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This paper proposes a distributed protocol for tracking the global maximum supremum (or minimum infimum) of a set of exogenous time-varying signals. Specifically, each agent has only access to one of these signals and, by implementing the proposed protocol, it is able to track in finite-time the maximum supremum (or the minimum infimum) of the exogenous time-varying signals in a distributed fashion. No assumption is made on the network size and, remarkably, the communication graph is directed (possibly switching) with the only requirement to be strongly connected at all times. The behavior of the protocol with open networks is discussed and numerical simulations are provided to corroborate the theoretical findings. [ABSTRACT FROM AUTHOR]

Abstract Boosted by trends such as Industrial IoT and Industry 4.0, industrial Ethernet networks (EtherNet/IP, EtherCAT and PROFINET IRT as top-3 players) have been commonly deployed in industrial automation. The aim of this paper is to provide a practical guideline for selecting the right protocol in industrial networked control systems (NCSs) by comparing the performance of these protocols. Communication delays are discussed, formulated and evaluated with a study of a typical NCS. Simulation results demonstrate that with different frame packing, media access scheme, etc., EtherNet/IP, EtherCAT and PROFINET IRT offer different levels of real-time capabilities which lead to different control performance. Highlights • EtherCAT, PROFINET IRT and EtherNet/IP offers various real-time capabilities. • A generic process is established to evaluate communication and control performance. • A guideline to choose the right protocol for a networked control system is provided. [ABSTRACT FROM AUTHOR]

Abstract Mobile sink has been used by many routing algorithms to improve the network lifetime in wireless sensor networks. Sink mobility brings new challenges to the sensor network. It suggests that sink position is continuously propagated through the network area to keep all sensor nodes updated with the direction of forwarding data to the sink. Unfortunately, frequent sink position updates can lead to both high-energy consumption and increased collisions in the network. In this paper, a new routing algorithm for wireless sensor networks is proposed, which uses a virtual multi-ring shaped infrastructure to advertise the mobile sink position to the network. In addition, the proposed algorithm supports several mobile sinks in the network. Simulation results indicate that the proposed algorithm reduces energy consumption and delay, and prolongs the sensor network lifetime when compared with the other similar algorithms. [ABSTRACT FROM AUTHOR]

Abstract Intelligent Transportation Systems use Vehicular Ad-hoc Networks to improve road safety. Dedicated Short Range Communications (DSRC or IEEE 802.11p) and Wireless Access in Vehicular Environments (WAVE or IEEE 1609 protocol suite) are the two important standards that govern communication in VANETs. However, DSRC based VANETs cannot guarantee to achieve the Quality of Service (QoS) requirements like reliability and latency under high vehicle density scenario due to network congestion. This paper studies the congestion behavior of IEEE802.11p/1609.4 based Medium Access Control by varying vehicle density in urban and highway conditions. Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is the default medium access mechanism in WAVE MAC. The metrics chosen for evaluating the performance of CSMA/CA are the average end-to-end delay, average throughput, packet delivery ratio, packet loss ratio and the number of packets lost. The simulation is carried out for both urban and highway scenario under varying vehicle density and communication load. The Simulation is performed using Omnet++ and SUMO based veins framework. The simulation results show that under high vehicle density and high communication load, CSMA/CA fails to meet the required QoS. [ABSTRACT FROM AUTHOR]

A cryptographic electronic voting system is proposed, to replace the conventional voting methods, which are widely used in most developing countries in the Middle East and North Africa (MENA) region. The proposed e-voting system is based on the concept of Prêt à Voter, which is a paper ballot e-voting scheme. Mixnet based e-voting schemes such as Prêt à Voter use mix servers to create anonymous channels. These schemes have some shortcomings; Mixnets need complex protocols for generating and maintaining shared mix keys, as well as for mixing and proving correctness of the shuffles. Moreover, Mixnets are complex to implement on a large scale. Mixnets are also vulnerable to corrupt or faulty mix servers as well. The proposed e-voting scheme eliminates the need for anonymous channels to anonymize the votes in Mixnet based e-voting schemes, yet provides comparable level of security and vote anonymity with less system complexity. The proposed e-voting scheme uses paper ballots, due to its familiarity among the public, but with strong cryptographic algorithms with proven security features, to provide enhanced level of ballot secrecy, verifiability and security. The proposed scheme is simple, secure, practical, and auditable. Security evaluation is conducted based on the critical and desirable properties of e-voting to support the claimed aspects. Threat analysis of the proposed e-voting system had been conducted to prove its resistance to well-known attacks on e-voting schemes and systems. A proof of concept implementation and simulation of the proposed e-voting scheme was developed to elucidate its efficiency, practicality, and scalability. The research proposal has the potential to be deployed as a trustworthy e-voting system, to replace the conventional voting methods in developing countries. [ABSTRACT FROM AUTHOR]

To investigate the energy consumption involved in a sampled-data consensus process, the problem of guaranteed cost consensus for sampled-data linear multi-agent systems is considered. By using an input delay approach, an equivalent system is constructed to convert the guaranteed cost consensus problem to a guaranteed cost stabilization problem. A sufficient condition for guaranteed cost consensus is given in terms of linear matrix inequalities (LMIs), based on a refined time-dependent Lyapunov functional analysis. Reduced-order protocol design methodologies are proposed, with further discussions on determining sub-optimal protocol gain and enlarging allowable sampling interval bound made as a complement. Simulation results illustrate the effectiveness of the theoretical results. [ABSTRACT FROM AUTHOR]

In order to increase the probability of delivering warning messages to all vehicles (or nodes) in the Zone Of Relevance (ZOR), Vehicular Ad Hoc Networks (VANETs) adopt the periodical broadcast to disseminate warning messages. The broadcast way brings the problem of how to set the suitable message lifetime for the propagation of the warning message. To tackle the aforementioned problem, this work adopts the following four steps to analyze the event-driven warning message propagation process and suggest a suitable message lifetime for the Vehicle-to-Vehicle (V2V) network. At first, an analytical model was proposed to investigate the event-driven warning message propagation process in a connected network, and thus assure that it is difficult to guarantee all nodes in the ZOR being in the same partition. Next, an analytical model was proposed to investigate the event-driven warning message propagation process in a partitioned network, and then the probability of delivering warning messages to all nodes in the ZOR for different traffic conditions is derived. Furthermore, to reduce redundancy caused by multi-hop broadcast, an direction-aware broadcast protocol was proposed for the partitioned network according to the proposed analytical models. At last, the impact of traffic characteristics on the setting of the suitable message lifetime was evaluated through numerical and simulation results. The results shown that the warning message propagation process depends on the traffic characteristics, e.g., nodes’ density, nodes’ speed and the dangerous time. The results also shown that when the message lifetime increases to certain values for different traffic conditions, the delivery probability is not increased, but just consuming power and causing serious redundancy. As a result, the work shown that the suitable message lifetime should be set according to the traffic condition of involved nodes. [ABSTRACT FROM AUTHOR]

This paper studies the potential of a novel approach to ensure more efficient and intelligent assignment of capacity through medium access control (MAC) in practical wireless sensor networks. Q-Learning is employed as an intelligent transmission strategy. We review the existing MAC protocols in the context of Q-learning. A recently-proposed, ALOHA and Q-Learning based MAC scheme, ALOHA-Q, is considered which improves the channel performance significantly with a key benefit of simplicity. Practical implementation issues of ALOHA-Q are studied. We demonstrate the performance of the ALOHA-Q through extensive simulations and evaluations in various testbeds. A new exploration/exploitation method is proposed to strengthen the merits of the ALOHA-Q against dynamic the channel and environment conditions. [ABSTRACT FROM AUTHOR]

Many applications of Wireless Sensor Networks such as Airborne Ad-hoc Networks (AANETs) or Underwater Wireless Sensor Networks (UWSNs) require the network architecture to be three-dimensional. In this paper, we present a terrestrial three-dimensional network architecture as well as protocol stack deployment for static sensor nodes placed at varying heights. A Dynamic Cluster-Based TDMA MAC (DCB-TDMA MAC) protocol has been developed for this network and simulated using Cooja platform. Cluster-Head nodes are rotated based on residual energy in order to maximize the lifetime of the network. Detailed working of protocol involving Time Synchronization, MAC, Cluster-Head rotation, Dynamic Routing is provided in this paper along with simulation results and analysis. [ABSTRACT FROM AUTHOR]

This paper is concerned with the state estimation problem for a class of artificial neural networks (ANNs) without the assumptions of monotonicity or differentiability of the activation functions. The measured outputs are corrupted by stochastic noise signal whose intensity is quantified by a nonlinear function. In order to accommodate the bandwidth limit of the communication channel between the ANN and the state estimator, an equal allocation scheme (i.e. Round-Robin protocol) of the communication resource is employed to effectively mitigate data congestions and save energies. A set of zero-order holders (ZOHs) is utilized to store the received measurements, such that the utilization of the received measurements can be maximized. An update matrix approach is developed to handle the time-varying yet periodic time-delays resulting from the adoption of the Round-Robin protocol. The aim of the proposed problem is to design a state estimator such that the error dynamics is exponentially ultimately bounded. A combination of the Lyapunov stability theory and the stochastic analysis technique is used to derive some easy-to-test conditions for the existence of the desired state estimator. The estimator gains are characterized by the solution to a convex optimization problem that is solved via the semi-definite programme method. Simulation results are given to demonstrate the effectiveness of the proposed estimation approach. [ABSTRACT FROM AUTHOR]

The CoRE working group at the IETF has proposed a Resource Directory (RD) solution to facilitate the discovery of the resources provided by constrained wireless sensor and actuator networks. For such a mechanism to be effectively deployable, nodes must first discover the existence of an RD in the network before being able to exploit its functionalities. This paper presents Proactive RD Discovery (PRD); a scalable, reliable, and effective mechanism to discover an RD. To achieve such qualities, the proposed mechanism deploys adaptive Trickle timers. PRD is implemented in Contiki OS and evaluated using emulated sensor/actuator nodes in the Cooja simulator. Simulation results show important performance enhancements in terms of energy consumption, generated traffic, RD discovery time, and reliability when compared with the default discovery mechanism bundled with the RD. [ABSTRACT FROM AUTHOR]

Designing a lightweight, secure communication protocol for Wireless Sensor Networks (WSNs) remains a challenging issue since sensor networks are resource limited and are left unattended. Sensor nodes in WSNs are subjected to varying forms of attacks. An adversary may destroy or damage the communications done in multi-hop WSNs by means of packet dropping and modification. Hence it is essential to have an efficient cryptographic scheme to protect the communications done in WSNs. This study introduces a Reliable Anonymous Secure Packet forwarding (RASP) scheme that can prevent not only traffic analysis attack but also the attacks done through compromised forwarding nodes. The mechanisms followed here are effective with low computation and communication overhead. The performance of the proposed scheme is evaluated over NS2 with a series of simulation. The simulated results show that the proposed scheme performs better than other comparable schemes. [ABSTRACT FROM AUTHOR]

In this paper we propose a novel distributed local interaction protocol for networks of multi-agent systems (MASs) in a multi-dimensional space under directed time-varying graph with the objective to achieve secure rendezvous or static containment within the convex hull of a set of leader agents. We consider the scenario where a set of anonymous adversarial agents may intrude the network (or may be hijacked by a cyber-attack) and show that the proposed strategy guarantees the achievement of the global objective despite the continued influence of the adversaries which cannot be detected nor identified by the collaborative agents. We characterize the convergence properties of the proposed protocol in terms of the characteristics of the underlying network topology of the multi-agent system. Numerical simulations and examples corroborate the theoretical results. [ABSTRACT FROM AUTHOR]

Connected dominating sets (CDSs) can be used as virtual backbones in mobile ad hoc networks (MANETs) to simplify the design of network primitives and improve their performance. An ideal CDS protocol for MANETs should create a small CDS and adapt to nodal mobility. Unfortunately, none of the CDS protocols capable of mobility handling have been shown to create a sub-optimal CDS in the past. In this paper, we first prove that our timer-based CDS protocols create a CDS with a sub-optimal size. Although the approximation factors of our timer-based protocols are not the best known result, our protocols can easily accommodate nodal mobility. In addition, we propose the Extended Mobility Handling (EMH) procedures for timer-based CDS protocols to further enhance CDS maintenance in MANETs. Simulation results show that our protocols incorporating EMH successfully prolong the CDS service time while maintaining a competitive size of CDS in MANETs. [ABSTRACT FROM AUTHOR]

Energy management techniques are significant for upcoming new generation networks to increase the lifetime of the network. An energy harvesting (EH) device converts different form of environmental energy to electricity and supplies to the intermediate nodes in the network. In this paper, an efficient energy scavenging scheme is proposed in multiple relay network, where the users cooperate each other to deliver the data to destination. Here, decode and forward (DF) relay protocol is considered in which the intermediate relay node acts as an energy harvesting device which receives signal from the source, scavenges energy from the environment and uses this energy to forward the information from source to destination. In the proposed work, first serial topology model is considered. The throughput maximization problem is formulated at individual user and relay using power splitting relay (PSR) and time switching relay (TSR) protocols. Second, the above problems are formulated in parallel topology model. Here, wireless network with three relay nodes are considered under two different traffic conditions: delay constrained (DC) and no delay constrained (NDC). Further, DC and NDC results are compared where NDC outperforms DC traffic conditions. Simulation results show that the throughput obtained via PSR protocol is larger compared to TSR protocol. Also, with the increase in number of EH nodes between source and destination throughput and life time of the network increases which finds application in 5G networks. Structural realization and analysis pertaining to power and throughput are implemented in MATLAB. [ABSTRACT FROM AUTHOR]

We introduce and describe here MICHE-I, a new iris biometric dataset captured under uncontrolled settings using mobile devices. The key features of the MICHE-I dataset are a wide and diverse population of subjects, the use of different mobile devices for iris acquisition, realistic simulation of the acquisition process (including noise), several data capture sessions separated in time, and image annotation using metadata. The aim of MICHE-I dataset is to make up the starting core of a wider dataset that we plan to collect, with the further aim to address interoperability, both in the sense of matching samples acquired with different devices and of assessing the robustness of algorithms to the use of devices with different characteristics. We discuss throughout the merits of MICHE-I with regard to biometric dimensions of interest including uncontrolled settings, demographics, interoperability, and real-world applications. We also consider the potential for MICHE-I to assist with developing continuous authentication aimed to counter adversarial spoofing and impersonation, when the bar for uncontrolled settings raises even higher for proper and effective defensive measures. [ABSTRACT FROM AUTHOR]

Vehicular ad hoc networks have emerged as a promising research area. Designing a realistic coverage protocol for RSU deployment in vehicular networks presents a challenge due to different service area, assorted mobility patterns, and resource constraints. In order to resolve these problems, this paper proposes a geometry-based sparse coverage protocol GeoCover , which aims to consider the geometrical attributes of road networks, movement patterns of vehicles and resource limitations. By taking the dimensions of road segments into account, GeoCover provides a buffering operation to suit different types of road topology. By discovering hotspots from trace files, GeoCover is able to depict the mobility patterns and to discover the most valuable road area to be covered. To solve the resource-constrained coverage problem, we provide two variants of sparse coverage which take into consideration budget constraints and quality constraints, respectively. The coverage problem is resolved by both genetic algorithm and greedy algorithm. The simulation results verify that our coverage protocol is reliable and scalable for urban vehicular networks. [ABSTRACT FROM AUTHOR]

The two important requirements for many Wireless Senor Networks (WSNs) are prolonged network lifetime and end-to-end reliability. The sensor nodes consume more energy during data transmission than the data sensing. In WSN, the redundant data increase the energy consumption, latency and reduce reliability during data transmission. Therefore, it is important to support energy efficient reliable data transport in WSNs. In this paper, we present a Hierarchical Energy Efficient Reliable Transport Protocol (HEERTP) for the data transmission within the WSN. This protocol maximises the network lifetime by controlling the redundant data transmission with the co-ordination of Base Station (BS). The proposed protocol also achieves end-to-end reliability using a hop-by-hop acknowledgement scheme. We evaluate the performance of the proposed protocol through simulation. The simulation results reveal that our proposed protocol achieves better performance in terms of energy efficiency, latency and reliability than the existing protocols. [ABSTRACT FROM AUTHOR]

In Underwater Acoustic Sensor Networks (UASNs), fundamental difference between operational methodologies of routing schemes arises due to the requirement of time-critical applications therefore, there is a need for the design of delay-sensitive techniques. In this paper, Delay-Sensitive Depth-Based Routing (DSDBR), Delay-Sensitive Energy Efficient Depth-Based Routing (DSEEDBR) and Delay-Sensitive Adaptive Mobility of Courier nodes in Threshold-optimized Depth-based routing (DSAMCTD) protocols are proposed to empower the depth-based routing schemes. The proposed approaches formulate delay-efficient Priority Factors (PF) and Delay-Sensitive Holding time ( DS HT) to minimize end-to-end delay with a small decrease in network throughput. These schemes also employ an optimal weight function WF for the computation of transmission loss and speed of received signal. Furthermore, solution for delay lies in efficient data forwarding, minimal relative transmissions in low-depth region and better forwarder selection. Simulations are performed to assess the proposed protocols and the results indicate that the three schemes largely minimize end-to-end delay of network. [ABSTRACT FROM AUTHOR]

Wireless sensor networks (WSNs) keep attracting the attention of researchers due to the newly emerging areas of application fueled by the development of inexpensive sensors and advanced communication technologies. A large group of applications - monitoring of pipelines, roads and bridges, as well as recently evolving IoT applications - specifically requires linear topology. Compared to traditional WSNs, these linear wireless sensor networks (LWSN) pose additional challenges in terms of overall delay and energy efficiency. Even though there are numerous and also very successful MAC protocols for WSN, very few of them take into consideration the specifics of linear topologies. Thus our aim is to address these challenges by proposing LINE-MAC, a MAC protocol tailored especially for LWSN. Our simulation results show that LINE-MAC achieves significant improvement in end-to-end delay, energy consumption and packet delivery ratio (PDR) compared to a general, energy and delay efficient MAC protocol for WSN. [ABSTRACT FROM AUTHOR]

The location-based routing protocol has been chosen as one of the efficient routing approaches in vehicular ad hoc networks in terms of low overhead and high scalability. Its critical advantage lies in performing a pathless routing such that a node having a packet forwards it to its neighbor node that provides the shortest physical distance to destination and this process continues until the packet reaches destination. The problem lies in that the link stability of the neighbors varies largely depending on the mobility of vehicles and the environmental factors that incur shadowing and fading effects. In this paper, we propose a new link quality prediction metric associated with location based protocols to improve the selection of next hop, that consider both the link quality assessment based on the transmission success rate and the link quality assessment based on the prediction of the future locations of vehicles. Simulation results are presented to demonstrate the efficiency of the proposed metric. [ABSTRACT FROM AUTHOR]

Abstract: Research on vehicular communications has been quite extensive over the past few decades. Most of the initial studies were theoretical and research has just recently moved to more experimental works. Conducting real field operational tests is extremely challenging due to the number of vehicles required, the lack of control over the environment and the cost of the necessary equipment and personnel. However, simulation tools may not reflect properly the highly dynamic and complex characteristics of the vehicular scenario. This article explores why practical research in the field of vehicular communications is so demanding, by reporting on our experience in prototyping and experimentally evaluating VARON. Published in 2008, VARON is a multi-hop wireless vehicular communication protocol which was already validated via extensive simulations. In this work, we have fully implemented it, first on a lab-based environment, and then in a real-life testbed. This long and exhausting process has shown that some common assumptions do not necessarily hold when evaluated under real situations, as well as taught us valuable lessons on how to design and conduct experiments with real vehicles. We believe that the experience and lessons learned during this process do not only apply to VARON, but also to other multi-hop wireless vehicular communication solutions, and that therefore these lessons are helpful for other researchers willing to validate their protocols in a real scenario. [Copyright &y& Elsevier]

Abstract: DCCP (Datagram Congestion Control Protocol) is a transport layer protocol that provides congestion control for unreliable data transmission. The congestion control mechanism embedded in DCCP adjusts the packet sending rate according to network condition. However, DCCP does not discriminate congestion losses and wireless link errors resulted from fading and thus it leads to unnecessary rate adjustment. In this paper, we proposed a mechanism to enhance bandwidth utilization of DCCP over wireless network. We employed a cross-layer loss discrimination scheme to distinguish congestion loss and fading loss. The cross-layer based mechanism detects frame loss in the data link layer in real-time to infer the actual fading loss rate. Thereafter, the fading loss can be excluded from the packet loss observed in the transport layer. Once the accurate congestion loss rate is calculated, the sender can make appropriate adjustment on the transmission rate that reflects the current congestion state along the transmitting path using the DCCP rate control procedure. Simulation results show that DCCP with our proposed CCID 3 rate control scheme can discriminate fading loss and achieve from 4.7% to 15.5% improvement on transmission throughput when the fading loss rate varies from 5% to 15% in wireless network. [Copyright &y& Elsevier]

Abstract: In this paper we present a multicast protocol for short range networks that exploits the characteristics of physical layer network coding. In our proposed protocol, named CooPNC, we provide a novel cooperative approach that allows collision resolutions with the use of an indirect inter-network cooperation scheme. Through this scheme, we provide a reliable multicast protocol for partially overlapping short range networks with low control overhead. We show that with CooPNC higher throughput and energy efficiency are achieved, while it presents lower delay compared to state of the art multicast protocols. We provide an overview of our protocol with a simple scenario of overlapping networks and we then generalise its operation for a scalable scenario. Through mathematical analysis and simulations we prove that CooPNC presents significant performance gains compared to the state of the art in multicast communications for short range networks. [Copyright &y& Elsevier]

Abstract: Gorrieri and Martinelli’s timed Generalized Non-Deducibility on Compositions ( ) schema is a well-known general framework for the formal verification of security protocols in a concurrent scenario. We generalise the schema to verify wireless network security protocols. Our generalisation relies on a simple timed broadcasting process calculus whose operational semantics is given in terms of a labelled transition system which is used to derive a standard simulation theory. We apply our framework to perform a security analysis of three well-known key management protocols for wireless sensor networks: , LEAP+ and LiSP. [Copyright &y& Elsevier]

Highlights: [•] Extended simulations for AODV, DSDV, and DSR routing protocols on MGM, GMM, and RPGM mobility models in addition to RWPM. [•] Longer duration considered for simulation of routing protocols over mobility models and first 500s discarded. [•] Results will help researchers to decide which routing protocol is better for which mobility model. [ABSTRACT FROM AUTHOR]

Abstract: Multi-hop broadcast is a critical component in embedded communication systems. Some vehicular ad-hoc network (VANET) applications in particular use broadcast communications extensively. Statistical broadcast methods offer an efficient means of propagating broadcast messages in this context due to their low overhead and high efficiency. Currently, five fundamental statistical broadcast methods are known: stochastic, counter, distance, location, and the latest method, distance-to-mean (DTM). Utilizing positional information, the DTM method calculates the spatial mean of the neighbors from which a node has received the message, then finds the distance from the node to that of spatial mean. This distance is used as the variable to discriminate between rebroadcasting and non-rebroadcasting nodes. Simulation results are presented exploring the reachability characteristics of DTM, indicating a behavioral phase transition with respect to decision threshold. Detailed comparative evaluations of a straightforward protocol built using DTM show it is more efficient than a similar protocol built using the distance method. DTM is also compared to p-persistence and is shown to exhibit a higher level of reachability across a broad range of scenarios. [Copyright &y& Elsevier]

Abstract: The credibility of mobile ad hoc network simulations depends on accurate characterisations of user behaviour, e.g., mobility and application usage. If simulated nodes communicate at different rates to real nodes, or move in an unrealistic fashion, this may have a large impact on the network protocols being simulated and tested. Many future mobile network protocols, however, may also depend on future mobile applications. Different applications may be used at different rates or in different manners. But how can we determine realistic user behaviour for such applications that do not yet exist? One common solution is again simulation, but this time simulation of these future applications. This paper examines differences in user behaviour between a real and simulated mobile social networking application through a user study (n =80). We show that there are distinct differences in privacy behaviour between the real and simulated groups. We then simulate a mobile opportunistic network application using two real-world traces to demonstrate the impact of using real and simulated applications. We find large differences between using real and synthetic models of privacy behaviour, but smaller differences between models derived from the real and simulated applications. [Copyright &y& Elsevier]

Abstract: Optical burst switching is a switching technology that is able to provide viable switching for optical internet with the present day technology. This paper presents a new medium access protocol for wavelength division multiplexing based optical burst switched metro ring network namely distributed queue optical burst switched ring (DQOBSR). It is a slotted, distributed queue access protocol with fixed bus structure and simple wavelength assignment. The topology consists of two unidirectional, counter rotating rings and the medium access protocol is based on distributed queuing. The protocol provides zero blocking with acceptable access delays. A mathematical model is also presented to determine the mean access delay which is the important performance parameter for the protocol. The simulation and model based results are compared and found to be in good agreement. [Copyright &y& Elsevier]

Abstract: Molecular communication is a nanoscale communication paradigm that utilizes molecules as a communication medium between nanoscale devices. Development and availability of simulators is critical in this emerging research area since research on molecular communication heavily depends on simulations as the only means to evaluate analytical models and protocols. This paper proposes a simulation framework for neuron-based molecular communication, which utilizes electrochemical signals through neuronal networks. The proposed framework is designed to integrate various simulation components such as visualizers and editors for neuronal networks, media access controllers to neuronal networks and communication schedulers for neuronal signal transmissions. This paper describes key simulation components in the proposed framework and validates them with a case study that implements a TDMA-based signaling protocol in a simulated neuronal network and examines its performance characteristics with evolutionary multiobjective optimization algorithms. [Copyright &y& Elsevier]

Abstract: Recently, LR-PON is considered as a desirable technology to provide a large scale of optical access cover. Upstream transmission (from ONUs to OLT) and downstream transmission (from OLT to ONUs) have been well studied in existing LR-PON architectures. However, little attention has been paid to efficient peer-to-peer communication which is extremely demanding in LR-PON. Therefore, in this paper, we will propose a decentralized LR-PON architecture supporting direct peer-to-peer communication among ONUs. Then a decentralized bandwidth allocation protocol which dedicates to maximize network throughput is proposed for efficient peer-to-peer communication and protecting peer-to-peer communication from the risk of OLT failure. The simulations demonstrate the effectiveness of our work. [Copyright &y& Elsevier]

Abstract: In vehicular ad hoc networks, many applications require a low latency and high reliability especially the safety applications. Reliable multi-hop broadcast protocols have been widely discussed recently. However, most of them use explicit acknowledgments and timeout retransmissions to provide reliability. The retransmission method incurs delays when a packet loss cannot be detected on time. Acknowledgment messages also increase the MAC layer contention time at each node. In order to provide a high reliability and low latency with a low overhead, we propose a mechanism which utilizes path diversity. In the proposed mechanism, a message is delivered through two different paths. By cooperation of these different paths, broadcast messages can be disseminated with a short delay and a high reliability compared with the acknowledgment based retransmission approach. Since the proposed mechanism does not use any explicit acknowledgment message, the message overhead is low. We evaluate the proposed mechanism using both theoretical analysis and computer simulations. [Copyright &y& Elsevier]

Abstract: Event monitoring is a common application in wireless sensor networks. For event monitoring, a number of sensor nodes are deployed to monitor certain phenomenon. When an event is detected, the sensor nodes report it to a base station (BS), where a network operator can take appropriate action based on the event report. In this paper, we are interested in scenarios where the event must be reported within a time bound to the BS possibly over multiple hops. However, such event reports can be hampered by compromised nodes in the middle that drop, modify, or delay the event report. To defend against such an attack, we propose Sem, a Secure Event Monitoring protocol against arbitrary malicious attacks by Byzantine adversary nodes. Sem provides the following provable security guarantees. As long as the compromised nodes want to stay undetected, a legitimate sensor node can report an event to the BS within a bounded time. If the compromised nodes prevent the event from being reported to the BS within the bounded time, the BS can identify a pair of nodes that is guaranteSchool of Electrical and Computer Engineeringed to contain at least one compromised node. To the best of our knowledge, no prior work in the literature can provide such guarantees. Sem is designed to use the minimum level of asymmetric cryptography during normal operation when there is no attack, and use cryptographic primitives more liberally when an attack is detected. This design has the advantage that the overall Sem protocol is lightweight in terms of the computational resources and the network traffic required by the cryptographic operations. We also show an operational example of Sem using TOSSIM simulations. [Copyright &y& Elsevier]

Abstract: To provide a common ground for the comparison of real-time multicore synchronization protocols we developed a framework that supports heterogenous levels of abstraction for simulated functionality and simulated timing. Our intention is to make the simulator available to the real-time research community and industrial users. For the latter we initially focus on automotive real-time systems. This paper describes the simulation framework and the novel idea of heterogenous abstraction levels that lies at the heart of its design. Notwithstanding the clear focus, we believe that the simulator itself as well as the concept of heterogenous abstraction levels can be useful in a significantly broader way. [Copyright &y& Elsevier]

Abstract: Femtocells are a promising technology to improve network performance with the short-range, low-power, and cost-beneficial small base stations. A femtocell is a low-power wireless access point that operates in licensed spectrum to connect a standard device to an operator’s network using a digital subscriber line (DSL) connection. Most of the energy consumption of the telecommunication networks is caused by the base stations. It is important to reduce the energy consumption of the base stations for green ICT (information and communication technology). A two-tier orthogonal frequency-division multiple access (OFDMA) macro-femtocell network is a key issue to significantly reduce the total power consumption of the base stations. In this paper, we develop a green handover protocol in two-tier OFDMA macrocell–femtocell networks. The green handover protocol allows the femtocell base station to completely switch off its radio communication and associated processing when not involved in an active call. To improve the energy efficiency of femtocell base station, the proposed green handover protocol intelligently switches on its radio communication and associated processing, or called a “wake up” from the idle mode, if the remaining data of a mobile host can be completely uploaded through the wake-up femtocell base station. Finally, the mathematical analysis and the performance simulation illustrate that the proposed protocol provides a more power-saving result compared with existing energy-saving handover protocols. [Copyright &y& Elsevier]

Abstract: This work extends our research on motion coordination of free-range vehicular systems based on concepts and results borrowed from resource allocation systems (RAS) theory, to vehicular systems with limited communication range among the vehicles. Similar to the earlier work, the employed model assumes the tessellation of the motion plane into cells, which are allocated to the traveling vehicles in a controlled manner that ensures collision-free and live motion. On the other hand, the limited communication range of the vehicles implies that full synchronization of their access to the considered cells is not possible any more, and yields new challenges for the deployed supervisory control policies. To enable the development of supervisory policies capable of providing the necessary partial synchronization of the cell allocation, we modify the structure of the adopted tessellation by allowing the concurrent occupation of a cell by up to two vehicles at a time, instead of only one, that was assumed earlier. This modification renders polynomially computable the relevant maximally permissive cell allocation policy, and it enables the implementation of this policy in the form of a distributed protocol that is feasible in the context of the communication constraints that are considered in this work. [Copyright &y& Elsevier]

Abstract: Gossiping, which broadcasts the message of every node to all the other nodes, is an important operation in multi-hop wireless networks. Interference-aware gossiping scheduling (IAGS) aims to find an interference-free scheduling for gossiping with the minimum latency. Previous work on IAGS mostly assumes that nodes are always active, and thus is not suitable for duty-cycled scenarios. In this paper, we investigate the IAGS problem in uncoordinated duty-cycled multi-hop wireless networks (IAGS-UDC problem) under protocol interference model and unbounded-size message model. We prove that the IAGS-UDC problem is NP-hard. We propose two novel algorithms, called MILD and MILD-R, for this problem with an approximation ratio of at most 3β 2(Δ +6)∣T∣, where β is , α denotes the ratio of the interference radius to the transmission radius, Δ denotes the maximum node degree of the network, and ∣T∣ denotes the number of time slots in a scheduling period. The total numbers of transmissions scheduled by both two algorithms are at most three times as large as the minimum total number of transmissions. Extensive simulations are conducted to evaluate the performance of our algorithms. [Copyright &y& Elsevier]

Abstract: The paper studies decentralized stabilizability for multi-agent systems with general linear dynamics. The stabilizability problem is formulated in a way that the protocol performance can be evaluated by means of the stabilizability region and the feedback gain. For fixed topology, it is proved that the system is stabilizable if and only if external control inputs are exerted on some indicated agents. The result is further shown to be a prerequisite for subsequent design of the corresponding decentralized external self-feedback control, which is also necessary and sufficient. Based on this, two methods are presented to find the agents under which stabilizability can be reached, and the region of stabilizability is given to evaluate the protocol performance. For switching interaction topology, it is shown that the system is stabilizable even if each of its subsystems is not. Finally, the results are employed to cope with the decentralized set-point formation control problem, for which some necessary and/or sufficient conditions are developed. Numerical simulations are presented to demonstrate the effectiveness of the proposed results. [Copyright &y& Elsevier]

Abstract: Polling is a widely used generic Media Access Control (MAC) scheme in Wireless Sensor Networks. In this paper, we proposed a new mechanism that improves the performance of the existing polling mechanism of a recent defined MAC protocol, baseline BAN MAC. In our mechanism, the poll message is placed inside the ACK packet. As a result, throughput is improved and latency is reduced. Simulations are performed on OMNeT++ based simulator Castalia and the results show that our method provides higher performance than the Poll mechanism used in baseline BAN MAC. [Copyright &y& Elsevier]

Abstract: In recent few years Wireless Sensor Networks (WSNs) have seen an increased interest in various applications like border field security, disaster management and medical applications. So large number of sensor nodes are deployed for such applications, which can work autonomously. Due to small power batteries in WSNs, efficient utilization of battery power is an important factor. Clustering is an efficient technique to extend life time of sensor networks by reducing the energy consumption. In this paper, we propose a new protocol; Energy Consumption Rate based Stable Election Protocol (ECRSEP). Our CH selection scheme is based on the weighted election probabilities of each node according to the Energy Consumption Rate (ECR) of each node. We compare results of our proposed protocol with Low Energy Adaptive Clustering Hierarchy (LEACH), Distributed Energy Efficient Clustering (DEEC), Stable Election Protocol (SEP), and Enhanced SEP(ESEP). Our simulation results show that our proposed protocol, ECRSEP outperforms all these protocols in terms of network stability and network lifetime. [Copyright &y& Elsevier]

Abstract: This paper considers a field with a number of isolated wireless sensor networks served by some mobile mules and base stations (BSs). Sensing data needs to be carried by mobile mules to BSs via opportunistic contact between them. Also, such contact may not be frequent. Thus there are four types of communications in this environment: (i) inter-node communications within a WSN, (ii) opportunistic WSN-to-mule communications, (iii) opportunistic mule-to-mule communications, and (iv) opportunistic mule-to-BS communications. In such disconnected WSNs, since sensors’ memory spaces are limited and data collection from isolated WSNs to mules and then to BSs relies on opportunistic communications in the sense that contact between these entities is occasional, storing and collecting higher-priority data is necessary. Therefore, there are two critical issues to be addressed: the data storage management in each isolated WSN and opportunistic data collection between these entities. We address the storage management problem by modeling the limited memory spaces of a WSN’s sensor nodes as a distributed storage system. Assuming that there is a sink in the WSN that will be visited by mobile mules occasionally, we address three issues: (i) how to buffer sensory data to reduce data loss due to a shortage of storage spaces, (ii) if dropping of data is inevitable, how to avoid higher-priority data from being dropped, and (iii) how to manage the data nearby the sink to facilitate the downloading jobs of mules when the downloading time is unpredictable. We propose a Distributed Storage Management (DSM) strategy based on a novel shuffling mechanism similar to heap sort. It allows nodes to exchange sensory data with neighbors efficiently in a distributed manner. For the opportunistic data collection problem, based on a utility model, we then develop an Opportunistic Data Exchange (ODE) strategy to guide two mules to exchange data that would lead to a higher reward. To the best of our knowledge, this is the first work addressing distributed storage strategy for isolated WSNs with opportunistic communications using mobile mules. We conduct extensive simulations to investigate the merit of DSM and ODE. The simulation results indicate that the level of data importance collected by our DSM is very close to a global optimization and our ODE could facilitate delivery of important data to BSs through mules. We also implement these strategies in a real sensor platform, which demonstrates that the simple and lightweight protocols can achieve our goals. [Copyright &y& Elsevier]

Abstract: The bandwidth is one of the most precious resources in Mobile Ad Hoc Networks (MANETs); their network protocols should therefore be able to achieve an increase in efficiency of bandwidth utilisation. TCP, which implements flow control to regulate the network traffic, plays a significant role in shaping the workload of the network. However, spurious TCP retransmissions can increase the link utilisation, consequently limiting the amount of spare bandwidth available as extensively reported in the literature. This problem is exacerbated by the presence of high priority traffic and traffic differentiation introduced in IEEE 802.11e. In this paper, we focus on the optimisation of TCP for resource efficiency, by limiting the number of contention-induced retransmissions. Using a cross-layer technique, TCP can be notified of the medium contention state and adjusts its retransmission timer accordingly. Our simulation results demonstrate the effectiveness of our proposal in various scenarios. A 15% gain in resource utilisation is obtained, fewer packets are retransmitted thus reducing the overall power consumption and TCP goodput is improved. [Copyright &y& Elsevier]

Abstract: In this paper, we propose a social approach for learning agents. In dynamic environments, smart agents should detect changes and adapt themselves, applying dynamic learning strategies and drift detection algorithms. Recent studies note that an ensemble of learners can be coordinated by simple protocols based on votes or weighted votes; however, they are not capable of determining the number of learners or the ensemble composition properly. Conversely, we show in this paper that Social Network Theory can provide the multi-agent learning community with sophisticated and well-founded reputation models that outperform well-known ensemble-based drift detection techniques, generating accurate and small ensembles of learning agents. Our approach is evaluated considering dynamic bilateral negotiation scenarios and benchmark databases, presenting statistically significant results that are better than those of other ensemble-based techniques. [Copyright &y& Elsevier]

Abstract: Directory-based cache coherency is commonly accepted as the design of choice to provide high performance and scalability in coherency maintenance for many-core CMPs. However, the on-chip area overhead required to encode sharer sets may compromise their success as core count increases. In this work, we propose the Express COherence NOtification (ECONO) protocol, a simple and efficient Dir0B cache coherence protocol that does not require sharer sets encoding while approaching performance of a conventional directory-based protocol. To accomplish that, ECONO relies on express coherence notifications which are broadcast atomically over a dedicated lightweight on-chip network leveraging state-of-the-art technology. Detailed full-system simulation using a representative set of benchmarks corroborates our statement. [Copyright &y& Elsevier]

Abstract: System level biological behaviour typically arises from highly dynamic, strongly nonlinear, tightly coupled interactions between component processes occurring across multiple space and time scales. The interdependent nature of these processes often makes it difficult to apply standard mathematical techniques to separate out the scales, uncouple the physical processes or average over contributions from discrete components. To make rapid progress we need to address interoperability challenges: to build integrated models from reusable components, and to relate simulation results to experimental data both for parameter fitting and model analysis. In this paper we describe how work we have done to address these issues in the domain of cardiac electrophysiology can be applied in a completely different field: multicellular models of intestinal crypts, with cells treated as discrete entities, and the sub-cellular, cellular, and tissue scales interacting. In this application the model and simulation are intertwined in software, with no suitable markup language model representation. Different modelling paradigms are available for each of the scales, and comparing their predictions is of particular interest. We use our concept of ‘functional curation’ to separate the experimental protocols applied to models from the model descriptions themselves, allowing easier comparison of model behaviour with experimental data. We also describe the use of ontological annotation for providing semantically rich model interfaces, facilitating coupling models to each other and to protocol descriptions. Finally, we show how these uses of semantic annotation and markup languages may be mixed incrementally with legacy code. This work suggests that the ideas we have developed have the potential to be useful across computational science, and we discuss these wider implications. [Copyright &y& Elsevier]

Abstract: Moon and Lee recently designed an authentication protocol for an ad hoc network using an identifier [Mathematical and Computer Modelling]. The main contribution of this method is that it can effectively reduce the authentication overheads compared with related works. Unfortunately, we have found that the authentication protocol has suffered from the man-in-the-middle attack. [Copyright &y& Elsevier]

Abstract: In this work we describe a framework which allows to perform secure computations on non-integer values. To this end, we encode values in a way similar to floating point representation and describe protocols that allow to perform efficient secure two party computations on such encoded values. We present two approaches to realize the functionality of the framework. Both approaches come with different properties and are ready to use in various application scenarios. We implemented the framework in C++ and ran several experiments. This allows for a complexity analysis and for a comparison of the two different approaches. We further describe applications to privacy-preserving computations, which greatly benefit from the use of the new framework. In particular, we show how to run an important algorithm in the context of data analysis using Hidden Markov Models (HMM), namely the Viterbi algorithm, in a secure manner. [Copyright &y& Elsevier]

Abstract: In the internet environment, the Diversity-path-aware Border Gateway Protocol (D-BGP) increases path diversity by advertising multiple paths. In case of a route failure, D-BGP, selects the most disjoint alternative path, but does not consider its quality moreover because update messages are propagated both for the best path and for alternate paths, D-BGP has messaging. To overcome these limitations, we propose a robust BGP protocol that increases fault tolerance and reduces update message overhead. After establishing shortest paths using D-BGP, our protocol selects an alternate path based on link availability of the link and bandwidth. It utilizes Path Exploration Damping (PED) to delay update messages of alternate paths with worst-case scenario. Simulation results justify that our proposed BGP is failure free and performs better than D-BGP. [Copyright &y& Elsevier]