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This paper presents a non-orthogonal multiple access (NOMA)-assisted full-duplex (FD) cooperative spectrum sharing protocol to achieve full-rate at a cell-edge primary user, where the secondary receiver helps the primary network relay the information to the cell-edge primary user. Unlike other FD cooperative schemes, the FD relay in the proposed system is not transmitting while receiving symbols from the primary transmitter. Hence, the proposed scheme can achieve full-rate at a primary user without degrading its outage performance. Further, it guarantees every alternate time-slots to the secondary network for accessing the licensed spectrum by employing a secondary receiver as a cooperative relay. In this paper, we derive the analytical expression for the outage probability and ergodic capacity. Moreover, we validate the derived expression through simulation and asymptotic results. The numerical and simulation results substantiate that the proposed scheme significantly outperforms other existing protocols. [ABSTRACT FROM AUTHOR]

Covert communications is critical in many application scenarios for ensuring transmission security and privacy. Two-way protocols are widely adopted in intelligent reflecting surface (IRS) assisted relaying networks to enable covert communications and prevent wireless signals from being overheard. To quantify the performance of covert communications in this special scenario, we derive the closed-form expression of outage probability and its asymptote in this paper. Considering the worst-case of covert communications, the optimal normalized power threshold of warden's detector is analyzed under a complex Gaussian distribution approximation. To meet the requirement of the detection error probability, the ratio of the transmission power between the covert nodes is investigated. Simulation results are provided to validate the theoretical expressions as well as the asymptotic analysis with a small number of reflecting elements. [ABSTRACT FROM AUTHOR]

As millimeter wave (mmWave) technology becomes more integrated into today's communication infrastructure, its application to mobile scenarios has attracted considerable interests. In particular, mmWave technology is one of the leading candidates in Vehicle-to-Everything (V2X) community to address the ever-rising data exchange demand from vehicles. However, the inherent directionality of the technology poses challenges to peer discovery and transmission scheduling in typical V2X scenarios, causing significant loss of network capacity. To mitigate this issue, we propose a novel sub-6 GHz V2X-assisted synchronous mmWave communication scheduler in this paper. The sub-6 GHz channel serves as control channel for mmWave scheduling. The scheduler carefully considers data importance and freshness in determining communication schedule, such that network utility across mmWave links is maximized. We formulate the scheduling problem into an integer linear programming (ILP) problem. However, ILP problem is NP-hard and has exponential computational complexity for the worst cases. We then develop a scheduling algorithm, maximum weight matching based iterative algorithm (MWMIA), that operates in polynomial time with performance guarantees for the NP-hard ILP, by leveraging structural properties of link conflicts. Comparative simulation studies verify the effectiveness of our scheduler against other solutions. [ABSTRACT FROM AUTHOR]

Recent research showcased several cyber-attacks against unmodified licensed vehicles, demonstrating the vulnerability of their internal networks. Many solutions have already been proposed by industry and academia, aiming to detect and prevent cyber-attacks targeting in-vehicle networks. The majority of these proposals borrow security algorithms and techniques from the classical ICT domain, and in many cases they do not consider the inherent limitations of legacy automotive protocols and resource-constrained microcontrollers. This paper proposes DAGA, an anomaly detection algorithm for in-vehicle networks exploiting $n-$ gram analysis. DAGA only uses sequences of CAN message IDs for the definition of the $n-$ grams used in the detection process, without requiring the content of the payload or other CAN message fields. The DAGA framework allows the creation of detection models characterized by different memory footprints, allowing their deployment on microcontrollers with different hardware constraints. Experimental results based on three prototype implementations of DAGA showcase the trade off between hardware requirements and detection performance. DAGA outperforms the state-of-the-art detectors on the most performing microcontrollers, and can execute with lower performance on simple microcontrollers that cannot support the vast majority of IDS approaches proposed in literature. As additional contributions, we publicly release the full dataset and our reference DAGA implementations. [ABSTRACT FROM AUTHOR]

Mobile terminals have been widely used in the communication applications (e.g., vehicular network, e-Health, smart grid and e-Commerce) as they can obtain all kinds of services and upload data for users anytime and anywhere. With the number of users increasing dramatically and user demands diversifying, multi-server architecture was proposed to solve issues on lack of service resources that single-server architecture remains. However, multi-server architecture faces a series of challenges in applications, such as security and authentication efficiency requirements. Thus, many authenticated key agreement (AKA) protocols are presented, yet most of them require unacceptable computation and communication overhead, which is inefficient indeed. In this paper, we propose an adaptive secure handover authenticated key agreement protocol for multi-server architecture. Specifically, broadcast mechanism is utilized to assist users to select appropriate service providers with the lowest cost. Users can realize efficient handover authentication with multiple servers in the proposed scheme, that is, after completing initial authentication, users can switch to other servers and complete authentication through simple operations. Security analysis shows the proposed protocol can meet all security requirements and compared with other relevant protocols, it greatly reduces the computation and communication overhead. In addition, the above advantages grow significantly as the number of servers to be authenticated increases. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a two-hop simultaneous wireless information and power transfer (SWIPT) amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay communication system with an energy-limited relay node. The relay node harvests energy based on the radio-frequency (RF) signal transmitted from the source node through the time-switching (TS) protocol and fully uses the harvested energy to precode and forward the information to the destination node. The non-linear energy harvesting models are considered at the relay node. With the consideration of the channel estimation error, the joint optimization of the TS factor, source and relay precoding matrices is proposed with robustness against the channel state information (CSI) mismatch to maximize the mutual information (MI) between the source and destination nodes. The optimal structure for the source and relay precoding matrices is derived to simplify the transceiver optimization problem. Numerical simulations show that the system performance provided by the proposed algorithms with robustness is better than the non-robust algorithm. [ABSTRACT FROM AUTHOR]

The recently proposed dual active protocol stack (DAPS) handover (HO) is one of the mobility enhancements that can effectively reduce the handover interruption time (HIT) in 5G networks. By using a DAPS solution, users can be connected to both the source cell and target cell during the HO execution phase, and thereby 0 ms of HIT becomes possible. However, the DAPS HO procedure may fail in 5G networks due to the channel characteristics of millimeter-wave (mmWave) signals. Since mmWave links are vulnerable to blockages, the received signal quality may degrade suddenly, which gives rise to an abrupt outage before DAPS HO can be completed. In this paper, a novel learning-based DAPS HO technology named intelligent DAPS (I-DAPS) HO is proposed to avoid sudden radio link failure (RLF) while providing a high data rate. The proposed I-DAPS HO uses a double deep Q-network (DDQN) deep reinforcement learning (DRL) framework, where blockage predictions are made based on past received signal data such that RLFs can be actively avoided. The performance evaluation demonstrates that the proposed I-DAPS HO scheme can effectively avoid RLF and improve the throughput performance compared to advanced 5G HO schemes. [ABSTRACT FROM AUTHOR]

Due to the deployment of 5G technology, the number of IoV (Internet of Vehicle) devices connected to the Internet will explosively grow. However, as a kind of edge network device, IoV devices also face some problems including weak password authentication, lack of security protection, and lagged firmware updating, which largely threaten the security and legitimacy of these devices. IoV device identification is important in discovering, monitoring, and protecting these devices. Although existing proactive identification methods based on device fingerprints can be used to identify the large-scale Internet-connected IoV devices, they can not meet the fine-grained requirements for security risk assessment. Due to the increase in the types and brands of IoV devices, the fingerprint granularity will be insufficient. In this paper, we proposed a retransmission-based TCP fingerprints for large-scale fine-grained proactive device identification. Firstly, a probing scheme was designed to obtain TCP retransmission packet and increase the granularity space of traditional TCP fingerprint by selecting the multi-group features of TCP retransmission messages. Then, according to the bagging strategy of ensemble learning, a combined classifier with five predominant machine learning algorithms was generated. The experimental results showed that the identification accuracy and recall of IoV devices respectively reached 96.7% and 95.2%. [ABSTRACT FROM AUTHOR]

The work presented in this paper describes a multi-issue negotiation protocol between active consumers and a management platform in order to establish load coordination in a highly congested network. The multi-issue negotiation protocol considers simultaneously the consumption interval, the price, and the size of the energy packages, which is the main contribution of this work. Regarding the implementation methodology, the proposed algorithms have been implemented using MATLAB classes that allow emulating the behaviour of a multi-agent system in which each vehicle is an agent that interacts with the platform, which is another agent. In the present work, and without loss of generality, the algorithm is applied to coordinate the charging of electric vehicles (EVs) in a distribution network in which building loads represent critical loads. The algorithm is tested in a realistic environment, and its stability and performance are evaluated. Furthermore, the description of the algorithm is provided in a generic form, and it could be applied to any other scenario. [ABSTRACT FROM AUTHOR]

In an Internet of Vehicle (IoV) system, federated learning (FL) is a new approach to process real-time vehicle data in a distributed way, which can improve the driving experience and service quality. However, due to the high mobility and uncertainty of vehicles, the existing federated learning protocols are difficult to meet the full requirements from an IoV system, such as efficient resource allocation, high precision learning, and fast convergence of learning algorithm. To solve the above problems, in this paper, we propose a semi-synchronous federated learning (Semi-SynFed) protocol, to improve the performance of machine learning at Internet of Vehicles. In Semi-SynFed, we first select appropriate nodes to participate the aggregation by its computing capacity, network capacity and learning value of training samples. Meanwhile, the dynamic waiting time technique is designed to adjust the server waiting time at each round dynamically, which makes federated learning process work much more efficient. Finally, a dynamic aggregation scheme is designed to aggregate model parameters in an asynchronous way. To evaluate the reliability of Semi-SynFed, we establish a simulation of IoVs based on the real world data. In the comparative experiments, the results show that the Semi-SynFed outperforms the existing federated learning protocols in terms of convergence speed and resource consumption. [ABSTRACT FROM AUTHOR]

Vehicular ad hoc network (VANET) underpins most intelligent transportation systems and given the open nature of the wireless communication environment, edge nodes in the VANET are subject to varying levels of attacks. While there are a large number of conditional privacy-preserving authentication protocols in the literature, most of these protocols (whose security is guaranteed by classical cryptographic primitives) are not designed to resist quantum attacks. In this paper, we propose a lattice-based conditional privacy-preserving authentication protocol for VANETs, designed to simultaneously achieve mutual authentication and privacy protection. We also show that our protocol is secure in the random oracle model, relying on the small integer solution problem. Additionally, we demonstrate the potential utility of our protocol by evaluating its performance. [ABSTRACT FROM AUTHOR]

Over the past decade, consumer vehicles have increasingly begun to resemble computers on wheels, with many newer vehicles containing over 100 independent electronic control units (ECU) that make independent decisions within the vehicle. Cost and power constraints for the vehicle significantly constrain processing capabilities and limitations on practical cybersecurity measures that may be employed in the vehicle today. Also, as automotive manufacturers are continuous integrators, many legacy communications links within vehicles were originally designed as standalone entities that assumed internal trust of communications between ECUs by virtue of closed bus structures and an emphasis on reliability, but not security. This paper presents a low-cost authentication mechanism to significantly improve message validation on wired message buses such as the Controller Area Network (CAN) bus by employing a co-channel underlay watermark that arrives time-aligned with the primary bus messages. Concept validation using a gate-level Simulink / HDL Coder simulation provided initial feasibility, while a complete CAN bus hardware testbed was constructed with a custom CAN transceiver built on a Red Pitaya software defined radio (SDR) connected to multiple commercial CAN transceivers to validate backwards compatibility. This testbed incorporates a custom transmission security (TRANSEC) engine that supports dynamic variation of the watermark, further improving security during deployment. Finally, this custom CAN testbed with the watermarking CAN transceiver was tested across a range of operational conditions, with initial performance results presented and discussed. Future work describes potential for near-term ruggedization and productization of the watermarking CAN transceiver. [ABSTRACT FROM AUTHOR]

The so-called Internet of Vehicle (IoV) systems will interconnect numerous vehicles to communicate significant information through an Internet of Things (IoT) enabled network. It has emerged as a promising system wherein various data authentication techniques have been introduced using clumsy certificate management and Diffie-Hellman (DH) assumption. However, in the presence of quantum cryptanalysis, DH-type problems could be solved in polynomial-time. In this paper, a novel certificateless data authentication protocol is designed, enabling security features in open wireless communication in the IoV. The proposed protocol resists a quantum attack using lattice cryptography. Further, a reliable blockchain mechanism is shown to provide vehicles’ trustworthiness in batch data verification. Rigorous formal analysis shows the ability of the proposed algorithm to resist existential unforgeability against the chosen-message attack. Nonetheless, the developed protocol supports other essential security functionalities, including unlikability, conditional-traceability, anti-replay, and data authenticity. Performance analysis exhibits the simulation orchestration and shows the way the proposed protocol outperforms other related techniques in energy consumption, data computation, communication, and cryptographic key storage overheads. [ABSTRACT FROM AUTHOR]

A hybrid satellite-terrestrial relay network (HSTRN) has been envisioned as a promising communication architecture for future wireless communications, which can prominently reduce the impact of shadow fading and expand service coverage. In this paper, we conduct theoretical performance analysis for a dual-hop communication system, consisting of multiple relays and multiple users in the HSTRN with the amplify-and-forward protocol. For the shadowing effect and the multipath effect, we introduce the shadowed-Rician distribution and Nakagami- $m$ fading to characterize the channel models for the satellite-relay and the relay-user links, respectively. Additionally, the opportunistic scheduling scheme is employed, where the optimal relay and the optimal user are selected from the alternative nodes with the maximum instantaneous signal-to-noise ratio. Thereafter, the analytical expressions including ergodic capacity and average symbol error rate (SER) are derived. More specifically, we also present the asymptotic behavior of the average SER at the high signal-to-noise ratio (SRN) regime. The theoretical analysis is validated by the numerical results. Moreover, the results also reveal that the performance of the system can be improved by increasing the number of relays and users under different channel parameters and various modulation schemes. [ABSTRACT FROM AUTHOR]

Free-space optics (FSO)-based, low-earth orbit (LEO) satellite-assisted Internet of vehicles (IoVs) has recently attracted research efforts worldwide. For the majority of Internet applications, transmission control protocol (TCP) is one of the most widely deployed protocols. Nevertheless, a complete understanding of the TCP performance over FSO-based satellite-assisted IoVs networks is still lacking in the literature. This is a highly challenging issue, as a consequence of the non-trivial interdependencies between transmission losses caused by the dynamics/uncertainty of atmospheric last-mile channels and the buffer overflows on the Internet, as well as their joint impact on the TCP congestion control mechanisms. This paper offers a comprehensive analytical framework that allows assessing the TCP throughput performance under the joint impact of congestion losses occurred in the Internet and transmission errors at the last-mile link from the satellite-to-vehicle. Internet access for emerging unmanned aerial vehicles (UAVs) is considered while the analysis can be also applied to other kinds of vehicles, which, in fact, require simpler channel models. The link-layer incremental redundancy hybrid automatic repeat request (IR-HARQ) protocol is employed at satellite-to-UAV channels to further improve the TCP throughput performance. Numerical results provide non-trivial findings and insights for the TCP performance in satellite/FSO-based IoVs, in which optimal UAV’s parameters are chosen to maximize the TCP throughput. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the performance of non-orthogonal multiple access (NOMA)-based overlay cognitive integrated satellite-terrestrial relay network with secondary network selection, where the selected secondary network accesses the licensed spectrum by assisting the communication of primary network with amplify-and-forward protocol. Besides, NOMA techniques are used to improve the spectrum efficiency. Specifically, the closed-form expressions of outage probability (OP) for both primary network and secondary network are obtained. To get inherent insights, the asymptotic analysis of OP is further derived at high signal-to-noise ratios. Moreover, the diversity orders of the both networks are further provided. Finally, Monte Carlo simulations are given to valuate our analysis, and the effects of key parameters on system performance are revealed. Through the comparison between orthogonal multiple access (OMA) scheme and NOMA scheme, the superiority of our proposed scheme is proved. [ABSTRACT FROM AUTHOR]

This paper presents a cross-layer design of error-control protocols with rate adaptation for free-space optical (FSO) burst transmission in satellite communication systems. While the prior works mostly focused on the design of error-control protocols for terrestrial-based FSO communications, using either hybrid automatic repeat request (HARQ) based stop-and-wait mechanism or pure sliding window ARQ, we instead propose a design of HARQ-based sliding window mechanism for the high data-rate and long-distance of FSO-based satellite systems. In particular, we model and analyze the performance of low-earth orbit (LEO) satellite-to-ground FSO systems over atmospheric turbulence channels when truncated incremental redundancy (IR) HARQ protocols, which combine the rate-compatible punctured convolutional (RCPC) codes and sliding window ARQ, are employed. For this purpose, the time-varying behavior of atmospheric turbulence channels is first captured by a finite-state Markov chain. Then, the channel model is used to develop the burst loss model to analytically derive the system performance metrics, including throughput, energy efficiency, and average frame delay. The results quantitatively demonstrate the impact of atmospheric turbulence and pointing error on the system performance and support the optimal selection of parameters. Additionally, the effectiveness of the proposed system is numerically confirmed. Monte Carlo simulations are also performed to validate the accuracy of theoretical derivations. [ABSTRACT FROM AUTHOR]

Integrated satellite-terrestrial (IST) networks will play a promising role in future peer-to-peer (P2P) distribution by bridging multiple isolated P2P sub-networks to provide real-time cross-regional file access in certain scenarios. However, due to the periodic orbital movements of satellites, highly time-varying visibility among peer nodes in IST networks imposes significant challenge on file lookup and retrieval, which is difficult to be solved with current methods in terrestrial P2P networks. Therefore, in this paper, we propose a contact-aware dual-layer Chord (DL-Chord) lookup mechanism for P2P-based IST networks by carefully considering link contacts among satellites and terrestrial P2P nodes. In the proposed DL-Chord mechanism, we develop a group of novel algorithms, comprising an orbital parameter-based dual-layer identification mapping scheme, a contact-based dual-layer finger table, an efficient file lookup algorithm, and a node updating scheme. Furthermore, a theoretical analysis is conducted based on the visibility of satellite constellations to evaluate the lookup performance of the proposed DL-Chord mechanism, i.e., average lookup delay (ALD) and average lookup rounds (ALR). Simulation results verify that the proposed mechanism achieves better efficiency in terms of ALD and ALR with a lower update cost than other similar schemes, i.e., the stochastic mapping-based original chord ring scheme (ORCO) and physical location-aware mapping-based wireless location-aware scheme (WILCO). [ABSTRACT FROM AUTHOR]

Cooperative Intelligent Transportation Systems (C-ITS) improve driving experience and safety through secure Vehicular Ad-hoc NETworks (VANETs) that satisfy strict security and performance constraints. Relevant standards, such as the IEEE 1609.2, prescribe network-efficient cryptographic protocols to reduce communication latencies through a combination of the Elliptic Curve Qu-Vanstone (ECQV) implicit certificate scheme and the Elliptic Curve Digital Signature Algorithm (ECDSA). However, literature lacks open implementations and performance evaluations for vehicular systems. This paper assesses the applicability of IEEE 1609.2 and of ECQV and ECDSA schemes to C-ITSs. We release an open implementation of the standard ECQV scheme to benchmark its execution time on automotive-grade boards. Moreover, we evaluate its performance in real road and traffic scenarios and show that compliance with strict latency requirements defined for C-ITS requires computational resources that are not met by many automotive-grade embedded hardware platforms. As a final contribution, we propose and evaluate novel heuristics to reduce the number of signatures to be verified in real C-ITS scenarios. [ABSTRACT FROM AUTHOR]

Vehicular Ad hoc networks (VANETs) plays an important role in reducing casualties, optimizing traffic distribution and improving traffic efficiency. Nevertheless, with the rapid growth of vehicles, the existing VANETs computing capacity will not be able to guarantee the service quality due to inefficient signature verification and identification. In this paper a small-batch verification and identification scheme is presented to speed up the signature verification and the invalid signature identification. In the proposed scheme, according to the signature number and the historical signature error rate, we first build an optimization model, which transforms the problem how to divide a batch of signatures into several appropriate small-batches into an integer programming problem, and then stores the optimal batch solution table in roadside units (RSUs). Moreover, in view of the current task, RSU can automatically divide a batch of signatures into several appropriate small-batches. After then, any invalid signature in these small-batches can be quickly identified by using of the exponentiation method. Finally, by comparison with the existing schemes, the total time delay is reduced to 50% in optimal circumstances. Simulation results show that the proposed scheme can achieve fast signature verification and invalid signature identification. [ABSTRACT FROM AUTHOR]

Unmanned Aerial Vehicles (UAVs) domain has seen rapid developments in recent years. UAVs have been deployed for many applications and missions like data transmission, cellular service provisioning, and computational offloading tasks etc. Yet, UAV deployment is still limited, partially owing to the security challenges it poses. UAVs are particularly vulnerable to physical capture, cloning attacks, eavesdropping, and man in the middle attacks. To address some of these security problems, this paper develops an authentication protocol for use in UAV swarms. To ensure physical security and rapid authentication, the proposed protocol uses Physical Unclonable Functions (PUFs). The protocol achieves high scalability compared to the state of the art by authenticating multiple devices at once. The proposed protocol supports dynamic topologies and multi-hop communication by using spanning tree-based traversal. It is also resistant to mobility, device tampering attack, etc., and its improvements are achieved at significantly lower communication and communication cost as compared to state-of-the-art protocols. [ABSTRACT FROM AUTHOR]

This paper investigates the outage and throughput performance of full-duplex (FD) cooperative relaying (CR) based non-orthogonal multiple access system (NOMA) with energy harvesting (EH) i.e., FD-CR-EH-NOMA system. We consider a network scenario, where the base station (BS) serves two downlink users, with the near user configured as a FD relay to deliver messages to the far user. We derive analytical expressions for the outage probabilities experienced by the users and the system outage probability of FD-CR-EH-NOMA network under time switching relaying (TSR) protocol in the presence/absence of direct link from BS to the far user. Assuming imperfect successive interference cancellation (i-SIC), we derive analytical expressions for (i) optimal power allocation (OPA) factor at the BS and (ii) optimal time switching (OTS) factor at the relay that independently minimizes the system outage probability. Further, we use the alternating optimization technique to determine the jointly optimal power allocation and time switching factors that minimize the system outage probability. Furthermore, we determine the OTS factor that maximizes the asymptotic throughput of the system in the delay-limited transmission mode. With the help of numerical and simulation investigations, we show that the system outage and throughput of the considered network improve significantly under the proposed schemes. [ABSTRACT FROM AUTHOR]

This paper investigates the error bounds for distance estimation in visible light communication (VLC) systems. More precisely, we study the effect of signal-dependent shot noise (SDSN) on the estimation error bounds for both synchronous and asynchronous systems. Moreover, a bi-directional synchronization protocol is exploited, which can mitigate the effects of clock-biasing between the transmitter and receiver. The results demonstrate that SDSN negatively affects the distance estimation bounds for all considered scenarios. Furthermore, the bi-directional distance estimation protocol outperforms the directional estimation techniques even in the case of perfect synchronization between the transmitter and receiver. [ABSTRACT FROM AUTHOR]

With the increasing connectivity between the Electronic Control Units (ECUs) and the outside world, safety and security have become stringent problems. The Controller Area Network (CAN) bus is the most commonly used in-vehicle network protocol, which lacks security mechanisms by design, so it is vulnerable to various attacks. In this paper, we propose a novel intrusion detection model called CNN-LSTM with Attention model (CLAM) for the in-vehicle network, especially CAN. The CLAM model uses one-dimensional convolution (Conv1D) to extract the abstract features of the signal values at each time step and feeds it into the Bidirectional Long Short Term Memory (Bi-LSTM) to extract the time dependence. By combining the attention mechanisms, we calculate the weight of each hidden state output by Bi-LSTM and perform a weighted summation, so that the model focuses only on locally important time steps, which can improve the convergence speed of the model and prediction accuracy. The proposed model uses the bit flip rate to extract continuous signal boundaries in the 64-bit CAN data, so it does not need to parse the CAN communication matrix and is suitable for different vehicles. The extensive evaluation results demonstrate that our proposed CLAM model can effectively detect CAN attacks, with an average F1-score of 0.951 and an error rate of 2.16%. Compared with the work in related research fields, the accuracy of attack detection is improved by 2.5%. [ABSTRACT FROM AUTHOR]

This paper focuses on the performance analysis of point-to-point communication, where the source node is powered with a fixed-power battery as well as a harvest-use battery. A time-switching scheme is implemented such that in each time frame the source either harvests energy or sends information to the destination node. Since switching takes place within a communication time frame, energy harvesting may not necessarily be beneficial in terms of improving the maximum achievable spectral efficiency or the energy efficiency of system. Here, we investigate and provide conditions under which harvesting can improve the system performance. We consider a scenario where the transmission power from the fixed battery is constant. Closed-form expressions for the conditions under which energy harvesting is proven beneficial are provided. The effects of important parameters, namely, time switching parameter, circuit powers, and harvested energy, on the system performance and on the condition for harvesting beneficialness, are investigated and discussed. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the performance of a hybrid receiver-based simultaneous wireless information and power transfer (SWIPT) two-way relay network over Nakagami-m faded channels. A hybrid receiver is adopted at the relay node that utilizes both the time switching (TS) and power splitting (PS) protocols for energy harvesting and information transmission. Amplify-and-forward relaying protocol is utilized at the relay node to process the information in half-duplex mode. In the considered network, impact of a practical non-linear power amplifier (NLPA) at the relay node is considered. Selection combining is performed at the destination node to utilize the direct-link and relay assisted signals. For the considered system, the analytical expressions of outage probability (OP) and asymptotic OP are derived over Nakagami-m faded channels for both the integer and non-integer value of m. The analytical expression of the system throughput and energy efficiency of the considered network are also derived. Further, the analytical expression of ergodic capacity is derived in terms of the Meijer-G function. By utilizing a cumulative distribution function based approach, analytical expressions of average symbol error rate (ASER) for general order hexagonal quadrature amplitude modulation (QAM), general order rectangular QAM, and 32-cross QAM schemes are derived. For different QAM constellations, a comparative ASER analysis is also illustrated. Furthermore, the impact of TS factor, PS ratio, energy conversion efficiency, NLPA, and threshold data-rates on the considered network is also highlighted. Finally, Monte-Carlo simulations are performed for validation of the derived analytical expressions. [ABSTRACT FROM AUTHOR]

Autonomous Vehicles ($AV$ s) take advantage of Machine Learning (ML) for yielding improved experiences of self-driving. However, large-scale collection of $AV$ s’ data for training will inevitably result in a privacy leakage problem. Federated Learning (FL) is proposed to solve privacy leakage problems, but it is exposed to security threats such as model inversion, membership inference. Therefore, the vulnerability of the FL should be brought to the forefront when applying to $AV$ s. We propose a novel Byzantine-Fault-Tolerant (BFT) decentralized FL method with privacy-preservation for $AV$ s called BDFL. In this paper, a Peer-to-Peer (P2P) FL with BFT is built by extending the HydRand protocol. In order to protect their model, each $AV$ uses the Publicly Verifiable Secret Sharing(PVSS) scheme, which allows anyone to verify the correctness of encrypted shares. The evaluation results on the MNIST dataset have shown that introducing decentralized FL into $ AV$ area is feasible, and the proposed BDFL is superior to other BFT-based FL method. Furthermore, the experimental results on KITTI dataset indicate the practicality of BDFL on improving performances of multi-object recognition in $ AV$ areas. Finally, the proposed PVSS-based data privacy preservation scheme is also justified its characteristic of no side-effect on models’ parameters by the experiments on the MNIST and KITTI datasets. [ABSTRACT FROM AUTHOR]

Automated and coordinated vehicle platoon driving is challenging as the complexity of vehicle control and the presence of unreliable wireless inter-vehicle communication. This subject has an interdisciplinary nature, involving control theories, vehicle dynamics, and communication. Due to the constant interaction between control logic and communication topology, a co-design approach for the controller and for reliable communication protocol becomes necessary. This paper describes the AddP-CACC - a consensus-based solution to vehicle platoons. The proposed solution turns the communication topology into a design parameter that dynamically reconfigures the controller. In addition, the controller automatically compensates for outdated information caused by network losses and delays. AddP-CACC was implemented in the PLEXE tool and was compared with other related works. Simulation results have shown the robustness and performance of the proposed solution in various scenarios that would include realistic propagation conditions with interference caused by other vehicles. The results have also evidenced the ability of the proposed solution to maintain a stable vehicular platoon by using different communication topologies, different vehicle flows, even in the presence of strong interferences, delays, and fading conditions. [ABSTRACT FROM AUTHOR]

This paper deals with the coordinated control of the multiple high-speed train system taking into account the sampled characteristic of the communication information. Considering the inertial lag of the servo motor/braking unit in practical scenarios, a third-order nonlinear model is adopted to capture the dynamics of a train, based on which the coordinated control problem is formulated. By virtue of the back-stepping linearization technique, the sampled-data communication based train coordination is transformed to the stabilization of a linear multiple-input system subject to periodic time-varying input delay. An event-triggering communication framework is constructed to lower the dependence on the communication resource. Furthermore, distributed low-gain feedback control protocols are established that, besides achieving coordination of the train operation, ensure the trains track the predefined train speed profile while avoiding unnecessary information transmission. Numerical experiments are carried out to verify the theoretical results. [ABSTRACT FROM AUTHOR]

In the near future, Vehicle-to-Vehicle (V2V) transmission will enable wireless broadcast communication among nearby vehicles. Benefits for users include improved driver safety and potentially optimized traffic. However, this communication is vulnerable to cyber attacks involving message manipulation. Research aimed at tackling this problem has resulted in the proposal of multiple authentication protocols. The security, privacy, and other desirable features of authentication in vehicular networks have been widely studied. However, the efficiency of such authentication schemes has not been suitably addressed. There is no model to evaluate the efficiency of the proposals in a practical context, where the delay introduced by V2V authentication may impact on driver safety. In this paper, we provide such a model for evaluation. We explicitly present the key factors involved to evaluate the computational delay in the V2V authentication protocols. Our model has clearly defined metrics for computing the delay and evaluating the impact. Developing this model enables future research in the design of secure and efficient V2V authentication protocols suitable for practical application. Applying the model to assess proposed authentication protocols permits categorization based on safety service they can support. We demonstrate the applicability of our model through case studies. Our model can effectively analyze the delay introduced by an authentication protocol, and determine whether this would result in a crash, in the real world vehicular environments. [ABSTRACT FROM AUTHOR]

Wireless-powered communication and reconfigurable intelligent surface (RIS) can complement each other for increasing energy utilization and spectrum efficiency by reconfiguring the surrounding radio environment, however, which has not been sufficiently studied by the existing works. In this paper, we propose a joint radio resource and passive beamforming optimization scheme for a downlink RIS-assisted wireless-powered communication network with a harvest-then-transmit protocol to improve system energy efficiency (EE). In the considered model, the single-antenna wireless devices (WDs) harvest wireless energy from a multi-antenna dedicated power station (PS) through the RIS in the downlink and transmit their independent information to a single-antenna receiver in the uplink by a time-division-multiple-access mode. Our goal is to maximize the total EE of all WDs. To make full use of the beamforming gain provided by both the PS and the RIS, we jointly optimize the active beamforming of the PS and the passive beamforming of the RIS. To deal with the challenging non-convex optimization problem with multiple coupled variables, we first consider fixing the passive beamforming, and converting the remaining radio resource allocation problem into an equivalent convex problem which is solved by using Lagrange dual theory. Then, we fix the optimized resource allocation parameters and optimize the passive beamforming of the RIS by using a semidefinite programming method. Simulation results demonstrate that the proposed algorithm achieves higher EE compared to the conventional schemes. [ABSTRACT FROM AUTHOR]

Two-Way Ranging (TWR) is a widely used method for distance estimation in asynchronous wireless networks, but the deviation between the clocks can lead to errors in distance estimation. The ultra-wideband (UWB) technology provides the best accuracy in distance estimation, but total emission time is drastically limited by harmonized standards. Localization accuracy, latency and network scalability are key performance metrics in wireless location characterization. This article advances a new sequencing of the localization process, called Double-Beacon Two-Way Ranging (DB-TWR) algorithm, and presents the related time-of-flight (ToF) estimation formula, which is able to compensate for clock error and to reduce the localization period. The Fine Time Measurement (FTM) protocol, specified by the Wireless LAN (WLAN) standard, uses the TWR method and as a result the clock deviation leads to systematic errors in ToF estimation. The paper proposes two additional timestamp s captures and a new ToF computation formula which compensates for clock deviation. The article provides a theoretical analysis and extensive simulations of errors propagation in the ranging process, both as a mean and as an uncertainty, and proves that the designed algorithms cancel the clock offsets entirely. [ABSTRACT FROM AUTHOR]

Inspired by the group activities of natural swarms (e.g., a flock of birds, a colony of ants, etc.), a fleet of mobile robots can be collaboratively put into work to accomplish complex real-world tasks. Depending on the nature and complexity of a problem, a multi-robot system (MRS) may need to be decomposed into several subgroups. This paper proposes a unified group coordinated control scheme for networked MRSs having multiple targets. A ‘discontinuous’ cooperative control law is first developed for a networked MRS to achieve individual sub-formations surrounding the assigned targets. A ‘continuous’ cooperative control protocol is then proposed to overcome the chattering phenomenon often caused by a discontinuous control action during hardware implementation. The closed-loop stability of the overall networked MRS is guaranteed via the Lyapunov theory and boundary-layer techniques. Finally, two hardware experiments (target-enclosing and object transportation) involving real mobile robots have been carried out to demonstrate the usefulness of the proposed scheme. [ABSTRACT FROM AUTHOR]

This paper presents an adaptive broadcast interval for data dissemination for an infrastructure-to-vehicle (I2V) environment. The roadside units (RSUs) disseminate the data to the vehicles after a specified broadcast time interval. Time interval tuning for the data dissemination is one of the parameters used to determine the effectiveness of the broadcast time interval at RSU for safety and infotainment message dissemination to the vehicles under a particular RSU coverage. We formulated the problem of computing an optimal broadcast time interval to maximize the service ratio, reducing the duplicate message overhead. The proposed scheme uses the software-defined network (SDN) architecture having OpenFlow-enabled RSUs and SDN controllers. Based on the global view of traffic-related information, the proposed SDN controller computes the broadcast time interval for data dissemination among the vehicles. We used the NS-3 simulator to evaluate the proposed scheme's performance by generating a real scenario of VANET traffic using SUMO. Simulation results show that the proposed SDN-based scheme increases the average service ratio by 15-20% and reduces duplicate message overhead by 7-10% in comparison to the other existing state-of-the-art schemes. [ABSTRACT FROM AUTHOR]

The goal of this paper is to design a fully distributed event-triggered control policy with intermittent communication to reach leader-follower consensus of vehicular platoons with nonzero leader's input and actuator uncertainties. The time-dependent event-triggered condition in a fully distributed manner is proposed for checking the necessary data transmission time. Meanwhile, a distributed control law based on estimated state is developed when the event-triggered condition is violated, which ensures the platoon can reach bounded consensus with an exponential convergence rate. Compared with existing related results, the fully distributed event-triggered mechanism is independent of any global information or leader's information. Moreover, Zeno behavior can be strictly ruled out for each vehicle. Finally, the effectiveness of the proposed event-triggered control policy is validated by numerical examples. [ABSTRACT FROM AUTHOR]

Billions of mobile sensing devices in Internet of Things (IoT) collect data from surrounding environment in which the Medium Access protocol is employed. Quorum-based protocols are most important medium access control protocol (MAC) for wake-up based devices. However, existing quorum-based protocols cannot achieve both low latency and long lifetime at the same time. In this paper, a novel Element Shift Quorum (ESQ) based MAC is proposed in the sensor based systems. Data transmission is usually launched from the periphery of the network through multi hop routing to the data collector (DC), thus the data operation time of devices are different based on the distance from the DC. In the ESQ protocol, the Quorum time slot (QTS) of sensing devices is scheduled in the time when the devices just have data to process, then the latency and energy consumption can be reduced. In this way, sufficient QTS are allocated for nodes when data operation is needed, and nodes can stay at sleeping state when no data forwarding is required, thus enhancing the energy efficiency and lowering the network delay. Theoretical analysis and experimental results show that, the lifetime is increased by 16% using the proposed method. Meanwhile, the latency is reduced by a factor between 9.08%-29.32%. [ABSTRACT FROM AUTHOR]