A scalable key management and clustering scheme for wireless ad hoc and sensor networks

This paper describes a scalable key management and clustering scheme for secure group communications in ad hoc and sensor networks. The scalability problem is solved by partitioning the communicating devices into subgroups, with a leader in each subgroup, and further organizing the subgroups into hierarchies. Each level of the hierarchy is called a tier or layer. Key generation, distribution, and actual data transmissions follow the hierarchy. The distributed, efficient clustering approach (DECA) provides robust clustering to form subgroups, and analytical and simulation results demonstrate that DECA is energy-efficient and resilient against node mobility. Comparing with most other schemes, our approach is extremely scalable and efficient, provides more security guarantees, and is selective, adaptive and robust.     

A virtual subnet scheme on clustering algorithms for mobile ad hoc networks

Resolving the broadcast storm problem is an important issue in mobile ad hoc networks (MANETs). In this paper, we propose an approach for constructing a virtual subnet whose nodes are logically related. The virtual subnet can be spread upon clusters of a MANET. An intelligent agent with a routing filtering table is proposed to assist the best known clustering algorithms, the original Least ID algorithm and the original Highest Connection Cluster (HCC) algorithm, to improve group communication efficiency. Our simulation covers the network factors of hop count, deprave rate, and delay time. The simulation results show that when the proposed intelligent agent is used with the HCC algorithm, the delay time was reduced by 81.84% as compared with flooding, and by 49.25% as compared with the Ad Hoc On-Demand Distance Vector (AODV) routing algorithm. The delay time for the Least ID algorithm assisted by the proposed agents reduced by 81.84% compared to that of flooding and by 50% compared to that of AODV.     

Secure and efficient key management in mobile ad hoc networks

In mobile ad hoc networks, due to unreliable wireless media, host mobility and lack of infrastructure, providing secure communications is a big challenge. Usually, cryptographic techniques are used for secure communications in wired and wireless networks. Symmetric and asymmetric cryptography have their advantages and disadvantages. In fact, any cryptographic means is ineffective if its key management is weak. Key management is also a central aspect for security in mobile ad hoc networks. In mobile ad hoc networks, the computational load and complexity for key management are strongly subject to restriction by the node's available resources and the dynamic nature of network topology. We propose a secure and efficient key management (SEKM) framework for mobile ad hoc networks. SEKM builds a public key infrastructure (PKI) by applying a secret sharing scheme and using an underlying multi-cast server groups. We give detailed information on the formation and maintenance of the server groups. In SEKM, each server group creates a view of the certificate authority (CA) and provides certificate update service for all nodes, including the servers themselves. A ticket scheme is introduced for efficient certificate service. In addition, an efficient server group updating scheme is proposed. The performance of SEKM is evaluated through simulation.     

A distributed group mobility adaptive clustering algorithm for mobile ad hoc networks

This paper proposes a distributed group mobility adaptive (DGMA) clustering algorithm for mobile ad hoc networks (MANETs) on the basis of a revised group mobility metric, linear distance based spatial dependency (LDSD), which is derived from the linear distance of a node’s movement instead of its instantaneous speed and direction. In particular, it is suitable for group mobility pattern where group partitions and mergence are prevalent behaviors of mobile groups. The proposed clustering scheme aims to form more stable clusters by prolonging cluster lifetime and reducing the clustering iterations even in highly dynamic environment. Simulation results show that the performance of the proposed framework is superior to two widely referenced clustering approaches, the Lowest-ID clustering scheme and the mobility based clustering algorithm MOBIC, in terms of average clusterhead lifetime, average resident time, average number of clusterhead changes, and average number of cluster reaffiliations.     

Cost-effective mobile ad hoc networks management

As there are more and more mobile devices in use, different mobile networking models such as ad hoc or mesh are attracting a large research interest. Self-organizing mobile ad hoc networks (MANET) allow devices to share their services and resources without any central administration or Internet support. In this respect they can become the backbone of the wireless grid or the gateway to existing grids. To achieve these goals, MANET management must be as effective as that of wired networks. This is, however, a challenging task due to network features like mobility, heterogeneity, limited resources of hosts and feeble communication. This paper presents a set of simple, cost-effective and resilient procedures for the basic tasks of MANET creation and management.     

Improved group-based cooperative caching scheme for mobile ad hoc networks

Data caching is a popular technique that improves data accessibility in wired or wireless networks. However, in mobile ad hoc networks, improvement in access latency and cache hit ratio may diminish because of the mobility and limited cache space of mobile hosts (MHs). In this paper, an improved cooperative caching scheme called group-based cooperative caching (GCC) is proposed to generalize and enhance the performance of most group-based caching schemes. GCC allows MHs and their neighbors to form a group, and exchange a bitmap data directory periodically used for proposed algorithms, such as the process of data discovery, and cache placement and replacement. The goal is to reduce the access latency of data requests and efficiently use available caching space among MH groups. Two optimization techniques are also developed for GCC to reduce computation and communication overheads. The first technique compresses the directories using an aggregate bitmap. The second employs multi-point relays to develop a forwarding node selection scheme to reduce the number of broadcast messages inside the group. Our simulation results show that the optimized GCC yields better results than existing cooperative caching schemes in terms of cache hit ratio, access latency, and average hop count.     

Performance analysis of hierarchical group key management integrated with adaptive intrusion detection in mobile ad hoc networks

We develop a mathematical model to quantitatively analyze a scalable region-based hierarchical group key management protocol integrated with intrusion detection to deal with both outsider and insider security attacks for group communication systems (GCSs) in mobile ad hoc networks (MANETs). Our proposed adaptive intrusion detection technique is based on majority voting by nodes in a geographical region to cope with collusion of compromised nodes, with each node preloaded with anomaly-based or misuse-based intrusion detection techniques to diagnose compromised nodes in the same region. When given a set of parameter values characterizing operational and environmental conditions, we identify the optimal intrusion detection rate and the optimal regional area size under which the mean time to security failure of the system is maximized and/or the total communication cost is minimized for GCSs in MANET environments. The tradeoff analysis in performance versus security is useful in identifying and dynamically applying optimal settings to maximize the system lifetime for scalable mobile group applications while satisfying application-specific performance requirements.     

A fuzzy-based Power-aware management for mobile ad hoc networks

In recent years, people have become more dependent on wireless network services to obtain the latest information at any time anywhere. Wireless networks must effectively allow several types of mobile devices send data to one another. The Mobile Ad Hoc Network (MANET) is one important type of non-infrastructure mobile network that consists of many mobile hosts, usually cellular phones. The power consumption rate and bandwidth of each mobile host device becomes an important issue and needs to be addressed. For increasing the reliability of the manager in Hierarchical Cellular Based Management (HCBM), this paper proposed a Power-aware protocol to select a stable manager from mobile hosts by fuzzy based inference systems based on the factors of speed, battery power, and location. Further, our protocol can trigger a mobile agent to distribute the managerial workload.     

Decentralized key generation scheme for cellular-based heterogeneous wireless ad hoc networks

With the support of cellular system a cellular-based mobile ad hoc network (MANET) offers promising communication scenarios while entails secure data exchange as other wireless systems. In this paper, we propose a novel decentralized key generation mechanism using shared symmetric polynomials in which the base stations (BSs) carry out an initial key generation by a symmetric polynomial in a distributed manner and then pass on the key material to mobile stations (MSs). Thereafter, our proposed key generation scheme enables each pair of MSs to establish a pairwise key without any intervention from the BS, thus reducing the management cost for the BS. The shared key between two MSs is computed without any interaction between them. In addition, the trust among MSs is derived from the cellular infrastructure, thus enjoying an equal security level as provided in the underlying cellular network. Simulations are done to observe the system performance and the results are very encouraging.     

Neighborhood tracking for mobile ad hoc networks

In mobile ad hoc networks (MANETs), node mobility causes network topologies to change dynamically over time, which complicates such important tasks as broadcasting and routing. In a typical efficient localized approach, each node makes forwarding decisions based on a neighborhood local view constructed simply by collecting received “Hello” messages. That kind of neighborhood local view can become outdated and inconsistent, which induces a low-coverage problem for efficient broadcasting tasks and a low-delivery ratio problem for efficient routing tasks. In this paper, we propose a neighborhood tracking scheme to guarantee the accuracy of forwarding decisions. Based on historical location information, nodes predict the positions of neighbors when making a forwarding decision, and then construct an updated and consistent neighborhood local view to help derive more precise forwarding decisions. The inaccuracy factors of our scheme are also discussed and an accessory method is provided for possible usage. Simulation results illustrate the accuracy of our proposed tracking scheme. To verify the effectiveness of our scheme, we apply it to existing efficient broadcast algorithms. Simulation results indicate that our neighborhood tracking scheme can improve the protocols coverage ratio greatly.     

Model checking mobile ad hoc networks

Modeling arbitrary connectivity changes within mobile ad hoc networks (MANETs) makes application of automated formal verification challenging. We use constrained labeled transition systems as a semantic model to represent mobility. To model check MANET protocols with respect to the underlying topology and connectivity changes, we introduce a branching-time temporal logic. The path quantifiers are parameterized by multi-hop constraints over topologies, to discriminate the paths over which the temporal behavior should be investigated; the paths that violate the multi-hop constraints are not considered. A model checking algorithm is presented to verify MANETs that allow arbitrary mobility, under the assumption of reliable communication. It is applied to analyze a leader election protocol.     

Optimizing communication in mobile ad hoc network clustering

Mobile ad hoc networks (MANETs) are gaining popularity in recent years due to their flexibility, the proliferation of smart computing devices, and developments in wireless communications. Clustering is an important research problem for MANETs because it enables efficient utilization of resources, and must strike a delicate balance between battery energy, mobility, node degree, etc. In this paper, we consider the typical communication workload of every mobile node as well as the additional communication workload of clusterheads in MANET clustering. We propose an algorithm that optimizes communication workload, power consumption, clusterhead lifetime, and node degree. Experiment results show that our clustering approach produces effectively balanced clusters over a diverse set of random scenarios.     

Group communications in mobile ad hoc networks

Efficient support of group communications is critical for most ad hoc network applications. However, manet group communications issues differ from those in wired environments because the wireless communications medium has variable and unpredictable characteristics, and the signal strength and propagation fluctuate with respect to time and environment. We provide an overview of group communications issues such as protocol design, state maintenance, and performance. We also discuss representative protocols and examine related issues such as reliability, power conservation, quality of service, security, and areas requiring additional research.     

Adaptive routing protocol for mobile ad hoc networks

Artificial immune systems (AIS) are used for solving complex optimization problems and can be applied to the detection of misbehaviors, such as a fault tolerant. We present novel techniques for the routing optimization from the perspective of the artificial immunology theory. We discussed the bioinspired protocol AntOR and analyze its new enhancements. This ACO protocol based on swarm intelligence takes into account the behavior of the ants at the time of obtaining the food. In the simulation results we compare it with the reactive protocol AODV observing how our proposal improves it according to Jitter, the delivered data packet ratio, throughput and overhead in number of packets metrics.     

Markovian-based traffic modeling for mobile ad hoc networks

Mobile ad hoc networks (MANETs) show very significant difference with respect to other computer networks due to the presence of extremely large packet loss bursts. The development of protocols for mobile ad hoc networks, especially multimedia protocols, require extensive evaluation either through simulation or real-life tests. Such testing consumes a great amount of resources both in terms of time and trace file sizes. Therefore, finding efficient means of reducing the amount of data that is stored and processed is quite important to accelerate the evaluation of different audio/video streaming applications. If, moreover, we are able to model the loss pattern experienced, we can further accelerate the evaluation process.In this work we propose two models based on hidden Markov chains that are able to grasp both packet arrivals and packet loss patterns in MANETs. A simpler two-state model is proposed to model losses when proactive routing protocols are used, while a more complex three-state model is proposed for reactive routing protocols. We also introduce a new set for packet loss pattern measurements that can be of interest for the evaluation of audio/video streaming applications.Experimental results show that the proposed models can adequately reproduce extremely long packet loss patterns, typical of MANET environments, with a high degree of accuracy. Overall, we find that the proposed models are able to significantly reduce both the simulation time and the trace file sizes required.     

Integrated location management and location-aided routing system for mobile ad hoc networks

We present an integrated location management and location-aided routing system for mobile ad hoc network (MANET) which organizes the MANET into a two-level routing hierarchy with the help of Voronoi diagrams. The location information of mobile nodes in a Voronoi zone is summarized using bloom filters and distributed among the location servers in the zones. In the integrated system, the destination's location is learned during routing in the overlay network of the hierarchy. Theoretical analysis and simulation results show that the proposed system reduces the routing time by about 25% over traditional location-aided routing techniques for transaction-type traffic while incurring only small management overhead and low storage requirement.     

Dynamic genetic algorithms for the dynamic load balanced clustering problem in mobile ad hoc networks

Clustering can help aggregate the topology information and reduce the size of routing tables in a mobile ad hoc network (MANET). To achieve fairness and uniform energy consumption, each clusterhead should ideally support the same number of clustermembers. However, a MANET is a dynamic and complex system and its one important characteristic is the topology dynamics, that is, the network topology changes over time due to the factors such as energy conservation and node movement. Therefore, in a MANET, an effective clustering algorithm should efficiently adapt to each topology change and produce the new load balanced clusterhead set quickly. The maintenance of the cluster structure should aim to keep it as stable as possible to reduce overhead. To meet this requirement, the new solution should keep as many good parts in the previous solution as possible. In this paper, we first formulate the dynamic load balanced clustering problem (DLBCP) into a dynamic optimization problem. Then, we propose to use a series of dynamic genetic algorithms (GAs) to solve the DLBCP in MANETs. In these dynamic GAs, each individual represents a feasible clustering structure and its fitness is evaluated based on the load balance metric. Various dynamics handling techniques are introduced to help the population to deal with the topology changes and produce closely related solutions in good quality. The experimental results show that these GAs can work well for the DLBCP and outperform traditional GAs that do not consider dynamic network optimization requirements.     

Modelling incentives for collaboration in mobile ad hoc networks

This paper explores a model for the operation of an ad hoc mobile network. The model incorporates incentives for users to act as transit nodes on multi-hop paths and to be rewarded with their own ability to send traffic. The paper explores consequences of the model by means of fluid-level simulations of a network and illustrates the way in which network resources are allocated to users according to their geographical position.     

A unified framework for cluster manager election and clustering mechanism in mobile ad hoc networks

In Mobile Ad-hoc NETwork (MANET), every node could become active dynamically. Therefore, those nodes will affect the stability of network topology because of clustering and de-clustering, and continuously make reconfiguration for the groups of network, all that will influence the overall function of network. How to choose a cluster manager to keep the stability of network topology is an important issue. In this paper, a mechanism for the designation of clustering and cluster manager is given by MANET. The mechanism is named as Unified Framework Clustering Mechanism (UFCM for short), which is a kind of processing mechanism under consideration in multi-network service, such as processing mode of initial state in the network system, processing mode of access of nodes in the group, and the processing mode concerned on failing to manage the group because the cluster manager is erroneous. Beyond that, we also propose a backup manager to take the work of the cluster manager when the cluster manager fails.     

Bio-inspired group mobility model for mobile ad hoc networks based on bird-flocking behavior

In this paper, we propose a novel group mobility model for mobile ad hoc networks (MANETs), named as Bird-Flocking Behavior Inspired Group Mobility Model (BFBIGM), which takes inspiration from the mobility of a flock of birds, flying in a formation. Most existing modeling techniques are deficient in successfully addressing many aspects in terms of the application of realistic forces on the movement of mobile nodes (MNs), the interaction of MNs within a group, and collision avoidance within a group and with environmental obstacles. The results obtained through experiments show that in terms of connectivity metrics, such as link duration, BFBIGM performs around 50% better in comparison to the popular existing mobility models like Random Waypoint (RWP) Model (Johnson et al. in Ad hoc networking, Addison-Wesley, Menlo Park, pp. 139–172,2001) and the Reference Point Group Mobility (RPGM) Model (Hong et al. in: Proceedings of the 2nd ACM international workshop on modeling, analysis and simulation of wireless and mobile systems, Seattle, WA, pp. 53–60,1999).