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1.
Sensors (Basel) ; 21(4)2021 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-33567489

RESUMO

Wireless Sensor Networks constitute an important part of the Internet of Things, and in a similar way to other wireless technologies, seek competitiveness concerning savings in energy consumption and information availability. These devices (sensors) are typically battery operated and distributed throughout a scenario of particular interest. However, they are prone to interference attacks which we know as jamming. The detection of anomalous behavior in the network is a subject of study where the routing protocol and the nodes increase power consumption, which is detrimental to the network's performance. In this work, a simple jamming detection algorithm is proposed based on an exhaustive study of performance metrics related to the routing protocol and a significant impact on node energy. With this approach, the proposed algorithm detects areas of affected nodes with minimal energy expenditure. Detection is evaluated for four known cluster-based protocols: PEGASIS, TEEN, LEACH, and HPAR. The experiments analyze the protocols' performance through the metrics chosen for a jamming detection algorithm. Finally, we conducted real experimentation with the best performing wireless protocols currently used, such as Zigbee and LoRa.

2.
Sensors (Basel) ; 22(1)2021 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-35009729

RESUMO

The emergence of Industry 4.0 technologies, such as the Internet of Things (IoT) and Wireless Sensor Networks (WSN), has prompted a reconsideration of methodologies for network security as well as reducing operation and maintenance costs, especially at the physical layer, where the energy consumption plays an important role. This article demonstrates through simulations and experiments that, while the cooperative scheme is more efficient when a WSN is at normal operating conditions, the collaborative scheme offers more enhanced protection against the aggressiveness of jamming in the performance metrics, thus making it safer, reducing operation and maintenance costs and laying the foundations for jamming mitigation. This document additionally offers an algorithm to detect jamming in real time. Firstly, it examines the characteristics and damages caused by the type of aggressor. Secondly, it reflects on the natural immunity of the WSN (which depends on its node density and a cooperative or collaborative configuration). Finally, it considers the performance metrics, especially those that impact energy consumption during transmission.

3.
Sensors (Basel) ; 19(11)2019 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-31159187

RESUMO

In this work, two new self-tuning collaborative-based mechanisms for jamming detection are proposed. These techniques are named (i) Connected Mechanism and (ii) Extended Mechanism. The first one detects jamming by comparing the performance parameters with respect to directly connected neighbors by interchanging packets with performance metric information, whereas the latter, jamming detection relays comparing defined zones of nodes related with a collector node, and using information of this collector detects a possible affected zone. The effectiveness of these techniques were tested in simulated environment of a quadrangular grid of 7 × 7, each node delivering 10 packets/sec, and defining as collector node, the one in the lower left corner of the grid. The jammer node is sending packets under reactive jamming. The mechanism was implemented and tested in AODV (Ad hoc On Demand Distance Vector), DSR (Dynamic Source Routing), and MPH (Multi-Parent Hierarchical), named AODV-M, DSR-M and MPH-M, respectively. Results reveal that the proposed techniques increase the accurate of the detected zone, reducing the detection of the affected zone up to 15% for AODV-M and DSR-M and up to 4% using the MPH-M protocol.

4.
Proc Natl Acad Sci U S A ; 115(46): 11736-11741, 2018 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-30381457

RESUMO

Amorphous packings of nonspherical particles such as ellipsoids and spherocylinders are known to be hypostatic: The number of mechanical contacts between particles is smaller than the number of degrees of freedom, thus violating Maxwell's mechanical stability criterion. In this work, we propose a general theory of hypostatic amorphous packings and the associated jamming transition. First, we show that many systems fall into a same universality class. As an example, we explicitly map ellipsoids into a system of "breathing" particles. We show by using a marginal stability argument that in both cases jammed packings are hypostatic and that the critical exponents related to the contact number and the vibrational density of states are the same. Furthermore, we introduce a generalized perceptron model which can be solved analytically by the replica method. The analytical solution predicts critical exponents in the same hypostatic jamming universality class. Our analysis further reveals that the force and gap distributions of hypostatic jamming do not show power-law behavior, in marked contrast to the isostatic jamming of spherical particles. Finally, we confirm our theoretical predictions by numerical simulations.

5.
Sensors (Basel) ; 17(7)2017 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-28678180

RESUMO

In this work, we present the design of a mitigation scheme for jamming attacks integrated to the routing protocols MPH, AODV, and DSR. The resulting protocols are named MPH-M (Multi-Parent Hierarchical - Modified), AODV-M (Ad hoc On Demand Distance Vector - Modified), and DSR-M (Dynamic Source Routing - Modified). For the mitigation algorithm, if the detection algorithm running locally in each node produces a positive result then the node is isolated; second, the routing protocol adapts their paths avoiding the isolated nodes. We evaluated how jamming attacks affect different metrics for all these modified protocols. The metrics we employ to detect jamming attack are number of packet retransmissions, number of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) retries while waiting for an idle channel and the energy wasted by the node. The metrics to evaluate the performance of the modified routing protocols are the throughput and resilience of the system and the energy used by the nodes. We evaluated all the modified protocols when the attacker position was set near, middle and far of the collector node. The results of our evaluation show that performance for MPH-M is much better than AODV-M and DSR-M. For example, the node energy for MPH-M is 138.13% better than AODV-M and 126.07% better than DSR-M. Moreover, we also find that MPH-M benefits much more of the mitigation scheme than AODV-M and DSR-M. For example, the node energy consumption is 34.61% lower for MPH-M and only 3.92% and 3.42% for AODV-M and DSR-M, respectively. On throughput, the MPH protocol presents a packet reception efficiency at the collector node of 16.4% on to AODV and DSR when there is no mitigation mechanism. Moreover, MPH-M has an efficiency greater than 7.7% with respect to AODV-M and DSR-M when there is a mitigation scheme. In addition, we have that with the mitigation mechanism AODV-M and DSR-M do not present noticeable modification. However, MPH-M improves its efficiency by 8.4%. We also measure the resilience of these algorithms from the average packet re-transmissions perspective, and we find that MPH-M has around a 15% lower change rate than AODV-M and DSR-M. The MPH-M recovery time is 5 s faster than AODV-M and 2 s faster than DSR-M.

6.
Chiropt. Neotrop. (Impr.) ; 19(3): 71-79, 2013. map, tab, ilus
Artigo em Inglês | VETINDEX | ID: biblio-1472010

RESUMO

Bats using echolocation for orientation in space and for foraging rely on the information provided by the echoes of their emitted signals. In the presence of conspecifics, signals of individuals may overlap in time and frequency and may impede the bats ability to process their own echo information. Adjustment of echolocation signal parameters as a mechanism to minimize the effects of signal overlap has been proposed for bats. We conducted a field study in Panama, confronting free-flying Greater bulldog bats Noctilio leporinus (Noctilionidae) with playbacks of conspecific search signals that matched the constant-frequency (QCF) signal component of the bats expected echo. Additionally, we recorded echolocation signals of bats flying in pairs to compare the results of our playback experiments with bats encountering conspecifics under natural conditions. Noctilio leporinus did not shift the frequency of its QCF components, neither when confronted with our playbacks nor in the presence of conspecifics. We discuss modifications of signal parameters and foraging behavior as strategies to avoid masking situations in N. leporinus.


Assuntos
Animais , Ecolocação , Orientação , Quirópteros , Comportamento Animal
7.
Chiropt. neotrop. ; 19(3): 71-79, 2013. mapas, tab, ilus
Artigo em Inglês | VETINDEX | ID: vti-13121

RESUMO

Bats using echolocation for orientation in space and for foraging rely on the information provided by the echoes of their emitted signals. In the presence of conspecifics, signals of individuals may overlap in time and frequency and may impede the bats ability to process their own echo information. Adjustment of echolocation signal parameters as a mechanism to minimize the effects of signal overlap has been proposed for bats. We conducted a field study in Panama, confronting free-flying Greater bulldog bats Noctilio leporinus (Noctilionidae) with playbacks of conspecific search signals that matched the constant-frequency (QCF) signal component of the bats expected echo. Additionally, we recorded echolocation signals of bats flying in pairs to compare the results of our playback experiments with bats encountering conspecifics under natural conditions. Noctilio leporinus did not shift the frequency of its QCF components, neither when confronted with our playbacks nor in the presence of conspecifics. We discuss modifications of signal parameters and foraging behavior as strategies to avoid masking situations in N. leporinus.(AU)


Assuntos
Animais , Quirópteros , Ecolocação , Orientação , Comportamento Animal
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