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Über dieses Buch

This volume constitutes the refereed proceedings of the Third International ICST Conference, ADHOCNETS 2011, held in Paris, France, in September 2011. The 15 revised full papers - selected from 42 submissions - and the 2 invited papers cover several fundamental aspects of ad hoc networking, including security, quality of service, radio and spectrum analysis, mobility, energy efficiency, and deployment. They are organized in topical sections on security and QoS, WSN development and evaluation, radio and spectrum analysis, mobile WSNs, mobile ad hoc networks, and energy.



Session 1 – Security and QoS

Secure Scheduling of Wireless Video Sensor Nodes for Surveillance Applications

In video surveillance with resource-constrained devices such as wireless video sensor nodes, power conservation, intrusion detection, and security are important features to guarantee. In this paper, we intend to preserve the network lifetime while fulfilling the surveillance application needs. We take into account security by considering that a malicious attacker can try to predict the behavior of the network prior to intrusion. These considerations lead to the definition of a novel chaos-based scheduling scheme for video surveillance. We explain why the chaos-based approach can defeat malicious intruders. Then, by simulations, we also compare our chaos-based scheduling to a classical random scheduling. Results show that in addition of being able to increase the whole network lifetime and to present comparable results against random attacks (low stealth time), our scheme is also able to withstand malicious attacks due to its fully unpredictable behavior.
Jacques M. Bahi, Christophe Guyeux, Abdallah Makhoul, Congduc Pham

A Hierarchical Deterministic Key Pre-distribution for WSN Using Projective Planes

We present a deterministic key pre-distribution scheme using projective planes where the nodes are organised hierarchically through a structure of (p 2 + p) -nary tree, where p is prime. Our scheme is incumbent to more efficient resilience and connectivity compared to the existing schemes. Each node in our scheme requires to store significantly less number of keys. Furthermore, any number of nodes can be intrinsically inserted in the system by attributing a very few keys to the recently introduced nodes only. Another interesting feature of our scheme is that such node insertions are done without interfering the normal functioning of the existing organised network.
Sarbari Mitra, Ratna Dutta, Sourav Mukhopadhyay

Towards a Complete Multi-layered Framework for IEEE-802.11e Multi-hop Ad Hoc Networks

Performance of IEEE 802.11 in multi-hop wireless networks depends on the characteristics of the protocol itself, and on those of the other layers. We are interested in this paper in modeling the IEEE 802.11e Enhanced Distributed Coordination Function. This paper investigates the intricate interactions among PHY, MAC and Network layers. For instance, we jointly incorporate the carrier sense threshold, the transmit power, the contention window size, the retransmissions retry limit, the multi rates, the routing protocols and the network topology. Then, we build a general cross-layered framework to represent multi-hop ad hoc networks with asymmetric topology and asymmetric traffic. We develop an analytical model that predicts the throughput of each connection as well as the stability of forwarding queues at intermediate nodes. To the best of our knowledge, our work is the first to consider general topology and asymmetric parameters setup in PHY/MAC/Network layers. Performance of such a system is also evaluated via simulation. We show that the performance measures of MAC layer are affected by the traffic intensity of flows to be forwarded. More precisely, attempt rate and collision probability are dependent on the traffic flows, topology and routing.
Rachid El-Azouzi, Essaid Sabir, Mohammed Raiss El Fenni, Sujit Kumar Samanta

Session 2 – WSN Development and Evaluation

Towards Realistic and Credible Wireless Sensor Network Evaluation

This position paper explores the problem of realistically evaluating wireless sensor network (WSN) applications, algorithms and protocols. It surveys the currently available techniques, such as simulators, testbeds and real world deployments and compares their properties and challenges. While we underline the significance of simulation tools, we also observe that the state of the art simulation models at all levels (from physical to application) still lack realistic behavior. To demonstrate this gap we performed a broad study of simulation models and real world behavior of wireless links and compared those in various settings, including outdoor environments and battery-based deployments. Based on the provided survey and wireless link case study, we outline a strategy of how to enable realistic, efficient, low-cost and repeatable WSN evaluation scenarios.
Kamini Garg, Anna Förster, Daniele Puccinelli, Silvia Giordano

Adaptive Hierarchical Network Structures for Wireless Sensor Networks

Clustering is a crucial network design approach to enable large-scale wireless sensor networks (WSNs) deployments. A large variety of clustering approaches has been presented focusing on various aspect such as minimizing communication overhead, controlling the network topology etc. Simulations on such protocols are performed using theoretical models that are based on unrealistic assumptions like ideal wireless communication channels and perfect energy consumption estimations. With these assumptions taken for granted, theoretical models claim various performance milestones that cannot be achieved in realistic conditions. In this paper, we design a new clustering protocol that adapts to the changes in the environment and the needs and goals of the user applications. We provide a protocol that is deployable protocol in real WSNs. We apply our protocol in multiple indoors wireless sensor testbeds with multiple experimental scenarios to showcase scalability and trade-offs between network properties and configurable protocol parameters. By analysis of the real world experimental output, we present results that depict a more realistic view of the clustering problem, regarding adapting to environmental conditions and the quality of topology control. Our study clearly demonstrates the applicability of our approach and the benefits it offers to both research & development communities.
Dimitrios Amaxilatis, Ioannis Chatzigiannakis, Shlomi Dolev, Christos Koninis, Apostolos Pyrgelis, Paul G. Spirakis

Algorithms on Improving End-to-End Connectivity and Barrier Coverage in Stochastic Network Deployments

When a wireless network is randomly deployed on a region, there is only a certain degree of probability that the connectivity and/or barrier coverage between two sites will be provided. Therefore, it is important to develop mechanisms that will assure the high probability for these two QoS parameters to be provided when the gaps appear in the network. This paper involves the mobile nodes in order for the connectivity and/or barrier coverage gaps to be filled. The simulation results aim to evaluate the network deployment parameters (i.e., density of stationary and mobile nodes with respect to the communication or sensing radii, the size of the deployment area, and the deployment manner) in order the end-to-end (EE) connectivity (and, in similar manner, barrier coverage) to be provided with the probability close to one. By finding the most appropriate paths between two sites, two algorithms presented in this paper provide the directions on using mobile nodes for the EE connectivity and the barrier coverage to be improved in stochastically deployed networks.
Zhilbert Tafa

Session 3 – Radio and Spectrum Analysis

Collaborative Spectrum Sensing Scheme: Quantized Weighting with Censoring

Spectrum vacancies that stem from current non-usage of the spectrum band by legacy primary users can be detected using various spectrum sensing techniques. These techniques depend on the actual knowledge of the radio environment being inspected, i.e. signal characteristics, noise levels etc. The simplest and most common spectrum sensing technique is energy based detection that needs no a priori knowledge about the monitored spectrum, but may lead to imprecision when assessing the possible presence (or absence) of a primary user. Therefore, possible collaboration among the nodes performing the energy based spectrum sensing (in terms of sensing reports exchanges) improves the reliability and avoids the hidden terminal problem caused by the shadowing from large obstacles. This paper introduces a novel collaborative spectrum sensing scheme with light communication overhead called Quantized Weighting with Censoring (QWC). The scheme includes censoring of the unreliable sensing reports in some range of uncertainty and introduces weighting coefficients for different quantization levels. The performances of the QWC scheme are compared with the Majority Voting (MV) and Equal Gain Combining (EGC) schemes. The results show that the QWC scheme outperforms the well known EGC scheme.
Valentina Pavlovska, Liljana Gavrilovska

Performance Analysis of Multichannel Radio Link Control in MIMO Systems

With rapid advances in wireless communications, multiple-input multiple-output (MIMO) antennas technology has been integrated into next-generation wireless communication standards. In this paper, we introduce a MIMO system model, propose a multichannel radio link control protocol and a dynamic channel scheduling policy. We then conduct a performance study on the multichannel link control protocol with two different scheduling policies (i.e., dynamic and static scheduling) using simulations. Simulation results show that the dynamic scheduling outperforms the static scheduling. It is observed that the average packet delay with the dynamic scheduling increases with the average error rate of parallel channels, but decreases with the variance in the error rates of parallel channels. More interestingly, the number of parallel channels has only an insignificant impact on the average packet delay, when the dynamic scheduling is applied in MIMO systems, from which we confirm that the use of parallel channels is a favorable option for packet data networking in the point of view of the link-layer performance.
Jun Li, Yifeng Zhou, Yuanyuan Liu, Louise Lamont

Improving Data Dissemination in Multi-hop Cognitive Radio Ad-Hoc Networks

In this paper, we present SURF, a distributed channel selection strategy for efficient data dissemination in multi-hop cognitive radio ad-hoc networks (CRNs). SURF classifies the available channels on the basis of primary radio unoccupancy and the number of cognitive radio neighbors using the channels. Through extensive NS-2 simulations, we compare the performance of SURF with three related approaches. Simulation results confirm that SURF is effective in selecting the best channels for efficient communication and for highest dissemination reachability in multi-hop CRNs.
Mubashir Husain Rehmani, Aline Carneiro Viana, Hicham Khalife, Serge Fdida

Session 4 – Mobile WSNs

Cooperative MAC Scheduling in CDMA-MANETs with Multiuser Detection

Code division multiple access mobile ad hoc networks (CDMA-MANETs) will be a next-generation wireless networking architecture to connect various military platforms. The classic contention-based MAC protocols are inappropriate for tactical ad hoc networks, where more rigid requirements for the quality of service (QoS) (e.g., guaranteed packet delivery) have to be satisfied. In this paper, we propose a contention-free medium access control (MAC) scheduling framework for CDMA-MANETs where each mobile unit is capable of multiuser detection (MUD) as well. In this MAC scheduling scheme, how and when a pending data packet is going to be transmitted are cooperatively determined by the respective transmitter-receiver pair. Furthermore, to fully utilize the functionality provided by multiuser detection, our proposed cooperative MAC scheduling scheme is able to schedule multiple transmitters to simultaneously transmit packets to a same receiver. Computer simulations are carried out to demonstrate the performance of the proposed cooperative MAC scheduling framework. It is confirmed from simulation results that the packet average delay increases with either the packet generation rate or the network size. More importantly, the proposed cooperative MAC scheduling framework is more suitable for MUD-enabled CDMA-MANETs with heavier network traffic and possibly a larger number of network nodes.
Jun Li, Yifeng Zhou, Mathieu Déziel, Louise Lamont

MobileR: Multi-hop Energy Efficient Localised Mobile Georouting in Wireless Sensor and Actuator Networks

This paper addresses the usage of actuators (sensors with controlled mobility) for routing in wireless sensor and actuator networks. Different routing protocols have been proposed to improve routing in terms of energy efficiency through the use of controlled mobility enabled sensors . We introduce MobileR. Unlike literature proposals also using actuators, MobileR considers the cost of a full path toward one of its neighbours instead of the cost of the direct edge toward it. To do so, MobileR computes in advance the possible routing paths over the next hops relying on the one-hop neighbours and their possible relocations. Moreover MobileR is fully localised and stateless. We evaluate our solution in terms of cumulative energy consumption with regard to network density. Experiments show that, with sufficient node degree, energy used for routing is significantly reduced and so network lifetime is extended.
Nicolas Gouvy, Nathalie Mitton

Neighbour Selection and Sensor Knowledge: Proactive Approach for the Frugal Feeding Problem in Wireless Sensor Networks

This paper examines new proactive solutions to the Frugal Feeding Problem (FFP) in Wireless Sensor Networks. The FFP attempts to find energy-efficient routes for a mobile service entity to rendezvous with each member of a team of mobile robots. Although the complexity of the FFP is similar to the Traveling Salesman Problem (TSP), we propose an efficient solution, completely distributed and localized for the case of a fixed rendezvous location (i.e., service facility with limited number of docking ports) and mobile capable sensors. Our proactive solution reduces the FFP to finding energy-efficient routes in a dynamic Compass Directed Gabriel Graph (CDGG) or Compass Directed Relative Neighbour Graph (CDRNG). The proposed graphs incorporate ideas from forward progress routing and the directionality of compass routing in an energy-aware graph. Navigating the CDGG or CDRNG guarantees that each sensor will reach the rendezvous location in a finite number of steps. The ultimate goal of our solution is to achieve energy equilibrium (i.e., no further sensor losses due to energy starvation) by optimizing the use of a shared recharge station. We also examine the impact of critical parameters such as transmission range, number of recharge ports and sensor knowledge for the two proposed graphs.
Elio Velazquez, Nicola Santoro

Session 5 – Mobile Ad Hoc Networks

Connectivity of Vehicular Ad Hoc Networks in Downtown Scenarios

We study the connectivity in vehicular ad-hoc networks in a downtown scenario, where the mobility of vehicles is constrained on a lattice-shaped road network. We theoretically investigate the connectivity under the Poisson-positioning assumption, where vehicles are positioned according to a Poisson process on each road at any arbitrary instants. We find that the Poisson-positioning assumption allows the existence of the finite critical-vehicle density; that is, if (and only if) the density of vehicles is greater than the finite critical density, then there exists a large (theoretically infinite) cluster of vehicles and an arbitrary pair of vehicles in the cluster is connected in single or multiple hops. Under the Poisson-positioning assumption, we derive two approximation formulas for the critical density, which are given as a function of the transmission range of each vehicle and the distance between intersections. We also consider the connectivity under more realistic movement patterns of vehicles where the Poisson-positioning assumption does not hold. We numerically find that, even in non-Poisson-positioning cases, there exists the critical vehicle density, which is larger than the one under the Poisson-positioning assumption. The effectiveness of deploying roadside-relay stations to provide better connectivity between vehicles is also investigated.
Shigeo Shioda

An Energy-Delay Routing Protocol for Video Games over Multihops Ad Hoc Networks

Nowadays, with the development of networked technologies and the great expansion of video games industry, almost all video games propose a multi-player mode. Development of portables consoles which integrate 802.11 technology offers to people the opportunity to play anywhere, at any time and with anybody. However, wireless networked conditions are not always optimal and directly impact the quality of game perceived by players. In this paper, we propose a multimetric ad hoc routing protocol, based on OLSR, which improves game experience in terms of fairness among players and gaming sessions lifetime. We consider the delay and the energy as metrics to route informations through the network. We compare our routing protocol with an energy-efficient OLSR version and a delay-efficient OLSR version. We show that our routing protocol provides better performances in terms of fairness while keeping a good network lifetime.
Arnaud Kaiser, Khaled Boussetta, Nadjib Achir

Session 6 – Energy

An Energy Analysis of IEEE 802.15.6 Scheduled Access Modes for Medical Applications

Medical body area networks will employ a range of implantable and body worn devices to support a wide range of applications with diverse QoS requirements. The IEEE 802.15.6 working group is developing a communications standard for low power devices operating on, in and around the body and medical devices are a key application area of the standard. The ISO/IEEE 11073 standard addresses medical device interoperability and specifies the required QoS for medical applications.
This paper investigates the lifetime of devices using the scheduled access modes proposed by IEEE 802.15.6, while satisfying the throughput and latency constraints of the ISO/IEEE 11073 applications. It computes the optimum superframe structure and number of superframes that the device can sleep to achieve maximum lifetime. The results quantify the maximum expected achievable lifetime for these applications and show that scheduled access mode is not appropriate for all application classes such as those with intermittent transfer patterns.
Christos Tachtatzis, Fabio Di Franco, David C. Tracey, Nick F. Timmons, Jim Morrison

A Localized Algorithm Based on Minimum Cost Arborescences for the MECBS Problem with Asymmetric Edge Costs

In this paper we describe a (distributed) localized approximation algorithm for the MECBS (Minimum Energy Consumption Broadcast Subgraph) problem with asymmetric edge costs, called LMCA (Localized algorithm for energy-efficient broadcast based on Local Minimum Cost Arborescences). Given a directed weighted graph G = (V, E) with edge weight function w and a source node s, the MECBS problem consists of finding a range assignment to V such that the induced graph contains a spanning directed tree rooted at s with minimized cost. This problem can be efficiently solved for some specific cases, but it is NP-hard in the general case. To the best of our knowledge, LMCA is the first localized algorithm to the MECBS problem with asymmetric edge costs (without restricting the way how edge costs might be asymmetric). We compared LMCA with blind flooding and with two alternative solutions we designed for the problem, LMCP and LBIPAsym (a variation of LBIP for the case of asymmetric edge costs). In our experiments, LMCA outperformed these algorithms. We additionally present and evaluate two slight variations of LMCA, called LMCAc and LMCAfl.
Frederico Barboza, Flávio Assis


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