Alejandro Quintero

VANET security surveys

Abstract Vehicular ad hoc networks (VANETs), a subset of Mobile Ad hoc NETworks (MANETs), refer to a set of smart vehicles used on the road. These vehicles provide communication services among one another or with Road Side Infrastructure (RSU) based on wireless Local Area Network (LAN) technologies. The main benefits of VANETs are that they enhance road safety and vehicle security while protecting drivers’ privacy from attacks perpetrated by adversaries. Security is one of the most critical issues related to VANETs since the information transmitted is distributed in an open access environment. VANETs face many challenges. This paper presents a survey of the security issues and the challenges they generate. The various categories of applications in VANETs are introduced, as well as some security requirements, threats and certain architectures are proposed to solve the security problem. Finally, global security architecture for VANETs is proposed.

Ant-based routing for wireless multimedia sensor networks using multiple QoS metrics

In wireless sensor networks, most routing protocols consider energy savings as the main objective and assume data traffic with unconstrained delivery requirements to be a given. However, the introduction of video and imaging sensors unveils additional challenges. The transmission of video and imaging data requires both energy efficiency and QoS assurance (end-to-end delay and packet loss requirements), in order to ensure the efficient use of sensor resources as well as the integrity of the information collected. This paper presents a QoS routing model for Wireless Multimedia Sensor Networks (WMSN). Moreover, based on the traditional ant-based algorithm, an ant-based multi-QoS routing metric (AntSensNet) is proposed. The AntSensNet protocol builds a hierarchical structure on the network before choosing suitable paths to meet various QoS requirements from different kinds of traffic, thus maximizing network utilization, while improving its performance. In addition, AntSensNet is able to use a efficient multi-path video packet scheduling in order to get minimum video distortion transmission. Finally, extensive simulations are conducted to assess the effectiveness of this novel solution and a detailed discussion regarding the effects of different system parameters is provided. Compared to typical routing algorithms in sensor networks and the traditional ant-based algorithm, this new algorithm has better convergence and provides significantly better QoS for multiple types of services in wireless multimedia sensor networks.

Assigning cells to switches in cellular mobile networks: a comparative study

Assigning cells to switches in cellular mobile networks is an NP-hard problem which, for realsize mobile networks, could not be solved by using exact methods. In this context, heuristic approaches like genetic algorithms, tabu search and simulated annealing can be used. This paper proposes a comparative study of three heuristics-tabu search, simulated annealing and Parallel Genetic Algorithms with Migrations (PGAM)-used to solve this problem. The implementation of these algorithms have been tested in order to measure the quality of solutions. The results obtained confirm the efficiency of the seheuristics to provide good solutions for medium- and large-sized cellular mobile networks, in comparison with the sequential genetic algorithm (SGA) and with other heuristic methods well known in the literature. The evaluation cost provided by tabu search, simulated annealing and PGAM are very similar. Those three algorithms provide better results than standard genetic algorithm and always find feasible solutions. In terms of CPU times, tabu search is the fastest method. Finally, the results have been compared with a lower bound on the global optimum; they confirm the effectiveness of the tabu search, simulated annealing and PGAM to solve this problem.

A user pattern learning strategy for managing users' mobility in UMTS networks

Third-generation mobile systems provide access to a wide range of services and enable mobile users to communicate regardless of their geographical location and their roaming characteristics. Due to the growing number of mobile users, global connectivity, and the small size of cells, one of the most critical issues regarding these networks is location management. In recent years, several strategies have been proposed to improve the performance of the location management procedure in 3G mobile networks. In this paper, we present a user pattern learning strategy (UPL) using neural networks to reduce the location update signaling cost by increasing the intelligence of the location procedure in UMTS. This strategy associates to each user a list of cells where she is likely to be with a given probability in each time interval. The implementation of this strategy has been subject to extensive tests. The results obtained confirm the efficiency of UPL in significantly reducing the costs of both location updates and call delivery procedures when compared to the UMTS standard and with other strategies well-known in the literature.

A memetic algorithm for assigning cells to switches in cellular mobile networks

Assigning cells to switches in cellular mobile networks is an NP-hard problem which, for real size mobile networks, could not be solved using exact methods. In this context, heuristic approaches like memetic algorithms can be used. This paper proposes a memetic algorithm (MA) to solve this problem. The implementation of this algorithms has been subject to extensive tests. The results obtained confirm the efficiency and the effectiveness of MA to provide good solutions for moderate- and large-sized cellular mobile networks, in comparison with tabu search and Merchant and Senguptas heuristics. This heuristic can be used to solve NP-hard problems, like designing and planning, in the next-generation mobile networks.

Evolutionary approach to optimize the assignment of cells to switches in personal communication networks

This paper proposes an evolutionary approach to solve the problem of assigning cells to switches in the planning phase of mobile cellular networks. Well-known in the literature as an NP-hard combinatorial optimization problem, this problem requires the recourse to heuristic methods, which can practically lead to good feasible solutions, not necessarily optimal, the objective being rather to reduce the convergence time toward these solutions. Computational results obtained from extensive tests confirm the effectiveness of this approach to provide good solutions to problems of a certain size. This approach can be used to solve NP-hard problems, like designing and planning, in the next generation networking systems.

Market oriented planning of power generation expansion using agent-based model

The deregulated electricity industry is characterized by structural change and strategic behaviors of market participants. There is a need of a novel model for medium and long term planning that could include games theoretical assumptions as well as other more complex assumptions. This paper proposes a new agent-based model designed to support decentralized planning activities in electricity supply industry, with a certain level of flexibility. In this model, the expansion planning method is developed around a multiagent simulation system where the interactions among agents in electricity market are simulated. An example is given to illustrate the proposed model.

A routing protocol based on node density for ad hoc networks

Abstract Ad hoc networks are a type of mobile network that functions without any fixed infrastructure. One of the weaknesses of ad hoc networks is that a route used between a source and a destination is likely to break during communication. To solve this problem, one approach consists of selecting routes whose nodes have the most stable behavior. Another strategy aims at improving the route repair procedure. This paper proposes a method for improving the success rate of local route repairs in mobile ad hoc networks. This method is based on the density of the nodes in the neighborhood of a route and on the availability of nodes in this neighborhood. Theoretical computation and simulation results show that the data packet loss rate decreased significantly compared to other methods which are well-documented in the literature. In addition, the time required to complete a local route repair following a failure was significantly reduced.

A fuzzy decision making strategy for vertical handoffs

The main concern of the next generation of mobile networks is the integration of heterogeneous wireless technologies around an IP backbone. However this integration invokes many challenges such as mobility management and handoff decision making. Various approaches have been proposed to deal with handover decision problem, yet handoff initiation and network destination selection remain critical issues which are widely based on the traditional RSS measurements. In this paper, we propose a new fuzzy decision making approach that considers a variety of context parameters to trigger handoffs and choose an optimal network destination with respect to mobile terminal requirements and nearby network capabilities. The obtained results show that the proposed decision making approach maximize user preferences compared to the RSS based decision methods.

Mobile services access and payment through reusable tickets

Third-generation mobile systems (3G) such as Universal Mobile Telecommunications Service (UMTS) bring mobile users a broad range of new value-added services (VASs). For mobile access across multiple service domains, the traditional access mechanisms require the exchange of authentication information between the home domain and the foreign domain using roaming agreements. This requirement involves complicated and expensive authentication activities in large scale mobile networks. This paper proposes a lightweight service access mechanism in which the computation complexity is low on the mobile device and the ticket can be reused. It introduces two hash chains: an authentication chain and a payment chain. The authentication chain allows a ticket to be reused and achieves mutual authentication and non-repudiation. The payment chain is lightweight, practical and likely to avoid re-initialization. Security analysis and comparison with related works indicate that our proposal is more appropriate for mobile communication networks.