Relay Devices Research Articles

Analysis of the behaviour of charged particles in electrical relay devices

This paper presents the results of analytical and experimental studies on the motion of a charged foreign object in an electrical relay. In the numerical approach, the motion of the lower and upper electrodes was solved by the finite element method. The colliding force between the foreign object and the electrodes was calculated by Hertzian contact theory. The electric field strength in the electrical relay was solved by the finite difference method. In the experimental approach, a spherical particle with a radius of 0.097mm made of polystyrene divinylbenzene was used as the foreign object. The validity of the analytical method was examined by comparing its results with the experimental results. It was shown that the motion of the particle is considerably affected by the electrostatic force.

A Robust Stackelberg Game Approach for Joint Relay Selection and Optimal Power Allocation for Cooperative Device-to-Device Communication Under Channel Uncertainties

Device-to-device (D2D) communication enables direct communication among users in close proximity, bypassing the core network. With relay assistance, D2D users can have the leverage of transmitting data directly over long distances with increased throughput. However, due to dynamic nature of wireless networks, there may be uncertainty in the channel parameters known to a user. In this paper, the authors address the joint problem of relay selection and optimal power allocation in single-source multi-relay D2D networks when the perfect channel state information for relay channels is unknown. The uncertainty has been modeled as a bounded difference between actual and nominal values. An incentive-based robust Stackelberg game is proposed in which the relay devices determine the price of power allocated to them by the source device. A closed form expression for the optimal power was obtained. Further, the Stackelberg equilibrium was derived and its existence and uniqueness was demonstrated. The performance of the proposed game with the nominal game was compared. Simulation results confirm the effectiveness of the robust game-theoretic solution in an incomplete information environment.

A Lightweight Elliptic-Elgamal-Based Authentication Scheme for Secure Device-to-Device Communication

Device-to-Device (D2D) is a major part of 5G that will facilitate deployments with extended coverage where devices can act as users or relays. These relays normally act as decode and forward relays (semi-intelligent devices) with limited computational and storage capabilities. However, introducing such a technology, where users can act as relays, presents a wide range of security threats, in particular, rogue relay devices or man in the middle attacks (M-I-T-M). Second, passing fewer control messages is always advisable when considering authenticity and secrecy. To mitigate M-I-T-M and to reduce communication costs, this paper presents a lightweight elliptic-ElGamal-based authentication scheme using PKI (FHEEP) in D2D communication. Pollard’s rho and Baby Step, Giant Step (BSGS) methods are used to evaluate the authenticity and secrecy of our proposed scheme. The communication cost is calculated based on the comparative analysis indicating that our proposed scheme outperforms the baseline protocol. The proposed scheme can be used for any infrastructure architecture that will enhance the security of any D2D settings with better performance.

Advanced Control Techniques for Enhance the Power System Stability at OOS Condition

<p>The power system stability is the accurate operation of the electric grid by restoring balance after being subjected to an abnormal condition such as fault, line switching, load rejection, and loss of excitation. Protective equipment in high voltage substations should fast and precisely localize the faults. Some abnormal conditions in the power system such as out-of-step (OOS) condition which is not a real fault, but the protection equipment will consider it is. This misjudgment will cause the loss of synchronism between areas within the power system or between interconnected systems and will lead to blackout of the national grid. This paper studied the OOS condition, philosophy of protection relay device and how to avoid the false operation for distance function by Out of Step Blocking (OSB) by using the advanced protection relay, to improve the stability of power system. </p>

On mapping of address and port using translation

Due to the shortage of IPv4 addresses, many hosts are currently assigned to a single IPv4 address by using one or a number of NAT devices. However, numerous NAT devices cannot be upgraded for executing 6to4 due to technical and/or economic reasons. Solutions depending on Double Network Address Translation 64 are a good way to utilise shared IP4 addressing. Mapping of address and port using translation (MAP-T) is a technique that accomplishes double translation on Border Relay (BR) and customer edge (CE) devices. IPv4 and IPv6 forwarding, IPv4 and IPv6 fragmentation functions, and NAT64 translation functions are used by MAP-T. This enables increasing numbers of IPv6 in both clients and servers in order to possess the best defence against certain attacks, such as routing loop attacks, spoofing attacks, denial-of-service attacks. We have here proposed some procedures for creating frameworks and sustaining secure IPv6 networks according to applications, environs and architecture.

RESEARCH OF TRANSIENT PROCESSES IN HIGH-VOLTAGE TRANSMISSION LINES 6–10 KV AND DEVELOPMENT OF MICROELECTRONIC SPECIAL PROCESSOR OF RELAY PROTECTION, INVARIANT TO CHANGE IN AMPLITUDES OF PHASE CURRENTS

The fast-acting algorithms of exposure and invariant authentication of transients in the lines of electricity transmission as load surge, short circuits and start of powerful electric engines were developed; based on that, the functions of relay defense device of high-voltage lines of electricity transmission were determined. The given structure of small, microelectronic fast-acting device of relay defense is with the extended functional possibilities of recognition of load surge and defense of high-voltage lines of electricity transmission from short circuits, the syntax of his functions was presented. This device can be used for load surge recognition and short circuits, invariant to the size of increase currents in the separate phases of electric lines. It allowed successful application of the developed method and device for simultaneous recognition of load surge, short circuits and starting of powerful electric engines. The information technology of designing structural solutions of relay protection special processor for high-voltage electricity transmission lines was presented.

Laboratory Test Bed for Analyzing Fault-Detection Reaction Times of Protection Relays in Different Substation Topologies

Visions of energy transition focus on activating end users, meaning that numerous flexible-distribution network-level devices become active participants in power-system operations. This implies a fast, reliable, and secure exchange of data, enabling the distribution-system operators to maintain, or even improve, the quality and delivery of service. With the introduction of the International Electrotechnical Commission (IEC) 61850 standard, the path is set for a single communication topology covering all substation levels. The standard has the potential to change the way substations are designed, built, tested, and maintained. This means that the key segment of the substation, its protection system, will go through a transition period with the end goal of having a digitized substation where all information exchange is performed over an Ethernet communication bus. This paper analyzes the performance impact of the IEC 61850-9-2LE on the protection system. To do this, a laboratory hardware-in-the-loop test setup was developed representing traditional-, hybrid-, and digital-substation topology. The setup serves to simulate faults and create transient waveforms in an extended IEEE 123-node test system, which is then used to detect the reaction times of protection relay devices. To verify the results, a significant number of tests was performed clearly showing the benefits of digitalizing the distribution system.

Social-Aware D2D Relay Networks for Stability Enhancement: An Optimal Stopping Approach

Device-to-device (D2D) relay network is regarded as a promising approach to extend the coverage area of cellular networks or improve the service quality for cell-edge users. However, the mobility of relay devices will negatively affect the stability of D2D communications. Aiming to improve the stability in mobile D2D communications and hence deliver more data traffic in D2D relay networks, in this paper, we exploit users’ social behaviors to dynamically detect better relay devices and substitute them for the existing ones. As the mobility of relays pose a critical challenge in achieving the tradeoff between the relay probing time and the optimality of relay selection, we propose the optimal stopping approach for mobile devices conducting the relay re-selection. Specifically, we embed social tie and centrality relationships between a potential relay and the end user to predict the date delivery performance of the potential relay in the D2D relay network. Our optimal stopping approach can be applied to different network topologies for mobile users with different social behaviors. The simulation results show that our proposed scheme can achieve the optimal tradeoff between the time used in relay probing and the optimality of the selected relay. Results also show that both short-term and long-term stability can be obtained and the amount of relayed data traffic can be maximized.

BiPAD: Binomial Point Process Based Energy-Aware Data Dissemination in Opportunistic D2D Networks

In opportunistic device-to-device (D2D) networks, the epidemic routing protocol can be used to optimize the message delivery ratio. However, it has the disadvantage that it causes excessive coverage overlaps and wastes energy in message transmissions because devices are more likely to receive duplicates from neighbors. We therefore propose an efficient data dissemination algorithm that can reduce undesired transmission overlap with little performance degradation in the message delivery ratio. The proposed algorithm allows devices further away than the k-th furthest distance from the source device to forward a message to their neighbors. These relay devices are determined by analysis based on a binomial point process (BPP). Using a set of intensive simulations, we present the resulting network performances with respect to the total number of received messages, the forwarding efficiency and the actual number of relays. In particular, we find the optimal number of relays to achieve almost the same message delivery ratio as the epidemic routing protocol for a given network deployment. Furthermore, the proposed algorithm can achieve almost the same message delivery ratio as the epidemic routing protocol while improving the forwarding efficiency by over 103% when k≥10.

SERS: Social-Aware Energy-Efficient Relay Selection in D2D Communications

The explosion of mobile applications and phenomenal adoption of mobile connectivity by end users have generated increasing amounts of mobile data traffic. Recognizing the need of increasing network capacity, cooperative device-to-device (D2D) communications and efficient power allocation have been proposed to address the imperative problem. Existing works mainly focus on relay selection and power control at physical layer. The social connections between mobile users, however, are omitted in consideration of improving the cooperative D2D communication quality. Leveraging social trust, we propose an innovative social-aware energy-efficient relay selection (SERS) mechanism that considers the hidden social ties among mobile users to ensure that more users are willing to participate in the cooperative communications. The proposed SERS takes both social and physical constraints into account to determine the best choice of relay devices. In SERS, we further develop an optimization problem based on game theory, aiming at reducing energy consumption and interference. In the game, social distance is treated as a penalty coefficient and performs distributed control of the transmission power for D2D communications. Simulations based on real-world social network data traces show that SERS achieves a significant performance gain, compared with other relay selection approaches.

Mobile User Connectivity in Relay-Assisted Visible Light Communications.

In this paper, we investigate relay-assisted visible light communications (VLC) where a mobile user acts as a relay and forwards data from a transmitter to the end mobile user. We analyse the utilization of the amplify-and-forward (AF) and decode-and-forward (DF) relaying schemes. The focus of the paper is on analysis of the behavior of the mobile user acting as a relay while considering a realistic locations of the receivers and transmitters on a standard mobile phone, more specifically with two photodetectors on both sides of a mobile phone and a transmitting LED array located upright. We also investigate dependency of the bit error rate (BER) performance on the azimuth and elevation angles of the mobile relay device within a typical office environment. We provide a new analytical description of BER for AF and DF-based relays in VLC. In addition we compare AF and DF-based systems and show that DF offers a marginal improvement in the coverage area with a BER < 10–3 and a data rate of 100 Mb/s. Numerical results also illustrate that relay-based systems offer a significant improvement in terms of the coverage compared to direct non-line of sight VLC links.

Adaptive OFDM With Index Modulation for Two-Hop Relay-Assisted Networks

In this paper, we propose an adaptive orthogonal frequency-division multiplexing (OFDM) index modulation (IM) scheme for two-hop relay networks. In contrast to the traditional OFDM IM scheme with a deterministic and fixed mapping scheme, in this proposed adaptive OFDM IM scheme, the mapping schemes between a bit stream and indices of active subcarriers for the first and second hops are adaptively selected by a certain criterion. As a result, the active subcarriers for the same bit stream in the first and second hops can be varied in order to combat slow frequency-selective fading. In this way, the system reliability can be enhanced. Additionally, considering the fact that a relay device is normally a simple node, which may not always be able to perform mapping scheme selection due to limited processing capability, we also propose an alternative adaptive methodology in which the mapping scheme selection is only performed at the source and the relay will simply utilize the selected mapping scheme without changing it. The analyses of average outage probability, network capacity and symbol error rate (SER) are given in closed form for decode-and-forward (DF) relaying networks and are substantiated by numerical results generated by Monte Carlo simulations.

Envisioned Wireless Big Data Storage for Low-Earth-Orbit Satellite-Based Cloud

Satellite-based communication technology regains much attention in the past few years, where the satellites mainly play the role as relay devices to the communication networks. In this article, we focus on the data storage leveraging the low-Earth-orbit satellite-based data center (also called space-based cloud), which has been considered as a very promising secure paradigm for data storage, especially in the big data era. We first propose a layered architecture for the space-based cloud infrastructure. Then a novel management framework is devised to enable the operability of the proposed architecture. Finally, some challenging open issues are revealed from both the academic and industrial perspectives.

On Bit Error Probability and Power Optimization in Multihop Millimeter Wave Relay Systems

5G networks are expected to provide gigabit data rate to users via the millimeter-wave (mmWave) communication technology. One of the major problems faced by mmWaves is that they cannot penetrate buildings. In this paper, we utilize multihop relaying to overcome the signal blockage problem in an mmWave band. The multihop relay network comprises a source device, several relay devices, and a destination device and uses device-to-device communication. Relay devices redirect the source signal to avoid the obstacles existing in the propagation environment. Each device amplifies and forwards the signal to the next device, such that a multihop link ensures the connectivity between the source device and the destination device. We consider that the relay devices and the destination device are affected by external interference and investigate the bit error probability (BEP) of this multihop mmWave system. Note that the study of the BEP allows quantifying the quality of communication and identifying the impact of different parameters on the system reliability. In this way, the system parameters, such as the powers allocated to different devices, can be tuned to maximize the link reliability. We derive exact expressions for the BEP of $M$ -ary quadrature amplitude modulation and $M$ -ary phase-shift keying in terms of multivariate Meijer’s G-function. Due to the complicated expression of the exact BEP, a tight lower bound expression for the BEP is derived using a novel Mellin-approach. Moreover, an asymptotic expression for the BEP at high SIR regime is derived and used to determine the diversity and the coding gain of the system. In addition, we optimize the power allocation at different devices subject to a sum power constraint such that the BEP is minimized. Our analysis reveals that optimal power allocation allows achieving more than 3-dB gain compared with the equal power allocation. This paper can serve as a framework for designing and optimizing mmWave multihop relaying systems to ensure link reliability.

On Mapping of Address and Port using Translation (MAP-T)

Due to the shortage of IPv4 addresses, many hosts are currently assigned to a single IPv4 address by using one or a number of NAT devices. However, numerous NAT devices cannot be upgraded for executing 6to4 due to technical and/or economic reasons. Solutions depending on Double Network Address Translation 64 are a good way to utilise shared IP4 addressing. Mapping of address and port using translation (MAP-T) is a technique that accomplishes double translation on Border Relay (BR) and customer edge (CE) devices. IPv4 and IPv6 forwarding, IPv4 and IPv6 fragmentation functions, and NAT64 translation functions are used by MAP-T. This enables increasing numbers of IPv6 in both clients and servers in order to possess the best defence against certain attacks, such as routing loop attacks, spoofing attacks, denial-of-service attacks. We have here proposed some procedures for creating frameworks and sustaining secure IPv6 networks according to applications, environs and architecture.

Quality driven modulation rate optimization for energy efficient wireless video relays

Modern mobile computing devices such as smart phones have become the major user-centric video data sources in future 5G wireless networks. However, battery energy efficiency becomes the critical bottleneck for such uplink multimedia contributors. In this paper we propose a new approach to reduce energy consumption while improving Quality of Experience (QoE), by innovatively investigating video encoding frame prioritization, mode, dependency, and rate control overheads, based on communication model of a transmitter device to an access-point via a relay device. In the proposed approach, we investigate various frame level encoding dependencies and different communication data rates to study their impacts on energy efficiency and QoE. We also incorporate some simple game theory concepts to determine the best compromise of energy-quality tradeoff between the transmitter and the relay. Simulation results demonstrate that cross layer exploration of encoding dependency and game theoretical rate control have significant energy saving and quality gain potentials.

Initial and midterm results of the Bolton Relay Thoracic Aortic Endovascular Pivotal Trial

ObjectiveTo report the initial and midterm results of the Bolton Relay Thoracic Stent Graft for the endovascular treatment of thoracic aortic lesions [thoracic endovascular aortic repair (TEVAR)]. MethodsThe Bolton Relay Thoracic Aortic Endovascular Pivotal Trial was a prospective, nonrandomized, multicenter, U.S. Investigational Device Exemption study conducted at 27 U.S. investigational sites. One hundred twenty TEVAR subjects were treated with the Relay device between January 2007 and May 2010, with 13 patients enrolled during the continued access phase through September 2012. TEVAR outcomes were compared with a prospectively and retrospectively enrolled surgical cohort consisting of 60 patients enrolled under similar inclusion/exclusion criteria. Follow-up examinations were prescribed at 1 month, 6 months, and yearly thereafter for 5 years. Major adverse events (MAEs) included stroke, paralysis/paraplegia, myocardial infarction, procedural bleeding, respiratory failure, renal failure, wound healing complications, and aneurysm-related mortality. ResultsStent grafts were successfully delivered and deployed in 129 of 133 patients (97.0%). At 30 days, a lower rate of mortality was observed in the TEVAR arm (5.3% vs 10.0%; P = .230), and TEVAR was associated with a significantly lower rate of MAEs (20.3% vs 48.3%; P < .001), primarily driven by a lower frequency of respiratory failure in the cohort (5.5% vs 21.6%; P = .007) and procedural bleeding. Freedom from aneurysm-related mortality through 5 years was similar at 91.3% for the TEVAR cohort and 89.4% for the surgical cohort (P = .406); with 5-year freedom from all-cause mortality at 57.1% and 50.2% (P = .289), respectively. Freedom from MAEs through 5 years was significantly higher in the TEVAR cohort (65.7% vs 44.7%; P = .001). Six TEVAR patients (4.5%) experienced core laboratory-reported type I or III endoleaks, and secondary procedures were performed in 10 patients (7.5%), with seven procedures to correct endoleak and one surgical conversion. Endograft migration occurred in three patients (2.3%) and wireform fractures were assessed in two patients (1.5%). Aneurysm sac size decreased or remained stable in 113 patients (85.0%) over 5-year follow-up. There were no instances of rupture or endograft occlusion. A 38-subject subset treated with the newer Relay Plus Delivery System had a significantly reduced MAE rate (15.8% vs 35.8%; P = .035), and fewer perioperative strokes (2.6% vs 12.6%; P = .108). ConclusionsData from the Relay TEVAR clinical trial demonstrate safety and effectiveness of the Relay device compared with surgical controls, indicating continued device durability with a low rate of device-related complications through 5 years.

Distributed quality of service routing protocol for multimedia traffic in WiMedia networks

Ultra-wideband (UWB) technology has emerged as a solution for the wireless interface between medical sensors and personal servers in future telemedicine systems. The WiMedia Alliance has specified a distributed medium access control protocol based on UWB for high-rate WPANs. In the cases of some applications, data traffic between the source device and destination device is transmitted via one or more intermediate links before it reaches the destination device. However, when all data frames do not transmit in the current DRP reservation block, a relay device cannot transmit the received data frame from the source device in the current DRP policy, until the next DRP duration reserved for forwarding to the destination device begins. This policy increases end-to-end latency between the source device and destination device significantly. Therefore, in this paper, we propose a novel reservation-based routing protocol to minimize the end-to-end delay between source and destination. The proposed routing protocol utilizes the number of medium access slots and hop-count to decide the optimal route between the source device and destination device. The simulation results show that the proposed protocol can enhance the throughput and delay performance and improve energy efficiency by minimizing the packet drop and collision.

Hybrid Recovery Strategy Based on Random Terrain in Wireless Sensor Networks

Providing successful data collection and aggregation is a primary goal for a broad spectrum of critical applications of wireless sensor networks. Unfortunately, the problem of connectivity loss, which may occur when a network suffers from natural disasters or human sabotages, may cause failure in data aggregation. To tackle this issue, plenty of strategies that deploy relay devices on target areas to restore connectivity have been devised. However, all of them assume that either the landforms of target areas are flat or there are sufficient relay devices. In real scenarios, such assumptions are not realistic. In this paper, we propose a hybrid recovery strategy based on random terrain (simply, HRSRT) that takes both realistic terrain influences and quantitative limitations of relay devices into consideration. HRSRT is proved to accomplish the biconnectivity restoration and meanwhile minimize the energy cost for data collection and aggregation. In addition, both of complexity and approximation ratio of HRSRT are explored. The simulation results show that HRSRT performs well in terms of overall/maximum energy cost.

Relay Positioning Strategy for Traffic Data Collection of Multiple Unmanned Aerial Vehicles Using Hybrid Optimization Systems: A FANET-Based Case Study

In the new context of Next Generation Networks, Aerial Ad Hoc Networks, also known as FANET (Flying Ad Hoc Network), are being used to monitor areas of difficult access. Owing to the dynamism and autoconfiguration of this type of network, a strategy is needed to position its devices (drones) to ensure it can achieve good performance. In light of this, this paper proposes a flight path planning model, which involves a metaheuristic optimization-based approach. The proposal relied on the artificial neural networks to optimize the positioning of the relay device, so that the throughput between the other devices could be increased; the benefits of the proposal were demonstrated through simulations.