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5G network slicing is promising in prioritizing time‐critical protection communication in wireless networks of smart grids. However, network slicing offered by telecommunication providers encompasses all smart grid applications, lacking granularity. Smart grid automation standards provide recommendations on prioritization of protection communication to improve reliability but only for wired connections. Therefore, this paper investigates hierarchical token bucket (HTB) traffic shaping and uplink (UL) bitrate adaptation of a live video stream for prioritizing protection communication within a 5G slice. An experimental setup combines controller‐hardware‐in‐the‐loop (CHIL) with a quality of service (QoS) measurement system for validation. The system under test consists of commercial 5G networks, intelligent electronic devices (IEDs), and merging units for validation with three smart grid applications: fault location, line differential, and intertrip protection. HTB traffic shaping improves protected faults by 47.57% in congested and 1.16% in non‐congested scenarios. UL bitrate of the video stream adaptation by 2 Mbps increases protected faults by 3.69%. HTB traffic shaping even improves prioritization with a wired connection without introducing additional delays. HTB traffic shaping must be deployed in routers to maintain good QoS for critical applications. Collaboration between utilities and telecommunication providers is essential to effectively deploy 5G network slicing on smart grids. [ABSTRACT FROM AUTHOR]

This study deals with the performance analysis of adaptive combining‐based hybrid free‐space optics (FSO)/radio‐frequency (RF) system in a terrestrial communication scenario with and without pointing errors. Here, outage probability and average symbol error rate (SER) are used as the performance metrics. Adaptive combining is a switching scheme in which the FSO link is active throughout, whereas the RF link is activated based on the transmission reliability of the FSO link and maximal‐ratio‐combining (MRC) of RF and FSO links is performed at the destination. The small‐scale fading in RF and atmospheric turbulence induced fading in FSO links have been characterised by Nakagami‐m and Gamma–Gamma distributions, respectively. In addition, the radial displacement between the beam centre and detector centre, which induces pointing errors, is modelled using Rayleigh distribution. The exact closed form expressions for the outage and average SER have been derived along with their corresponding asymptotic expressions. Diversity gain of the system has also been determined using the asymptotic expressions. Further, the variation in the performance of the system has been analysed with respect to various parameters including link distance, fading severity parameter, average signal‐to‐noise of the RF link, and the pointing errors parameter. [ABSTRACT FROM AUTHOR]

Research on underwater acoustic sensor networks has become a compelling field in recent years since resources on land are being depleted. Therefore, robust and efficient routing protocols are needed to ensure the reliability of message gathering and transmitting in underwater sensor networks. In the process of biological foraging in nature, creatures such as insects can find paths while adapting to dynamic environmental conditions through group cooperation, which provides a new perspective for research on routing protocols. In this study, the authors proposed an ant colony algorithm‐based routing protocol (ACAR). In ACAR, the pheromone with a novel physical meaning and concentration changing mechanism is utilised to guide ants (path establishing packets) to the sink node. In addition, node depth information is used to decrease redundancy in the underwater environment. The routing process can be summarised in three parts: pheromone list setup, routing decision and damaged path repair. Simulation results, carried out on an underwater simulator based on NS‐2, showed that ACAR outperforms other schemes with regards to network lifetime with a relatively better delivery ratio and latency in the proposed network scenarios. [ABSTRACT FROM AUTHOR]

This study deals with the performance analysis of adaptive combining‐based hybrid free‐space optics (FSO)/radio‐frequency (RF) system in a terrestrial communication scenario with and without pointing errors. Here, outage probability and average symbol error rate (SER) are used as the performance metrics. Adaptive combining is a switching scheme in which the FSO link is active throughout, whereas the RF link is activated based on the transmission reliability of the FSO link and maximal‐ratio‐combining (MRC) of RF and FSO links is performed at the destination. The small‐scale fading in RF and atmospheric turbulence induced fading in FSO links have been characterised by Nakagami‐m and Gamma–Gamma distributions, respectively. In addition, the radial displacement between the beam centre and detector centre, which induces pointing errors, is modelled using Rayleigh distribution. The exact closed form expressions for the outage and average SER have been derived along with their corresponding asymptotic expressions. Diversity gain of the system has also been determined using the asymptotic expressions. Further, the variation in the performance of the system has been analysed with respect to various parameters including link distance, fading severity parameter, average signal‐to‐noise of the RF link, and the pointing errors parameter. [ABSTRACT FROM AUTHOR]

Research on underwater acoustic sensor networks has become a compelling field in recent years since resources on land are being depleted. Therefore, robust and efficient routing protocols are needed to ensure the reliability of message gathering and transmitting in underwater sensor networks. In the process of biological foraging in nature, creatures such as insects can find paths while adapting to dynamic environmental conditions through group cooperation, which provides a new perspective for research on routing protocols. In this study, the authors proposed an ant colony algorithm‐based routing protocol (ACAR). In ACAR, the pheromone with a novel physical meaning and concentration changing mechanism is utilised to guide ants (path establishing packets) to the sink node. In addition, node depth information is used to decrease redundancy in the underwater environment. The routing process can be summarised in three parts: pheromone list setup, routing decision and damaged path repair. Simulation results, carried out on an underwater simulator based on NS‐2, showed that ACAR outperforms other schemes with regards to network lifetime with a relatively better delivery ratio and latency in the proposed network scenarios. [ABSTRACT FROM AUTHOR]

In this study, the performance of downlink simultaneous wireless information and power transfer (SWIPT) networks over Nakagami‐m fading is analysed. The SWIPT network is modelled as a two‐tier heterogeneous network, where one tier is the information transmission network and the other is the power transmission network. The seamless integration enables both data and energy to be transferred from access points to the users. Using the stochastic geometry theory, the expressions for outage probability at the information receiver are derived in decoupled and integrated SWIPT networks. Also, the average harvested energy at the power receiver is derived assuming a non‐linear energy harvesting model. Simulation results validate the analytical expressions and the impacts of various system parameters on the SWITP performance are investigated. [ABSTRACT FROM AUTHOR]

Fast session transfer (FST) is introduced by wireless gigabit (WiGig) standards to transfer the data communication session among wireless fidelity (Wi‐Fi) and WiGig channels based on the availability. In the conventional Wi‐Fi/WiGig FST decision‐making, the session of data transmission is transferred from Wi‐Fi to WiGig whenever it is possible regardless of the traffic loads on both bands and the expected WiGig blocking probability. Also, WiGig to Wi‐Fi FST occurs whenever the WiGig signal is lost even if the WiGig link is undergoing an instant path blocking. This results in Wi‐Fi/WiGig load imbalance as well as large average delay in user data delivery. In this study, a novel Wi‐Fi/WiGig FST decision‐making algorithm is proposed utilising fuzzy logic while considering the coverage probability of the WiGig link, the sizes of the users' remaining messages relative to the available data rates of both bands, and the probability of WiGig path blocking. Furthermore, a WiGig interruption‐classification methodology is proposed to detect the occurrence of the WiGig instant path blocking and then decide if it is better to wait for WiGig signal recovery or immediately transfer to Wi‐Fi. Simulation analysis demonstrates the effectiveness of the proposed Wi‐Fi/WiGig FST decision‐making algorithm, over the conventional one. [ABSTRACT FROM AUTHOR]

Ever since the idea of buffers was incorporated in wireless communications, buffer‐aided relaying has become an emerging breakthrough in the world of transmitting and receiving signals. Equipping the relays with buffers adds a new degree of freedom capable of enhancing numerous quality‐of‐service (QoS) metrics including throughput, outage probability, power efficiency and physical‐layer security. The QoS enhancement is achieved by compromising the end‐to‐end delay that is inflicted by storing the packets in the relays' buffers until a suitable source–relay or relay–destination link is selected. In this context, the selection of a relay for transmission/reception is important since it governs the QoS‐delay trade‐off that can be contemplated. In this survey, the authors review and analyse various link selection protocols in buffer‐aided relaying systems. These relaying strategies are categorised and contrasted according to their performance levels, limitations, applications, system model assumptions and complexity. Finally, they discuss current challenges, and highlight future research directions. [ABSTRACT FROM AUTHOR]

In this study, a simple two‐user multiple‐input multiple‐output (MIMO) relaying scenario is considered. To efficiently exploit the spectrum resources, a generalised singular value decomposition (GSVD) based precoding scheme with non‐orthogonal multiple access (NOMA) is proposed, which converts the multiple channels into several parallel single channels. The performance of the proposed GSVD‐MIMO relaying scheme is evaluated by using the distribution characteristics of squared generalised singular values of two users' channel matrices and the eigenvalues of the relay's channel matrix to obtain the expressions of the average data rate and outage probabilities. Both the asymptotic case and a practical scenario with nodes equipped with finite numbers of antennas are analysed because the distribution characteristics of squared generalised singular values in the two cases are different. Two special cases, single‐input multiple‐output and multiple‐input single‐output are considered. Simulation experiments are carried out to verify the effectiveness and accuracy of the obtained analytical results. [ABSTRACT FROM AUTHOR]

Securing wireless communication, being inherently vulnerable to eavesdropping and jamming attacks, becomes more challenging in resource‐constrained networks such as internet‐of‐things. Towards this, physical layer security (PLS) has gained significant attention due to its low complexity. The authors address the issue of random inter‐node distances in secrecy analysis and develop a comprehensive quality‐of‐service (QoS) aware PLS framework for the analysis of both eavesdropping and jamming capabilities of the attacker. The proposed solution covers the spatially stochastic deployment of nodes. The secrecy performance is characterised against both attacks using inter‐node distance‐based probabilistic distribution functions. The model takes into account the practical limits arising out of underlying QoS requirements, which include the maximum distance between legitimate users driven by transmit power and receiver sensitivity. A novel concept of eavesdropping zone is introduced, and the relative impact of jamming power is investigated. Closed‐form expressions for asymptotic secrecy outage probability are derived offering insights into the design of optimal system parameters for desired security level against the attacker's capability of both attacks. The analytical framework, validated by numerical results, establishes that the proposed solution offers a potentially accurate characterisation of the PLS performance and key design perspective from point‐of‐view of both legitimate user and attacker. [ABSTRACT FROM AUTHOR]

It can be intuitively inferred that a high‐quality depth map can be used to quickly detect the salient region in stereo vision, implying that depth information plays an essential role in stereoscopic visual attention. However, existing methods generally use the depth map as an auxiliary cue to improve the saliency detection performance. In this study, the authors present an algorithm to directly detect the salient object from a high‐quality depth image. The proposed algorithm utilises a depth reliability indicator to assess the confidence of a depth image. Depth compactness, a novel feature that incorporates the depth reliability of the super‐pixels, is computed as a primary salient feature. Moreover, in order to enhance another salient feature (i.e. depth contrast), they develop a coarse background filtering method to suppress background interference. Experimental results demonstrate that the proposed method performs favourably against the popular depth‐aware saliency detection approaches at a lower computational cost. [ABSTRACT FROM AUTHOR]

Wireless sensor network (WSN) comprises of numerous sensors deployed either directly or randomly in the region of interest. Due to the limited power of the sensors, these networks are energy‐constrained and thus need efficient power utilisation. Efficient clustering and cluster head (CH) selection ensures balanced energy distribution to the sensors within the WSN and hence prolong the network lifetime. This study proposes the method for evaluating the threshold for the CH selection after each round, which increases the network lifetime and throughput significantly. The threshold for CH selection is modified considering the normalised first‐order and second‐order statistical parameters, such as mean average low‐energy adaptive clustering hierarchy (AvgLEACH) and variance (VarLEACH) of the overall network energy. These methods have been formulated after studying the effect of the number of working nodes in each round on the threshold value selection. Apart from including energy parameter to the threshold equation, the methods of VarLEACH and AvgLEACH are augmented with a residual energy parameter that is local to the nodes and named as VarRLEACH and AvgRLEACH. The simulation results comparing all the methods suggest that the proposed method AvgRLEACH outperforms LEACH by a factor of 1.5 in delivering data to the base station and outlives the network driven by LEACH protocol by 30–40%. [ABSTRACT FROM AUTHOR]

This paper reports the results of experimental studies of six different wireless sensor nodes and networks under a radiation environment with a dose rate of 20 K Rad (Si)/h. The wireless nodes evaluated are ZigBee, WirelessHART, ISA 100.11a, LoRa, and 433/915 MHz point‐to‐point devices made from commercial off‐the‐shelf (COTS) components. The experiments were carried out using a 60Co gamma source, while the devices are at on‐power operating states, and their operating statuses have been continuously monitored to determine the first instance of failure and the rate of gradual degradation in terms of communication channel performance and quality of the wireless signals. Observations indicate that the different devices and networks exhibit varying levels of radiation tolerance. For example, some can only survive for less than one hour, but others are operating satisfactorily for several hours. Furthermore, before a device suffers a fatal hardware failure, the performance degradation progresses slowly. It is believed that this is the first time that such results are reported in the open literature. Their significance is that the results can provide some practical guidance to select the most suitable wireless devices for the design and construction of remote monitoring systems for high‐level radiation environments. [ABSTRACT FROM AUTHOR]

This Letter proposes a stochastic model of the wearable sensor nodes of a wireless body area network (WBAN) based on Markov decision process (MDP). The proposed technique tackles the problem of maximising the likelihood of data transmission while minimising the computational cost and energy. Suitable transmission strategies subject to the energy level of the nodes and channel conditions are needed to be investigated to strike a balance between network lifetime and packet delivery ratio. MDP formulation of the problem is solved offline to find out the optimal transmission strategies for the representative input conditions. The results of this offline computation approach can directly map to optimal transmission policies for intra-WBAN communications. The experimental results demonstrate the robustness of the proposed scheme in handling both favourable and unfavourable operating conditions. [ABSTRACT FROM AUTHOR]

Sustainable operation of energy‐restrained wireless network services requires multiple objectives to be satisfied synchronously. Among these objectives, reduced spectrum outage, energy conservation, and minimal packet transmission failures considerably affect the energy harvesting operation of these networks. These three objectives are associated with disparate protocol layers incorporating the transport, medium access control, and physical layers of traditional networking architecture. The authors investigate energy harvesting wireless communications by formulating the multi‐objective optimisation problem comprising these global networking criteria, which are simultaneously optimised with the heuristic design procedure. For this, they employ a Pareto‐based evolutionary genetic algorithm technique built in the wireless network design and operation to find the optimal set of all non‐dominated solutions traversing the entire design search space. Besides, iterative implementation of the presented genetic optimisation model with distinct feasible integrations of crossover and mutation operations is performed to evaluate the proficiency of the proposed scheme for evaluating the Pareto‐optimal frontier set. The influence of different combinations of these operations is examined and adaptively applied with appropriate genetic parameters tuning for efficient meta‐heuristic search through the candidate solution space. Simulation results demonstrate that the proposed hybrid genetic mechanism outperforms the existing methods in terms of throughput, energy efficiency, and loss rate. [ABSTRACT FROM AUTHOR]

In this study, a dual‐hop cooperative communication system with radio frequency (RF) energy harvesting was investigated in two cases of linear and non‐linear energy harvesting models. In the proposed system, the signal is transmitted directly from a source node to a destination node or sent with support of selected relay nodes. While both the source node and the destination node are powered normally, the relay nodes are powered by harvesting technique. To choose the best relay node, a selection combination method was applied at the destination node in both cases of amplify‐and‐forward and decode‐and‐forward protocols. To evaluate the system performance, the outage probability of the cooperative communications over independent identically distributed Nakagami‐m was derived and analysed with arbitrary m parameter whereas this parameter was fixed to be integral value in previous research studies. Furthermore, the approximate and asymptotic operations are applied to simplify the outage probability expressions. The simulation program was developed based on the Monte Carlo method and MATLAB software with two aims of evaluating the system performance and verifying the theoretical results. The simulation results demonstrate that the analysis and evaluation of the study are considerably accurate. [ABSTRACT FROM AUTHOR]

This Letter investigates the impacts of hardware impairments (HIs) and channel estimation errors (CEEs) on the secrecy performance of satellite communication networks with one legitimate user and one eavesdropper. Particularly, the authors derive the closed‐form expression for the secrecy outage probability (SOP) of the considered secrecy satellite communication networks. Besides, in order to research the impact of the HIs and CEEs at high signal‐to‐noise ratios, they obtain the asymptotic expression for the SOP, which gives efficient and fast method to evaluate the effect of the considered system parameters on the secrecy system performance. At last, Monte Carlo computer results are given to verify the effects of HIs and CEEs on the secrecy system performance. [ABSTRACT FROM AUTHOR]

On‐going research on remote communication and sensing essentially made accessible the flexible technology called 'wireless sensor network (WSN)', which is independent, self‐organising and self‐healing in nature. The WSN comprises an extensive number of homogeneous or heterogeneous sensor nodes that may be deployed in a uniform or non‐uniform manner in a targeted zone. The organisation of WSN can be stretched out from residential to a harsh and hostile environment. The manageability of WSN is very subjective to an efficient adaptation to the failure situations. In this line of thought, clustering has been proven as an efficient strategy for prolonging the sensor network lifetime and selecting the correct topological structure for the sensor network. The authors' first present a survey of existing survey works from 2002 to 2019 and then present a tutorial on existing fault‐tolerant protocols with a comparative analysis. The target audience of this work is novice researchers in the field of WSN to get a preliminary idea about clustering and its objective. [ABSTRACT FROM AUTHOR]

Reliability evaluation of power distribution systems is a well‐studied and understood problem, but topology analysis efficiency and failure feature description are still limiting the practical application of reliability evaluation in distribution systems. One approach the authors proposed in this study is to incorporate the machine‐learning technique into the simulation‐based reliability evaluation method, and assess the system reliability in an empirical fashion. In this study, a framework for performing the machine‐learning‐based reliability evaluation, and corresponding modelling processes are first established. Then, by inducing a supervised learning algorithm named perceptron, a state‐space classification‐based (SSC) method for system state assessment, the core procedure of reliability evaluation, is proposed. On this basis, a reliability evaluation algorithm combining the SSC‐based system state assessment and sequential Monte Carlo simulation is proposed, where the workload of topology analysis required in conventional reliability evaluation methods can be released. Furthermore, extensive case studies are conducted on the Roy Billinton Test System (RBTS) bus 2 system and an actual distribution system to verify the proposed models and algorithms. Results show that the proposed framework supports a more efficient reliability evaluation pattern while ensuring the evaluation accuracy. [ABSTRACT FROM AUTHOR]

Clustering, an energy efficient approach is preferred in wireless sensor network due to the limited energy consumption of sensor nodes. Clustering saves energy as the communication is restricted to a few nodes, thereby increasing the network lifetime. Recently, an iterative linear regression‐based clustering is proposed to improve the cluster quality in a wireless sensor network. The quality of clusters so obtained is evaluated through Matlab using the cluster validity analysis platform. However, the performance of the clusters so obtained using iterative linear regression in terms of energy efficiency is not dealt. Hence, an attempt is made to investigate the performance of the network through real time experiments. The network performances are studied in terms of intra‐cluster and inter‐cluster energy consumption, first node death, half node death and last node death. To prove the effectiveness of the proposed technique, it is compared with the standard k‐means clustering algorithm. The results reveal that the clusters obtained using iterative linear regression is efficient in enhancing the lifetime of the wireless sensor network. [ABSTRACT FROM AUTHOR]

Persistent sensing requires sensor nodes to keep functioning for a longer duration. Different amounts of incoming packets on some sensor nodes after deployment lead them to deplete their energy faster compared to other nodes without sending the information about their death to the sink node. It results in the formation of energy holes in the network and hence packet loss problem starts. In this study, this problem is overcome by prior notification to the sink about scarcity of resources by setting a dynamic threshold and also, packet delivery is sustained by using a fault tolerance strategy. Simulation analysis shows that proposed work is doing better in terms of packet delivery ratio and number of dead nodes. Also, network lifetime of the proposed work is found to be 73% of the total time duration while its competitor approach has network lifetime 64%. [ABSTRACT FROM AUTHOR]

In this paper, a novel dual‐hop relay‐assisted hybrid Free Space Optical / Radio Frequency (FSO / RF) communication system is presented. In this structure an access point connects users within the building to the Base Station via a hybrid parallel FSO / RF link, this link is proposed firstly. The parallel combination of FSO and RF links and use of an access point will increase capacity, reliability and data rate of the system. It is the first time that the effect of the number of users on the performance of a dual‐hop relay‐assisted hybrid parallel FSO / RF system is investigated. FSO link is considered in Gamma‐Gamma atmospheric turbulence with the effect of pointing error and RF link is considered in Rayleigh fading. For the first time, closed‐form expressions are derived for Bit Error Rate (BER) and Outage Probability Pout of the proposed system. Derived expressions are verified through MATLAB simulations. It is shown that performance of the proposed system is almost independent of atmospheric turbulence intensity, thereby when atmospheric turbulence strengthens, low power consumption is required for performance maintenance. Hence the proposed structure is suitable for mobile systems in which a small battery supplies transmitter power. [ABSTRACT FROM AUTHOR]

Fast‐moving nodes in vehicular ad hoc network (VANET) make network topology very dynamic, which deteriorates communication reliability and scalability. To overcome this problem, a hierarchical topology can be created using a clustering algorithm. This study presents a novel hesitant fuzzy (HF) multi‐criteria ranking framework to deal with cluster‐heads (CHs) election problem in VANET. An analogy is suggested between 'ranking of HF elements' and 'CH selection in VANET'. Within the proposed framework, a multiple criteria decision‐making (MCDM) method should be used to calculate vehicle eligibility to become CH. In this study, technique for order of preference by similarity to ideal solution (TOPSIS), Vlse Kriterijumska Optimizacija Kompromisno Resenje (VIKOR) and EVAluation of MIXed data (EVAMIX) MCDM methods are applied. A simulation study, under a highway scenario, is conducted to investigate the performance of HF‐TOPSIS, HF‐VIKOR and HF‐EVAMIX‐based clustering algorithms. Obtained results show that CH election based on HF‐EVAMIX leads to more stable clustering in comparison with HF‐TOPSIS, HF‐VIKOR and the conventional threshold‐based method. [ABSTRACT FROM AUTHOR]

Social opportunistic networks are a subclass of opportunistic networks which rely upon the predictability and established patterns of human social behaviour to facilitate the sharing of information by performing message routing. While the forwarding step purely depends upon the movement paradigm of nodes in the network, the said movement makes the network unreliable due to frequent disconnections and delay, and spasmodically connected environment. Various protocols have been developed so far for routing in such networks, whose primary aim is to ensure efficient and reliable message delivery. This study proposes a heuristic‐based scheme for routing messages from the source to the destination using the Ant Algorithm. Problems related to frequent disconnections and inefficient routing are overcome in the proposed protocol through features such as pheromones. This protocol is thoroughly examined via simulation and analysis to assess the performance with other routing protocols in social opportunistic networks under various parameters. The performance criterion for the comparisons includes overhead ratio, average residual energy, average latency, number of dead nodes and average buffer time. The examinations have shown that the authors algorithm is superior to protocols such as Prophet, Epidemic and ProWait on the basis of average latency and buffer time. [ABSTRACT FROM AUTHOR]

Cross-connection is the only point in the communications field that has not been automated. With the many fibre networks that have been built, there is strong demand from operators for an automatic optical distribution frame (AODF) to reduce operational costs and provide high-level services. From the twisting relationships between the fibre patch cords on the main distribution frame (MDF), the relationship between the input lines and output lines on the MDF is reversed to be perpendicular to each other, and one-dimensional arrays of input lines and output lines (1D to 1D) are formed to construct the model. According to the model, the AODF prototype of the 1D to 1D form was fabricated with the smallest Lucent connector connector and verified through several cross-connect experiments. The prototype designed has a simple structure, a three-degrees-of-freedom Cartesian coordinate robot can meet switch requirements, and there is non-winding between the fibres after multiple cross-connects. Compared to the single-layer and double-layer form tests, the switch process requires multiple hand-over operations, and handovers take a long time in the switch process. Further research is needed to optimise the handover method and greatly improves the switching speed. [ABSTRACT FROM AUTHOR]

In this Letter, the authors propose a novel low‐density parity‐check (LDPC) coding scheme to transmit extra bits aided by rotated signal constellations without any additional cost in transmission power or bandwidth. In the proposed scheme, the LDPC coded data are modulated by a rotated two‐dimensional signal constellation, in which the rotation angle is specified by the given extra bits. At the receiver, the rotation angle is estimated with the aid of the statistical learning of the syndrome of the LDPC code. After recovering the rotation angle, the coded payload data can be decoded by the LDPC decoder. The simulation results show that, for an LDPC code of length 2304, up to four extra bits can be transmitted with negligible influence on the reliability of the LDPC coded data. [ABSTRACT FROM AUTHOR]

In the presence of deep submicron noise, providing reliable and energy‐efficient network on‐chip operation is becoming a challenging objective. In this study, the authors propose a hybrid automatic repeat request (HARQ)‐based coding scheme that simultaneously reduces the crosstalk induced bus delay and provides multi‐bit error protection while achieving high‐energy savings. This is achieved by calculating two‐dimensional parities and duplicating all the bits, which provide single error correction and six errors detection. The error correction reduces the performance degradation caused by retransmissions, which when combined with voltage swing reduction, due to its high error detection, high‐energy savings are achieved. The results show that the proposed scheme reduces the energy consumption up to 51.7% as compared with other schemes while achieving the target link reliability level. Also, it shows improved network performance as compared with ARQ‐based scheme and close to forward error correction‐based schemes. [ABSTRACT FROM AUTHOR]

In the study, a wireless energy harvesting-based two-unicast network is proposed. The proposed model consists of two source–destination pairs, in which two source nodes transmit information to their respective destination nodes via the help of the same relay node. Each transmission can be divided into two time slots each with the same time duration. In the first time slot, two source nodes transmit the signals to their opposite destination nodes, and the energy-constrained relay node harvests energy using the power splitting relaying protocol. In the second time slot, adopting the amplify-and-forward mode, the relay node forwards the mixed signals to two destination nodes and each destination node can subtract the signal of another destination, which is received in the first time slot, and obtain its own signal. The performances of the proposed scheme are evaluated in terms of outage probability and throughput. Numerical results corroborate the derived analytical expressions and show that the proposed scheme nearly doubles the maximal throughput compared with the conventional one. [ABSTRACT FROM AUTHOR]

In this paper, a novel multi‐hop hybrid Free Space Optical (FSO)/RF link is presented; it is made up of two main parts. The first part establishes the connection between the mobile user and source base station, and the second part establishes the connection between the source and the destination base stations. In the first part, a mobile user wants to connect to the source base station via a long range link; therefore, a fixed gain amplify and forward relay with multiple receive antennas is used for communication establishment. In the second part, the source and the destination base stations are connected via a multi‐hop hybrid parallel FSO/RF link with demodulate and forward relaying. Considering the FSO link in Gamma‐Gamma atmospheric turbulence with the effect of pointing error in moderate to strong regime and the Negative Exponential atmospheric turbulence in saturate regime, and the RF link in Rayleigh fading, new closed form exact and asymptotic expressions are derived for the Outage Probability and Bit Error Rate of the proposed structure. [ABSTRACT FROM AUTHOR]

Wireless multimedia sensor networks (WMSNs) are receiving increasing consideration in the deployment of unmanned surveillance systems for applications such as monitoring battle field and security surveillance. However, ensuring high levels of coverage of the monitored area and concurrently maximising the WMSN lifetime remains a challenging issue. The authors introduce a novel distributed algorithm in this study, for scheduling multimedia sensor nodes (MSNs) activity that maximises coverage and minimises energy consumption. The proposed activity scheduling algorithm incorporates an approach that enables each MSN in WMSN to efficiently extract its cover sets to ensure that the critical points are monitored, and thereby minimise and effectively balance the network energy utilisation. They introduce a new way to select the most suitable cover set of an MSN by assigning priority for each cover set based on the correlation of visual information from the camera observations. The efficacy of the proposed approach is studied through rigorous simulations. Their simulation work and results comparison with existing approaches demonstrate that their proposed scheme exceeds current results in terms of network lifetime, capture rate and percentages of dead and active nodes. [ABSTRACT FROM AUTHOR]

Routeing protocol for low‐power and lossy networks (RPL) are widely used in dynamic wireless sensor network. Several types of researches worked on RPL and designed hybrid energy‐efficient cluster‐parent‐based RPL, queue utilisation (QU)‐RPL, improved RPL, attack detection RPL etc. to support from vulnerable threats, provide efficient routeing and balance dynamic nodes in the network. Previous research findings dealt with certain limitations and problems. In this study, a new coordinative‐balanced clustering algorithm is proposed which is enabled to balance destination‐oriented directed acyclic graph (DODAG) that is formed in each cluster. Pruning of nodes from DODAG effectively maintains cluster with minimised complexity. This study also resolves the problem of two common security attacks such as distributed denial of service attack (DDoS) and version number attack. Then, enriched‐ant colony optimisation is used for DDoS detection and a secure route is chosen to perform data transmission. At the instance of selecting best parent for forwarding data, the authors use residual energy and scoring factor. Scoring factor of each node denotes the legitimacy to be selected as the best parent. Finally, results obtained from Network Simulator 3 indicate better performances on the following metrics: packet delivery ratio, end‐to‐end delay, node death minimisation, packet loss rate and power consumption. [ABSTRACT FROM AUTHOR]

In this study, free space optical communication has been studied for different atmospheric conditions. Spatial modulation (SM) has been used to improve the performance of two‐way relay cooperative communication. The proposed system employs decode and forward (DF) relaying technique along with physical layer network coding, hence it has been named as optical SM based DF two‐way relay. It enables full‐duplex communication thereby enhancing the system efficiency. The transmit optical source index as well as the information are exchanged between the two bidirectional nodes. Performance analysis of the system has been carried out in terms of lower and upper bounds of outage probability and average data rate for N‐γ cascaded fading channels. The analytical results have been validated by means of Monte Carlo simulations. The variation of the performance due to change in different parameters has also been reported in this study. [ABSTRACT FROM AUTHOR]

Nowadays, trust models of wireless sensor networks (WSNs) security have flourished due to the day‐to‐day attack challenges, which are most popular for internet of things (IoT). This article proposes a trust model based on non‐zero‐sum game approach for clustered‐WSNs (CWSNs) security to maximise the data trustworthiness transmission. The proposed model is developed for two different attack‐defence scenarios. In the first scenario, the trust model is used to face a denial‐of‐service (DoS) attack in which the attacker is able to drop or partially drop the delivered acknowledgments (ACKs) from a cluster member (CM) to the cluster head (CH). In the second scenario, the model target is to protect CWSNs from ON–OFF attack where the attacker is capable to frequently infect the CMs. Simulation results show improved performance of protecting the CWSNs against DoS/ON–OFF attacks and maximising data trustworthiness represented by the CMs compliance of sending the ACKs to the CH. Consequently, this mechanism can attain the appropriate security and performance for WSN‐based IoT systems. [ABSTRACT FROM AUTHOR]

In this work, the distributed base station (DBS) with remote radio head (RRH) is considered as the envisioned architecture of the fifth generation (5G) network. DBS network architecture supports easier scalability for network expansions using remote antennas in the form of RRHs. RRHs have been used in this work in order to compensate for the high path loss and penetration loss that characterise millimetre wave (mmWave) communications. The band of interest is the pioneer band at 26 GHz, which has been recently released for 5G services focused on areas of high traffic demand in the UK. DBS architecture can minimise the number of base stations required for the same quality of service (QoS). An algorithm has been developed for DBS scheduling. In addition to that, the gain of using DBS has been demonstrated in terms of: increasing the user data throughput, decreasing the unnecessary handovers as a result of dense network deployment, increasing the coverage probability in terms of line‐of‐sight (LoS) coverage, and minimising the impact of shadow fading. The results have shown significant improvement in terms of peak, average, and cell‐edge data throughput, and the LoS coverage probability has been improved due to the spatial distribution of RRHs. [ABSTRACT FROM AUTHOR]

In this work, a novel dual-hop relay-assisted hybrid free space optical/radio frequency (FSO/RF) communication system is presented. In this system, RF signal is transmitted from two antennas, and then forwarded by a single antenna relay through FSO channel. This is the first time that performance of using Alamouti coding (AC) or antenna selection (AS) at the transmitter of a hybrid FSO/RF system is investigated. FSO link has gamma-gamma atmospheric turbulence, and in order to get closer to the actual results, the effect of pointing error is also considered. For the first time closed-form expressions are derived for bit error rate and outage probability $\left({P_{{\rm out}}} \right)$Pout of the proposed system and validated through MATLAB simulations. Results indicate that in this structure, there is slight performance difference between AC and AS schemes. Hence, due to more complexity, power consumption and latency of AC, AS is recommended. Dual-hop, hybrid FSO/RF system significantly improves performance and reliability of the system, and is particularly suitable for long-range applications that direct RF communication between source and destination is not possible. Considering these advantages this structure is particularly suitable for mobile communications which has power and processing limitations. [ABSTRACT FROM AUTHOR]

Wireless sensor network (WSN) is considered as the resource constraint network, in which the entire nodes have limited resources. In WSN, prolonging the lifetime of the network remains as the unsolved point. Accordingly, this study intends to propose a hybrid GGWSO (Grouped Grey Wolf Search Optimisation) algorithm to improve the performance of a cluster head selection in WSN, so that the network's lifetime can be extended. The proposed method concerns the main constraints associated with distance, delay, energy, and security. This study compares the performance of the proposed GGWSO with several traditional algorithms like artificial bee colony (ABC), fractional ABC, group search optimisation and Grey Wolf optimisation‐based cluster head selection. During the performance analysis, the various ranges of risk, such as 20, 60, and 100% are added to validate the performance variations, by evaluating the number of alive nodes, and normalised network energy remained in the network. The simulation results have shown that there is a need for a hybrid model for attaining the superior results. [ABSTRACT FROM AUTHOR]

This study presents a full‐duplex (FD) relaying non‐orthogonal multiple access (NOMA) scheme with self‐interference at relay taken into account, where a sender communicates with multiple terminals simultaneously with the help of an FD amplify‐and‐forward relay. The relay is equipped with two antennas, one for transmission and the other for reception. Moreover, with a direct link as a useful information transmission link, selection combining is applied to merge the information from the sender and the relay. General closed‐form expressions of the outage probability are deduced and the upper bound of the ergodic sum rate is derived, including half‐duplex (HD) mode relay as a special case. Compared with the HD relaying scheme, the authors can observe that the FD relaying scheme can achieve higher ergodic sum rate in the moderate‐ and high‐SNR regions and that the outage behaviour can be improved in most cases (if the self‐interference is not extremely severe). More importantly, the use of NOMA in FD relaying system is shown to outperform conventional orthogonal multiple access (OMA) network in terms of terminal fairness. Extensive simulation results are presented to confirm their conclusions and provide a significant reference for the system design. [ABSTRACT FROM AUTHOR]

Industrial automation has been widely used in electric power substations. In this context, the IEC 61850 standard provides for the utilisation of redundancy in the data link layer to increase frame reception probability. This study aims to evaluate the availability of two power substation automation architectures based on the IEC 62439‐3 standard, which describes two redundancy protocols named parallel redundancy protocol (PRP) and high‐availability seamless redundancy (HSR). The authors evaluate both architectures using either PRP or HSR protocol against using no redundancy protocols. The reliability block diagram method has been used, and afterwards, the mean time to failure and availability have been calculated. Results show that the utilisation of redundancy protocols allied to the repair during the mission allows classifying the architectures in the higher availability class according to CEI IEC 870‐4. [ABSTRACT FROM AUTHOR]

The aim of this study is to describe the authors' efforts to accomplish the green vehicular ad hoc network (GVANET) project. The goal is to realise the concept of a self 'renewably' powered communication infrastructure appropriate for intelligent transportation systems. The work in this project was started in 2009 with the intention of representing the necessary steps must be taken to achieve such system and to declare the usefulness of adopting environmental energy resources in building mission critical systems. The other objectives of this project are presenting a reasonably cost, reliable, secured and easy to install communication infrastructure. Their plan to implement the GVANET was achieved after passing two design levels: device level and system level. In the device level, they suggest that the architecture of a road side unit (RSU) must be enhanced to maintain its robustness and availability against the different failure events which may occur due to many reasons such as power supply shortage or denial of service attacks. The design philosophy in the system level concentrates on building a sustainable, secured, reliable and scalable communication infrastructure to solve the different systematic problems raised when implementing the RSU as a member of the GVANET. [ABSTRACT FROM AUTHOR]

The target coverage optimisation is an important problem in directional sensor networks (DSNs). In this study, the authors present a novel algorithm, called cover critical target first (CCTF), for improving the coverage ratio in DSN. CCTF simultaneously maximises the number of covered targets, reduces the number of active sensors, and extends network lifetime. For a set of uncovered targets, CCTF always finds the highest priority target which has the minimum number of covering sensors. Among sensors that could cover this target, CCTF activates a sensor that covers more additional targets besides the found target. CCTF's performance is evaluated in terms of coverage ratio, the number of active sensors, and power consumption through extensive simulation. The simulation indicates that CCTF is robust against orientation and localisation errors. [ABSTRACT FROM AUTHOR]

One of the lifetime maximisation methods for wireless sensor network (WSN) depends on organising the dense sensors into groups which can work in a cooperative sequential manner. Each group contains a subset of sensors that cover all the monitored area and is called a complete cover or simply a cover. Increasing the number of organised covers and maximising the covers lifetime enable longer network lifetime. Here, the authors investigate the WSN lifetime problem as a two‐objective optimisation problem. The first objective is to find the maximum number of covers. The second objective considers the problem of wasted energy. Minimising the wasted energy in the critical sensors is achieved by defining a difference factor (DF). The DF is an indication of the difference between the critical sensor lifetime and the cover lifetime. This second objective is compared with other choices in the literature such as minimising the overlapping and minimising the variance. This optimisation problem is addressed using non‐dominated sorting genetic algorithm‐II (NSGA‐II). Simulation results are conducted for the network lifetime when using one‐objective and different two‐objective optimisation problem. The choice of DF as the second objective is proved to overcome drawbacks of other second objectives choices. [ABSTRACT FROM AUTHOR]

In wireless sensor networks (WSNs), the existing cluster‐based private data aggregation techniques are energy‐intensive due to high message transmission complexity. Reliable data transmissions are also vital for resource constraint WSNs. To address these issues, the authors propose a reliability enabled private data aggregation technique that has message transmission complexity of O(N). Every node in the cluster cleaves its data into n integrants using simple modular arithmetic with suitable prime moduli and transmits to the cluster heads (CHs) for intermediate aggregation. The CHs, in turn, forward the partial aggregate data to the base station where the final aggregate is recovered using an elegant Chinese remainder theorem. The authors use data privacy, communication overhead, and reliability metrics to gauge the performance of the proposed work. Numerical and simulation results demonstrate that the proposed solution outperforms the existing schemes having O(N2) communication complexity. [ABSTRACT FROM AUTHOR]

The authors investigate the performance and reliability improvement of multiple relay cooperative free space optical (FSO) communication over direct link. Multiple gain combiner (MGC) method has been introduced as a diversity combining method which assures to provide a close to optimum performance as compared to maximal ratio combining (MRC). As compared to MRC, the proposed MGC technique does not require prior channel information and adaptive gain adjustment. Bit error rate (BER) performance improvement with different combining techniques, including MGC, in cooperative FSO system for different channel environments has been included in this study. BER performance for multiple relays for various combining techniques: selection combining, equal gain combining, MRC and MGC have been compared and it is seen that the performance of MGC is close to optimum MRC. High availability of the system is achieved by using multiple relays in the cooperative system. Markov model analysis for availability and mean time between failures of FSO systems in multiple relays cooperative communication has been done to verify the reliability improvement of a cooperative system with increasing number of relays. [ABSTRACT FROM AUTHOR]

Here, the authors propose an energy‐efficient strategy using multiple antennas for secure distributed detection in wireless sensor networks (WSNs). In multiple access channel, it is possible to communicate between sensors and ally fusion centre with perfect secrecy by an encryption with channel state information (CSI). However, the sensors in an active group may need to constantly report in the encryption as long as the CSI remains unchanged, which deteriorates the energy efficiency in terms of the lifetime of WSN. The authors solve the problem by using random beamforming (e.g. antenna subset modulation). Furthermore, the authors investigate the impact of the number of active antennas on the network lifetime. Through the analysis and simulation, the authors demonstrate that the proposed strategy has a higher energy efficiency than the conventional strategy, while maintaining the same reliability and security. [ABSTRACT FROM AUTHOR]

In an unreliable cluster‐based, broadcast vehicular network setting, the authors investigate the transmission reliability and throughput performance of random network coding (RNC) as a function of the percentage of packet generation rate and transmit power‐to‐noise ratio. In this study, a novel scheme called reliable and efficient cooperative cross‐layer medium access control (RECMAC) is proposed. The proposed scheme consists of a source vehicle broadcasting packets to a set of receivers (i.e. one‐to‐many) over independent broadcast erasure channels. The source vehicle performs RNC on N packets and broadcasts the encoded message to a set of receivers. In each hop, several vehicles form a cluster and cooperatively transmit the encoded or re‐encoded packet. The combination of the RNC, cluster based, and cooperative communications enables RECMAC to optimally minimise data redundancy, which means less overhead, and improve reliability as opposed to coding‐based solutions. Theoretical analyses and simulation results show that under the same conditions RECMAC scheme can achieve improved performance in terms of transmission reliability and throughput. [ABSTRACT FROM AUTHOR]

Free space optics (FSO) communication links are impaired by the fading due to turbulence and misalignment. In this paper, we theoretically analyze the pointing error effects on performance of FSO systems using multi‐pulse pulse position modulation (MP‐PPM) over the Gamma‐Gamma turbulence channel. We consider the moderate and strong atmospheric turbulence regimes with the combined effect of the pointing errors (PEs), and study the link average symbol error rate (ASER) and the outage probability. The numerical results are presented to show the impact of the pointing error on the ASER and the system outage. However, to overcome the channel degradation resulting from the turbulence effects and the PE, the single‐input multiple‐output (SIMO) system with maximal ratio combining (MRC) diversity is used. Exact close‐form expressions for ASER and outage probability are derived and verified by using Monte Carlo simulation. We concluded that the optimal values of the system parameters are, the transmitted power is 20 dBm, jitter variance should be less than 0.5 m and laser beam width equals 0.2 cm. These values are significantly reduced the impacts of misalignment and fading whereas outage probability is less than at maximum jitter variance. [ABSTRACT FROM AUTHOR]

In this study, the authors consider the physical‐layer security for transmission in underlay cognitive radio networks, where consisting of a primary source–destination pair, a secondary transmitter–receiver pair and a common eavesdropper (E). To transmit data in a secure and reliable manner, they propose a transmission protocol for an underlay cognitive radio network. In particular, the secondary user is allowed to operate on the primary spectrum bandwidth when the interference threshold is satisfied. To protect the transmission confidentiality of primary system, PS node transmits a signal, which is linearly combined with the jamming signal (as artificial noise) and expectation signal, to interfere E. Furthermore, they propose a superimposed coding to combine with the artificial noise and expectation signal at PS node. We also analyse the performance of the proposed transmission protocol. We obtain the outage probability of secondary and primary systems. Simultaneously, they derive the closed‐form expression of intercept probability for primary system. In addition, they verify the performance of their proposed transmission protocol by numerical experiment. The numerical results show that their proposed transmission protocol not only has the better outage performance for secondary system but also has the better intercept performance for primary system. [ABSTRACT FROM AUTHOR]

The reduction of energy consumption and the successful delivery of data are important for a wireless body sensor network (WBSN). Many studies have been performed to improve energy efficiency, but most of them have not focused on the biosensor nodes in the WBSN bottleneck zone. Energy consumption is a critical issue in WBSNs, as the nodes that are placed next to the sink node consume more energy. All biomedical packets are aggregated through these nodes forming a bottleneck zone. This study proposes a novel mathematical model for body area network topology to explain the deployment and connection between biosensor nodes, simple relay nodes, network coding (NC) relay nodes and the sink node. Therefore, this study is dedicated to research both the energy saving and delivery of data if there is a failure in one of the links of the transmission, which relates to the proposed random linear NC model in the WBSN. Using a novel mathematical model for the WBSN, it is apparent that energy consumption is reduced and data delivery achieved with the proposed mechanism. This study details the stages of the research work. [ABSTRACT FROM AUTHOR]

Duty‐cycled technology has been introduced as an efficient way to preserve node energy and prolong network lifetime for wireless sensor networks (WSNs). However, many applications with real‐time feature require that some message must be sent to the sink node within a limited time. The authors propose a novel data collecting scheme – MTDR which aims to minimise transmission delay in low‐duty‐cycle WSNs. In MTDR, all the nodes are assigned to the corresponding levels according to the hop count to the sink node, and calculate their minimum transmission delay to the sink node based on the shortest path structure. Finally, simulation results show that their proposed algorithm can achieve better performance compared with some related works. [ABSTRACT FROM AUTHOR]

Coverage problem in sensor network ensures quality of monitoring of a given region. Depending on applications, different measures of coverage are there such as area coverage, sweep coverage, barrier coverage and so on. Barrier coverage ensures monitoring only the boundary of a region. Barrier coverage is a critical issue in wireless sensor networks for border protection, the performance of which is highly related to the locations of sensor nodes. The objective of the sensors is to detect objects that cross the boundary. The primary objective of this study is to restore barrier coverage after sensor failure with the help of mobile sensors. Battery life of the sensors is one of the critical parameters of a sensor network. To increase the lifetime of the sensor network, the authors' restoring scheme tries to keep the total displacement incurred by the mobile sensors to minimum. A localised distributed barrier coverage restoring scheme is proposed. It first finds the existence of alternate barrier locally. If alternate barrier is not found, an alternate barrier is reconstructed by shifting the existing nearby sensors in a cascaded manner. Simulation results are presented in detail to evaluate the performance of their algorithm. [ABSTRACT FROM AUTHOR]