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Network data constantly evolves with new network applications and protocols. There is a need for robust techniques to detect anomalous behaviour. Offline models trained with static data lose validity when new variants of traffic emerge. They require retraining but the need for ground truth and lengthy training times make this task challenging. Meanwhile, online models which detect outliers in streaming data are susceptible to the curse of dimensionality and natural variability. Today’s anomalies may be tomorrow’s new traffic and existing methods do not provide a way to differentiate between them. We propose a framework that makes the most of both approaches: an offline deep learning model extracts features of normal traffic and provides a bias for an online outlier detection model to select data for training. The online model retains its previously learnt knowledge and retrains itself with new data. Online thresholds are updated in a drifting manner and the Mann-Whitney U test is incorporated to prevent inaccurate updates. We perform analysis on the scores, develop heuristics to detect new traffic and evaluate using three deep learning models and four outlier detection methods on the UNSW-NB15 and CTU-13 datasets. The framework improves upon any individual offline or online models in isolation. [ABSTRACT FROM AUTHOR]

Emerging embedded systems, such as autonomous vehicles, demand highly efficient remote data transfer, whereas existing networking hardware and protocols cause high communication latency and CPU consumption. In this article, we propose embedded RDAC (eRDAC), an efficient and reliable remote direct access and control solution for embedded systems. The proposed remote access controller in eRDAC has a two-layer protocol offload engine that employs the command/response protocol on UDP to ensure the data reliability and security, and a multichannel DMA controller with configurable priority to improve the efficiency. Besides, a reusable hardware Ethernet MAC is implemented to support not only remote access commands but also standard Ethernet communication. We implement eRDAC on FPGA and the corresponding software in the Linux system. Experimental results show that eRDAC can reduce the latency of remote I/O reading/writing by 74.3%/74.9% ($3.76\times /3.98\times $ performance improvement) and reduce the latency of remote memory reading and writing with 1024B by 54.2% compared to the socket-based communication. Meanwhile, eRDAC can cut off the consumption of the remote processor and achieve 0.250mJ/Mb energy consumption with only 25-mW power. [ABSTRACT FROM AUTHOR]

Bundle protocol (BP) was proposed as the core protocol of delay/disruption-tolerant networking for space. A hybrid reliable transmission mechanism based on integrating "proactive" retransmission and "reactive" retransmission of BP bundles has been presented as a means of achieving highly reliable file/data delivery in deep-space communications. Transmission overhead imposed by reliable delivery of data packets/bundles is consistently one of the key factors for efficient data delivery in space communications. It is especially important in deep-space networks, where the available electrical power on spacecraft for data delivery is a scarce resource but substantial energy is needed to propagate data over an extremely long deep-space channel. In this article, a detailed study of the transmission overhead for the hybrid retransmission approach of BP for reliable deep-space communications is presented. An analytical framework is presented for modeling the transmission overhead of BP as influenced by variations in channel quality, file size, bundle size, and retransmission timeout interval length. Its energy resource consumption is also briefly discussed. The analytical framework is validated by realistic file transfer experiments using a PC-based testbed infrastructure; the framework is found to be able to predict the performance with respect to the transmission overhead of BP. [ABSTRACT FROM AUTHOR]

Entanglement-based quantum networks can provide unconditionally secure communication by distributing entangled pairs between distant end nodes. To achieve end-to-end entanglement distribution, multiple operations of entanglement swapping in a quantum repeater chain are always required. However, due to the non-determinism of entanglement swapping caused by imperfect physical devices, the execution pattern of swapping operations has a direct impact on the performance of entanglement distribution, which can be categorized into an entanglement access control (EAC) problem. In this article, we attribute the EAC problem to two aspects: the matching optimization within quantum nodes, and the swapping conflict avoidance between quantum nodes. Accordingly, we propose an asynchronous entanglement distribution protocol which contains a custom weighted maximum matching algorithm, and a reliable signaling interaction mechanism to avoid a swapping conflict, respectively. Based on the proposed protocol, quantum repeaters autonomously decide their behaviors and spontaneously construct the end-to-end entangled pairs asynchronously. Simulation results show that our protocol can significantly improve the entanglement distribution rate and fidelity of end-to-end entangled pairs while simplifying the deployment and management process of the quantum networks. [ABSTRACT FROM AUTHOR]

Due to the explosive increase of electric vehicles (EVs) and universal charging stations (CS), achieving fast authentication is an important topic in the vehicle-to-grid (V2G) network at present. Fast authentication cannot only forcefully defend potential adversaries but also can greatly speed up the charging process between EVs and CSs. Although many researchers have realized this problem and proposed some lightweight cryptographic protocols for fast EV charging, desired security features are not entirely satisfied, such as man-in-the-middle attacks, replay attacks, and impersonation attacks. In this article, we propose an ultra super fast authentication protocol for EV charging by utilizing the characteristics of extended chaotic maps. Furthermore, in view of the unsolved security issues mentioned previously, our proposed protocol can provide elaborate solutions to eliminate these possible attacks in a provable manner. Finally, compared with the relevant authentication protocols for V2G network, the communication and computation costs of our protocol are decreased a lot. [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]

Most existing network communication systems, such as the Internet, are built around the TCP/IP protocol stack. However, TCP/IP cannot effectively support the upcoming network communication systems with more wireless communication links and higher requirements in terms of throughput, latency, and reliability. In this article, we introduce a general network communication protocol design based on batched network coding (BNC), which includes the existing framework as a special case and whose design can be guided by channel coding theory. BNC-based protocols can have significant throughput gain for single-hop or multihop wireless communications and provide better trade-off among throughput, latency and reliability. [ABSTRACT FROM AUTHOR]

Satisfying the stringent 5G quality of service requirements necessitates efficient resource utilization by mobile networks. Consequently, we argue that multi-connectivity (MC) is an effective solution to leverage the limited radio resources from multiple base stations in order to enhance user throughput, provide seamless connectivity, and increase data reliability. For this, we study different MC architectures, where distinct network entities and protocol layers are used to split or aggregate the user traffic. The benefits and challenges of MC are analyzed as well as the open issues that network/device vendors and mobile network operators have to address for its use. Finally, through experimental evaluations, we illustrate the importance of MC design decisions for overall network performance. [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]

The low-rate denial of service (LDoS) attack mainly exploits security vulnerabilities of adaptive mechanisms in network protocols and application services. The high-rate attack pulses within a short time interval are sent periodically, which will result in the degradation of service quality. The attack traffic is similar to normal traffic from legitimate users in the network, consequently, it is easy to escape the traditional detection methods because of its intermittence. Research works have demonstrated that there are fractal characteristics (self-similarity) of the network traffic over the large scale of time. Although the fractal characteristics of the network traffic will be changed under the LDoS attack, the variations of the fractal characteristics in some network states are not apparent in real-time detection. Based on the fractal characteristics, the fractal residual of the network traffic is analyzed through the Hurst parameters calculating process by R/S algorithm in this article. It can be found that the fractal residual of the network traffic can better reflect the different states of the LDoS attack. Combining the idea behind the sliding window, a novel fractal residual based real-time detection (FR-RED) method of the LDoS attack is proposed. The effectiveness of the method in this article is verified by performing some experiments on two platforms, the NS2 and test-bed. The results manifest the beginning and end of the LDoS attack can be estimated in real-time with high detection accuracy. [ABSTRACT FROM AUTHOR]

Backscatter radio is an intriguing technology for Internet of Things applications, which enables ultra-low-power devices to communicate with each other. Most of the existing works on the combination of the backscatter communications and the “harvest-then-transfer” (HTT) protocol focus on the throughput maximization, yet the study on the energy efficiency (EE) maximization is still lacking. Driven by this observation, this paper studies the EE maximization for an RF-powered backscatter network with the HTT protocol. Multiple hybrid devices (HDs) can either use the backscatter mode by backscattering energy signals from the power beacon (PB) to the reader or use the HTT protocol to first harvest energy from the PB, and then to transmit data to the reader. The proposed scheme aims to optimize multiple parameters including PB's transmit power and time, HDs’ transmit power and time allocation between the backscatter mode and the HTT mode for maximizing the EE of all the HDs. An iterative algorithm is developed to find the optimal solution for the proposed resource allocation scheme. Simulation results demonstrate the superiority of the proposed scheme in terms of EE of all the HDs. [ABSTRACT FROM AUTHOR]

Named Data Networking (NDN) architectural features, including multicast data delivery, stateful forwarding, and in-network data caching, have shown promise for applications such as video streaming and file sharing. However, collaborative applications, requiring multi-producer participation, introduce new NDN design challenges. in this article, we highlight these challenges in the context of the Network Time Protocol (NTP) and one of its most widely-used deployments for NTP server discovery, the NTP pool project. We discuss the design requirements for the support of NTP and NTP pool and present general directions for the design of a time synchronization protocol over NDN, called Named Data Networking Time Protocol (NDNTP). [ABSTRACT FROM AUTHOR]

In this paper, we study the optimal power allocation for a radio frequency (RF)-powered cooperative network and propose energy-saving time switching relaying (ES-TSR) and energy-saving power splitting relaying (ES-PSR) protocols with an iterative energy-saving (ES) algorithm. In particular, we develop the analytical expressions of the channel capacity and the total energy consumption for the considered cooperative network. We formulate the system energy efficiency maximization problems and then provide the corresponding solutions by deriving the source's optimal transmit power in terms of energy fraction consumed with time switching (TS) factor and power splitting (PS) factor for the proposed ES-TSR and ES-PSR protocols, respectively, in each transmission block. From the past approaches, the optimal power allocation to maximize the system energy efficiency of the RF-powered cooperative networks has been studied under the assumption that the relay must utilize all of its harvested power in each transmission block. This work considers optimal power allocation to maximize the system energy efficiency for the case when the relay node can save energy for the next transmission block. Our simulation results show that the proposed ES-TSR and ES-PSR protocols outperformed the existing TS-based and PS-based relaying protocols with $\text{14.22}\%$ and $\text{8.4}\% $ , respectively, in paticular when the number of transmission blocks $\boldsymbol{L} = 10$. [ABSTRACT FROM AUTHOR]

This paper presents a protocol that enables an unlimited number of Wi-Fi users to position themselves within a meter-level accuracy and navigate indoors using time-delay-based Wi-Fi measurements. The proposed protocol, called collaborative time of arrival, is broadcast-based and relies on cooperation between the network sensors that support IEEE 802.11 fine-timing measurements (FTMs) capabilities, which are enabled in state-of-the-art Wi-Fi chipsets. The clients can estimate and track their position by passively listening to timing measurements that are exchanged between the FTM-sensors. The passive nature of the clients’ operation enables them to maintain their privacy by not exposing their presence to the network. This paper outlines the principles of the protocol and the mathematical background of the position estimation algorithms. Both theoretical analysis of the expected positioning accuracy, as well as real-life system performance examples, are provided. The protocol’s performance analysis is based on a publicly available database of real network measurements. [ABSTRACT FROM AUTHOR]

IoT has evolved from an experimental to a backbone technology able to connect myriads of people, things, and services for a large range of businesses. At the same time, the emergence of SDN can ideally handle IoT challenges for elasticity, heterogeneity, and mobility, offering an architecture that abstracts decision making away from the data plane and providing a programmable network facility. Along these lines, we propose MINOS, a multi-protocol SDN platform for IoT that implements service awareness utilizing appropriate SDN abstractions and interfaces for logically centralized network control of diverse and resource-constrained IoT environments, two network protocols that are deployable and configurable on demand, and a GUI that provides a bespoke dashboard and a real-time visualization tool. Due to its components, MINOS enables experimentation with novel network control features and protocols that realize optimized routing over heterogeneous IoT nodes, application of real-time strategies as a response to dynamic network conditions, support of individual protocol configurations per node, and flexibility to accommodate new protocols and control algorithms. Our results demonstrate MINOS as an enabling platform for two protocols, CORAL-SDN and Adaptable-RPL, which, in comparison with the state-of-the-art IoT routing protocol RPL, improve the packet delivery ratio with relatively small control overhead. [ABSTRACT FROM AUTHOR]

We describe a new vision of joint computation and communication resource management that goes beyond the end-to-end and client-server model of the current Internet. Enabled by a growing trend toward embedding processing and networking capabilities into "smart" network nodes and devices, for example, smartphones, watches, appliances, and automobiles, Dispersed Computing describes a new resource-centric architecture that leverages the diversity of networked computation points within the network, and the heterogeneity of network links and protocol stacks that connect them. We describe this new, resource-centric architecture as an evolution of both fog/edge networking and active networks. We illustrate the fundamental principles and the advantages over the current Internet architecture, and highlight several commercial use cases enabled by a dispersed computing architecture. [ABSTRACT FROM AUTHOR]

The increasing growth of Internet of Things (IoT) applications induces the need for easy integration of third-party peripherals, which is restricted in present IoT devices. In this paper, we present a novel plug-and-play (PnP) solution for the above stated problem. The proposed PnP solution, named SensPnP, is the combination of embedded hardware and firmware that has the capability of integrating third-party embedded sensors with the IoT devices without any prior information about the sensors and the Internet. We present an architecture of a PnP-enabled IoT device, which supports heterogeneous embedded peripheral communication protocols. A novel embedded protocol detection approach for enabling seamless integration of sensor with IoT device is proposed. To enable sensor communication, we propose an algorithm for automatic driver management of the connected sensor with an IoT device. This is achieved through a low-cost and low power switching and identification hardware with a light-weight identification and driver management firmware stack. To show the effectiveness of the proposed solution, we practically implemented a prototype in a real test-bed. The analysis of the PnP time, protocol identification time, the memory footprint, lifetime, and overall cost of the proposed PnP solution under different operating conditions establishes superiority of its circuitry and firmware. Experimental results show that SensPnP requires minimal memory footprint, reduced energy consumption, and reduced PnP time compared to the existing solutions. Additionally, the overall cost analysis shows that the cost of SensPnP is noticeably less compared to existing solutions. Thus, the cost-efficiency of SensPnP makes it more acceptable to the consumers when compared with existing solutions. [ABSTRACT FROM AUTHOR]

Wind energy is one of the most attractive and one of the fastest growing sources of green energy in the world. With the expansion of wind parks, there is a growing need for an efficient coordination of the diverse energy production systems, as well as a tighter coupling between the production and the consumer side of the grid. Current grid operators have unnecessarily high costs due to the lack of an integrated management system toward a diverse set of proprietary network protocols, complex and error prone operation of the networks, as well as rigid security mechanisms. Network softwarization concepts, that is, SDN and NFV, offer great potential for reducing capital and operational expenditures by providing simplified network management and automated control. Recent works have demonstrated the feasibility of achieving stringent industrial-grade quality of service and fine grain security control with SDN and NFV. In this article, we provide an insight into wind park communication network requirements, analyze the technological benefits of the network softwarization, and demonstrate the economic profits in a case study of a typical Northwestern Europe wind park. [ABSTRACT FROM AUTHOR]

A secret-key agreement for in-band full-duplex (FD) technology can be regarded as a valuable method for establishing security at the physical layer level. In this paper, we study an FD system model in conjunction with a secret-key agreement. The legitimate users interact through two-way channel probing and one-way reconciliation. We first introduce two complementary key generation models for FD and half-duplex (HD) settings, and compare their performances by introducing the key-reconciliation function. Furthermore, we study the impact of probing-reconciliation tradeoff and the role of a strong eavesdropper, and analyze the system performance in the high-signal-to-noise ratio regime. We show that under certain conditions, the FD mode negatively affects the capabilities of the eavesdropper and offers several advantages in terms of secret-key rate over the conventional HD setups. Our analysis reveals that the perfect self-interference cancelation is not necessary to obtain performance gains over the HD mode. [ABSTRACT FROM AUTHOR]

With the development of vehicle networks, the information transmission between vehicles is becoming increasingly important. Many applications, particularly regarding security, are based on communication between vehicles. These applications have strict requirements for factors such as the quality of communication between vehicles and the time delay. Many theoretical communication protocols ignore the presence of buildings or other obstacles that are present during practical use, especially in urban areas. These obstacles can cause a signal to fade or even block direct communication. Many vehicles are often parked at the roadside. Because of their location, these parked vehicles can be used as relays to effectively reduce the shadowing effect caused by obstacles and even solve communication problems. In this paper, we study the problem of parked-vehicle-assistant relay routing communication in vehicle ad hoc networks. We propose an efficient parked vehicle assistant relay routing algorithm that is composed of four parts: a periodic Hello packet exchange mechanism, candidate relay list update, communication link quality evaluation, and candidate relay list selection. Simulation results reveal obvious advantages for indexes such as the quality of communication, success rate, and time delay. [ABSTRACT FROM AUTHOR]

Content caching on the edge of 5G networks is an emerging and critical feature to quench the thirst for content of future connected cars. However, the tight packaging of 5G cells, the finite storage capacity at the edge, and the need for content availability while driving motivate the need to develop smart edge caching strategies adapted to the mobility characteristics of connected cars. In this paper, we propose a scheme called RoadsIde CacHe (RICH), which optimally caches content at edge nodes where connected vehicles require it most. In particular, our scheme is designed to ensure in-order delivery of content chunks to end users. Unlike blind popularity decisions, the probabilistic caching used by RICH accounts for the user mobility information that the system can realistically acquire. Furthermore, we provide a complete system architecture and define the protocols through which the different system entities can interact. We assess the performance of our approach against state-of-the-art solutions, under realistic mobility datasets and system scenarios. Our RICH edge caching scheme improves significantly the content availability at the caches and reduces the required backhaul bandwidth, with beneficial effects for both the end users and the network operators. [ABSTRACT FROM AUTHOR]

The number of IoT devices has been growing significantly, and mobile network traffic is also increasing explosively. In order to meet the human desire to explore unknown areas, edgeless communications have always been one of the directions for the development of wireless networks. H-STIN is a promising solution to face the problem of large bandwidth requirement, massive machine type communication, and edgeless communication requirements. However, it is difficult to integrate communication protocols, routing problems, and resource allocation in the large-scale and heterogeneous network architecture. Therefore, this article proposes a potential H-STIN architecture based on the development trends of the Internet of Things, mobile networks, and satellite networks. Since TN has adequate computation resource and routing architecture, the backbone network is given to support an entire network, and AS is adopted to achieve regional self-optimization. The SSTIS is composed of the perception layer, the cognition layer, and the intelligence layer. It integrates IoT, SDN, and network functions virtualization technologies to achieve self-monitoring, crisis forecasting, and optimal control. Finally, the promising technical challenge, including integrated route planning and large-scale resource allocation, is given. [ABSTRACT FROM AUTHOR]

Existing CoAP primarily focuses on communication (i.e., client/server-based request/response interaction) between constrained devices in a constrained network. Constrained networks may have large latencies and constrained devices may not be able to respond in a timely manner. Therefore, incorporating delay awareness in the CoAP protocol may prove beneficial for communications between devices. This article presents a new method to support a delay-aware CoAP messaging model, where a Delay- Indicator is proposed to be contained in messages to reflect delay tolerance information. Furthermore, the DelayIndicator can be leveraged by CoAP Clients and CoAP Servers to improve their operations of entering sleep mode to save energy while not violating delay tolerances. With this new enabler, a timeout mechanism for CoAP Responses is put forward to enhance CoAP performance. Simulation results show that incorporating delay awareness in CoAP significantly improves messaging performance. [ABSTRACT FROM AUTHOR]

Multimedia cloud computing has appeared as a very attractive environment for the business world in terms of providing cost-effective services with a minimum of entry costs and infrastructure requirements. There are some architecture proposals in the related literature, but there is no multimedia cloud computing architecture with hybrid features specifically designed for mobile devices. In this article, we propose a new multimedia hybrid cloud computing architecture and protocol. It merges existing private and public clouds and combines IaaS, SaaS and SECaaS cloud computing models in order to find a common platform to deliver real time traffic from heterogeneous multimedia and social networks for mobile users. The developed protocol provides suitable levels of QoS, while providing a secure and trusted cloud environment. [ABSTRACT FROM AUTHOR]

Fuel utilization efficiency and cost reduction are two major goals in designing in-vehicle networks. Aiming to address these two issues, we investigate in-vehicle networking protocols from both wired and wireless perspectives by first presenting representative solutions in each area, then identifying the challenges to current solutions, and finally advocating the use of the automotive Ethernet. Also, we propose a priority-based scheduler for the automotive Ethernet. Our preliminary experiments show that the proposed scheduler is effective and flexible, and thus is applicable to next-generation in-vehicle networks. We hope that further studies in this area can be inspired by our work and will be forthcoming in years to come. [ABSTRACT FROM AUTHOR]

Network latency and reliability are becoming critical performance indicators for future mission critical services based on wireless connectivity. In this article we present a portable and low-cost measurement framework for quantifying the endto- end (E2E) latency and reliability of communication systems based on single or multiple links. The proposed framework is tailored for characterization of access diversity mechanisms, for example, multi-connectivity or hybrid access methods, which are expected to be essential for ultra-reliable wireless communications in 4G and 5G networks. An active-probe measurement approach is adopted, consisting of a client that transmits timestamped packets to a server, and vice versa, via one or multiple communication links under test. The setup allows us to measure the one-way latency performance in uplink and downlink separately, and allows fully synchronized measurements of multiple links in parallel to understand the benefits of multi-connectivity mechanisms. Traffic generation is flexible in terms of packet size, transport protocol (TCP or UDP), and inter-arrival time interval of the generated packets, hence being a powerful tool for benchmarking the performance for different application-specific message flows. Special emphasis is put on the tail of the latency distribution, that is, the latency that can be achieved with a certain probability constraint, for example, 99.9 percent or beyond. Given the challenge of measuring such rare events, we measure and validate the stability of the measurement equipment to ensure that the observed performance is not compromised by undesired behavior or malfunction of the equipment. The system has a measurement error below 400 μs with 99.9 percent confidence and below 3.1 ms with 99.999 percent confidence. The capability and applicability of the measurement framework is illustrated by a measurement test of two simultaneous LTE connections that provide robust communications to an aerial drone. [ABSTRACT FROM AUTHOR]

In real-time systems, the application’s behavior has to be predictable at compile-time to guarantee timing constraints. However, modern streaming applications which exhibit adaptive behavior due to mode switching at run-time, may degrade system predictability due to unknown behavior of the application during mode transitions. Therefore, proper temporal analysis during mode transitions is imperative to preserve system predictability. To this end, in this paper, we initially introduce mode-aware data flow (MADF) which is our new predictable model of computation to efficiently capture the behavior of adaptive streaming applications. Then, as an important part of the operational semantics of MADF, we propose the maximum-overlap offset which is our novel protocol for mode transitions. The main advantage of this transition protocol is that, in contrast to self-timed transition protocols, it avoids timing interference between modes upon mode transitions. As a result, any mode transition can be analyzed independently from the mode transitions that occurred in the past. Based on this transition protocol, we propose a hard real-time analysis as well to guarantee timing constraints by avoiding processor overloading during mode transitions. Therefore, using this protocol, we can derive a lower bound and an upper bound on the earliest starting time of the tasks in the new mode during mode transitions in such a way that hard real-time constraints are respected. [ABSTRACT FROM AUTHOR]

The amazing proliferation of communication technologies for embedded systems opens the way for completely new applications but forces designers to adopt new methodologies to meet time-to-market constraints. Computer-Aided Design (CAD) has been traditionally applied to computers and embedded systems in isolation without considering them as a global inter-connected system. The paper contributes to fill this gap by proposing 1) a communication-aware design flow for network-interconnected embedded systems and 2) a formal framework to efficiently synthesize their network aspects by formulating and solving an optimization problem. Presented case studies show the potentiality of the proposed approach to address heterogeneous scenarios, e.g., related to smart spaces up to the ever-more-mentioned Internet-of-Things. [ABSTRACT FROM AUTHOR]

In this paper, a relay based network is considered where the source transmits confidential message to the destination via a nonregenerative relay. Due to the fact that the relay is unidentified, and thus may wiretap the relayed message from source to destination. In this regard, two new half-duplex nonorthogonal amplify-and-forward (NAF) secure communication protocols are proposed, with different assumptions on the transmission ability of the destination, i.e., NAF-I for destination without transmission ability and NAF-II for destination with transmission ability. We separately derive the sufficient and necessary conditions to yield positive secrecy rate for these protocols under fixed source/destination transmission power, and discuss their joint power allocation that maximizes the system secrecy rate. Despite the nonconvexity of the considered power allocation problems, alternative optimization approach is proved useful in dealing with these problems, and the corresponding algorithms are proposed. We further prove the convergence of the proposed algorithms and analyze their complexity. The discussion is also extended to the orthogonal amplify-and-forward (OAF) based protocols, i.e., OAF-I or OAF-II, for comparison purpose. Our numerical results demonstrate the gain of the secrecy rate performance of the proposed NAF protocols over existing transmission protocols, and also verify the effectiveness of the designed alternative optimization algorithms. [ABSTRACT FROM AUTHOR]

This paper considers a wireless powered communication network, where a multiantenna power beacon (PB) is employed to assist an energy constrained source to establish secure communications with a destination in the presence of multiple eavesdroppers. We propose a two-phase communication protocol termed as accumulate then transmit to enhance network secrecy. In the energy harvesting phase, the PB transfers radio frequency energy to charge the source; then in the information transmission phase, the PB acts as a friendly jammer to protect the source transmission against eavesdropping. We study the dynamic energy state transitions at the source using an energy discretization method and a finite-state Markov chain. Closed-form expressions are derived for connection outage probability, secrecy outage probability, and effective secrecy throughput, with the aim to evaluate both reliability and security of the proposed protocol. Furthermore, numerical results reveal the impacts of various system parameters on the secrecy performance and demonstrate the superior performance of our proposed protocol over an existing scheme. [ABSTRACT FROM AUTHOR]

The amount and diversity of devices that integrate connection capabilities continues to grow, and both the public and private sectors continue to explore various application areas and paradigms that involve these connected objects. Yet as the IoT field evolves, so too must its security capabilities. This article presents an analysis of IoT security issues and an overview of the current and future trends in this area. [ABSTRACT FROM AUTHOR]

Network slicing is a fundamental capability for future Fifth Generation (5G) networks to facilitate the cost-effective deployment and operation of multiple logical networks over a common physical network infrastructure in a way that each logical network (i.e. network slice) can be customized and dimensioned to best serve the needs of specific applications (e.g. mobile broadband, smart city, connected car, public safety, fixed wireless access) and users (e.g. general public, enterprise customers, virtual operators, content providers). The practical realization of such capability still raises numerous technical challenges, both in the Core and RAN parts of the 5G system. Through a comprehensive analysis of the impact that the realization of RAN slicing has on the different layers of the radio interface protocol architecture, this article proposes a framework for the support and specification of RAN slices based on the definition of a set of configuration descriptors that characterize the features, policies and resources to be put in place across the radio protocol layers of a next-generation RAN node. [ABSTRACT FROM PUBLISHER]

A cooperative wireless-powered communication network protocol is proposed, in which user far away from a hybrid access point (H-AP) is capable of harvesting wireless powers by overhearing the uplink signals of users that are relatively nearer to the H-AP, in addition to downlink signal broadcast by the H-AP. In this setting, time allocations for the downlink transmission of the H-AP and the uplink transmission for the users are jointly optimized for two different purposes. First, the weighted sum-rate maximization problem is solved for a given total transmission time. Then, the total transmission time is minimized under a minimum rate constraint, and an efficient algorithm is also presented to solve the optimal solution by a line search strategy. Numerical results demonstrate that the proposed schemes significantly increase the far user's rate, which in turn improves user fairness and transmission delay. [ABSTRACT FROM PUBLISHER]

We consider the secrecy rate for the multiple-input single-output optical wireless scattering communication, where the detected signal can be characterized by discrete photoelectrons. Assuming a legitimate receiver and an eavesdropper, we propose two secure communication protocols, the non-jamming protocol, and the cooperative jamming protocol, where for the former the transmitter does not send jamming signals but for the latter the transmitter sends jamming signals. We formulate the corresponding power and duty cycle optimization problems for both protocols. We also analyze the properties on the optimal solution, and adopt the alternating optimization to obtain a tractable solution. Moreover, we analyze the condition on the positive secrecy rate for the case where all the sub-channels to the receiver are weaker than their counterparts to the eavesdropper, where the secrecy transmission cannot be realized via a non-jamming protocol. The performance of the proposed two protocols is evaluated by numerical results. It is seen that for the iterative optimization solution, two to three iterations suffice for the convergence of the secrecy rate. [ABSTRACT FROM AUTHOR]

Multimedia cloud computing has appeared as a very attractive environment for the business world in terms of providing cost-effective services with a minimum of entry costs and infrastructure requirements. There are some architecture proposals in the related literature, but there is no multimedia cloud computing architecture with hybrid features specifically designed for mobile devices. In this article, we propose a new multimedia hybrid cloud computing architecture and protocol. It merges existing private and public clouds and combines IaaS, SaaS and SECaaS cloud computing models in order to find a common platform to deliver real time traffic from heterogeneous multimedia and social networks for mobile users. The developed protocol provides suitable levels of QoS, while providing a secure and trusted cloud environment. [ABSTRACT FROM AUTHOR]

Opportunistic routing and network coding are two promising techniques that have been proposed for wireless networks. These techniques have significantly improved the performance of multi-hop wireless networks by utilizing the broadcast nature of wireless media and optimizing the capacity of lossy wireless networks. Recent research has shown that the combination of opportunistic routing and network coding in a single joint protocol outperforms each of them individually. This article explains the motivation and interaction effect of the joint protocols. We provide a taxonomy of joint protocols and illustrate the benefit and cost by highlighting their fundamental components and comparing different solutions. We also present a conclusion along with the outline of future research direction. [ABSTRACT FROM AUTHOR]

Fuel utilization efficiency and cost reduction are two major goals in designing in-vehicle networks. Aiming to address these two issues, we investigate in-vehicle networking protocols from both wired and wireless perspectives by first presenting representative solutions in each area, then identifying the challenges to current solutions, and finally advocating the use of the automotive Ethernet. Also, we propose a priority-based scheduler for the automotive Ethernet. Our preliminary experiments show that the proposed scheduler is effective and flexible, and thus is applicable to next-generation in-vehicle networks. We hope that further studies in this area can be inspired by our work and will be forthcoming in years to come. [ABSTRACT FROM AUTHOR]

The problem of device-independent randomness amplification against no-signaling adversaries has so far been studied under the assumption that the weak source of randomness is uncorrelated with the (quantum) devices used in the amplification procedure. In this paper, we relax this assumption, and reconsider the original protocol of Colbeck and Renner using a Santha-Vazirani (SV) source. To do so, we introduce an SV-like condition for devices, namely that any string of SV source bits remains weakly random conditioned upon any other bit string from the same SV source and the outputs obtained when this further string is input into the devices. Assuming this condition, we show that a quantum device using a singlet state to violate the chained Bell inequalities leads to full randomness in the asymptotic scenario of a large number of settings, for a restricted set of SV sources (with 0 \leq \varepsilon < (2^(1/12) - 1)/(2(2^(1/12) + 1)) \approx 0.0144 ). We also study a device-independent protocol that allows for correlations between the sequence of boxes used in the protocol and the SV source bits used to choose the particular box from whose output the randomness is obtained. Assuming the SV-like condition for devices, we show that the honest parties can achieve amplification of the weak source, for the parameter range $0 \leq \varepsilon <0.0132$ , against a class of attacks given as a mixture of product box sequences, made of extremal no-signaling boxes, with additional symmetry conditions. Composable security proof against this class of attacks is provided. [ABSTRACT FROM PUBLISHER]

Today, millions of physical devices are visible on the Internet through IP addresses, such as wearables, residential routers, cameras and industrial control devices. Users can access and control online devices, while attackers also target them, bringing potential security concerns. In this article, we propose a conceptual framework for discovering, recognizing and managing these online devices at the Internet-wide scale. It is the first work of Internet-wide device search, including three modules: network measurement, fingerprinting, and applications. We have implemented a prototype system and real-world experiments to illustrate the effectiveness of the framework. Furthermore, we explore the use and application of the system through searching camera devices in the whole IPv4 space. We deployed the system on Amazon EC2 to search for webcams and ICS devices nine times from April 2015 to April 2016, and we found 1.3 million webcams in total. In a comprehensive analysis of our dataset, we have characterized the use of online physical devices on the Internet. [ABSTRACT FROM AUTHOR]

M2M communication is an important component for future wireless networks. M2M systems consist of a large number of devices that can operate with minimum or no human intervention. However, spectrum demand rises exponentially with the increase in the number of connected devices. Cognitive 5G networks are key to address the issue of spectrum scarcity. Further, use of multiple gateways in cognitive 5G networks for M2M communication can increase system throughput, coverage, and energy efficiency. Nevertheless, using multiple gateways for the secondary M2M devices may cause interference to the primary M2M devices. Existing gateway selection protocols for cognitive M2M communication mostly use single channel CSMA, and thus are not efficient in terms of reducing the interference. Thus, in this article, we propose a DGAP based on multi-channel CSMA for M2M communication in 5G networks. Further, we propose a Lo-DGAP, where each gateway transmits only the worst primary M2M device information rather than transmitting all neighboring primary M2M device information. The proposed Lo-DGAP increases the throughput of the system by reducing the message header payload and is also energy- efficient. Simulation results demonstrate the effectiveness of the proposed schemes in terms of network lifetime and energy consumption. [ABSTRACT FROM AUTHOR]

As we enter the era of many-core, providing the shared memory abstraction through cache coherence has become progressively difficult. The standard directory-based coherence does not scale well with increasing core count. Timestamp-based hardware coherence protocols introduced recently offer an attractive alternative solution. This paper proposes a timestamp-based coherence protocol, called TC-Release++ , that efficiently supports cache coherence in large-scale systems. Our approach is inspired by TC-Weak, a recently proposed timestamp-based coherence protocol targeting GPU architectures. We first design TC-Release in an attempt to straightforwardly port TC-Weak to general-purpose many-cores. But re-purposing TC-Weak for general-purpose many-core architectures is challenging due to significant differences both in architecture and the programming model. Indeed the performance of TC-Release turns out to be worse than conventional directory protocols. We overcome the limitations and overheads of TC-Release by exploiting simple hardware support to eliminate frequent memory stalls, and an optimized lifetime prediction mechanism to improve cache performance. The resulting optimized coherence protocol TC-Release++ is highly scalable (storage scales logarithmically with core count) and shows better performance (3.0 percent) and comparable network traffic (within 1.3 percent) relative to the baseline MESI directory protocol. We use Murphi to formally verify that TC-Release ++ is error-free and imposes small verification cost. [ABSTRACT FROM PUBLISHER]

On-chip bus implementations must be bug-free and secure to provide the functionality and performance required by modern system-on-a-chip (SoC) designs. Regardless of the specific topology and protocol, bus behavior is never fully specified, meaning there exist cycles/conditions where some bus signals are irrelevant, and ignored by the verification effort. We highlight the susceptibility of current bus implementations to Hardware Trojans hiding in this partially specified behavior, and present a model for creating a covert Trojan communication channel between SoC components for any bus topology and protocol. By only altering existing bus signals during the period where their behaviors are unspecified, the Trojan channel is very difficult to detect. We give Trojan channel circuitry specifics for AMBA AXI4 and advanced peripheral bus (APB), then create a simple system comprised of several master and slave units connected by an AXI4-Lite interconnect to quantify the overhead of the Trojan channel and illustrate the ability of our Trojans to evade a suite of protocol compliance checking assertions from ARM. We also create an SoC design running a multiuser Linux OS to demonstrate how a Trojan communication channel can allow an unprivileged user access to root-user data. We then outline several detection strategies for this class of Hardware Trojan. [ABSTRACT FROM AUTHOR]

The Internet of Things has been widely deployed in various areas of daily life through heterogeneous communications protocols. Each unstandardized protocol focuses on a specific IoT communication pattern. Inspired by the Internet architecture over which divergent devices can easily be accessed and a considerable number of applications can be run, we propose a generic architecture for IoT. This architecture supports two DIY areas: network DIY for data aggregation and application DIY for service cooperation. To connect these two DIYs, a centralized controller has been designed to provide standardized interfaces for data acquisition, organization, and storage, and to support elastic and supportive computing. With these properties, divergent devices can coexist in a uniform microworld, and rich services can be developed and provided on demand to interoperate with physical devices. This article discusses the background, design principles, and advantages of the proposed architecture, as well as open problems and our initial solution, which substantiates a novel IoT architecture and new research ground. [ABSTRACT FROM PUBLISHER]

Wireless customers expect to have a guaranteed quality of experience at all times, at any location, and through different devices. Wi-Fi has become an access network of preference for service/ network providers and customers as well for public and private access. This sets a challenging requirement for next-generation Wi-Fi technology to provide seamless and uniform network quality of service). Consequently, the necessity for self-optimization of network and radio frequency segments becomes critical. This article surveys challenges and use cases of Wi-Fi self-optimizing networks (Wi-SONs) that have not been presented to date. We address technology and design challenges that shape Wi-SON as a very complex problem. [ABSTRACT FROM PUBLISHER]

Toward ITS, academia and industry aim to utilize all possible radio access technologies in order to support reliable services and applications in VANETs. Thus, the inclusion of already deployed Wi-Fi networks in VANET topology is a crucial step for the next generation vehicular networks. However, the VANET topology also requires preservation of the features already offered by DSRC and the core cellular network. As a result, the coexistence of multiple different access technologies results in high complexity in terms of the control and management of the network infrastructure. To this end, software defined networking provides a promising opportunity to simplify the management and control of clumsy network infrastructures by decoupling the data and control planes in order to provide elasticity for current networks. In this article, we propose an architectural model that exploits this opportunity in order to enhance VANET with Wi-Fi access capability. Moreover, we offer a novel software defined VANET architecture that consists of soft OpenFlow switches with Wi-Fi capabilities as both roadside units and vehicles. In particular, we first investigate existing test tools and environments for software defined wireless networks and also supply a novel testbed architecture in order to provide a feasible test environment for evaluating the proposed architecture. Additionally, we propose a Wireless Access Management (WAM) protocol that provides wireless host management and basic flow admission with respect to the available bandwidth to validate the capability of the offered architecture. The observation results of the deployed testbed prove the conformity of the offered 802.11 architecture to the VANET. [ABSTRACT FROM PUBLISHER]

We provide a framework to analyze multi-level checkpointing protocols, by formally defining a k -level checkpointing pattern. We provide a first-order approximation to the optimal checkpointing period, and show that the corresponding overhead is in the order of \sum _{\ell =1}^{k}\sqrt{2\lambda _\ell C_\ell} , where \lambda _\ell$ is the error rate at level  $\ell$ , and $C_\ell$ the checkpointing cost at level $\ell$ . This nicely extends the classical Young/Daly formula on single-level checkpointing. Furthermore, we are able to fully characterize the shape of the optimal pattern (number and positions of checkpoints), and we provide a dynamic programming algorithm to determine the optimal subset of levels to be used. Finally, we perform simulations to check the accuracy of the theoretical study and to confirm the optimality of the subset of levels returned by the dynamic programming algorithm. The results nicely corroborate the theoretical study, and demonstrate the usefulness of multi-level checkpointing with the optimal subset of levels. [ABSTRACT FROM AUTHOR]

Modern planetary scale distributed systems largely rely on a State Machine Replication protocol to keep their service reliable, yet it comes with a specific challenge: latency, bounded by the speed of light. In particular, clients of a single-leader protocol, such as Paxos, must communicate with the leader which must in turn communicate with other replicas: inappropriate selection of a leader may result in unnecessary round-trips across the globe. To cope with this limitation, several all-leader and leaderless alternatives have been proposed recently. Unfortunately, none of them fits all circumstances. In this article we argue that the “right” choice of the number of leaders depends on a given replica configuration and the workload. Then we present \mathsf Droopy and \mathsf Dripple , two sister approaches built upon state machine replication protocols. \mathsf Droopy dynamically reconfigures the set of leaders. Whereas, \mathsf Dripple coordinates state partitions wisely, so that each partition can be reconfigured (by \mathsf Droopy ) separately. Our experimental evaluation on Amazon EC2 shows that, \mathsf Droopy and \mathsf Dripple reduce latency under imbalanced or localized workloads, compared to their native protocol. When most requests are non-commutative, our approaches do not affect the performance of their native protocol and both outperform a state-of-the-art leaderless protocol. [ABSTRACT FROM AUTHOR]

This paper is concerned with the performance analysis of a dual-hop random access network, where a single gateway is employed to connect a random number of independent users which are hidden from their destination(s). The gateway is an amplify-and-forward (AF) relay and is the only mean to connect users to their destinations. We develop accurate mathematical models for the multiple access interference, which take into account, in addition to the distribution of the number of active users and their random locations, the effects of fading and thermal noise at both the relay and destinations. A new unified mathematical method is developed, which leads to the derivation of new analytical expressions for the overall spectral efficiency of the dual-hop random access network over Rayleigh- and Nakagami- m fading channels. The accuracy of the new mathematical results is confirmed by Monte Carlo simulation. The results of this paper can be used to estimate the aggregate throughput of a dual-hop system employing the slotted-Aloha-type protocols. [ABSTRACT FROM AUTHOR]

We focus on protocols for auditable restoration of distributed systems. The need for such protocols arises due to conflicting requirements (e.g., access to the system should be restricted but emergency access should be provided). One can design such systems with a tamper detection approach (based on the intuition of In-case-of-emergency-break-glass). However, in a distributed system, such tampering, which are denoted as auditable events, is visible only for a single node. This is unacceptable since the actions they take in these situations can be different than those in the normal mode. Moreover, eventually, the auditable event needs to be cleared so that system resumes the normal operation. With this motivation, in this paper, we present two protocols for auditable restoration, where any process can potentially identify an auditable event. The first protocol has an unbounded state space while the second protocol uses bounded state space that does not increase with the length of the computation. In both protocols, whenever a new auditable event occurs, the system must reach an auditable state where every process is aware of the auditable event. Only after the system reaches an auditable state, it can begin the operation of restoration. Although any process can observe an auditable event, we require that only authorized processes can begin the task of restoration. Moreover, these processes can begin the restoration only when the system is in an auditable state. Our protocols are self-stabilizing and can effectively handle the case where faults or auditable events occur during the restoration protocol. Moreover, they can be used to provide auditable restoration to other distributed protocols. [ABSTRACT FROM PUBLISHER]

Cache coherence plays a major role in manycore systems. The verification of deadlocks is a challenge in particular, because deadlock freedom is an emerging property. Formal methods often decouple verification of the protocol from verification of the communication interconnect. Modern communication fabrics, however, become more advanced and include a network topology, routing, arbitration, synchronization, and more. In this paper, an integrated approach is proposed that allows cross-layer verification of both the cache coherence protocol and the communication fabric all at once. An automated methodology for deriving cross-layer invariants is proposed. These invariants relate the state of the application-layer protocols to en route packets in the communication fabric. Using the invariants, we derive formal proofs of deadlock-freedom for two case studies: a directory-based MI protocol in a 2D mesh, and a ring-based snoopy protocol in a 2D torus. Additionally, we show that our methodology can be used to derive the smallest possible queue sizes that ensure absence of deadlocks. Our methodology is generally applicable and shows promising scalability. [ABSTRACT FROM PUBLISHER]