Optimal RoadSide Units Distribution Approach in Vehicular Ad hoc Network

A vehicular ad hoc network is a particular type of ad hoc mobile network. It is characterized by high mobility and frequent disconnection between vehicles. For this, the roadside units (RSUs) deployment permits to enhance the network connectivity. The objective of this work is to provide an optimized RSUs placement for enhancing the network connectivity and maximizing the accident coverage with reducing the deployment cost. In this paper, we propose our approach called Optimized RoadSide units Deployment (ORSD). The proposed approach comprises a two-step, in the first step, ORSD finds the RSUs candidate locations based on network density and connectivity. We calculated the connectivity of each segment based on speed and arrival information’s.  The second step permit to find the optimal solution of our proposed objective function. The objective function permits to enhance the network connectivity and maximizing the accident coverage.  To find the optimal solution of our objective function is an NP-complete problem of order o(n²) .  Therefore, we propose to solve this problem in two phases, so that it becomes a simple linear problem to solve. The ORSD is proposed for urban and high way scenarios. The extensive simulation study is conducted in order to assess the effectiveness of the proposed approach. We use the Simulator of Urban MObility (SUMO) for generating different traffic scenarios. We develop scripts to extract different information as density, speed and travel time in each segment. Then, we develop an algorithm to calculate connectivity probability for each segment. Then, we implement our objective function to finds optimal RSUs positions in terms of connectivity, accident cover and cost

Multiplicative Multiresolution Decomposition for Lossless Volumetric Medical Images Compression

With the emergence of medical imaging, the compression of volumetric medical images is essential. For this purpose, we propose a novel Multiplicative Multiresolution Decomposition (MMD) wavelet coding scheme for lossless compression of volumetric medical images. The MMD is used in speckle reduction technique but offers some proprieties which can be exploited in compression. Thus, as the wavelet transform the MMD provides a hierarchical representation and offers a possibility to realize lossless compression. We integrate in proposed scheme an inter slice filter based on wavelet transform and motion compensation to reduce data energy efficiently. We compare lossless results of classical wavelet coders such as 3D SPIHT and JP3D to the proposed scheme. This scheme incorporates MMD in lossless compression technique by applying MMD/wavelet or MMD transform to each slice, after inter slice filter is employed and the resulting sub-bands are coded by the 3D zero-tree algorithm SPIHT. Lossless experimental results show that the proposed scheme with the MMD can achieve lowest bit rates compared to 3D SPIHT and JP3D

Secure Communications by Tit-for-Tat Strategy in Vehicular Networks

International audienceSecure communication is one of the main challenges of ad hoc Vehicle Networks (VANET). Intrusion detection of malicious nodes is one of the solutions to secure communication in VANETs using hybrid architecture (V2V and V2I). This article proposes an approach based on game theory, in particular the “Tit-for-Tat” (TfT) strategy as a suitable paradigm for human cooperation in order to detect malicious nodes in passive and active attacks. This article analyzes the performance of the proposed approach and the “TfT” strategy contribution in VANET security

Vertical Handover Decision Algorithm for Multimedia Streaming in VANET

International audienceVehicular ad hoc networks represent one of the most important applications of wireless ad hoc networks. In highways, where different networks exist, frequent and sometimes unnecessary switches from one network to another may occur, which degrade network performance and affect applications, especially those that require high quality networks such as multimedia applications (Video conferencing, Video On-Demand, etc.). This work presents an analytical model and a Vertical Handover decision method for Highways called VHH. It is based on position, velocity, jitter, and density as mandatory inputs which aim to both minimize Vertical handover frequency and avoid unnecessary handoffs and ping pong effect between different networks, in the goal of enhancing multimedia streaming services in highways. A simulation is provided to prove the performance of the algorithm

An Optimized Roadside Units (RSU) Placement for Delay-Sensitive Applications in Vehicular Networks

International audienceOver the last few years, a lot of applications have been developed for Vehicular Ad Hoc NETworks (VANETs) to exchange information between vehicles. However, VANET is basically a Delay Tolerant Network (DTN) characterized by intermittent connectivity, long delays and message losses especially in low density regions [1]. Thus, VANET requires the use of an infrastructure such as Roadside Units (RSUs) that permits to enhance the network connectivity. Nevertheless, due to their deployment cost, RSUs need to be optimally deployed. Hence, the main objective of this work is to provide an optimized RSUs placement for delay-sensitive applications in vehicular networks that improves the end-to-end application delay and reduces the deployment cost. In this paper, we first mathematically model the placement problem as an optimization problem. Then, we propose our novel solution called ODEL. ODEL is a two-steps technique that places RSUs only in useful locations and allows both vehicle-to-vehicle and vehicle-to-infrastructure communication: (i) the first step is comprehensive study that looks for the RSUs candidates locations based on connectivity information, and (ii) the second step uses genetic algorithm and Dijkstra algorithm to reduce the number of RSUs based on the deliverance time requirement and the deployment cost. We show the effectiveness of our solution for different scenarios in terms of applications delay (reduced by up to 84%) and algorithm efficiency (computation performance reduced by up to 79% and deployment cost reduced at least by up to 23%)

Routing Protocol Based on Neighbor Interference Level for Mobile Wireless Networks

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Self-Organization Framework for Mobile Ad Hoc Networks

International audienceMobile ad hoc networks (MANETs) face a number of challenges, in particular due to dynamic network topology and large variable number of mobile nodes. To overcome these problems an effective solution is to define a self-organizing architecture that facilitates the network management task and permits to deploy wide panoply of services. One method to organize such networks is to define a virtual backbone that covers all the nodes in the network. In this paper we propose new self-organization architecture based on an optimized CDS construction. In this approach, the neighbors select CDS nodes intelligibly. In the selection processes, a new weight parameter depending on energy, link quality and connectivity is introduced in order to increase the CDS lifetime and hence the network performances. To study the benefits of this new architecture, we propose a new routing protocol called "PROC" (Proactive Routing based on Optimized CDS). Simulation results, using NS2, show that PROC minimizes the overhead and the energy consumption compared to the well-known OLSR routing protocol