability are derived for the given scenarios that are corroborated through extensive simulations in MATLAB.

Energy harvesting relays are gathering significant research interest due to their applications in large-scale networks. This work focuses on the performance evaluation of two-way decode-and-forward (DF) relay with energy harvesting capability. More specifically, using relay activation threshold as power constraint, we determine the performance of two-way DF relay. The aggregated received power at relay is used to define power shortage event. We also derive a closed-form expression of intercept probability in the presence of cluster of eavesdroppers. Impact of power splitting factor and relay activation threshold on secrecy performance of two-way DF relay has also been assessed. Extensive simulations are performed in MATLAB to verify the derived analytical expressions.

In recent years, several innovative algorithms for localization of wireless sensor networks (WSNs) have been proposed by the researcher. Since wireless sensor nodes have limited processing power and the channel conditions are difficult to predict, therefore, there is a need of a low complexity localization technique that can efficiently identify channel condition and select an appropriate method of localization. In this regard, this article presents a robust localization scheme that minimizes localization delays while consuming minimal energy of wireless nodes. Extensive simulations are performed which illustrate that the proposed technique reduces the delays in localization and increases the lifetime of nodes while maintaining a fairly low mean location estimation error. The results also demonstrate that the proposed scheme performs fairly well even with limited numbers of anchor nodes in the network.

Rapid innovations in wireless communication have unveiled new and exciting challenges. One of the major challenges is the maximization of transmission rate due to growing demand of multimedia and safety related applications. Among several solutions proposed in the literature, arguably the most promising one for future 5G technologies is massive Multiple Input Multiple Output (MIMO). Various studies have indicated the utility of massive MIMO in forthcoming networks. Therefore, this paper presents a review of recent studies in massive MIMO along with a comprehensive overview of latest research issues. We also provide future prospect of massive MIMO by discussing how massive MIMO can be integrated with imminent technologies for better utilization of resources. In short, this survey act as a a principal guide for interested readers in massive MIMO.

The emergence of Simultaneous Wireless Information and Power Transfer (SWIPT) has opened new avenues to address the issue of energy shortage in wireless networks. The ability to transfer power and information across the network can not only help the edge devices to communicate efficiently but also prolong the lifetime of devices near the base station. In cooperative networks it can provide the much needed flexibility at relays to harvest the energy from a distant source. Aforementioned reasons are some of the key motivations to review the advances in SWIPT. Therefore, this paper provides a review of recent studies in SWIPT from a technical point of view. In particular we discuss the fundamentals of separated and integrated receiver architectures in SWIPT. We then provide the tradeoff between rate and energy in SWIPT by using data outage and energy shortage probabilities. This review also act as a corner stone to understand the significance of green communication in future 5G technologies.

This work investigates the secrecy performance of a simultaneous wireless information and power transfer system that operates in the presence of cooperating eavesdroppers. The multi-antenna access point’s transmission is used for information-decoding by a multi-antenna node and forenergy-harvesting(EH) by multiplesingle-antennanodes. However, some of the nodes authorized for EH only attempt to eavesdrop on the ongoing information transmission by utilizing a generalized on–off power splitting architecture. We derive aclosed-form expressionfor the secrecyoutage probabilityof the consideredMultiple-Input-Multiple-OutputMultiple-Eavesdroppers system. Theoretical and simulation results are provided to validate the derived results.

Wireless Body Area Networks (BANs) have drawn significant attention of research community all over the world due to their applications in healthcare. This paper adopts the cluster based approach to analytically model the implications of inter-body interference in BANs. To be specific, we derive exact closed-form expression for outage probability for co-channel interference under Rayleigh and Rician fading. We consider two cases, where in first case channel between sensors and cluster head is Rice distributed and channel between main and interfering cluster head is Rayleigh distributed. In second case, channel between sensors and cluster head is Rayleigh distributed and channel between main and interfering cluster head is Rice distributed. We also evaluate the significance of Rician-K factor for both cases. Extensive simulations are performed to validate our findings which clearly show the effect of inter-body interference on the performance of BANs.

Wireless Body Area Networks (BANs) have become one of the most anticipated technologies of the current century due to their application oriented nature. The main objective of this paper is to quantify and analyze the impact of co-channel interference on BANs under generalized fading. Specifically, this paper adopts the cluster based approach to analytically model and derive a closed-form expression for packet error probability under generalized fading channel. Interference from nearby cluster using the same frequency band, is considered while deriving the expression. A mathematical expression for antenna selection scheme is also obtained to enhance the performance of the desired cluster. Extensive simulations are performed to validate our findings which clearly prove the practical significance of our analytical model.