Modeling vanet deployment in urban settings

... (VANETs) has prompted greater research into simulation models that better reflect urban VANET deployments. Still, we lack a systematic understanding of the required level of simulation details in modeling various real-world urban constraints. In this work, we developed a series of simulation models that account for street layout, traffic rules, multilane roads, acceleration-deceleration, and RF attenuation due to obstacles. Using real and controlled synthetic maps, we evaluated the sensitivity of the simulation results toward these details. Our results indicate that the delivery ratio and packet delays in VANETs are more sensitive to the clustering effect of vehicles at intersections and their accelerationdeceleration. The VANET performance appears to be only marginally affected by the simulation of multiple lanes and careful synchronization at traffic signals. We also found that the performance in dense VANETs improves significantly when routing decisions are limited to a wireless backbone of mesh nodes, whereas in sparse VANETs, performance improves when vehicles also participate in ad hoc routing. Finally, through measurement and analysis of signal strengths around urban city blocks, we show that the effect of signal attenuation due to physical obstacles can potentially be parameterized in simulations. Our work provides a starting point for further understanding and development of more accurate VANET simulation models

Antecedents to User Adoption of Interactive Mobile Maps

There are several studies on user adoption of new technologies. These studies attempt to determine the underlying antecedents or factors that spur users’ adoption or acceptance of such technologies. The original Technology Acceptance Model (TAM) included perceived usefulness and perceived ease of use as determinants of users’ adoption of information technologies. This model was later extended to include perceived enjoyment and other variables. However, in the context of interactive mobile maps, this model or its extensions have not been applied yet. This informed and underscored the objective of this investigation. This study is aimed at applying the TAM model’s extension to the context of interactive mobile maps. This study therefore examines perceived usefulness, perceived ease of use and perceived enjoyment as antecedents to user adoption of interactive mobile maps using TAM model. The model was used to evaluate users’ adoption of the technology (interactive mobile map) with perceived usefulness, perceived ease of use and perceived enjoyment as antecedents. A survey approach was used and the findings revealed that all the three factors used in this study explain well the variance in user adoption of interactive mobile maps. Perceived usefulness, perceived ease of use, and perceived enjoyment have significant positive effect on user adoption of interactive mobile maps. In sum, this study further confirms and validates the TAM model

Antecedents to user adoption of interactive mobile maps

There are several studies on user adoption of new technologies.These studies attempt to determine the underlying antecedents or factors that spur users’ adoption or acceptance of such technologies.The original Technology Acceptance Model (TAM) included perceived usefulness and perceived ease of use as determinants of users’ adoption of information technologies.This model was later extended to include perceived enjoyment and other variables.However, in the context of interactive mobile maps, this model or its extensions have not been applied yet.This informed and underscored the objective of this investigation.This study is aimed at applying the TAM model’s extension to the context of interactive mobile maps.This study therefore examines perceived usefulness, perceived ease of use and perceived enjoyment as antecedents to user adoption of interactive mobile maps using TAM model.The model was used to evaluate users’ adoption of the technology (interactive mobile map) with perceived usefulness, perceived ease of use and perceived enjoyment as antecedents. A survey approach was used and the findings revealed that all the three factors used in this study explain well the variance in user adoption of interactive mobile maps.Perceived usefulness, perceived ease of use, and perceived enjoyment have significant positive effect on user adoption of interactive mobile maps. In sum, this study further confirms and validates the TAM model

Modeling, Evaluation, and Scale on Artificial Pedestrians: A Literature Review

Modeling pedestrian dynamics and their implementation in a computer are challenging and important issues in the knowledge areas of transportation and computer simulation. The aim of this article is to provide a bibliographic outlook so that the reader may have quick access to the most relevant works related to this problem. We have used three main axes to organize the article's contents: pedestrian models, validation techniques, and multiscale approaches. The backbone of this work is the classification of existing pedestrian models; we have organized the works in the literature under five categories, according to the techniques used for implementing the operational level in each pedestrian model. Then the main existing validation methods, oriented to evaluate the behavioral quality of the simulation systems, are reviewed. Furthermore, we review the key issues that arise when facing multiscale pedestrian modeling, where we first focus on the behavioral scale (combinations of micro and macro pedestrian models) and second on the scale size (from individuals to crowds). The article begins by introducing the main characteristics of walking dynamics and its analysis tools and concludes with a discussion about the contributions that different knowledge fields can make in the near future to this exciting area

Multicast outing protocols and architectures in mobile ad-hoc wireless networks

The basic philosophy of personal communication services is to provide user-to-user, location independent communication services. The emerging group communication wireless applications, such as multipoint data dissemination and multiparty conferencing tools have made the design and development of efficient multicast techniques in mobile ad-hoc networking environments a necessity and not just a desire. Multicast protocols in mobile adhoc networks have been an area of active research for the past few years. In this dissertation, protocols and architectures for supporting multicast services are proposed, analyzed and evaluated in mobile ad-hoc wireless networks. In the first chapter, the activities and recent advances are summarized in this work-in-progress area by identifying the main issues and challenges that multicast protocols are facing in mobile ad-hoc networking environments and by surveying several existing multicasting protocols. a classification of the current multicast protocols is presented, the functionality of the individual existing protocols is discussed, and a qualitative comparison of their characteristics is provided according to several distinct features and performance parameters. In the second chapter, a novel mobility-based clustering strategy that facilitates the support of multicast routing and mobility management is presented in mobile ad-hoc networks. In the proposed structure, mobile nodes are organized into nonoverlapping clusters which have adaptive variable-sizes according to their respective mobility. The mobility-based clustering (MBC) approach which is proposed uses combination of both physical and logical partitions of the network (i.e. geographic proximity and functional relation between nodes, such as mobility pattern etc.). In the third chapter, an entropy-based modeling framework for supporting and evaluating the stability is proposed in mobile ad-hoc wireless networks. The basic motivations of the proposed modeling approach stem from the commonality observed in the location uncertainty in mobile ad-hoc wireless networks and the concept of entropy. In the fourth chapter, a Mobility-based Hybrid Multicast Routing (MHMR) protocol suitable for mobile ad-hoc networks is proposed. The MHMR uses the MBC algorithm as the underlying structure. The main features that the proposed protocol introduces are the following: a) mobility based clustering and group based hierarchical structure, in order to effectively support the stability and scalability, b) group based (limited) mesh structure and forwarding tree concepts, in order to support the robustness of the mesh topologies which provides limited redundancy and the efficiency of tree forwarding simultaneously, and c) combination of proactive and reactive concepts which provide the low route acquisition delay of proactive techniques and the low overhead of reactive methods. In the fifth chapter, an architecture for supporting geomulticast services with high message delivery accuracy is presented in mobile ad-hoc wireless networks. Geomulticast is a specialized location-dependent multicasting technique, where messages are multicast to some specific user groups within a specific zone. An analytical framework which is used to evaluate the various geomulticast architectures and protocols is also developed and presented. The last chapter concludes the dissertation

GAME THEORETIC APPROACH TO RADIO RESOURCE MANAGEMENT ON THE REVERSE LINK FOR MULTI-RATE CDMA WIRELESS DATA NETWORKS

This work deals with efficient power and rate assignment to mobile stations (MSs) involved in bursty data transmission in cellular CDMA networks. Power control in the current CDMA standards is based on a fixed target signal quality called signal to interference ratio (SIR). The target SIR represents a predefined frame error rate (FER). This approach is inefficient for data-MSs because a fixed target SIR can limit the MS's throughput. Power control should thus provide dynamic target SIRs instead of a fixed target SIR. In the research literature, the power control problem has been modeled using game theory. A limitation of the current literature is that in order to implement the algorithms, each MS needs to know information such as path gains and transmission rates of all other MSs. Fast rate control schemes in the evolving cellular data systems such as cdma2000-1x-EV assign transmission rates to MSs using a probabilistic approach. The limitation here is that the radio resources can be either under or over-utilized. Further, all MSs are not assigned the same rates. In the schemes proposed in the literature, only few MSs, which have the best channel conditions, obtain all radio resources. In this dissertation, we address the power control issue by moving the computation of the Nash equilibrium from each MS to the base station (BS). We also propose equal radio resource allocation for all MSs under the constraint that only the maximum allowable radio resources are used in a cell. This dissertation addresses the problem of how to efficiently assign power and rate to MSs based on dynamic target SIRs for bursty transmissions. The proposed schemes in this work maximize the throughput of each data-MS while still providing equal allocation of radio resources to all MSs and achieving full radio resource utilization in each cell. The proposed schemes result in power and rate control algorithms that however require some assistance from the BS. The performance evaluation and comparisons with cdma2000-1x-Evolution Data Only (1x-EV-DO) show that the proposed schemes can provide better effective rates (rates after error) than the existing schemes

Dépistage d'unités mobiles dans les systèmes cellulaires

Fonctionnement général des réseaux mobiles -- Architecture générale des réseaux mobiles -- Aspects économiques de la configuration des réseaux mobiles -- Méthodes d'allocation des canaux de base -- Contrôle optimal d'admission des appels -- Planification des zones de localisation -- Localisation des unités mobiles -- Stratégies de dépistage des unités mobiles -- Stratégies de mise à jour -- Mécanismes d'établissement de communications -- Revue des schémas de gestion de localisation -- Modèle de dépistage sous contrainte de délai -- Description du modèle proposé Par Hao et Akyildiz -- Algorithme de calcul des probabilités d'état -- Analyse de la courbe de coût total -- Algorithme de gestion de mobilité proposé -- Mise en oeuvre et analyse des résultats -- Mise en oeuvre de l'algorithme -- Résultats numériques -- Comparaison avec l'algorith me de Ho et Akyildiz

Modèles et algorithmes pour la gestion de la localisation dans les réseaux à composantes mobiles multiservices

Éléments de la problématique -- Esquisse méthodologique et principales contributions de la thèse -- Gestion de mobilité et de localisation dans les SCP -- Normes et protocoles pour la gestion de localisation -- Modèles classiques pour la gestion de localisation -- Modèle de champ mémoire -- Idée et concept de base -- Comportement du modèle de champ mémoire -- Description des algorithmes -- Analyse de performance -- Analyse comparative des modèles de champ mémoire et IS-41 -- Modèle de champ mémoire versus modèle des pointeurs de renvoi -- Schéma global de gestion de localisation -- Idée de base du schéma global de gestion de localisation -- Procédures de mise à jour et de recherche de localisation -- Analyse de performance -- Schéma hybride pour la gestion de localisation -- Architecture centralisée versus architecture répartie -- Schéma hybride pour la gestion de localisation -- Analyse de performance du schéma hybride -- Résultats numériqeus de simulation -- Analyse de performance par rapport à CMR

Geometry-based stochastic physical channel modeling for cellular environments

Telecommunication has experienced significant changes over the past few years and its paradigm has moved from wired to wireless communications. The wireless channel constitutes the basic physical link between the transmitter and the receiver antennas. Therefore, complete knowledge of the wireless channel and radio propagation environment is necessary in order to design efficient wireless communication systems. This PhD thesis is devoted to studying the spatial and temporal statistics of the wireless channel in cellular environments based on a geometry-based stochastic physical channel modeling approach. Contributions in this thesis report include the following: • A new physical channel model called the eccentro-scattering model is proposed to study the spatial and temporal statistics of the multipath signals in cellular environments. • Generic closed-form formulas for the probability density function (pdf) of angle of arrival (AoA) and time of arrival (ToA) of the multipath signals in each cellular environment are derived. These formulas can be helpful for the design and evaluation of modern communication systems. • A new Gaussian scattering model is proposed, which consists of two Gaussian functions for the distribution of scatterers around base station (BS) and mobile station (MS) and confines these scatterers within a scattering disc. • The effect of mobile motion on the spatial and temporal statistics of the multipath signals in cellular environments is discussed. Three motion scenarios are considered for the possible trajectory of the mobile unit. Furthermore, two different cases are identified when the terrain and clutter of mobile surrounding have additional effect on the temporal spread of the multipath signals during motion. • The physical channel model is employed to assess the performance of a RAKE receiver in cellular environments. • Comparisons between uniform scattering and Gaussian scattering, which are the two assumptions for the distribution of scatterers usually used in the derivation of the pdf of AoA, are also presented. • An overview of earlier physical channel models and comparisons between these models and with the proposed model are presented