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Internet applications such as video gaming virtual/ augmented reality necessitate efficient fifth-generation (5G) millimeter-wave (mmWave) cellular networks. The Transmission Control Protocol (TCP) is an essential protocol for network connectivity. However, TCP faces challenges in efficiently utilizing the available bandwidth of 5G mmWave cellular networks while maintaining low latency, mainly due to constraints like Non-Line of Sight (NLoS) conditions. This paper introduces Round-Trip-Time Variations-TCP (RTTV-TCP), enhancing TCP performance in 5G mmWave cellular networks. Simulation scenarios for a 5G mmWave cellular network have been conducted to evaluate RTTV-TCP's performance, comparing it to legacy TCP variants such as NewReno, HighSpeed, CUBIC, Bottleneck Bandwidth and Round-trip propagation time (BBR), FB-TCP (Fuzzy Based-TCP). The results demonstrate that RTTV-TCP achieves higher average throughput than these TCP variants while maintaining the same level of delay in 5G mmWave cellular networks. RTTV-TCP outperforms NewReno and CUBIC by a very significant margin, demonstrating a 208% improvement compared to HighSpeed and a 6% increase compared to BBR protocol in the worst Packet Error Rate (PER) scenario and when the buffer size matches the Bandwidth Delay Product (BDP). [ABSTRACT FROM AUTHOR]

Abstract Broadcast of beacon messages including geographic coordinates, node speeds, and directions are among the most commonly used methods in routing protocols of VANETs to obtain neighboring positions. Broadcast of periodic beacon messages in fixed time intervals will reduce network performance due to increased channel load and contention. In this paper, an adaptive update strategy for sending beacon messages according to the VANETs' characteristics (position, speed, and direction) and the nature of broadcast wireless channel in an opportunistic routing strategy is studied. It is based on two rules: 1) an estimation of the lifetime of the links between vehicles' beacon messages are sent after the expiration of the estimated time to inform their local topology and 2) if the forwarding set of consecutively received data packets is changed, a beacon message is sent to maintain the accuracy of the topology. The simulation results show that the proposed strategy significantly reduces the cost of routing and improves network performance in terms of packet-delivery ratios, average end-to-end delay, and routing overhead. [ABSTRACT FROM AUTHOR]

Abstract 1 1 Video demonstrations and a video presentation providing a summary of the paper can be found at https://goo.gl/EDvxhk. Low-cost Unmanned Aerial Vehicles (UAVs), also known as drones, are increasingly gaining interest for enabling novel commercial and civil Internet-of-Things (IoT) applications. However, there are still open challenges that restrain their real-world deployment. First, drones typically have limited wireless communication ranges with the ground stations preventing their control over large distances. Second, these low-cost aerial platforms have limited computation and energy resources preventing them from running heavy applications onboard. In this paper, we address this gap and we present Dronemap Planner (DP), a service-oriented cloud-based drone management system that controls, monitors and communicates with drones over the Internet. DP allows seamless communication with the drones over the Internet, which enables their control anywhere and anytime without restriction on distance. In addition, DP provides access to cloud computing resources for drones to offload heavy computations. It virtualizes the access to drones through Web services (SOAP and REST), schedules their missions, and promotes collaboration between drones. DP supports two communication protocols: (i.) the MAVLink protocol, which is a lightweight message marshaling protocol supported by commodities Ardupilot-based drones. (ii.) the ROSLink protocol, which is a communication protocol that we developed to integrate Robot Operating System (ROS)-enabled robots into the IoT. We present several applications and proof-of-concepts that were developed using DP. We demonstrate the effectiveness of DP through a performance evaluation study using a real drone for a real-time tracking application. [ABSTRACT FROM AUTHOR]

Abstract To cope with the diversity of Internet of Things (IoT) requirements, a large number of Medium Access Control (MAC) protocols have been proposed in scientific literature, many of which are designed for specific application domains. However, for most of these MAC protocols, no multi-platform software implementation is available. In fact, the path from conceptual MAC protocol proposed in theoretical papers, towards an actual working implementation is rife with pitfalls. (i) A first problem is the timing bugs, frequently encountered in MAC implementations. (ii) Furthermore, once implemented, many MAC protocols are strongly optimized for specific hardware, thereby limiting the potential of software reuse or modifications. (iii) Finally, in real-life conditions, the performance of the MAC protocol varies strongly depending on the actual underlying radio chip. As a result, the same MAC protocol implementation acts differently per platform, resulting in unpredictable/asymmetrical behavior when multiple platforms are combined in the same network. This paper describes in detail the challenges related to multi-platform MAC development, and experimentally quantifies how the above issues impact the MAC protocol performance when running MAC protocols on multiple radio chips. Finally, an overall methodology is proposed to avoid the previously mentioned cross-platform compatibility issues. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we present a finite-block-length comparison between the orthogonal multiple access (OMA) scheme and the non-orthogonal multiple access (NOMA) for the uplink channel. First, we consider the Gaussian channel, and derive the closed form expressions for the rate and outage probability. Then, we extend our results to the quasi-static Rayleigh fading channel. Our analysis is based on the recent results on the characterization of the maximum coding rate at finite block-length and finite block-error probability. The overall system throughput is evaluated as a function of the number of information bits, channel uses and power. We find what would be the respective values of these different parameters that would enable throughput maximization. Furthermore, we analyze the system performance in terms of reliability and throughput when applying the type-I ARQ protocol with limited number of retransmissions. The throughput and outage probability are evaluated for different blocklengths and number of information bits. Our analysis reveals that there is a trade-off between reliability and throughput in the ARQ. While increasing the number of retransmissions boosts reliability by minimizing the probability of reception error, it results in more delay which decreases the throughput. Nevertheless, the results show that NOMA always outperforms OMA in terms of throughput, reliability and latency regardless of the users priority or the number of retransmissions in both Gaussian and fading channels. [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 We consider an ad hoc radio network in which nodes perform some distributed algorithms. We provide a framework, that at the cost of increasing time complexity, prevents an outer, passive adversary from gaining significant information about the execution of the algorithm. The main idea we utilize is adding some extra obfuscating rounds to conceal the real execution. Despite the fact that we assume a relatively weak model of the adversary, trying to solve the problem, we encounter several non-trivial issues. First of all, the proposed method needs to be universal and work in on-line mode. Moreover, the method should entail possibly small time overhead and provide a provable security. Finding a satisfactory solution is particularly difficult due to the very restrictive, in terms of nodes capabilities, communication model. The main result presented in this paper is an efficient general method for obfuscating an execution of any underlying algorithm and its rigid analysis. We provide security guarantees against a passive adversary, with an ability of eavesdropping every transmission in the network, that aims at learning the execution of the algorithm. We also present a specialized algorithm for a secure listing of all present (active) nodes, that does not reveal any substantial information about the network to the outer adversary. [ABSTRACT FROM AUTHOR]

Abstract In a globalized world, the mobile user roams frequently from one place to other. Global mobility network provides roaming services to a mobile user when the mobile user is away from his home network and wants to avail the services of the foreign network. Roaming authentication protocol supports authentication between the mobile user and the foreign server in global mobility network so that the malicious user can not get access the roaming services in the foreign network. Moreover, privacy-preserving authentication between the mobile user and the foreign server is an essential technology for the secure access of global mobility network because mobile user's privacy protection has become a major issue due to increasingly misuse of consumer's private data by various organizations and individuals. Many privacy-preserving two-factor authentication protocols have been proposed to provide secure roaming services in global mobility network but they failed to support privacy and security while ensuring efficient typo detection by the smart card. We propose a privacy-preserving secure two-factor authentication protocol for roaming service in global mobility network which not only ensures the privacy of the mobile user but also provides efficient typo detection using fuzzy verifier and honeyword technique. Moreover, the proposed protocol overcomes the problem of desynchronization attack using public key encryption technique based on quadratic residue assumption with low computational load at the mobile user. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we propose two relay selection methods to enhance system outage performance for energy harvesting (EH) based two-way relaying protocols in wireless adhoc networks. In the proposed protocol, two source nodes communicate with each other via the assistance of multiple decode-and-forward (DF) relays using three-phase digital network coding. At the first and second phases, two sources broadcast their data to the relays. Employing a power-splitting model, the relays would harvest energy from radio frequency (RF) signals of the sources to transmit the data at the third phase. We propose a simple partial relay selection (PRS) method and an opportunistic relay selection (ORS) method to enhance the reliability of data transmission at the cooperative phase. For performance evaluation, we derive exact and asymptotic expressions of the system outage probability (SOP) for the proposed protocols over block Rayleigh fading channels. Finally, Monte Carlo simulations are presented to verify the theoretical derivations as well as to compare the performance of the proposed protocols with that of the random relay selection protocol. [ABSTRACT FROM AUTHOR]

Abstract Temporal/spatial disruptions and IP changing caused by host mobility lead the user applications to fail. This remains a problem due to the ossification of the TCP/IP protocol stack and the lack of support of existing solutions in enabling connection failure tolerance at application layer. To preserve integrity and transmission consistency upon erroneous communication events caused by host mobility, enabling mobility awareness is a key requirement for the current user applications. In this paper, we provide a comprehensive study on mobility-aware application protocols that ensure reliability and resiliency for long-lived TCP sessions established between clients and severs that migrate across different wireless IP networks on the Internet. To this end, we modeled and simulated such protocols through general-purpose state machines, which we conceived regarding the Socket semantic to resume session from broken connections. Simulations results revealed how internal and external factors, i.e., protocol design decisions and mobile environment conditions, respectively, can and cannot influence performance. When comparing results with TCP-Migrate – a well-known transport layer mobility protocol, handover delays in application protocols are longer in single jumps between mobile client and stationary server, but shorter in double jumps, when both client and server are mobile entities. [ABSTRACT FROM AUTHOR]

Abstract Offloading data traffic from Infrastructure-to-Device (I2D) to Device-to-Device (D2D) communications is a powerful tool for reducing congestion, energy consumption, and spectrum usage of mobile cellular networks. Prior network-level studies on D2D data offloading focus on high level performance metrics as the offloading efficiency , and take into account the radio propagation aspects by using simplistic wireless channel models. In this work, we consider a D2D data offloading protocol tailored to highly dynamic scenarios as vehicular environments, and evaluate its performance focusing on physical layer aspects, like energy consumption and spectral efficiency. In doing this, we take into account more realistic models of the wireless channel, with respect to the simplistic ones generally used in the previous studies. Our objective is twofold: first, to quantify the performance gain of the considered D2D offloading protocol with respect to a classic cellular network, based on I2D communications, in terms of energy consumption and spectral efficiency. Second, to show that using simplistic channel models may prevent to accurately evaluate the performance gain. Additionally, the use of more elaborated models allows to obtain insightful information on relevant system-level parameters settings, which would not be possible to obtain by using simple models. The considered channel models range from widely used models based on deterministic path loss formulas, to more accurate ones, which include effects like multipath fading and the associated frequency selectivity of wideband channels. These models have been proposed and validated, in the recent years, through large-scale measurements campaigns. Our results show that the considered protocol is able to achieve a reduction in the energy consumption of up to 35%, and an increase in the system spectral efficiency of 50%, with respect to the benchmark cellular system. The use of different channel models in evaluating these metrics may result, in the worst case, in a sixfold underestimation of the achieved improvement. [ABSTRACT FROM AUTHOR]

Abstract An important objective of cryptographic schemes is to withstand various attacks, including leakage attacks. Otherwise, leakage of the secret key may cause serious threats to the security of computer systems. However, leakage attacks have not received adequate attention in the literature. For example, most of the existing security protocols in the wireless sensor networks (WSNs) lack the consideration of leakage attacks. Instead, they are only designed in the traditional security model, in which an adversary is assumed not to obtain any information of the internal secret states. Obviously, this is not ideal because partial information of the secret key may be leaked in practice due to side channel attacks or fault injection attack. In this paper, we propose a new construction of secure continuous leakage-resilient certificate-based signcryption (CBS) scheme with access control without using bilinear pairings, and its security can be proved based on the assumptions that solving the classical decisional Diffie-Hellman problem and discrete logarithm problem is infeasible. We then propose a novel certificate-based access control scheme for the WSNs. The analysis shows that our construction not only achieves high computational efficiency in the continuous leakage setting, but also has superior performance regarding communication efficiency and storage requirement. [ABSTRACT FROM AUTHOR]

In unsecured 6LoWPANs, the nodes can be easily identified by their IPv6 as well as MAC addresses. An adversary can snoop (and later, spoof) these addresses, thereby posing a major threat against the node’s identity and communication integrity. Such threats necessitate enabling privacy by obscuring the node’s addresses. This study proposes a protocol for dynamic, auto-configuring and conflict-free IPv6 addressing scheme that attempts to ensure privacy of nodes. In the proposed protocol, each node obtains a three-level hierarchical IPv6 address space which is dynamically generated on basis of congruence classes. Use of congruence classes, along with hierarchical addressing, facilitates generation of inter-leaved (and hence, disjoint) and non-fragmented address space for each node, resulting in conflict free address auto-generation. Nodes auto-configure their address sets independently with congruence seeds shared by routers, potentially reducing router complexity. To ensure the MAC address privacy, MAC address also changes when IPv6 address changes and it is derived from the interface identification (IID) part of the IPv6 address. The proposed protocol runs on Contiki operating system, simulated in Cooja. Simulated results highlight lower latency and optimal communication costs when compared with existing protocols. [ABSTRACT FROM AUTHOR]

The explosive growth of “things” connected to the Internet (Internet of Things, IoT) raises the question of whether existing ready-to-go networking protocols are enough to cover social and mobile IoT’s demands. IoT aims to interconnect static devices attached to some physical infrastructure. However, mobility is a major factor present in everyday life, and naturally the “things” can move around (Internet of Mobile Things, IoMT) and create social ties (Social IoT, SIoT) in the cyber-physical space. In that context, we present Mobile Matrix ( μ Matrix), a routing protocol that uses hierarchical IPv6 address allocation to perform any-to-any routing and mobility management without changing a node’s address. In this way, device mobility is transparent to the application level favoring IoMT and SIoT implementation and broader adoption. The protocol has low memory footprint, adjustable control message overhead, and it achieves optimal routing path distortion. Moreover, it does not rely on any particular hardware for mobility detection (a key open issue), such as an accelerometer. Instead, it uses a passive mechanism to detect that a device has moved. We present analytic proofs for the computational complexity and efficiency of μ Matrix, as well as an evaluation of the protocol through simulations. We evaluate the protocol performance under human and non-human mobility models. For human mobility, we generated mobility traces using Group Regularity Mobility (GRM) Model, setting its parameters based on real human mobility traces. For the non-human mobility, we propose a new mobility model, to which we refer as Cyclical Random Waypoint (CRWP), where nodes move using a simple Random Waypoint and, eventually, return to their initial position. We compared μ Matrix with three baseline protocols: Routing Protocol for low-power and lossy networks (RPL), Mobility Management RPL (MMRPL), and Ad hoc On-Demand Distance Vector (AODV). The results show that μ Matrix and RPL offer  ≈ 99.9% of bottom-up delivery rate, but only μ Matrix offer  ≥ 95% of top-down traffic in highly dynamic and mobile scenarios, while other protocols  ≤ 75%. Moreover, μ Matrix uses up to 65% of the routing table while RPL and AODV fulfill theirs in all scenarios, which leads to poor top-down and any-to-any reliability. [ABSTRACT FROM AUTHOR]

In reactive unicast routing protocols, Route Discovery aims to include only bidirectional links in discovered routing paths. This is typically accomplished by having routers maintain a “blacklist” of links recently confirmed (through Route Reply processing) to be unidirectional – which is then used for excluding subsequent Route Discovery control messages received over these links from being processed and forwarded. This paper first presents an analytical model, which allows to study the impact of unidirectional links being present in a network, on the performance of reactive routing protocols. Next, this paper identifies that despite the use of a “blacklist”, the Route Discovery process may result in discovery of false forward routes, i.e., routes containing unidirectional links – and proposes a counter-measure denoted Forward Bidirectionality Check . This paper further proposes a Loop Exploration mechanism, allowing to properly include unidirectional links in a discovered routing topology – with the goal of providing bidirectional connectivity even in absence of bidirectional paths in the network. Finally, each of these proposed mechanisms are subjected to extensive network simulations in static scenarios. When the fraction of unidirectional links is moderate (15–50%), simulations find Forward Bidirectionality Check to significantly increase the probability that bidirectional routing paths can be discovered by a reactive routing protocol, while incurring only an insignificant additional overhead. Further, in networks with a significant fraction of unidirectional links ( ≥ 50%), simulations reveal that Loop Exploration preserves the ability of a reactive routing protocol to establish bidirectional communication (possibly through non-bidirectional paths), but at the expense of a substantial additional overhead. [ABSTRACT FROM AUTHOR]

To provide a tool for performance evaluation of IEEE 802.15.4 with sleep mode enabled, a novel model based on real time queueing analysis is proposed in this paper. A low-rate wireless personal area network (LR-WPAN), composed of multiple nodes which send packets to the coordinator, is considered. The queueing behaviour of IEEE 802.15.4 node with sleep mode enabled differs from others because the packet arrivals in sleep period accumulate at the beginning of the active period, which makes a heavier load in the beginning than at any other time. This model analyses this behaviour by dividing the active portion of the superframe into backoff slots and then using an embedded discrete-time Markov chain model. The concept of virtual service time is introduced into this model which makes the proposed queueing model novel and different from typical ones. The accuracy of the proposed model is validated by Monte Carlo simulations in existing typical application scenarios, which indicates that the proposed queueing model can accurately evaluate the performance of IEEE 802.15.4 in the context of the application scenarios described in the simulations. [ABSTRACT FROM AUTHOR]

In this paper, we present a very fast and simple protocol for polling tags in an RFID system formed by one or more readers, and a multitude of tags. Actually, the protocol is time-optimal for single reader systems, while being very fast for multiple readers systems. The main idea of the protocol described in this paper, is to associate a short and unique number (called “nickname” in the following) to each tag in the reader’s range, and by using such nicknames as the polling order. We first describe the single reader version of the protocol. For this version, the used nicknames are the integers 1 , 2 , … , n if the set of tags to be polled is formed by n tags. They can be seen as the time slot in which a tag has to communicate with the reader. We also provide a procedure to assign a nickname for a new tag, as well as a way to delete a tag from the polling order, while keeping the above consecutivity property about nicknames. When polled, the tags transmit a proper (usually short) message. Polling protocols, sometime with little changes, sometime with no change, can be efficiently used for solving several practical problems related to the use of RFID systems. Some of the most prominent ones, and those considered in this paper, are the problems of exactly determine missing tags, the collection of information associated to the tags, the probabilistic determination of missing tags (useful for raising a warning), and the determination of the presence of cloned tags, again for raising a proper warning. We formally show that the protocol is time-optimal. Besides, the protocol is privacy preserving since tags ID’s are never transmitted during the polling procedure. In the protocol version for large, multireader RFID systems, we take an approach completely different from that used so far for any multireader protocol. Up to now, in the proposed protocols for this and related problems, first readers are scheduled so that those with overlapping ranges never operate at the same time. Then, single reader protocol for each so scheduled reader are applied. Here, we schedule the tags instead of the readers so that tags whose transmission can be received by a common reader, never operate at the same time. Then, we show that our polling protocol for single reader systems can be effectively used along with such a tags scheduling strategy, in multireader systems. The time performance improvement of our protocol over the known ones for multireader systems is very large, going from two to seven times, as shown by a simulation experiment we set up, and whose results are also presented. [ABSTRACT FROM AUTHOR]

In hostile environments where explosives and natural calamities probably occur, wireless sensor networks (WSNs) are susceptible to multiple collocated failures and could be partitioned into disjoint segments. Federating the segments would be essential for restoring connectivity and enabling data sharing in the network. The federation may be achieved by populating relay nodes and providing perpetual inter-segment paths. In this paper, we tackle the federation problem while considering constrained relay availability, i.e., a limited number ( k ) of mobile relays to provide intermittent inter-segment connectivity that makes the problem more challenging. We propose LEEF, a novel algorithm for achieving energy-efficient federation with low inter-segment data delivery latency. LEEF strives to group the segments into k clusters in a star topology where a cluster at the center of the area serves as a hub between each pair of segment-clusters. Each cluster is served by a distinct mobile relay. In addition, LEEF opts to equalize the energy consumed by the k mobile relays due to travel and wireless communication. We analyze the properties of LEEF mathematically and validate its performance through extensive simulation experiments. [ABSTRACT FROM AUTHOR]

The popularization of wireless networks and mobile applications has increased the importance of RFID technologies. However, since wireless networks does not guarantee transmission channel security, putting private user information at risk for unintentional disclosure. Previous research has introduced a security mechanism to provide privacy and authentication. This mechanism is based on quadratic residue, does not require a secure channel and fits EPC Class-1 Gen-2 specifications. However, this mechanism cannot resist replay attacks, and lacks an efficient means of its server is not able to find determining validating values, making it difficult to implement. This paper proposes an improvement scheme that uses virtual IDs and time parameters. It does not need a secure channel, fits EPC Class-1 Gen-2 specifications, is resistant to replay attacks, and can efficiently find validation information. The proposed scheme is applied to mobile devices as a proof of concept for use in wireless/mobile RFID systems. [ABSTRACT FROM AUTHOR]

Rendezvous in cognitive radio ad-hoc networks is an essential step for a pair of unknown cognitive radio (CR) users to initiate a communication. Most of the existing studies address rendezvous problems as a design of a search strategy to meet on the same channel at the same time. However, in a multi-user environment, a rendezvous cannot guarantee even if two users are on the same channel at the same time due to channel contention and the multi-channel hidden node problem. To overcome problems, we propose a novel cognitive radio rendezvous (CR-RDV) protocol by integrating the rendezvous and medium access control (MAC) issues. We modify the traditional backoff strategy based on remaining transmission time and packet length to avoid the concurrent transmission with the primary users (PUs). Moreover, an additional sensing period is introduced immediately after the RTS packet to solve the blocking problem in the multi-user environment. The proposed CR-RDV protocol is analysed based on the modified Bianchi model and an absorbing Markov chain model to capture the multi-user and rendezvous channel contention. Through extensive simulations, we show that the proposed CR-RDV protocol outperforms the existing methods with respect to throughput, delay, and packet dropping. [ABSTRACT FROM AUTHOR]

IEEE 802.11ad defines a new physical and medium access control layer for IEEE 802.11 networks to operate in the unlicensed 60 GHz millimeter wave spectrum for multi-gigabit wireless communications. Higher frequency waves have higher propagation loss but smaller antenna size. Hence, for millimeter wave networks, higher number of antennas can be packed together, enabling beamforming with very large gains. In this paper, we propose a novel Directional MAC protocol for Basic Stations (DMBS) with the goal of fully leveraging spatial reusability, and limiting deafness and hidden terminal problems with minimal overhead, and without using any complicated hardware for localization. The distinguishing features of DMBS are threefold. First, DMBS extends the association beamforming training time (A-BFT) of IEEE 802.11ad, during which the stations perform initial beamforming training with the access point (AP), by an intelligent listening mechanism. This mechanism allows the stations to passively learn about the best direction of the neighboring stations, decreasing the associated beamforming training overhead. Second, DMBS determines the best transmission direction by using multi-directional sequential (circular) RTS/CTS (Request To Send/ Clear To Send) (CRTS/CCTS) packets, and tracks the best direction by updating its beamforming table upon reception of every RTS/CTS packet, without requiring any additional hardware for localization. If the location information of the destination is up-to-date, the source station only transmits directional RTS/CTS (DRTS/DCTS) in the known direction. Third, DMBS uses two network allocation vectors (NAVs). The first NAV, denoted by NAV1, is used to reduce deafness by determining the busy nodes upon the reception of every RTS/CTS packet. The second NAV, called NAV2, is used to limit hidden terminal problem while maximizing spatial reusability by determining whether a transmission can interfere with active communication links. If NAV2 is set, then the node defers its multi-directional communication but still communicates directionally. We provide a novel Markov chain based analytical model to calculate the aggregate network throughput of DMBS. We demonstrate via extensive simulations that DMBS performs better than existing directional communication protocols in terms of throughput for different network sizes, mobilities and number of receivers. [ABSTRACT FROM AUTHOR]

Fault diagnosis has been considered as a very challenging problem in wireless sensor network (WSN) research. Faulty nodes having different behavior such as hard, soft, intermittent, and transient fault are called as heterogeneous faults in wireless sensor networks. This paper presents a heterogeneous fault diagnosis protocol for wireless sensor networks. The proposed protocol consists of three phases, such as clustering phase, fault detection phase, and fault classification phase to diagnose the heterogeneous faulty nodes in the wireless sensor networks. The protocol strategy is based on time out mechanism to detect the hard faulty nodes, and analysis of variance method (ANOVA test) to detect the soft, intermittent, and transient faulty nodes in the network. The feed forward probabilistic neural network (PNN) technique is used to classify the different types of faulty nodes in the network. The performance of the proposed heterogeneous fault diagnosis protocol is evaluated using network simulator NS-2.35. The evaluation of the proposed model is also carried out by the testbed experiment in an indoor laboratory environment and outdoor environment. [ABSTRACT FROM AUTHOR]

Internet of Things (IoT) has revolutionized the networking by connecting the real world entities to the Internet. IoT connects the communication devices and has an incredible impact on perspective analytics on the massive volume of data produced every day. An attacker may exploit vulnerabilities of IoT entities and compromise users' security and privacy. Development of solutions to address security and privacy issues of IoT is in premature stage and considered as challenge. This challenge becomes more critical when the devices in the network are resource-constrained in terms of energy, processing and memory. The IPv6 over Low-Power Wireless Personal Area Networks (6LoWPAN) has emerged in recent years as an adaptation layer to carry IPv6 packets over IEEE 802. 15. 4. Many IoT applications use Routing Protocol for Low Power and Lossy Networks (RPL) as a network layer protocol developed for routing in 6LoWPAN. Security is challenging in resource constrained environment where encryption may not be a viable solution. Version number attack is one of the most common network layer attacks against RPL based 6LoWPAN. The RPL specification does not address the integrity of the version number and therefore leaves version number mechanism as a weak point in terms of security. This paper investigates the impact of version number attack in RPL networks while considering mobility of the sensor nodes. We propose a solution that utilizes Q-Learning strategy to detect the malicious nodes that are performing version number attack. The proposed approach detects malicious nodes with reasonable accuracy while imposing significantly less overhead on the nodes of low power and lossy networks. There are other approaches too like Message Authentication Codes (MAC) based on symmetric keys but these techniques have memory and communication overhead. So we propose different approach Q-Learning to detect the attacker nodes. • Attacks in RPL based IoT. Why version number attack? • Detection of version number attack in RPL based IoT using Q-Learning. • Performance evaluation using different metrics like Packet Delivery Ratio, Average End-to-End Delay, Power Consumption. [ABSTRACT FROM AUTHOR]

During the last few years, wireless low-power communications experienced an increasing coexistence and traction as a result of the higher demand posed by power constrained applications. On the other hand, this increasing wireless coexistence is a growing concern and Low-power wireless communication protocols have been shown to experience a significant timeliness and reliability degradation under certain interference profiles. Therefore, the support of real-time communications over license-free bands in open environments, encompassing multiple real-time stations with an unknown number of unconstrained stations, is a challenging task. Provided that this impairment has hindered their wide adoption in demanding real-time scenarios, the Wireless Flexible Time Triggered (WFTT) protocol has been recently proposed targeting applications with stringent timeliness requirements. This protocol works on the medium access determinism granted by the bandjacking technique in open environments, where different technologies may contend for the medium. Besides providing a deeper definition of the WFTT architecture and protocol operation, this paper presents a thorough analysis addressing its specifications, implementation feasibility and testbed based results. These provide strong evidence that the WFTT protocol is able to support real-time communications, even in environments affected by high levels of interference from neighboring contention-based communication technologies such as Wi-Fi. [ABSTRACT FROM AUTHOR]

The goal of the Internet of Things (IoT) is to create an integrated ecosystem for devices to communicate over the Internet. To achieve this goal, efficient inter-operation is needed among Device to Device (D2D) communication technologies that make up the ecosystem. Currently, these technologies operate in vertical silos with different protocols. We explore the challenges associated with the integration and interoperability of these D2D technologies by focusing on network layer functions such as addressing, routing, mobility, security and resource optimization. We identify the limitations of the current TCP/IP architecture for D2D communication in the IoT environment. We also discuss some of the limitations of the 6LoWPAN architecture and describe how it has been adopted for D2D communication. Finally, we present solutions to address the limitations we have identified for the network layer functions as applicable to D2D communication in the IoT environment. [ABSTRACT FROM AUTHOR]

Establishing a unified time reference may be required for the operation of Wireless Sensor Networks (WSNs). Such a requirement may be imposed by the management strategy in the network, e.g., using time based medium access arbitration, or simply due to the dynamic nature of the application, e.g. target tracking. Contemporary clock synchronization protocols introduce significant messaging overhead and thus do not suit the resource-constrained WSNs. In the paper, we propose a novel solution called Synchronization through Piggybacked Reference Timestamps (SPiRT). SRiRT exploits the popularity of two-tier network architectures in WSN, where nodes are grouped into disjoint clusters. Each cluster-head synchronizes its clock to that of a reference node in the network through message exchange. Since cluster members can overhear the cluster-head transmissions, SPiRT takes advantages of such synchronization traffic to adjust the clock of the cluster members. SPiRT calls for appending the reference timestamps in the cluster-head messages so that a cluster member can estimate their clock adjustment. This cuts on energy consumption and increases the synchronization efficiency of SPiRT. We further propose an extension of SPiRT (E-SPiRT) that operates over multi-hop in order to achieve network-wide (global) synchronization. SPiRT and E-SPiRT are validated through simulation and implementation on a Micaz based testbed. The validation results confirm the effectiveness of SPiRT and E-SPiRT and show that they outperform competing schemes in the literature. [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]

Data from running vehicles are invaluable to numerous ITS and urban computing applications. This paper studies the issue of collecting data from multiple vehicles to a roadside base station via vehicle-to-vehicle and vehicle-to-infrastructure communications. Existing data collection approaches in VANET have mainly focused on the network problems, such as packet loss, network clustering or data aggregation, but the impact of real-time traffic condition is barely considered. In this paper, we investigate the data collection problem in VANETs under rapid evolving traffic conditions. Our approach can adaptively choose to carry or forward the data packet, based on current traffic information. The objective is to minimize the network communication overhead while satisfying the data collection time constraint. We formulate the data collection problem as a scheduling optimization problem and prove it is NP-complete. An optimal dynamic programming solution and a genetic algorithm based heuristic solution are developed to solve the problem under different application scenarios. Extensive evaluations validate that our proposed solution outperforms some existing ones in terms of effectiveness and efficiency. [ABSTRACT FROM AUTHOR]

In the context of Opportunistic Ad Hoc Networking paradigms, group communication schemes (Manycast) are difficult to conduct. In this article, we propose a general delivery scheme for Manycast group communications based on mobile code. Our proposal extends network addressing by moving from the static header field paradigm to a software code-based addressing scheme. We allow messages to be delivered using built-in software codes that consider application-defined, context-aware or history-based information. Additionally, we allow messages to carry a delivery state that permits them to perform refined delivery-decision-making methods. As a consequence of this scheme, we have found that new group communication schemes, besides the traditional ones, may be beneficial to improve the network performance and to provide new functionalities to emerging scenarios like intermittently connected networks of heterogeneous physical objects. We present an application of this scheme to solve, following an analytical delivery method, the problem of sending a message to k and only k nodes of a heterogeneous and opportunistic network scenario that fit best a given criterion. We show, using simulations, that our proposal performs better than traditional approaches. Finally, to show that our proposal is feasible, we present an implementation of our proposal in a real Opportunistic Ad Hoc network, a DTN network, compatible with the de facto standard Bundle Protocol. [ABSTRACT FROM AUTHOR]

Existing data management protocols for socially-aware networks assume that users are cooperative when participating in operations such as data forwarding. However, selfishness as a non-cooperative act of misbehavior can seriously degrade network performance and fairness, particularly in Ad-hoc Social Networks (ASNETs). Therefore, detecting and counteracting selfishness on performance of cooperative users are crucial to the success of ASNETs. In this paper, we propose BoDMaS, a biologically inspired method, to detect and mitigate the impact of node selfishness on data management performance and efficiency of ASNETs. In design of BoDMaS, we consider social willingness (which depends on depth of social relationship among users) as a social behavior and bacteria chemical products as a counter to achieve optimal ASNETs performance. Counter is a parameter attached to individual user counting successful data operations performed in relation with others. Using social willingness and counter, BoDMaS assesses and classifies users, and counteracts their selfishness. BoDMaS is evaluated from different aspects demonstrating its ability to accurately detect and counteract selfishness in replication operations for ASNET environments. [ABSTRACT FROM AUTHOR]

In this paper, we propose an efficient and secure key establishment protocol that is tailored for Wireless Mesh Networks. The protocol is based on identity-based key establishment, but without the utilization of a trusted authority for private key generation. Instead, this task is performed by the collaboration of mesh nodes; a number of users exceeding a certain threshold form a coalition to generate private keys for the network users. We performed simulative performance evaluation in order to show the effect of both the threshold value and the network size, i.e., total number of nodes, on the latency of key establishment and on the success percentage of user private key generation. Results reveal a trade-off between resiliency and efficiency; increasing the threshold value also increases the resiliency of the network, but negatively effects its latency and success percentage. For the threshold values that are smaller than 10 and for a minimum of 40 mesh nodes, at least 93% of the user private keys can be computed within at most 2 min. We also discuss the security of our protocol. We show that our protocol is secure against both outsider malicious and insider semi-honest adversaries. [ABSTRACT FROM AUTHOR]

Characterizing the contacts between nodes is of utmost importance when evaluating mobile opportunistic networks. The most common characterization of inter-contact times is based on the study of the aggregate distribution of contacts between individual pairs of nodes, assuming an homogenous network, where contact patterns between nodes are similar. The problem with this aggregate distribution is that it is not always representative of the individual pair distributions, especially in the short term and when the number of nodes in the network is high. Thus, deriving results from this characterization can lead to inaccurate performance evaluation results. In this paper, we propose new approaches to characterize the inter-contact times distribution having a higher representativeness and, thus, increasing the accuracy of the derived performance results. Furthermore, these new characterizations require only a moderate number of contacts in order to be representative, thereby allowing to perform a temporal modelization of traffic traces. This a key issue for increasing accuracy, since real-traces can have a high variability in terms of contact patterns along time. The experiments show that the new characterizations, compared with the established one, are more precise, even using short time contact traces. [ABSTRACT FROM AUTHOR]

Recent advances in Unmanned Aerial Vehicle (UAV) technologies have enhanced Wireless Sensor Networks (WSNs) by offering a UAV as a mobile data gathering node. These systems are called WSN-UAV that are well-suited for remote monitoring and emergency applications. Since previous Medium Access Control (MAC) protocols proposed in WSNs are not appropriate in the presence of a UAV, few researches have proposed new MAC protocols to meet WSN-UAV requirements. MAC protocols of WSN-UAV should be extremely efficient and fair due to the time-limited presence of the UAV in the neighborhood of each sensor. However, issues such as high throughput in dense networks, fairness among sensors, and efficiency have not been resolved yet in a satisfactory manner. Moreover, previous works lack analytical evaluation of their protocols. In this paper, we present a novel MAC protocol in WSN-UAV, called Advanced Prioritized MAC (AP-MAC), that can provide high throughput, fairness, and efficiency, especially in dense networks. We also analytically evaluate AP-MAC using a 3-dimensional Markov chain and validate its correctness using simulation. Simulation results under various scenarios confirm that AP-MAC can approximately improve throughput and fairness up to 20% and 25%, respectively, leading to higher efficiency compared with previous work in WSN-UAV systems such as Prioritized Frame Selection (PFS). [ABSTRACT FROM AUTHOR]

The Constrained Application Protocol (CoAP) has been designed by the Internet Engineering Task Force (IETF) for Internet of Things (IoT) communications. CoAP is a lightweight, request/response-based RESTful protocol that has been tailored to fulfill the requisites of IoT environments, such as severely limited device hardware and link capacities. In IoT networks, congestion is a major issue that causes performance losses or may even render the network useless. Thus, the use of a congestion control mechanism is essential for the performance of such networks. CoAP defines a very basic congestion control mechanism for the reliable exchange of messages between endpoints, however it does not specify congestion control for communications without end-to-end reliability, even though the latter represent a relevant share of CoAP communications. Two extensions to CoAP, Observe and Simple CoAP Congestion Control/Advanced (CoCoA), introduce rate control mechanisms for such communications yet these extensions have not yet been compared or evaluated. In this paper, we empirically evaluate these rate control mechanisms for unreliable CoAP communications between devices over emulated GPRS/UMTS links and in a real IEEE 802.15.4 multihop testbed of constrained devices. The results show that in contrast to Observe, CoCoA performs better than, or at least similarly to, default CoAP in terms of both packet delivery ratio and delay in all analyzed scenarios. [ABSTRACT FROM AUTHOR]

Vehicular ad hoc networks (VANETs) are self-organized networks designed to improve the drivers’ safety and the efficiency of vehicular traffic management. In this kind of networks, packet losses are common in the path from source to destination, mainly due to the high mobility of the nodes (i.e., vehicles). Reliability mechanisms at different layers are used to mitigate the impact of this issue. In this work, we explain how the loss of acknowledgment frames (ACK) at the medium access control (MAC) layer with the recovery procedure of VANET routing protocols lead to an unexpected generation of duplicate packets. We propose two incoming filters with different levels of detection of duplicate packets at routing layer to prevent the propagation of unnecessary packet copies, so that the available bandwidth will increase as a consequence. To evaluate the behavior of our proposals, we employed two VANET routing protocols: the topological iAODV [1] and the geographical MMMR [2]. We carried out simulations with three vehicle densities in an urban scenario and with two different mechanisms to adapt the size of the contention window (CW), which is an important factor in VANETs to avoid collisions. The extensive statistical analysis of the results show that our approaches are effective to reduce the traffic load in both routing protocols in terms of routing operations, idle time, duplicate packets and end-to-end delay. We also observed an expected minimum degradation of the packet delivery ratio in the geographical routing protocol, thus the benefits of the proposal are clear. [ABSTRACT FROM AUTHOR]

Mobile RFID tag reading on conveyor belt represents a practical scenario used widely in the supply chain industry. Typically, in RFID tag reading MAC protocols, the time the protocol takes to complete the reading of all the tags is directly proportional to the number of tags. As a natural scalability problem, when the number of mobile tags is large, the protocol that is initiated and coordinated by a reader will not be able to read all the tags, as the tags move away from the reader’s range. In this paper, we tackle this problem, by showing how a large number of tags moving on a conveyor belt can be read using a tandem of communicating readers placed along the axis of the conveyor belt. The tags that are unread by a reader could be read by the reader next in the sequence. Rather than restarting the protocol at the next reader in the sequence to read the unread tags, it can use the information from the previous reader (we call it information sharing) to improve protocol performance and hence reduce the reading time. Thanks to the advanced RFID technologies offering enhanced tag persistent times. The tags can now preserve their states in ‘power-off’ conditions for significantly longer distances in the conveyor-belt. We show that this information sharing significantly enhances the tag reading performance (in terms of number of tag reads) as compared with the traditional tag reading protocols. In our experiments, we consider the tandem reader arrangement with information sharing for ALOHA, Tree, and two different combinations of ALOHA and Tree (a.k.a. hybrid) protocols. Our performance evaluation study corroborated with extensive simulation results show that the aforementioned protocols augmented with our novel information sharing frameworks outperform their respective primitive ‘as-is’ version counterparts. [ABSTRACT FROM AUTHOR]

VANETs have emerged as an exciting research and application area. Increasingly vehicles are being equipped with embedded sensors, processing and wireless communication capabilities. This has opened a myriad of possibilities for powerful and potential life-changing applications on safety, efficiency, comfort, public collaboration and participation, while they are on the road. Although, considered as a special case of a Mobile Ad Hoc Network, the high but constrained mobility of vehicles bring new challenges to data communication and application design in VANETs. This is due to their highly dynamic and intermittent connected topology and different application’s QoS requirements. In this work, we survey VANETs focusing on their communication and application challenges. In particular, we discuss the protocol stack of this type of network, and provide a qualitative comparison between most common protocols in the literature. We then present a detailed discussion of different categories of VANET applications. Finally, we discuss open research problems to encourage the design of new VANET solutions. [ABSTRACT FROM AUTHOR]

IEEE 802.11 MAC is designed for single channel and based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). The throughput of network is limited by the bandwidth of the single channel and the CSMA-based MAC protocol with omnidirectional antennas can cause the serious unfairness or flow starvation. By exploiting the multiple channels and using the directional antennas, nodes located in each other’s vicinity may communicate simultaneously. This helps to increase the spatial reuse of the wireless channel and thus increase the network performance. In this paper, we propose a Multi-channel MAC protocol with Directional Antennas (MMAC-DA) that adopts IEEE 802.11 Power Saving Mechanism (PSM) and exploits multiple channel resources and directional antennas. Nodes have to exchange control packets during the Announcement Traffic Indication Message (ATIM) window to select data channels and determine the beam directions which are used to exchange data packets during the data window. The simulation results show that MMAC-DA can improve the network performance in terms of aggregate throughput, packet delivery ratio, energy efficiency and fairness index. [ABSTRACT FROM AUTHOR]

Public key management in mobile ad hoc networks (MANETs) has been studied for several decades. However, the unique characteristics of MANETs have imposed great challenges in designing a fully distributed public key management protocol under resource-constrained MANET environments. These challenges include no centralized trusted entities, resource constraints, and high security vulnerabilities. This work proposes a fully distributed trust-based public key management approach for MANETs using a soft security mechanism based on the concept of trust. Instead of using hard security approaches, as in traditional security techniques, to eliminate security vulnerabilities, our work aims to maximize performance by relaxing security requirements based on the perceived trust. We propose a composite trust-based public key management (CTPKM) with the goal of maximizing performance while mitigating security vulnerability. Each node employs a trust threshold to determine whether or not to trust another node. Our simulation results show that an optimal trust threshold exists to best balance and meet the conflicting goals between performance and security, by exploiting the inherent tradeoff between trust and risk. The results also show that CTPKM minimizes risk (i.e., information leakout) using an optimal trust threshold while maximizing service availability with acceptable communication overhead incurred by trust and key management operations. We demonstrate that CTPKM outperforms both existing non-trust-based and trust-based counterparts. [ABSTRACT FROM AUTHOR]

We present the Extended Minimum Estimated Expected Delay (EMEED) protocol for routing in wireless mobile Delay-Tolerant Networks (DTNs) comprising very large numbers of nodes with nonuniform, correlated mobility patterns. Under EMEED, packets are routed on graphs that are created taking into account (i) estimates of the expected delays until node pairs are within R C hops of each other and (ii) information on which node pairs are currently within R C hops of each other — R C is a tunable parameter. EMEED is inspired by the Minimum Estimated Expected Delay (MEED) protocol; it may be viewed as an extension of the basic routing method of MEED coupled with a suite of mechanisms that maintain the resulting control overhead at manageable levels. Packet replication is not employed. We evaluate the performance of EMEED through simulations in a pocket switched network and a vehicular DTN, comparing it with MEED, BUBBLE, Spray & Wait and flooding. We find that EMEED is superior to these other protocols in terms of jointly optimizing the packet delivery rate and the wireless channel usage efficiency. [ABSTRACT FROM AUTHOR]

Large scale, duty-cycled, wireless sensor networks provide support for applications ranging from anomaly detection to vehicle tracking. In order meet the requirements of these applications an autonomous configuration and maintenance method that is efficient and effective is required. When selecting a management solution it is important to consider both the direct and indirect costs associated with the different solution. For example, the overhead associated with communication synchronization and scheduling is an example of an indirect cost that can significantly impact the network lifetime. Further, an effective solution needs to recognize that in-network data aggregation and analysis presents significant benefits and should configure the network with a structure that benefits application layer functions. NOA, the proposed network management protocol, utilizes a multi-parent hierarchical logical structure. The multi-parent structure provides application layer functions with significant inherent benefits such as, but not limited to: elimination of the single-parent network divisions, data resolution guarantees when comparisons are performed at data aggregation points, and redundancies for communication as well as in-network data aggregation, analysis and storage. [ABSTRACT FROM AUTHOR]

Though lots of research results about self-healing key management under unreliable links have been proposed, there are still some shortcomings, such as the inefficiency of broadcasts, lack of broadcast authentication, limited sessions for key issues, disastrous risks of access polynomials, and the vulnerability of collusion attacks. In this paper, we propose two modified access polynomial based self-healing key management schemes with broadcast authentication and enhanced collusion resistance. First, two kinds of attacks are introduced to break the security of access polynomials. Then, a modified security model is given, and collusion resistance capability is redefined from the perspective of session interval from node revocation to node addition, which does not depend on the number of collusive nodes. Next, based on sliding window and modified access polynomial, Sch-I and Sch-II are proposed to achieve the security and tolerate packet losses, which allow pairwise keys between member nodes and group manager to be updated dynamically. Finally, theoretical analysis validates that the proposed schemes have δ self-healing capability, any -wise forward security and backward security, and enhanced collusion resistance capability, and can also avoid the flaws of access polynomials and reduce the resource consumption. Compared with existing schemes, they are quite suitable for practical applications. [ABSTRACT FROM AUTHOR]

IEEE 802.15.4 standard specifies the Medium Access Control (MAC) and Physical (PHY) layer for wireless sensor networks (WSN) applications with limited power and low data rate. This standard supports time critical applications by allowing TDMA based access in beacon enabled networks. In these networks, the PAN coordinator exchanges data with the end devices through guaranteed time slots (GTS). The PAN coordinator can allocate GTS on a first come first serve (FCFS) basis in response to the requests by end devices. In original standard, the coordinator can assign up to the maximum seven GTSs. This fixed number of GTS allocation may result in inefficient utilization of channel bandwidth. In this paper, we propose a new GTS allocation scheme that will set the GTS size adaptively in accordance with the data size of the end device. We call it as GTS Size Adaptation Algorithm (GSAA) and it will optimally use the GTS resources. Simulations have been performed to validate the proposed GSAA. [ABSTRACT FROM AUTHOR]

The Internet-of-Things (IoT) represents the third wave of computing innovation and relies on small, cheap and/or energy efficient devices, densely deployed in various spaces. Automatically managing, updating and upgrading the software on these devices, particularly the network stacks, with new, improved functionality is currently a major challenge. In this paper we propose GITAR, a generic extension for Internet-of-Things architectures, that enables dynamic application and network level upgrades in an efficient way. GITAR consists of four design concepts which can be applied to any operating system running on IoT/M2M devices. The proof of concept implementation in this paper uses the Contiki OS and the evaluation, based on analytical and experimental methods, shows that GITAR i) is up to 14% more efficient in terms of memory usage and ii) has less or similar run-time CPU overhead as state of the art solutions while offering upgrade functionality down to the network level and iii) can reuse existing Contiki network protocols for dynamic updates without requiring modifications to the code. [ABSTRACT FROM AUTHOR]

As underwater communications adopt acoustics as the primary modality, we are confronting several unique challenges such as highly limited bandwidth, severe fading, and long propagation delay. To cope with these, many MAC protocols and PHY layer techniques have been proposed. In this paper, we present a research platform that allows developers to easily implement and compare their protocols in an underwater network and configure them at runtime. We have built our platform using widely supported software that has been successfully used in terrestrial radio and network development. The flexibility of development tools such as software defined radio, TinyOS, and Linux have provided the ability for rapid growth in the community. Our platform adapts some of these tools to work well with the underwater environment while maintaining flexibility, ultimately providing an end-to-end networking approach for underwater acoustic development. To show its applicability, we further implement and evaluate channel allocation and time synchronization protocols on our platform. [ABSTRACT FROM AUTHOR]

The Sapienza University Networking framework for underwater Simulation Emulation and real-life Testing (SUNSET) is a toolkit for the implementation and testing of protocols for underwater sensor networks. SUNSET enables a radical new way of performing experimental research on underwater communications. It allows protocol designers and implementors to easily realize their solutions and to evaluate their performance through simulation, in-lab emulation and trials at sea in a direct and transparent way, and independently of specific underwater hardware platforms. SUNSET provides a complete toolchain of pre-deployment and deployment time tools able to identify risks, malfunctioning and under-performing solutions before incurring the expense of going to sea. Novel underwater systems can therefore be rapidly and easily investigated. Heterogeneous underwater communication technologies from different vendors can be used, allowing the evaluation of the impact of different combinations of hardware and software on the overall system performance. Using SUNSET, underwater devices can be reconfigured and controlled remotely in real time, using acoustic links. This allows the performance investigation of underwater systems under different settings and configurations and significantly reduces the cost and complexity of at-sea trials. This paper describes the architectural concept of SUNSET and presents some exemplary results of its use in the field. The SUNSET framework has been extensively validated during more than fifteen at-sea experimental campaigns in the past four years. Several of these have been conducted jointly with the NATO STO Centre for Maritime Research and Experimentation (CMRE) under a collaboration between the University of Rome and CMRE. [ABSTRACT FROM AUTHOR]

Underwater Acoustic Sensor Networks (UWSN) is challenging research area due to limited bandwidth, low data rate, severe multipath, and high variability in the channel conditions. These complicated and non-linear channel characteristics render incorrect most simplifying assumptions used in simulations. We believe that, while researchers have proposed several novel protocols, their use of models and simulations as the only form of validation and intra-protocol comparison remains removed from reality. We argue that research experimentation is hindered by two fundamental constraints: high cost of underwater networking experiments, and lack of a single, easily-replicable platform for evaluation. We present here Underwater Platform to Promote Experimental Research (UPPER): a low-cost and flexible underwater platform designed to enable cost-effective and repeatable experimentation. We utilize commercial off-the-shelf (COTS) components to provide a HW/SW integrated solution that interfaces to two version of our custom hydrophones, from laptops that act as an Software-Defined Radio (SDR)-based physical layer, while allowing higher layer protocols to interact via a flexible API. With a total cost of $25 and $65 for each version of our underwater communication platform, we evaluate the platforms to demonstrate their data rates (50–600 bps) and range (5–10 m for v1, 30–50 m for v2), thus indicating a cost-range tradeoff. We believe our platform removes the barrier to validating simulation results in underwater environments while also allowing a fair comparison between protocols. [ABSTRACT FROM AUTHOR]

In-band full-duplex (IB-FD) wireless is a promising next generation communication technology which can double the spectral efficiency with respect to the conventional in-band half-duplex (IB-HD) radio. Hidden stations degrade the performances of any practical wireless networks, but unlike IB-HD networks, hidden station scenarios are different in IB-FD wireless networks. In this paper, we have presented a novel energy-efficient medium access control protocol exploiting the network allocation vector, whereby mitigating the hidden station problem in an IB-FD wireless network. Moreover, an analytical model has been devised to unveil the impact of the distance between a primary–secondary transceiver pair in order to select a secondary receiver to initiate a successful relay like IB-FD link, thereby diminishing the inter-station interference problem. In addition, we have shown that the number of IB-FD transmission link increases if the secondary transmitter uses adaptive transmission power. We have evaluated the performance of the proposed protocol through detailed simulations using a modified version of NS-3 in which the wireless module has been re-designed to accommodate the concept of IB-FD radio. Results show that our proposed protocol achieves at least 61% and 41% throughput gain and consumes 58% and 60% lower energy than IEEE 802.11 DCF RTS–CTS and FD-MAC protocols, respectively. Our proposed protocol outperforms the baseline protocols with respect to throughput, energy consumption, average re-transmission rate, average packet drop rate, etc. The proposed scheme can be very useful to IB-FD wireless networks which contain bandwidth-hungry applications. [ABSTRACT FROM AUTHOR]

The Internet of Things or “IoT” defines a highly interconnected network of heterogeneous devices where all kinds of communications seem to be possible, even unauthorized ones. As a result, the security requirement for such network becomes critical whilst common standard Internet security protocols are recognized as unusable in this type of networks, particularly due to some classes of IoT devices with constrained resources. The document discusses the applicability and limitations of existing IP-based Internet security protocols and other security protocols used in wireless sensor networks, which are potentially suitable in the context of IoT. The analysis of these protocols is discussed based on a taxonomy focusing on the key distribution mechanism. [ABSTRACT FROM AUTHOR]

The study of polling disciplines for receiver-initiated MAC protocols has not received much attention in the literature, and simple schemes such as round-robin or uniform prioritization are usually assumed. However, not only the order, but also the rate at which nodes are polled is significant: a polling rate that is too slow may render low throughput and high delays, whereas the opposite may lead to excessive control traffic and frame collisions. Ideally, a receiver-initiated MAC protocol would perform best if nodes could know “whom” and “when” to poll based on data availability. This paper investigates the performance of three polling disciplines when applied to a specific receiver-initiated unicast MAC protocol that is based on a reversal of the binary exponential backoff (BEB) algorithm of the IEEE 802.11. With the BEB algorithm, the polling rate is self-regulated according to channel conditions and traffic availability at polled nodes. Additionally, this paper extends the BEB-based MAC protocol by introducing a new control frame and a frame reordering technique at MAC queues to speed up polling rounds. The performance of the polling disciplines are also compared to the traditional IEEE 802.11 with respect to control overhead, delay, fairness, and throughput, according to different topologies and traffic scenarios. [ABSTRACT FROM AUTHOR]