We propose in this paper a new HyperGraph-based Similarity Algorithm (HGSA) to measure the semantic similarity between services with focus on Web services. HGSA relies on a term-similarity function that considers several parameters such as node’s local density, depth, number of relation factors, and link strength. This function is leveraged to build a similarity matrix between Web services. Computing the similarity between Web services is reduced to applying the Hungarian method to this matrix. We study the complexity of the proposed algorithm and provide experiments that show that it outperforms other related approaches in terms of accuracy.

Abstract A great interest in vehicular ad‐hoc networks has been noticed by the research community. General goals of vehicular networks are to enhance safety on the road and to ensure the convenience of passengers by continuously providing them, in real time, with information and entertainment options such as routes to destinations, traffic conditions, facilities' information, and multimedia/Internet access. Indeed, time efficient systems that have high connectivity and low bandwidth usage are most needed to cope with realistic traffic mobility conditions. One foundation of such a system is the design of an efficient gateway discovery protocol that guarantees robust connectivity between vehicles, while assuring Internet access. Little work has been performed on how to concurrently integrate load balancing, quality of service (QoS), and fault tolerant mechanisms into these protocols. In this paper, we propose a reliable QoS‐aware and location aided gateway discovery protocol for vehicular networks by the name of fault tolerant location‐based gateway advertisement and discovery. One of the features of this protocol is its ability to tolerate gateway routers and/or road vehicle failure. Moreover, this protocol takes into consideration the aspects of the QoS requirements specified by the gateway requesters; furthermore, the protocol insures load balancing on the gateways as well as on the routes between gateways and gateway clients. We discuss its implementation and report on its performance in contrast with similar protocols through extensive simulation experiments using the ns‐2 simulator. Copyright © 2013 John Wiley & Sons, Ltd.

The RSU deployment algorithms to cover interest regions have emerged as promising areas of research in vehicular ad hoc networks. However, there is few research on the discovery of the interest regions. Besides, the deployment algorithms are usually proposed for either continuous coverage or sparse coverage. The wisdom of the model selection are rarely addressed. In this paper, we proposed a new algorithm to discover interest regions. A budget-constrained coverage selection algorithm is also presented to help network designers choose suitable coverage models to meet the budget and quality requirements. The algorithms are implemented on top of Ns2 and the simulations are carried out using SUMO and OpenStreet Maps. The performance comparison between our algorithm and other two clustering algorithms prove that our algorithm has a better performance in terms of contact time for both sparse coverage and continue coverage.

Time-sensitive mobile service with vehicular networks depend on continuous coverage on the road system. It is a challenge to meet a tight budget while maintaining coverage quality. In order to resolve the problem, we model the road system as an undirected graph and reduce it to a Knapsack Constrained Steiner Tree model. Since the reduced model is an NP-hard problem, we resolve it by using Lagrangian decomposition approach. The terminal nodes in the graph are hotspots, where most vehicles accumulate; and, the paths connecting these hotspots are measured by a new metric: coverage value. We evaluated the our scheme by comparing it with the Maximum Continuous Coverage protocol in terms of the packet drop rate in the NS2 simulation. The final result shows that our coverage is reliable, and suitable for urban vehicular networks.

Animal-Vehicle Collisions (AVCs) have been a challenging problem since the creation of cars. Consequently, such collisions cause hundreds of human and animal deaths, thousands of injuries, and billions of dollars in property damage every year. To cope with this challenge, vehicles have to be equipped with smart systems able to detect animals (e.g., moose), which cross roadways, and warn drivers about the imminent danger. In this paper, we develop a new animal detection system following two criteria: detection accuracy and detection speed. To achieve these requirements, a two-stage strategy system is investigated. In the first stage, we use the LBP-Adaboost algorithm which supplies the second stage by a set of ROIs containing moose and other similar-objects. Whereas the second stage is based on an adapted version of HOG-SVM classifier. In this stage, the non-moose ROIs are rejected. To train and test our system, we create our own dataset, which is frequently updated by adding new images. Through an extensive set of simulations, we show that our system is able to detect more than 83% of moose.

A reliable solution for the task of unicast video streaming over urban VANETs is of great demand. Single path solutions which address this topic are highly prone to collision at a high data rates which are necessary for high quality videos. Multipath solution solves this problem by distributing the heavy traffic load into a set of paths. Among numbers of multipath works, only 2-path LIAITHON+takes into consideration the high dynamic topology of VANETs, route coupling effect, and path length growth. In this paper, we make several improvements on top of the 2-path LIAITHON+. We evaluate the use of more than two paths in this multipath solution. Moreover, the impact of added redundancy on the both 2-path and 3-path LIAITHON+is investigated as a solution for packet loss.

In recent years, we have witnessed a growing interest in Vehicular Networks from both the research community and industry. Several potential applications of Vehicular Networks are envisioned such as road safety and security, streaming services, traffic monitoring and driving comfort, just to mention a few. It is critical that the existence of convenience or driving comfort services do not negatively affect the performance of safety services. In essence, the dissemination of safety services or the discovery of convenience applications require the communication among service providers and service requesters through constrained bandwidth resources. Therefore, service discovery techniques for vehicular networks must efficiently use the available common resources. In this paper, we present a bandwidth-efficient and scalable hybrid adaptive service discovery protocol (VSDP) for Vehicular Networks. VSDP aims at providing high success ratio while guaranteeing low response time and good scalability when the number of requests increases. Our proposed protocol finds the service provider and its routing information simultaneously which results in overall bandwidth savings. It uses diverse channels to exchange discovery and routing packets, thereby decreasing the congestion on single channels and decreasing the delay of service discovery. Our proposed service discovery protocol adapts the advertisement zone size of service providers based on an efficient adaptation mechanism that takes into consideration network condition and application requirements. The adaptation process is based on an adjustment technique and a prediction technique. We discuss the implementation of our protocol, present its proof of correctness as well as the performance evaluation through an extensive set of simulation experiments and using different mobility models. Our results show the scalability of our protocol. They indicate that our techniques can achieve significant success rate (more than 90 percent), while guaranteeing low response time (in the order of milliseconds) and low bandwidth usage when compared to existing service discovery techniques.

Vehicular ad hoc networks are emerging as a promising approach to improve traffic safety and provide a wide range of wireless applications to drivers and passengers on the road. In order to perform reliable and trusted vehicular communications, one requirement is to ensure peer vehicle credibility by means of validating digital certificate attached to messages that are transmitted by other vehicles. However, in vehicular communication systems, certificate validation is more time consuming than in traditional networks because each vehicle receives a large number of messages in a short period. Another concern is the unsuccessful delivery of information between vehicles and other entities on the road due to their high mobility rate. For these reasons, we seek new solutions that will aid in speeding up the process of certificate validation. In this article, we propose a certificate revocation status validation scheme using the concept of clustering from data mining that can meet the aforementioned requirements. We employ the technique of k-Means clustering to boost the efficiency of certificate validation, thereby enhancing the security of a vehicular ad hoc network. Additionally, a comprehensive security analysis for this scheme is presented; the analysis shows that this scheme can effectively improve the validation of certificates and thus increase the communication security in vehicular ad hoc networks. Copyright © 2012 John Wiley & Sons, Ltd.

As the scale of distributed simulations, such as HLA-base simulations, grow due to the complexity in modelling real systems, balancing systems become essential for enabling the execution of these simulations or preventing simulation performance loss. This loss is greatly produced by non-dedication or heterogeneity of resources in large-scale environments or by simulations that might generate dynamic load oscillations. In light of avoiding load imbalances in such conditions, a distributed balancing system has been developed. However, in order to enable load balancing systems to effectively and properly react to load imbalances, they need to be properly deployed and configured in environments where are occasionally unknown due to the lack of previous information about them or to the dynamic changes that might occur as time passes. As a result, an autonomous configuration scheme is proposed to increment the distributed balancing system and allow it to flexibly adapt to the environment where it is deployed. Experiments have been performed in defined scenarios in order to assess the benefit in incorporating such dynamic configuration solution on the balancing system.

IEEE 802.11 is an economical and efficient standard that has been applied to vehicular networks. The long handoff latency of the traditional handoff scheme for IEEE 802.11, however, becomes an important issue for seamless connections in vehicular environments, as more handoffs may be triggered due to higher mobility of vehicles. This paper presents a new fast location-based handoff scheme particularly designed for vehicular networks. With the position and direction of a vehicle and locations of its surrounding access points (APs), our algorithm can accurately predict the next AP that the vehicle may visit. Time spent on scanning APs in handoff procedures is therefore significantly saved. The AP selection scheme can also reduce the total number of handoffs by selecting APs on the vehicle's advancing path. Finally, simulation results demonstrate that the proposed scheme attains low prediction error rates, low layer-2 handoff latency and the reduced number of unnecessary handoffs.

This paper presents an improved authentication scheme for Radio-frequency identification (RFID) applied in VANETs. As often being considered as a precondition for the realization of IoT, RFID can be utilized in the vehicles, so as to make the vehicles identifiable and inventoriable by computers as long as they are fitted out with radio tags. One of the main concerns is to address the large number of security and privacy issues. A few light symmetric key management schemes have been proposed for RFID scenarios. We suggest EKA2 which is a new certificate revocation status validation scheme, and we use the concept of clustering from data mining to evaluate the trustiness of digital certificates.

We tackle the issue of providing video streaming support over Vehicular Ad Hoc Networks (VANETs). Video streaming imposes stringent requirements in terms of delivery ratio and delay in order to provide a satisfying level of service at the user's end. In our work, we investigate the use of Erasure Coding to overcome packet loss and to fulfill video streaming requirements of delivery ratio. We have investigated two distinct coding techniques and evaluated thoroughly their peculiarities. This study has shown how Erasure Coding could improve delivery ratio without affecting end-to-end delay.

Some research indicates that the TCP congestion control mechanism may cause the burstiness of traffic flow. A group of TCP segments are delivered simultaneously, while an acknowledgement (ACK) of a retransmission is successfully received. This burstiness leads to a network with high level contention , which extremely increases the probability of packet loss on wireless networks. TCP pacing is one of the solutions for TCP burstiness on multi-hop network. The idea is to spread the TCP segment transmissions over the whole Round Trip Time (RTT). Most of the pacing protocols attempt to insert a delay interval into the TCP segment flows or ACK flows, without noticing a Cross Layer pacing algorithm on IEEE802.11 with deferring and backoff mechanism. In this paper, we measure and analyze the way contention window size (CW) affects TCP throughput in different scenarios; and, we propose a cross layer TCP pacing protocol by controlling the lower bound of contention window for the optimization of the overall TCP throughput on multi-hop topology. Finally, a comparison of simulations is presented in order to verify the improvement achieved by our protocol.

SUMMARY In this paper, we suggest a cryptographic protocol for symmetric key exchange based on a set of m commutative square singular matrices of dimension n×n. The suggested scheme provides a concurrent technique for users of symmetric‐key cipher systems to securely exchange their private keys over public channels. This protocol is shown to possess a high level of security based on the algorithm's parameters. We also present a scheme for generating pseudorandom numbers from a single chaotic map for use in various applications, in particular, the suggested key exchange protocol.Copyright © 2011 John Wiley & Sons, Ltd.

The Hierarchically Distributed Tree (HD Tree) is a new data structure within distributed environment. It is designed to better preserve data locality when the number of nodes in a tree grows exponentially. By adding extra links to a corresponding complete tree, multiple routing paths are available between each pair of tree nodes. Therefore the routing strategy for HD Tree could be designed to be highly flexible and error resilient. The routing traffic can be controlled dynamically, making the traffic load balanced among all the nodes. However, within an HD Tree, there are some nodes, which we name SPeers, that are different from the others. They have less connected neighbours. What's more, every SPeer has only one parent and in the case of parent node failure, a leaf SPeer node could be isolated from the system. So a new method by which to connect all the SPeers is needed. In this paper, a new routing strategy is proposed, in order to make the routing between SPeers more error resilient. This strategy could be used as an alternative approach to previously developed algorithms. In addition, it is proven that when combined with other strategies, it will achieve better routing performance.

Vehicular ad hoc networks (VANETs) are emerging as a promising approach to improve traffic safety and provide a wide range of wireless applications to passengers in vehicles. To launch reliable and trusted vehicular communications, one prerequisite is to ensure peer vehicles' credibility, by means of digital certificate validation from messages that are sent out by other vehicles. However, in vehicular communication systems, certificate validation is more time sensitive than in traditional networks, because each vehicle receives a large number of messages in a short period of time. Another issue that needs to be tackled is the unsuccessful delivery of information between vehicles and other entities on the road due to their high rate of mobility. For these reasons, we need new solutions to speed up the process of certificate validation. In this article, we propose a certificate revocation status validation scheme; this uses the concept of clustering in the realm of data mining, which can meet the aforementioned requirements. We employ the technique of k-means clustering to boost up the efficiency of certificate validation, thereby enhancing the security of VANETs. Additionally, a comprehensive analysis in terms of security for the scheme is presented; and the analytical results demonstrate that this scheme can effectively improve the validation of a certificate, thus securing the vehicular communication in vehicular networks.

This paper investigates techniques for supporting individual users in choosing appropriate Web services according to their specific needs, and accessing their favorite Web services. It also examines the provision of visualization of Web services that can be made available to service consumers as well as service providers who promote their Web services. To achieve these goals, we propose a three-layer architecture: a data layer for handling measurements of quality attribute of Web services; a Web service middleware processing layer, which computes quality attribute weights for ranking Web services; and finally, a visualization layer for monitoring the quality of Web services. The proposed architecture is implemented and tested on real world Web services drawn from the QWS database of Web services. Our Web services visualization technique is more convenient and user-friendly compared to current basic text based Web services discovery techniques.

With the increasing popularity of using Web services, Quality of Service (QoS) is becoming a significant concern for both service consumers and providers. Several models for considering functional and non-functional QoS requirements for the purpose of Web service discovery and selection have been proposed. We present in this paper a new Web services selection model based on fuzzy logic. In this model, the non-functional QoS requirements are taken into account for the appropriate selection of required services. Our model can handle consumers' imprecise preferences with fuzzy sets. Moreover, a new fuzzy ranking algorithm that is based on the dependencies between quality attributes is proposed. The experimental results obtained from real world Web service domains revealed better performance of our algorithm compared to Entropy-based ranking algorithms.