International Journal Papers
Permanent URI for this collectionhttp://dl.cerist.dz/handle/CERIST/17
Browse
10 results
Search Results
Item A distributed mutual exclusion algorithm over multi-routing protocol for mobile ad hoc networks(Taylor et Francis, 2008-04-15) Derhab, Abdelouahid; Badache, NadjibIn this paper, we propose a new architecture to solve the problem of mutual exclusion in mobile ad hoc networks (MANET). The architecture is composed of two layers: (i) a middleware layer that contains a token-based distributed mutual exclusion algorithm (DMEA) and (ii) a network layer that includes two routing forwarding strategies: one to route request messages and the other to route the token message. We also propose a request ordering policy that ensures the usual mutual exclusion properties and reduces the number of hops traversed per critical section (CS) access. The paper also addresses the problem of network partitioning and unreachable nodes. The proposed mutual exclusion algorithm is further enhanced to provide fault tolerance by preventing the loss of the token and generating a new token if the token loss event occurs. The performance complexity as well as the experimental results show that the proposed algorithm experiences low number of hops per CS access.Item Balancing the tradeoffs between scalability and availability in mobile ad hoc networks with a flat hashing-based location service(2008-06) Derhab, Abdelouahid; Badache, NadjibIn this paper, we propose FSLS (Flat-based Some-for-some Location Service), a new location service for ad hoc mobile networks. The location service is based on the hash-based sets system that can offer a high location information availability. The network area is divided into non-overlapping zones. A node identifier is mapped to a set of home zones, each of which contains a unique location server, which makes FSLS works as a some-for-some approach. Using cross-layer design, the service can tolerate server mobility and server failures, and last for a long time period. We analyze FSLS and six other existing location services. The theoretical analysis as well as simulation results show that FSLS offers a good trade-off between location availability and scalability. It comes second after a quorum-based location service in terms of location availability and it is the closest competitor to a hierarchical location service in terms of scalability.Item Self-stabilizing algorithm for high service availability in spite of concurrent topology changes in ad hoc mobile networks(Elsevier, 2008-06) Derhab, Abdelouahid; Badache, NadjibMobile nodes in ad hoc networks move freely and run out of battery power so quickly, which leads to frequent network partitioning. Network partitioning considerably reduces service availability when the server node is not in the same partition as the client nodes. In order to provide a continuous service availability for all mobile nodes, we propose a self-stabilizing algorithm that can tolerate multiple concurrent topological changes and can incur a cost of one server per long-lived connected component. By using (1) the time interval-based computations concept that distinguishes between disjoint and concurrent computations, and (2) Markov chain model, the proposed algorithm can within a finite time converge to a legitimate state even if topological changes occur during the convergence time. Our simulation results show that the algorithm can ensure very high service availability, and each node has a strong path to the server of its network component over 98% of the time.Item Gestion de clés et sécurité multipoint: étude et perspectives(Springer-Verlag, 2003) Seba, Hamida; Bouabdallah, Abdelmadjid; Badache, Nadjib; Bettahar, Hatem; Tandjaoui, DjamelLa communication multipoint (ou communication de groupe) est un moyen efficace pour envoyer des données aux membres d’un groupe. Plusieurs types d’applications utilisant les communications multipoint nécessitent un certain niveau de sécurité: authentification, intégrité, confidentialité et contrôle d’accès. Comme les techniques implémentant ces services dans les communications point-à-point ne peuvent être appliquées telles quelles aux communications de groupe, la sécurité des communications de groupe a fait l’objet de plusieurs travaux. La gestion de clés qui constitue la brique de base des services de sécurité a été largement étudiée et a donné lieu à plusieurs publications. Dans cet article, nous décrivons les différentes approches existantes pour gérer et distribuer les clés dans un groupe. Nous discutons les avantages et les inconvénients des protocoles proposés dans la littérature et présentons une classification et une étude comparative de ces protocoles. Nous terminons cet article par quelques critiques et perspectives.Item Mobi_Causal: a protocol for causal message ordering in mobile computing systems(ACM, 2005-04) Benzaid, Chafika; Badache, NadjibThis paper presents, Mobi_Causal, a new protocol to implement causal ordering in mobile computing systems. The implementation of causal ordering proposed in this paper uses the new timestamping mechanisms proposed by Prakash and Singhal for mobile environments; dependency sequences and hierarchical clocks. Our protocol, compared with previous proposals, is characterized by the elimination of unnecessary inhibition delay in delivering messages while maintaining low message overhead. Our protocol requires minimal resources on mobile hosts and wireless links. The proposed protocol is also scalable and can easily handle dynamic change in the number of participating mobile hosts in the system.Item Security Issues of Mobile Ad hoc and Sensor Networks(IEEE Communications Society, 2005-12) Djenouri, Djamel; Khelladi, Lyes; Badache, NadjibSecurity in mobile ad hoc networks is difficult to achieve, notably because of the vulnerability of wireless links, the limited physical protection of nodes, the dynamically changing topology, the absence of a certification authority, and the lack of a centralized monitoring or management point. Earlier studies on mobile ad hoc networks (MANETs) aimed at proposing protocols for some fundamental problems, such as routing, and tried to cope with the challenges imposed by the new environment. These protocols, however, fully trust all nodes and do not consider the security aspect. They are consequently vulnerable to attacks and misbehavior. More recent studies focused on security problems in MANETs, and proposed mechanisms to secure protocols and applications. This article surveys these studies. It presents and discusses several security problems along with the currently proposed solutions (as of July 2005) at different network layers of MANETs. Security issues involved in this article include routing and data forwarding, medium access, key management and intrusion detection systems (IDSs). This survey also includes an overview of security in a particular type of MANET, namely, wireless sensor networks (WSNs).Item On Eliminating Packet Droppers in MANET: A Modular Solution(Elsevier, 2009-08) Djenouri, Djamel; Badache, NadjibIn this paper we deal with misbehaving nodes in mobile ad hoc networks (MANETs) that drop packets supposed to be relayed, whose purpose may be either saving their resources or launching a DoS attack. We propose a new solution to monitor, detect, and safely isolate such misbehaving nodes, structured around five modules: (i) The monitor, responsible for controlling the forwarding of packets, (ii) the detector, which is in charge of detecting the misbehaving of monitored nodes, (iii) the isolator, basically responsible for isolating misbehaving nodes detected by the detector, (iv) the investigator, which investigates accusations before testifying when the node has not enough experience with the accused, and (v) finally the witness module that responds to witness requests of the isolator. These modules are based on new approaches, aiming at improving the efficiency in detecting and isolating misbehaving nodes with a minimum overhead. We describe these modules in details, and their interactions as well. We also mathematically analyze our solution and assess its performance by simulation, and compare it with the watchdog, which is a monitoring technique employed by almost all the current solutions.Item Struggling against selfishness and black hole attacks in MANETs(John Wiley & Sons, 2008-08) Djenouri, Djamel; Badache, NadjibSince mobile ad hoc networks (MANETs) are infrastructureless and multi-hop by nature, transmitting packets from any node to another usually relies on services provided by intermediate nodes. This reliance introduces a new vulnerability; one node could launch a Black Hole DoS attack by participating in the routing protocol and including itself in routes, then simply dropping packets it receives to forward. Another motivation for dropping packets in self-organized MANETs is resource preservation. Some solutions for detecting and isolating packet droppers have been recently proposed, but almost all of them employ the promiscuous mode monitoring approach (watchdog (WD)) which suffers from many problems, especially when employing the power control technique. In this paper we propose a novel monitoring approach that overcomes some WD's shortcomings, and improves the efficiency in detection. To overcome false detections due to nodes mobility and channel conditions we propose a Bayesian technique for the judgment, allowing node redemption before judgment. Finally, we suggest a social-based approach for the detection approval and isolation of guilty nodes. We analyze our solution and asses its performance by simulation. The results illustrate a large improvement of our monitoring solution in detection versus the WD, and an efficiency through our judgment and isolation techniques as wellItem New power-aware routing for mobile ad hoc networks(Inderscience, 2006) Djenouri, Djamel; Badache, NadjibSince devices used in wireless mobile ad hoc networks are generally supplied with limited autonomous resources, energy conservation is one of the most significant aspects in these networks. Recent studies show that the energy consumed for routing data-packets in mobile ad hoc networks can be significantly reduced compared with the min-hop full-power routing protocols. One of the promising mechanisms proposed in literature to reduce the energy consumption is the transmission power control. In this paper, we define new routing metrics to strike a balance between the required power minimisation and batteries freshness consideration. We also define a new technique which allows the distribution of the routing task over nodes. Using these metrics and techniques we derive from DSR [2] a new power-aware and power-efficient routing protocol, whose performance is analysed by simulation in different situations of mobility and network load.Item Ad hoc networks routing protocols and mobility(2006-04) Djenouri, Djamel; Derhab, Abdelouahid; Badache, NadjibAn ad hoc network is a temporary infrastructureless network, formed dynamically by mobile devices without turning to any existing centralized administration. To send packets to remote nodes, a node uses other intermediate nodes as relays, and ask them to forward its packets. For this purpose, a distributed routing protocol is required. Because the devices used are mobile, the network topology is unpredictable, and it may change at any time. These topology changes along with other intrinsic features related to mobile devices, such as the energy resource limitation, make ad hoc networks challenging to implement efficient routing protocols. In this paper, we drive a GloMoSim based simulation study, to investigate the mobility effects on the performance of several mobile ad hoc routing protocols.