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Routing Protocol for Low Power and Lossy Networks (RPL) is the de-facto routing standard in IoT networks. It enables nodes to collaborate and autonomously build ad-hoc networks modeled by tree-like destination-oriented direct acyclic graphs (DODAG). Despite its widespread usage in industry and healthcare domains, RPL is susceptible to insider attacks. Although the state-of-the-art RPL ensures that only authenticated nodes participate in DODAG, such hard security measures are still inadequate to prevent insider threats. This entails a need to integrate soft security mechanisms to support decision-making. This paper proposes iTRPL , an intelligent and behavior-based framework that incorporates trust to segregate honest and malicious nodes within a DODAG. It also leverages multi-agent reinforcement learning (MARL) to make autonomous decisions concerning the DODAG. The framework enables a parent node to compute the trust for its child and decide if the latter can join the DODAG. It tracks the behavior of the child node, updates the trust, computes the rewards (or penalties), and shares them with the root. The root aggregates the rewards/penalties of all nodes, computes the overall return, and decides via its ϵ -Greedy MARL module if the DODAG will be retained or modified for the future. A simulation-based performance evaluation demonstrates that iTRPL learns to make optimal decisions with time. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates the performance of MIMO ad hoc networks that employ transmit diversity, as delivered by the Alamouti scheme, and/or spatial multiplexing, according to the Vertical Bell Labs Layered Space-Time system (V-BLAST). Both techniques are implemented in the ns-3 network simulator by focusing on their overall effect on the resulting signal-to-interference-plus-noise ratio (SINR) at the intended receiver. Unlike previous works that have studied fully-connected scenarios or have assumed simple abstractions to represent MIMO behavior, this paper evaluates MIMO ad hoc networks that are not fully connected by taking into account the impact of multiple antennas on the carrier sense activity in CSMA-like medium access control (MAC) protocols. In addition to presenting a performance evaluation of ad hoc networks operating according to each individual MIMO scheme, this paper proposes simple modifications to the IEEE 802.11 DCF MAC to allow the joint operation of both MIMO techniques. Hence, each pair of nodes is allowed to select the best MIMO configuration for the impending data transfer. The joint operation is based on three operation modes that are selected based on the estimated SINR at the intended receiver and its comparison with a set of threshold values. The performance of ad hoc networks operating with the joint MIMO scheme is compared with the performance when using each individual MIMO scheme and the standard single-input single output (SISO) IEEE 802.11. Performance results are presented based on MAC-level throughput per node, delay, and throughput fairness under saturated traffic conditions. [ABSTRACT FROM AUTHOR]

The fast evolutions of Internet of Things (IoT) technologies have been accelerating their applicability in different sectors of life and becoming a pillar for sustainable development. However, this revolutionary expansion led to a substantial increase in attack surface, raising many concerns about security threats and their possible consequences. Machine learning has significantly contributed to designing intrusion detection systems (IDS) but suffers from critical limitations such as data privacy and sovereignty, data imbalance, concept drift, and catastrophic forgetting. This collectively makes existing IDSs an improper choice for securing IoT environments. This paper presents a federated learning approach called FIDWATCH to continuously monitor and detect a broad range of IoT security threats. The local side of FIDWATCH introduces contrastive focal loss to enhance the ability of the local model (teacher) to discriminate between diverse types of IoT security threats while putting an increased emphasis on hard-to-classify samples. A fine-grained Knowledge Distillation (KD) is introduced to allow the client to distill the required teacher's knowledge into a lighter, more compact model termed the pupil model. This greatly assists the competence and flexibility of the model in resource-constrained scenarios. Furthermore, an adaptive incremental updating method is introduced in FIDWATCH to allow the global model to exploit the distilled knowledge and refine the shared dataset. This helps generate global anchors for improving the robustness of the mode against the distributional shift, thereby improving model alignment and compliance with the dynamics of IoT security threats. Proof-of-concept simulations are performed on data from two public datasets (BoT-IoT and ToN-IoT), demonstrating the superiority of FIDWATCH over cutting-edge performance with an average f1-score of 97.07% and 95.63%, respectively. [ABSTRACT FROM AUTHOR]

In order to establish communication links among different communication devices or machines, the Medium Access Control (MAC) has to schedule the simultaneous transmissions by the contending nodes to constrain the probability of outage at each receiver. An efficient channel access scheme should be able to schedule the highest number of concurrent transmissions while being easy to implement with minimal coordination between the contending nodes. The existing MAC schemes provide network-wide solutions without adaptiveness, such as in existing guard zone-based solutions. On the other hand, an adaptive channel access scheme is proposed in this paper, which instead of declaring a network-wide fixed guard zone employs each interferer's Transmitter–Receiver (Tx–Rx) separation to conclude its incorporation in the scheduled transmissions. The suggested scheme warrants the spatial separation among the scheduled links by suppressing the dominant interferers. The proposed MAC design functions approximately as good as the centralized, otherwise infeasible, joint scheduling and power control algorithm. In addition, the recommended scheme has proved its strength by outperforming both Carrier Sense Multiple Access (CSMA) and fix-sized guard zone schemes by significant margins under strict outage constraints and high contention density. The proposed scheme provided up to 100% and 60% better transmission capacity when compared with CSMA and fix-sized guard zone-based scheme, respectively. This paper also presents the closed-form results for the optimal guard zone size multiplier and the corresponding throughput capacity in terms of various network variables, such as contention density, outage constraint, Tx–Rx separation, network's path loss exponent and spreading factor. [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]

Abstract: Mobile ad hoc networks are able to extend the coverage area of Internet access points by establishing multihop communication paths. Due to diverse factors such as the mobility of the nodes, the propagation conditions or the traffic status, the communication paths present a lifetime. In fact, the quality of the Internet connection mainly depends on the durability of the employed communication routes. In order to improve the network performance, the nodes should select the best route in terms of its remaining lifetime. Since the factors impacting the route lifetime are unpredictable, the route remaining lifetime cannot be analytically derived. Under these circumstances, a fuzzy-logic system outstands as a potential solution to estimate the stability of the routes. This paper analyses the potentiality of this kind of solution. In particular, the paper presents a fuzzy logic system which should be installed in the mobile nodes to distributedly identify the stable routes. In particular, the system is supported by an interval-based type-2 fuzzy logic. Being a type-2 fuzzy logic system, it is able to cope with inexact estimations. This ability is necessary to avoid the use of additional messages which will occupy the scarce wireless medium. On the other hand, an interval-based fuzzy system provides the simplicity demanded by the energy-constrained mobile devices. As a novelty, the two outputs of the interval-based fuzzy system are employed. The use of each output depends on the traffic state of the mobile node. By means of extensive simulations, we demonstrate the goodness of the proposed system. [Copyright &y& Elsevier]

Abstract: In this paper we study the fundamental scheduling, multiplexing and diversity trade-off in MIMO ad hoc networks. In particular, we propose a unified framework for the scheduling-multiplexing and scheduling-diversity sub-problems that constitutes a major step towards solving the overall problem. The two sub-problems are motivated by a fundamental trade-off between scheduling full multiplexing (diversity) gain non-interfering links and scheduling interfering links using lower multiplexing (diversity) gain in conjunction with interference nulling. First, we cast each sub-problem as a cross-layer optimization problem that jointly decides the scheduling and MIMO stream allocation, subject to signal-to-interference-and-noise-ratio (SINR) constraints. Second, we characterize the problem as non-convex integer programming which is quite challenging to solve. Hence, we shift our focus to characterize the optimal for the simple case of two links. The main result of this paper is that the two fundamentally different sub-problems give rise to structurally similar SINR-based decision rules which constitute the basis for a resource allocation algorithm with linear complexity in the number of links, namely Iterative MIMO Link Scheduling (IMLS), that solves the two sub-problems and achieves significant gains for any number of links. Numerical results exhibit more than twofold/quadratic improvement over scheduling non-interfering links with full multiplexing/diversity gain, for plausible scenarios. IMLS and its variants reveal an important throughput-fairness trade-off which is an interesting topic for future research. [Copyright &y& Elsevier]

Abstract: The future ubiquitous ambient systems will probably be incomplete without underwater wireless networks. In this paper we present an analytic model for the throughput of the IEEE 802.11 medium access control (MAC) protocol in underwater acoustic networks. Underwater acoustic networks suffer from long propagation delays and low bit rates. The IEEE 802.11 medium access control (MAC) protocol, designed for free space radio channels, faces diffculties in the underwater channel. This paper proposes a model to analyze the IEEE 802.11 throughput in underwater acoustic networks. The proposed model is verified with detailed simulations and is accurate for a continuous range of propagation delays from less than a microsecond to over a full second, making it suitable for a detailed throughput performance analysis of the 802.11 MAC protocol in underwater acoustic networks. [Copyright &y& Elsevier]

Abstract Visible light communication (VLC) is a wireless technology complementary to well-understood radio frequency (RF) communication that is promising to help alleviate the spectrum crunch problem in overcrowded RF spectrum bands. While there has been significant advancement in recent years in understanding physical layer techniques for visible light point-to-point links, the core problem of developing efficient networking technology specialized for visible-light networks is substantially unaddressed. This article discusses the current existing techniques as well as the main challenges for the design of visible-light ad hoc networks - referred to as LANETs. The paper discusses typical architectures and application scenarios for LANETs and highlights the major differences between LANETs and traditional mobile ad hoc networks (MANETs). Enabling technologies and design principles of LANETs are analyzed and existing work is surveyed following a layered approach. Open research issues in LANET design are also discussed, including long-range visible light communication, full-duplex LANET MAC, blockage-resistant routing, VLC-friendly TCP and software-defined prototyping, among others. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we analyze the average end-to-end delay and maximum achievable per-node throughput in random access multihop wireless ad hoc networks with stationary nodes. We present an analytical model that takes into account the number of nodes, the random packet arrival process, the extent of locality of traffic, and the back off and collision avoidance mechanisms of random access MAC. We model random access multihop wireless networks as open G/G/1 queuing networks and use the diffusion approximation in order to evaluate closed form expressions for the average end-to-end delay. The mean service time of nodes is evaluated and used to obtain the maximum achievable per-node throughput. The analytical results obtained here from the queuing network analysis are discussed with regard to similarities and differences from the well established information-theoretic results on throughput and delay scaling laws in ad hoc networks. We also investigate the extent of deviation of delay and throughput in a real world network from the analytical results presented in this paper. We conduct extensive simulations in order to verify the analytical results and also compare them against NS-2 simulations. [Copyright &y& Elsevier]

Abstract: This paper shows a novel self-organizing approach for routing datagrams in ad hoc networks, called Distributed Ant Routing (DAR). This approach belongs to the class of routing algorithms inspired by the behavior of the ant colonies in locating and storing food. The effectiveness of the heuristic algorithm is supported by mathematical proofs and demonstrated by a comparison with the well-known Ad hoc On Demand Distance Vector (AODV) algorithm. The differences and the similarities of the two algorithms have been highlighted. Results obtained by a theoretical analysis and a simulation campaign show that DAR allows obtaining some important advantages that makes it a valuable candidate to operate in ad hoc networks and the same method helps in the selection of the algorithm parameters. Since the approach aims at minimizing complexity in the nodes at the expenses of the optimality of the solution, it results to be particularly suitable in environments where fast communication establishment and minimum signalling overhead are requested. These requirements are typical of ad hoc networks with critical connectivity, as described in the paper. Thus the performance of the proposed algorithm are shown in ad hoc networks with critical connectivity and compared to some existing ad hoc routing algorithms. [Copyright &y& Elsevier]

Anonymity and authenticated key exchange should be paid much more attention in secure mobile ad hoc routing protocols, especially in privacy-vital environment. However, as far as we know, few papers on secure routing protocols have addressed both the anonymity and authenticated key exchange. Therefore, in this paper, we present a new secure anonymous routing protocol with authenticated key exchange for ad hoc networks. In comparison with other previous secure routing protocols, our proposed protocol not only provides the anonymity to the route from the source to the destination, but also integrates the authenticated key exchange into the routing algorithm. [Copyright &y& Elsevier]

Abstract: In this paper we consider on-line disjoint path routing in energy-constrained ad hoc networks. The objective is to maximize the network capacity, i.e. maximize the number of messages routed successfully by the network without any knowledge of future disjoint path connection request arrivals and generation rates. Specifically, in this paper we first present two centralized on-line algorithms for the problem. One is based on maximizing local network lifetime, which aims to minimize the transmission energy consumption, under the constraint that the local network lifetime is no less than γ times of the optimum after the realization of each disjoint path connection request, where γ is constant with 0< γ ⩽1. Another is based on the exponential function of energy utilization at nodes, and the competitive ratio of this latter algorithm is also analyzed if admission control mechanism is employed. We then conduct extensive experiments by simulations to analyze the performance of the proposed algorithms, in terms of network capacity, network lifetime, and the transmission energy consumption for each disjoint path connection request. The experimental results show that the proposed algorithms outperform those existing algorithms that do not take into account the power load balancing at nodes in terms of maximizing the network capacity. [Copyright &y& Elsevier]

Abstract: This paper describes an ad hoc networking scheme and routing protocol for emergency communications. The objective of the network is to collect damage assessment information quickly and stably in a disaster. The network is configured with a hybrid wireless network, combining ad hoc networks and a cellular network to maintain connectivity between a base station (BS) and nodes even in a disaster. In the event that a direct link between the BS and a node is disconnected due to damage or obstacles, the node switches to the ad hoc mode, and accesses the BS via neighboring nodes by multihopping. The routing protocol proposed in this paper discovers and builds a route by way of monitoring neighbors’ communications instead of broadcasting a route request packet. The network employs a dedicated medium access control protocol based on TDM (Time Division Multiplexing) for multihopping in ad hoc networks to maintain accessibility and to perform a short delay. Experiments showed that approximately 90% of nodes are capable of reaching the BS within a few hops, even in conditions where only 20% of nodes maintain direct connections to the BS. In addition, the results showed that it is feasible for the network to operate in a short delay for delivering a packet to the BS. However, throughput is not retrieved sufficiently due to the restriction of the access protocol, whereas reachability does improve sufficiently. Therefore, the network is suitable for collecting damage assessment information and transmitting urgent traffic quickly and stably, while the data is restricted to a small amount. [Copyright &y& Elsevier]

Research on multi-path routing protocols to provide improved throughput and route resilience as compared with single-path routing has been explored in details in the context of wired networks. However, multi-path routing mechanisms have not been explored thoroughly in the domain of ad hoc networks. In this paper, we propose a new routing protocol which increases the network throughput. The protocol is a multi-path routing protocol with a load balance policy. The simulations show a significant improvement in terms of connection throughput and end-to-end delay, when compared to single-path routing. The second significant contribution of this paper is a theoretical analysis allowing to compare reactive single-path and multi-path routing with load balance mechanisms in ad hoc networks, in terms of overheads, traffic distribution and connection throughput. The results reveal that multi-path routing (using a load balance policy) provides better performance than reactive single-path routing in terms of congestion and connection throughput, provided that the average route length is smaller than certain upper bounds which are derived and depend on parameters specific to the network. These upper bounds are very crucial because they can be taken into account as constraints in the route discovery mechanism so that the multi-path routing protocol is guaranteed to lead to an increase performance than a simple single-path one. Also, our analysis provide some insight into choosing the right trade-off between increased overheads and better performance. We show in particular that for certain networks, a multi-path routing strategy is not worth considering. [Copyright &y& Elsevier]

IEEE 802.11 MAC mainly relies on two techniques to combat interference: physical carrier sensing and RTS/CTS handshake (also known as “virtual carrier sensing”). Ideally, the RTS/CTS handshake can eliminate most interference. However, the effectiveness of RTS/CTS handshake is based on the assumption that hidden nodes are within transmission range of receivers. In this paper, we prove using analytic models that in ad hoc networks, such an assumption cannot hold due to the fact that power needed for interrupting a packet reception is much lower than that of delivering a packet successfully. Thus, the “virtual carrier sensing” implemented by RTS/CTS handshake cannot prevent all interference as we expect in theory. Physical carrier sensing can complement this in some degree. However, since interference happens at receivers, while physical carrier sensing is detecting transmitters (the same problem causing the hidden terminal situation), physical carrier sensing cannot help much, unless a very large carrier sensing range is adopted, which is limited by the antenna sensitivity. In this paper, we investigate how effective is the RTS/CTS handshake in terms of reducing interference. We show that in some situations, the interference range is much larger than transmission range, where RTS/CTS cannot function well. Two independent solutions are proposed in this paper. One is a simple enhancement to the IEEE 802.11 MAC protocol. The other is to utilize directional antennas. Simulation results verify that the proposed schemes indeed can help IEEE 802.11 resolve most interference caused by large interference range. [Copyright &y& Elsevier]

In this paper we address the goal of achieving higher throughput capacity in multi-hop wireless ad hoc networks than estimated by capacity scaling laws of Gupta and Kumar (2000) [1]. By exploiting the implications pointed in earlier research, a cross-layer design based channel quality aware rate adaptive MAC algorithm CQRA-MAC is proposed to achieve this goal. CQRA-MAC dynamically switches the MAC transmission rate on the basis of channel quality experienced at the physical layer. The proposed algorithm is implemented by modifying the IEEE 802.11 model of Qualnet 4.5 simulator and its performance is evaluated in static and mobile network scenarios following the random access transport capacity approach. Experimental results show that CQRA-MAC achieves higher throughput than DCF and ARF. The achieved throughput capacity is quantified in terms of measurable network parameters and thus validates equations of random access transport capacity framework (Andrews et al., 2010) [9]. [ABSTRACT FROM AUTHOR]

Without pre-defined infrastructures, vehicles connect to each other to form Vehicular Ad-Hoc Networks (VANETs) to deliver data among vehicles. Dissemination of messages, for example accident alert messages or congestion messages is critical in VANETs. People’s lives may be at stake in accidents. Modeling and predicting VANETs’ message dissemination opens an opportunity to adopt appropriate strategies to alert severe accidents, manage traffic, evacuate vehicles from disasters, or recover from accidents. However, modeling data dissemination is challenging due to vehicles’ high mobility, which results in network topologies rapidly changing and data transmission being unstable. This paper presents analytical data dissemination models on VANETs. We model data dissemination as a new production adoption process and as a time-dependent stochastic process. The fact that information value or importance is decreasing with time and distance is also considered. The analytical models allow prediction and evaluation of information diffusion and enable intelligent traffic management. [ABSTRACT FROM AUTHOR]

In multihop wireless ad hoc networks, it is important to maintain the outcome fairness of throughput and to maximize the throughput. In this paper, we propose a novel opportunistic scheduling framework by considering outcome fairness and throughput simultaneously. Since the data rate fluctuates intensively due to channel errors, we first devise a data rate estimation method with an adaptive sliding window to accurately and adaptively estimate the data rate. Then, we present a framework together with two mechanisms. The first proposed mechanism is ROSA-WOM, with the weighted objective function method to configure the data rate. The other one is ROSA-MGCF, and it is a maximum total goodput method under a constrained fairness index. The proposed mechanisms are able to schedule the flows fairly even when the data rate of all flows is more than the channel capacity. We establish a testbed to evaluate these two mechanisms. The experiment results show that our proposed mechanisms can not only trade off with different fairness and throughput requirements, but also effectively provide robust service isolation, outcome fairness, and high throughput in the presence of channel errors. [ABSTRACT FROM AUTHOR]

Ad hoc networks have been serving us in one way or the other, for two decades, through their vast variety of applications in majority fields. Due to their features such as hostile deployments, high level of mobility, limited resources and physical insecurity, they are in front line to attackers. First line of defense (cryptographic techniques, fire walls etc.) stops these attacks. But what would happen if the attacker break through this defense system? Second of line of defense also called intrusion detection system (IDS), would stop and mitigate these threats before they harm the network or its resources. Various schemes have been proposed to provide quality IDS that could mitigate the latest threats in ad hoc networks. In this review paper, we gave a detailed overview of ad hoc networks in the start. We explored ad hoc networks security followed by description about IDS. Next, we elaborated the taxonomy of IDS, containing types of IDS based on numerous parameters. In the trailing section, we compared wide variety of IDS schemes based on different methodology/techniques, to show their importance and performance in the field of intrusion detection. Finally, we concluded the paper with informative future research directions in the state of the art research fields that would open up ways for researchers in that area. [ABSTRACT FROM AUTHOR]

Information broadcasting in MANETs is an essential building block for cooperative operations, group discussions, and common announcements (e.g., filling routing tables). The flooding is the simplest broadcasting scheme used in MANETs. In this scheme, source nodes broadcast at once packets to all neighbors. Broadcasting through flooding causes increased messages redundancy, collision, and wastage of bandwidth and energy. Several approaches have been proposed to solve these issues and could be classified into two main categories: static schemes and adaptive schemes. In this paper, we introduce an adaptive scheme for information broadcasting in MANETs. This scheme allows nodes to select an appropriate action, either to rebroadcast or to discard receiving messages. The decision is based on the amount and timestamps of received messages. Simulations have been conducted and results show that the proposed scheme reduces the number of packet transmissions, has better latency and SRB, good reachability, and low energy consumption. [ABSTRACT FROM AUTHOR]

Mission-critical military operations with dismounted soldiers are frequently characterized by high battlefield dynamics. In such scenarios a mobility model can manage soldiers’ movements dynamically especially under enemy attacks. This paper presents a group mobility model simulating realistic soldier and leader battlefield behaviors. Our model analyzes communication between a group of dismounted soldiers deployed in a mobile ad hoc network (MANET) and their leader under several perturbation factors (e.g., noise and enemies attacks) which affect movements and topology connectivity. Results show that the dismounted soldiers’ collective movement improves the capacity of communication channels, whereas noise uncertainty may dramatically destroy the network. Moreover, the enemy’s presence, another disorder parameter, changes qualitatively and quantitatively the army’s wireless communication topology. Enemy numbers decrease almost linearly the throughput at the sink node (commander). A discussion of results follows, using distributions of path lifetimes, path lengths, packet delivery and group sizes in the communication soldiers’ network. [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]

Range extension is a promising feature offered by cooperative transmission (CT), also known as virtual multiple-input–single-output (VMISO). Many authors have considered how the diversity and array gains from CT may benefit a wireless multi-hop network, when the gains are used for increasing link reliability and reducing transmit power. However, relatively less attention has been given to the benefits of CT range extension and few testbed implementations of CT have been demonstrated. In this paper, we focus on how CT range extension can impact the lower three layers, especially medium access control (MAC) and routing for ad hoc and sensor multi-hop networks (AHSMNs). We assume cooperators decode and forward the packets. Various analytical models, performance analyses, and experimental results using software-defined radios in an indoor office environment are discussed. For wireless sensor networks (WSNs), we review CT range extension at the network layer, to eliminate the energy hole that forms around sink nodes in non-CT networks, and we review cooperator selection and duty cycle scheduling algorithms at Layer 2, to maximize the lifetime of a multi-hop WSN. For ad hoc networks, we emphasize a family of lightweight broadcasting and unicasting protocols based on a simple form of CT called the opportunistic large array (OLA). Experimental results, including OLA-based unicast routing and diversity order effects in two-hop CT networks, are discussed. [ABSTRACT FROM AUTHOR]

An accurate reproduction of real human movement is essential in simulations of MANETs in order to obtain meaningful performance results. Existing models capturing real world mobility features often require knowledge of the underlying dynamics of the target scenario, therefore limiting the application scope. In this paper we tackle this problem from a different perspective. Rather than considering the details of the target scenario, we extract features from a sample trace, and synthesize traces that have similar features. In particular, as human activities are often socially organized, resulting in a tendency of forming groups, we propose an N-body mobility model that captures the group forming tendency from traces of a small number of nodes, and reproduces them in mobility traces of a larger population. Through simulation we show that the N-body model is capable of synthesizing the group forming behavior similar to that observed from sample traces. [ABSTRACT FROM AUTHOR]

Due to the properties of ad-hoc networks, it appears that designing sophisticated defence schemes with more computing capital is impossible in most situations. Recently, an inconsistency in the ad-hoc design of intrusion detection in the network has gotten a lot of coverage, with these intrusion detection techniques operating in either cluster-based or host-based configurations. The host and cluster-based systems have advantages and disadvantages, such as the network preserve security in case of delay in replacing a cluster head. Many detection systems in these networks use a supervised learning method to learn from shared routing knowledge. Deep learning is the trending supervised learning method which is been suggested for many applications, due to its deep feature extraction and classification capability. The deep learning method is best suitable to resolve the problems of the ad hoc network. But due to its limitation of supervised learning nature, more research finds are needed before implementation. These intelligence methods need a massive labeled dataset to self-train and take a decision in real-time. Also, these methods will be vulnerable to new attacks. To address the issues posed, the deep learning approach requires a technique of incorporating unsupervised learning behaviours. This paper proposes and highlights the methodology - Deep Embedded Median Clustering (DEMC), which performs two-phase operations (1) Organization of latent feature space (2) K-median clustering to cluster the Z with Kullback–Leibler divergence as the objective function. Many researchers suggested various methodologies for better anomaly detection in the network, but the knowledge gap and the possibilities for a better solution still exist. This study explores the new possibility and potential of an unsupervised learning technique that works with the nature of deep learning for analyzing and detecting anomalies and intrusion in ad hoc networks. The test to check the DEMC ability has been organized, and the findings are tabulated for analysis. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we address the problem of finding the optimal performance region of a wireless ad hoc network when multiple performance metrics are considered. Our contribution is to propose a novel cross-layer framework for deriving the Pareto optimal performance bounds for the network. These Pareto bounds provide key information for understanding the network behavior and the performance trade-offs when multiple criteria are relevant. Our approach is to take a holistic view of the network that captures the cross-interactions among interference management techniques implemented at various layers of the protocol stack (e.g. routing and resource allocation) and determines the objective functions for the multiple criteria to be optimized. The resulting complex multiobjective optimization problem is then solved by multiobjective search techniques. The Pareto optimal sets for an example sensor network are presented and analyzed when delay, reliability and energy objectives are considered. [Copyright &y& Elsevier]

Abstract: Medium access control (MAC) protocol is essential since it is to address how to resolve potential contentions and collisions among wireless nodes and give them equal share of channel bandwidth. However, due to the existence of hidden/exposed terminal problem and partially connected network topology, IEEE 802.11 standard, the de facto and widely accepted wireless MAC protocol, does not function well in mobile ad hoc networks (MANETs) because it brings intensive collisions, unfair channel access, and quickly degraded system throughput in multi-hop environments, especially when the whole system is also dense and congested. One approach to alleviate this problem is to use multi-channel MAC protocol because these nodes can access the wireless channel simultaneously as long as they choose the different channels to transmit their packets. Nowadays, the modern wireless MAC protocols usually support multiple channels, where mobile nodes adapt their channels based on their channel selection strategies to transmit their own packets. In this paper, we put forth an adaptive channel allocation strategy for IEEE 802.11 based multi-channel MAC protocol in MANETs. An analytic model is also carried out to study the normalized saturation throughput of proposed scheme. In addition to theoretical analysis, simulations are conducted to evaluate the performance of the proposed scheme in congested multi-hop environments, and the results indicate that our adaptive channel allocation strategy did achieve far better performance than the legacy single channel IEEE 802.11 protocol without loss of simplicity. [Copyright &y& Elsevier]

Abstract: Mobile wireless ad hoc networks need to maximize their network lifetime (defined as the time until the first node runs out of energy). In the broadcast network lifetime problem, all nodes are sending broadcast traffic, and one asks for an assignment of transmit powers to nodes, and for sets of relay nodes so that the network lifetime is maximized. The selection of a dynamic relay set consisting of a single node (the ‘master’), can be regarded as a special case, providing lower bounds to the optimal lifetime in the general setting. This paper provides a preliminary analysis of such a ‘dynamic master selection’ algorithm, comparing relaying to direct routing. [Copyright &y& Elsevier]

Abstract: Mobile ad hoc networks (MANET) have a set of unique challenges, particularly due to mobility of nodes, that need to be addressed to realize their full potentials. Because the mobile nodes of a MANET are free to move rapidly and arbitrarily, the network topology may change unexpectedly. This paper presents a decentralized approach to maintain the connectivity of a MANET using autonomous, intelligent agents. Autonomous agents are special mobile nodes in a MANET, but unlike other nodes, their function is to proactively prevent network bottlenecks and service problems by intelligently augmenting the network topology. To achieve this function without depending on a central network management system, autonomous agents are expected to dynamically relocate themselves as the topology of the network changes during the mission time. A flocking-based heuristic algorithm is proposed to determine agent locations. A computational study is performed to investigate the effect of basic flocking behaviors on the connectivity of a MANET. [Copyright &y& Elsevier]

Abstract: This paper studies a density driven virtual topography based publish/subscribe service for mobile ad hoc networks. Two variants of the service are presented and evaluated by extensive simulations; the first is very communication frugal while the latter trades a higher message overhead for faster latency. Both variants are also being compared to two other representative approaches for publish/subscribe in ad hoc networks, a dissemination tree based scheme and an efficient flooding based scheme. It is shown that the density-driven approach outperforms the others in most tested scenarios. [Copyright &y& Elsevier]

Abstract: Wireless ad hoc network (WANET) is a decentralized type of the wireless network. There are various challenges that are faced in the ad hoc environment. Wireless ad hoc networking is the enabling technology for paramount civilian and military applications requiring easy and quick (and often unmanned and cheap) network deployments. The security of communication in ad hoc wireless network is very important especially in military applications. The wireless nature of communication and any lack of network security infrastructure raise several security problems. Asymptotic notations solve the problem of large wireless networks. The main objective of the system is performance degradation of the secure network. In this paper mainly considering, order to reduce delay and increase throughput. The network performance can be calculated by using probability (p<1). Here we implemented LEACH algorithm for an efficient energy saving and thus increases the life time of wireless network. The simulation results show the presented algorithm is more efficient energy saving and fewer packets are damaged; thus provides secure wireless network. [Copyright &y& Elsevier]

Abstract: This paper presents a comparative analysis between the mechanisms of media access control IEEE 802.11 and MMAC-CR (Multichannel MAC protocol for Cognitive Radio) in MANETs (Mobile Ad Hoc Networks). The IEEE 802.11 standard allows the use of multiple channels available at the physical layer, but its MAC protocol is designed for a single channel. However, a MAC protocol of a single channel does not work well in a multichannel environment due to the hidden terminal problem. The simulation results show how the MMAC-CR protocol allows a better use of spectral opportunities thereby increasing the throughput of the MANET network. [Copyright &y& Elsevier]

Abstract: Dynamic spectrum access has been proposed as a means to share scarce radio resources, and requires devices to follow protocols that access spectrum resources in a proper, disciplined manner. For a cognitive radio network to achieve this goal, spectrum policies and the ability to enforce them are necessary. Detection of an unauthorized (anomalous) usage is one of the critical issues in spectrum etiquette enforcement. In this paper, we present a network structure for dynamic spectrum access and formulate the anomalous usage detection problem using statistical significance testing. The detection problem investigated considers two cases, namely, the authorized (primary) transmitter is (i) mobile and (ii) fixed. We propose a detection scheme for each case by exploiting the spatial pattern of received signal energy across a network of sensors. Analytical models are formulated when the distribution of the energy measurements is given and, due to the intractability of the general problem, we present an algorithm using machine learning techniques to solve the general case when the statistics of the energy measurements are unknown. Our simulation results show that our approaches can effectively detect unauthorized spectrum usage with a detection probability above 0.9 while keeping the false alarm rate less than 0.1 when only one unauthorized radio is present, and the detection probability is even higher for more unauthorized radios. [Copyright &y& Elsevier]

Abstract: Although more than a decade has passed from the proposal of the Cognitive Radio paradigm, in these years the research has mainly focused on physical and medium access issues, and few recent works focused on the problem of routing in cognitive networks. This paper addresses such a problem by evaluating the feasibility of reactive routing for mobile cognitive radio ad hoc networks. More specifically, we design a reactive routing protocol for the considered scenario able to achieve three goals: (i) to avoid interferences to primary users during both route formation and data forwarding; (ii) to perform a joint path and channel selection at each forwarder; (iii) to take advantage of the availability of multiple channels to improve the overall performance. Two different versions of the same protocol, referred to as Cognitive Ad-hoc On-demand Distance Vector (CAODV), are presented. The first version exploits inter-route spectrum diversity, while the second one exploits intra-route spectrum diversity. An exhaustive performance analysis of both the versions of the proposed protocol in different environments and network conditions has been carried out via numerical simulations. The results state the suitability of the proposed protocol for small mobile cognitive radio ad hoc networks. [Copyright &y& Elsevier]

Abstract: In this paper we present a mobility model for ad hoc networks consisting of human-operated nodes that are deployed in obstacle-constrained environments. According to this model, the network nodes move around the obstacles in a way that resembles how humans bypass physical obstructions. A recursive procedure is executed by each node at its current position to determine the next intermediate destination point until the final destination point is reached. The proposed mobility model is validated using real-life trace data and studied using both mathematical analysis and simulations. Furthermore, the model is extended to incorporate several operational aspects of ad hoc networks in mission critical scenarios, where it is best applicable. These extensions include hierarchical node organization, distinct modes of node activity, event-based destination selection and impact of the physical obstacles on signal propagation. The model is implemented as an add-on module in Network Simulator (ns-2). [Copyright &y& Elsevier]

Abstract: Ad hoc networks are highly dynamic networks where the nodes are battery-powered. Routing in such networks is an issue of upcoming concern due to the possibility of frequent link breakage as a result of node mobility and/or high rate of energy depletion of nodes. Also to fulfill certain quality parameters, presence of multiple node disjoint paths become essential. Such paths aid in the optimal traffic distribution and reliability in case of path breakages. In this paper we propose a fuzzy controlled power aware multicast routing (FPMR) protocol that takes into account estimated network evolution in terms of residual energy of nodes w.r.t. approximated energy required to complete the multicast operation, link stability, geographical positions of multicast receivers etc. Extensive simulation experiments have been conducted to compare the performance of FPMR with other state-of-the –art multicast protocols. The results w.r.t. a wide range of parameters show that FPMR attains significantly high packet delivery ratio at much lesser cost than its competitors, thereby improving the lifetime of nodes. [Copyright &y& Elsevier]

Abstract: AODV protocol is based on the minimum delay path as the route selection criteria, regardless of the size of the load path nodes, routing has a large selection of blindness in real-time requirements in the network transmission higher than the amount of information large, the occupancy of the route longer the case, often a bottleneck node problem, leading to some of the routing node congestion and delays or even data loss and a series of problems; This paper presents a web-based time-delay In AODV routing protocol, based on adding random selection algorithm, the traffic in accordance with the principles of ADM allocated to different paths, thereby reducing the network congestion and reduce network latency and improve the network QOS. [Copyright &y& Elsevier]

Abstract: With the introduction of mobile ad hoc networks, nodes are able to participate in a dynamic network which lacks an underlying infrastructure. Before two nodes agree to interact, they must trust that each will satisfy the security and privacy requirements of the other. In this paper, we proposed a kind of trust model to solve this problem. Referring to the trust relationship models of social persons, trust relationship is built among the nodes in the ad hoc network, and the trustworthiness of nodes is evaluated by utilizing Bayesian method based on their behaviors. By updating the trust-based connection between each node, a novel self-organization topology is built on the top of the physical topology. The best security path can be selected from this topology graph. Simulation experiments show that the proposed model not only increases the route selection ratio, but also improves the interaction performance of the entire network. [Copyright &y& Elsevier]

Abstract: This paper proposes a dynamic mobile ad hoc network (MANET) management system to improve network connectivity by using controlled network nodes, called agents. Agents have predefined wireless communication capabilities similar to the other nodes in the MANET, however their movements, and thus their locations, are dynamically determined to optimize network connectivity. A new approach to measuring connectivity using a maximum flow formulation is proposed – this is both responsive and tractable. Furthermore, users’ locations are predicted for several time steps ahead and this is shown to improve network connectivity over the network operation period. A particle swarm optimization (PSO) algorithm uses the maximum flow objective to choose optimal locations of the agents during each time step of network operation. The proposed MANET management system is rigorously tested on numerous static and dynamic problems. Computational results show that the proposed approach is effective in improving the connectivity of MANETs and predicting movements of user nodes and deploying agents accordingly significantly improves the overall performance of a MANET. [Copyright &y& Elsevier]

Abstract: It is expected that many networks will be providing services at a time in near future and those will also produce different interfering signals for the current Slotted ALOHA based systems. A random packet destruction Denial of Service (DoS) attacking signal can shut down the Slotted ALOHA based networks easily. Therefore, to keep up the services of Slotted ALOHA based systems by enhancing the secured operating regions in the presence of the interfering signals from other wireless systems and DoS attacking signals is an important issue and is investigated in this paper. We have presented four different techniques for secured operating regions enhancements of Slotted ALOHA protocol. Results show that the interfering signals from other wireless systems and the DoS attacking signals can produce similar detrimental effect on Slotted ALOHA. However, the most detrimental effect can be produced, if an artificial DoS attack can be launched using extra false packets arrival from the original network. All four proposed secured operating regions enhancement techniques are easy to implement and have the ability to prevent the shutdown of the Slotted ALOHA based networks. [Copyright &y& Elsevier]

Abstract: With the increasing popularity of multimedia, there is a growing tendency in mobile ad hoc networks (MANETs) to establish stable routes with long route lifetimes, low control overhead and high packet delivery ratios. According to recent analytical result, the lifetime of a route, which can reflect the route stability, depends on the length of the route and the lifetime of each link in the route. This paper presents a Greedy-based Backup Routing (GBR) protocol that considers both route length and link lifetime to achieve high route stability. In GBR, the primary path is constructed primarily based on a greedy forwarding mechanism, whereas the local-backup path for each link is established according to the link lifetime. Both analytical and simulation results demonstrate that GBR has excellent performance in terms of route lifetime, packet delivery ratio, and control overhead. [Copyright &y& Elsevier]

Abstract: Ad hoc wireless network consists of a set of wireless nodes communicating with each other without a pre-defined infrastructure. They communicate by forwarding packets which can reach wireless nodes that do not exist in the range of the direct radio transmission. Designing ad hoc network routing protocols is a challenging task because of its decentralized infrastructure which makes securing ad hoc networks more and more challenging. Dynamic Source Routing (DSR) protocol is a popular routing protocol designed for use in wireless ad hoc networks. Mobile agent is a promising technology used in diverse fields of network applications. In this paper, we try to implement DSR using mobile agents for securing this type of wireless network. Hybrid encryption technique (symmetric key encryption/public key encryption) is used to improve performance; where symmetric keys are used to encrypt routing data to authenticate and authorize node sending data, while, public keys are used for the exchange of symmetric keys between nodes. We found that DSR may be secured using mobile agents with competitive performance. [Copyright &y& Elsevier]

Abstract: One of the most overlooked factors in evaluating performance of ad hoc routing protocols is the variation in received signal strength known as fading. Many types of routing protocols have been proposed based on simplified assumptions and unrealistic propagation models that neglect the effect of fading. The choice of propagation models have a great impact on performance, so realistic models are necessary to consider the effect of fading as far as an accurate analysis of performance of the routing protocols is concerned. In this paper, comparative analysis of two on demand ad hoc routing protocols is performed in order to study the impact of mobility and fading on performance. The non-fading models such as free space and two ray ground are simulated for comparison with fading models such as Shadowing, Ricean, and Rayleigh fading. The simulation results reveal that the fading models have a significantly degraded network performance with respect to two mobility scenarios. [ABSTRACT FROM AUTHOR]

Abstract: Recently, ubiquitous computing and pervasive environments evolved tremendously and became an integral part of many fields and application domains. This is widely attributed to their seamless integration with many everyday components and efficiency in handling business and personal tasks. As a result, technologies to facilitate their development, integration and security also evolved. Middleware is an essential layer in the architecture of these new systems, and recently, more emphasis has been put on security middleware as an enabling component for ubiquitous applications. This is due to the high levels of personal and private data sharing in these systems. In this paper, we review some representative security middleware approaches and highlight their various properties, characteristics, and challenges. The review reveals that several options are available; however, there are still many issues and challenges to be addressed to achieve more efficient security middleware. [Copyright &y& Elsevier]

Abstract: Path compression techniques are efficient on-demand routing optimizing techniques for mobile Ad Hoc networks. However, there is no efficient model for path compression techniques. This paper analyzed the principles and characteristics of path compression algorithms and proposed dynamic model which provided theoretical basis to improve or propose path compression algorithms. This model took the mobility and expansibility of Ad Hoc networks into account and was efficient to analyze or evaluate path compression algorithms. The quantitative relationship and probability expression for pivotal compression events were given based on the model. The simulation results of SHORT (self-healing and optimizing routing techniques) and PCA (path compression algorithm) show that it is a correct and efficient dynamic model for path compression. Finally, some suggestions and application scenarios about the model were proposed. [Copyright &y& Elsevier]

Abstract: Due to the limited lifetime of the nodes in ad hoc network, energy efficiency needs to be an important design consideration in any routing algorithm for ad hoc and sensor networks. In most of the existing position-based routing algorithms the nodes use the maximum transmission power to discover neighbors, which may cause excessive power consumption. This paper presents several localized power-aware 3D position-based routing algorithms that increase the lifetime of a network by maximizing the average lifetime of its nodes. New algorithms are semi-beaconless, using for neighbor discovery an optimal transmission range (OR) for control packets, and, if needed, maximal transmission range (MR) during routing process, and using adjusted transmission radius for message transmission. PAGR algorithm selects neighbor closest to destination among those within OR if any exists providing progress, or otherwise among those within MR. If greedy progress is not possible, PAGR:CFace(1) variant resorts to face routing on projected network in coordinate plane until recovery is possible, at which point PAGR algorithm resumes. We evaluate our algorithms and compare their power savings with the current power-aware routing algorithms. The simulation results show a significant improvement in the overall network lifetime. [Copyright &y& Elsevier]

Abstract: Many routing protocols and applications developed for ad hoc networks rely on location information of participating nodes. The exposure of such information, however, presents significant safety threats to the networks. In this paper, we investigate the problem of preventing an adversary from locating (and thus destroying) nodes based on their location information they disclose in communications. Our idea is to reduce location resolution to achieve a desired level of safety protection. We define the safety level of a geographic region to be the ratio of its area and the number of nodes inside it. The higher safety level a region has, the less attractive for an adversary to search over it for the nodes. When a node has to disclose its location, it can compute a cloaking box that meets a desired level of safety requirement and report that as its current location information. To implement this simple idea, there are several challenges. First, each cloaking box must be as small as possible in order to minimize the impact of reduced location resolution on the efficiency of network operating and applications. Second, nodes must be able to compute their cloaking boxes without having to reveal their accurate position. Finally, given a sequence of cloaking boxes, they must not be correlated to refine an area whose safety level is less than the requirement. Our research addresses these challenges with cost-effective solutions in the context of both stationary and mobile ad hoc networks. We evaluate the performance of our techniques through both mathematical analysis and simulation. In addition, we present a new geographic routing protocol which can work with blurred location information and evaluate the impact of location resolution reduction on the performance of this technique. [Copyright &y& Elsevier]

Abstract: Cognitive radio (CR) technology is envisaged to solve the problems in wireless networks resulting from the limited available spectrum and the inefficiency in the spectrum usage by exploiting the existing wireless spectrum opportunistically. CR networks, equipped with the intrinsic capabilities of the cognitive radio, will provide an ultimate spectrum-aware communication paradigm in wireless communications. CR networks, however, impose unique challenges due to the high fluctuation in the available spectrum as well as diverse quality-of-service (QoS) requirements. Specifically, in cognitive radio ad hoc networks (CRAHNs), the distributed multi-hop architecture, the dynamic network topology, and the time and location varying spectrum availability are some of the key distinguishing factors. In this paper, intrinsic properties and current research challenges of the CRAHNs are presented. First, novel spectrum management functionalities such as spectrum sensing, spectrum sharing, and spectrum decision, and spectrum mobility are introduced from the viewpoint of a network requiring distributed coordination. A particular emphasis is given to distributed coordination between CR users through the establishment of a common control channel. Moreover, the influence of these functions on the performance of the upper layer protocols, such as the network layer, and transport layer protocols are investigated and open research issues in these areas are also outlined. Finally, a new direction called the commons model is explained, where CRAHN users may independently regulate their own operation based on pre-decided spectrum etiquette. [Copyright &y& Elsevier]

Abstract: Recent technological advances have led to a growing interest in multi-antenna wireless ad hoc networks in which each node has more than one antenna. This paper proposes a cross-layer approach called QoS-aware smart antenna protocol (QSAP) for such networks that assures quality of service (QoS) needs of applications with reduced energy consumption. The proposed scheme adaptively allocates the degrees of freedom present in the multi-antenna system at each node to reduce the transmit energy while meeting the QoS needs of the application. The effectiveness of the proposed approach is demonstrated through simulations. The simulations show that the cross-layer aspects of the proposed approach result in considerable energy savings compared to schemes which meet the QoS needs without the cross-layer interaction. [Copyright &y& Elsevier]