Leila Ben Saad

An adaptive timer for RPL to handle mobility in wireless sensor networks

This paper focuses on the performance of wireless sensor networks characterized by a hybrid topology composed of mobile and static sensor nodes. The Routing Protocol for Low power and lossy networks (RPL), which is standardized as an IPv6 routing protocol for low power and lossy networks, uses the trickle timer algorithm to handle changes in the network topology. However, this algorithm is not well adapted to dynamic environments. This paper enhances the trickle timer in order to fit with mobility requirements. Most of previous works have improved this algorithm without considering the random movement of nodes. In this work, the proposed timer algorithm takes into consideration the random trajectory of mobile nodes, pause time and nodes velocity. It is also dynamically adjusted to prevent from node disconnections. The performance of the modified protocol is evaluated and compared with native RPL, MERPL and RPL with reverse Trickle. The results show that our protocol optimization offers better performance.

RPL protocol adapted for healthcare and medical applications

This paper focuses on wireless sensor networks (WSNs) for healthcare and medical applications which aim to look after patients by monitoring vital signs, diagnostics and drug administrations. WSNs in such applications are usually composed of different types of small-size battery powered sensors. In fact, wearable sensors are used to collect information about the signs of a person that needs a medical care. Static sensors, deployed inside the hospital or the home building, are used to collect information about indoor environment. The collected data is then transmitted towards the sink. Since some patients can move, WSN topology is hybrid and composed of mobile and static nodes. Routing Protocol for Low Power and Lossy Networks (RPL), an IPv6 distance vector routing protocol designed for static wireless sensor network, can be adapted to our need. So in this paper, we propose to modify RPL in order to fit with an hybrid topology. The performance of the modified protocol is evaluated and compared with the existing RPL protocol. The results show that our protocol optimization for healthcare application offers better performance.

An intrusion detection system for selective forwarding attack in IPv6-based mobile WSNs

Selective forwarding attack is considered among the most dangerous attack in wireless sensor networks, particularly in mobile environment. The attackers compromise legitimate nodes and selectively drop some packets. In addition to that, the movement of some nodes increases link failures, collisions and packet loss. So, it will be more difficult to detect malicious nodes from legitimates ones. This paper focuses on detecting selective forwarding attackers in IPv6-based mobile wireless sensor networks when the standardized IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) is used. Contrarily to previous works which propose solutions to detect selective forwarding attack in static wireless sensor networks, this paper deals with the case of networks with mobile sensors and proposes a novel intrusion detection system that combines Sequential Probability Ratio Test with an adaptive threshold of acceptable probability of dropped packets. Extensive simulations were performed and the results show that the detection probability is 100%.

Lifetime optimization of sensor-cloud systems

Sensor-Cloud is an emerging technology and popular paradigm of choice in systems development for various real-life applications. It consists in integrating wireless sensor networks with cloud computing environment. In fact, the cloud provides new opportunities of massive data storage, processing and analysing that wireless sensor networks can not offer. Despite the fact that the cloud have helped to overcome many wireless sensor networks limitations, there are other challenging issues that need to be addressed. The major problem that can significantly affect Sensor-Cloud performance is the short lifetime due to limited energy supply of sensors and sometimes some sinks. In this work, we propose a Sensor-Cloud Optimization problem (SCL-OPT) that maximizes lifetime as well as increases energy efficiency of sensors and sinks layers.

Topology design to increase network lifetime in WSN for graph filtering in consensus processes

Graph filters, which are considered as the workhorses of graph signal analysis in the emerging field of signal processing on graphs, are useful for many applications such as distributed estimation in wireless sensor networks. Many of these tasks are based on basic distributed operators such as consensus, which are carried out by sensor devices under limited energy supply. To cope with the energy constraints, this paper focuses on designing the network topology in order to maximize the network lifetime and reduce the energy consumption when applying graph filters. The problem is a complex combinatorial problem and in this work, we propose two efficient heuristic algorithms for solving it. We show by simulations that they provide good performance in terms of the network lifetime and the total energy consumption of the filtering process.

An Efficient Intrusion Detection System for Selective Forwarding and Clone Attackers in IPv6-based Wireless Sensor Networks under Mobility

Securityinmobilewirelesssensornetworksisabigchallengebecauseitaddsmorecomplexityto thenetworkinadditiontotheproblemsofmobilityandthelimitedsensornoderesources.Evenwith authenticationandencryptionmechanisms,anattackercancompromisenodesandgetallthekeying materials.Therefore,anintrusiondetectionsystemisnecessarytodetectanddefendagainsttheinsider attackers.Currently,thereisnointrusiondetectionsystemappliedtoIPv6-basedmobilewireless sensornetworks.Thispaperismainlyinterestedindetectingtheselectiveforwardingandcloneattacks becausetheyareconsideredamongthemostdangerousattackers.Inthiswork,theauthorsdesign, implement,andevaluateanovelintrusiondetectionsystemformobilewirelesssensornetworksbased onIPv6routingprotocolforlowpowerandlossynetworks.Thenewintrusiondetectionsystemcan beextendedtootherattackssuchaswormholeandsybilattacks.Thesimulationsresultsshowthat thedetectionprobabilityis100%forselectiveattackersundersomecases. KEyWoRDS Clone Attack, Intrusion Detection System, Mobile Wireless Sensor Networks, RPL Protocol, Security, Selective Forwarding Attack

Enhancing lifetime of IPv6-based wireless sensor networks with address coding

Due to the scarce energy resources of sensor nodes, wireless sensor networks (WSNs) need strategies to optimise the energy consumption of sensors to extend the network lifetime. However, improving the lifetime of WSNs remains a very challenging problem. Since, a sensor device spends most of its energy in transmitting packets, it is important to shorten the length of these packets through data compression. Nevertheless, compression deals only with data while address compression is not considered. In this work, Slepian-Wolf source coding and address allocation are used jointly to reduce the size of the emitted addresses and improve the network lifetime. The proposed approach is studied in both cluster-based and multi-hop networks where two address allocation algorithms, that guarantee high correlation between addresses, are proposed. The simulation results show that a significant network lifetime improvement can be achieved by using this solution in both cluster-based and multi-hop networks.

Coded addresses in multi-hop wireless sensor networks.

Network lifetime improvement of multi-hop wireless sensor networks is a challenging problem. In fact, the network lifetime can be extended by energy saving techniques such as energy-efficient protocols. However, one of the most promising research directions to overcome the network lifetime problem is the compression. Indeed, compression consists in minimizing the size of packets transmitted by the sensors. Nevertheless, compression deals only with data while addresses compression is not considered. In this work, Slepian-Wolf source coding and address allocation are used jointly in multi-hop wireless sensor networks to reduce the size of the transmitted addresses. Our simulation findings demonstrate significant gains in network lifetime, while keeping energy dissipation at very satisfactory levels even in multi-hop networks.