138 research outputs found

    Adaptive real-time predictive collaborative content discovery and retrieval in mobile disconnection prone networks

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    Emerging mobile environments motivate the need for the development of new distributed technologies which are able to support dynamic peer to peer content sharing, decrease high operating costs, and handle intermittent disconnections. In this paper, we investigate complex challenges related to the mobile disconnection tolerant discovery of content that may be stored in mobile devices and its delivery to the requesting nodes in mobile resource-constrained heterogeneous environments. We propose a new adaptive real-time predictive multi-layer caching and forwarding approach, CafRepCache, which is collaborative, resource, latency, and content aware. CafRepCache comprises multiple multi-layer complementary real-time distributed predictive heuristics which allow it to respond and adapt to time-varying network topology, dynamically changing resources, and workloads while managing complex dynamic tradeoffs between them in real time. We extensively evaluate our work against three competitive protocols across a range of metrics over three heterogeneous real-world mobility traces in the face of vastly different workloads and content popularity patterns. We show that CafRepCache consistently maintains higher cache availability, efficiency and success ratios while keeping lower delays, packet loss rates, and caching footprint compared to the three competing protocols across three traces when dynamically varying content popularity and dynamic mobility of content publishers and subscribers. We also show that the computational cost and network overheads of CafRepCache are only marginally increased compared with the other competing protocols

    Exploiting Mobile Social Networks from Temporal Perspective:A Survey

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    With the popularity of smart mobile devices, information exchange between users has become more and more frequent, and Mobile Social Networks (MSNs) have attracted significant attention in many research areas. Nowadays, discovering social relationships among people, as well as detecting the evolution of community have become hotly discussed topics in MSNs. One of the major features of MSNs is that the network topology changes over time. Therefore, it is not accurate to depict the social relationships of people based on a static network. In this paper, we present a survey of this emerging field from a temporal perspective. The state-of-the-art research of MSNs is reviewed with focus on four aspects: social property, time-varying graph, temporal social property, and temporal social properties-based applications. Some important open issues with respect to MSNs are discussed

    Content Dissemination in Mobile Social Networks

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    Mobile social networking(MSN) has emerged as an effective platform for social network users to pervasively disseminate the contents such as news, tips, book information, music, video and so on. In content dissemination, mobile social network users receive content or information from their friends, acquaintances or neighbors, and selectively forward the content or information to others. The content generators and receivers have different motivation and requirements to disseminate the contents according to the properties of the contents, which makes it a challenging and meaningful problem to effectively disseminate the content to the appropriate users. In this dissertation, the typical content dissemination scenarios in MSNs are investigated. According to the content properties, the corresponding user requirements are analyzed. First, a Bayesian framework is formulated to model the factors that influence users behavior on streaming video dissemination. An effective dissemination path detection algorithm is derived to detect the reliable and efficient video transmission paths. Second, the authorized content is investigated. We analyze the characteristics of the authorized content, and model the dissemination problem as a new graph problem, namely, Maximum Weighted Connected subgraph with node Quota (MWCQ), and propose two effective algorithms to solve it. Third, the authorized content dissemination problem in Opportunistic Social Networks(OSNs) is studied, based on the prediction of social connection pattern. We then analyze the influence of social connections on the content acquirement, and propose a novel approach, User Set Selection(USS) algorithm, to help social users to achieve fast and accurate content acquirement through social connections

    Cooperative mechanisms for information dissemination and retrieval in networks with autonomous nodes

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    Αυτή η διατριβή συνεισφέρει στη βιβλιογραφία με το να προτείνει και να μοντελοποιήσει καινοτόμους αλγορίθμους και σχήματα που επιτρέπουν στις διεργασίες διάδοσης και ανάκτησης πληροφοριών – και γενικότερα της διαχείρισης περιεχομένου – να εκτελεστούν πιο αποτελεσματικά σε ένα σύγχρονο περιβάλλον δικτύωσης. Εκτός από τη διάδοση και ανάκτηση των πληροφοριών, άλλες πτυχές της διαχείρισης περιεχομένου που εξετάζουμε είναι η αποθήκευση και η κατηγοριοποίηση. Η πιο σημαντική πρόκληση που αφορά πολλά από τα σχήματα που προτείνονται στην παρούσα εργασία είναι η ανάγκη να διαχειριστούν την αυτονομία των κόμβων, διατηρώντας παράλληλα τον κατανεμημένο, καθώς και τον ανοικτό χαρακτήρα του συστήματος. Κατά το σχεδιασμό κατανεμημένων μηχανισμών σε δίκτυα με αυτόνομους κόμβους, ένα σημαντικό επίσης Ζητούμενο είναι να δημιουργηθούν κίνητρα ώστε οι κόμβοι να συνεργάζονται κατά την εκτέλεση των καθηκόντων επικοινωνίας. Ένα καινούργιο χαρακτηριστικό των περισσοτέρων από τα προτεινόμενα σχήματα είναι η αξιοποίηση των κοινωνικών χαρακτηριστικών των κόμβων, εστιάζοντας στο πώς τα κοινά ενδιαφέροντα των κόμβων μπορούν να αξιοποιηθούν για τη βελτίωση της αποδοτικότητας στην επικοινωνία. Για την αξιολόγηση της απόδοσης των προτεινόμενων αλγορίθμων και σχημάτων, κυρίως αναπτύσσουμε μαθηματικά στοχαστικά μοντέλα και λαμβάνουμε αριθμητικά αποτελέσματα. Όπου είναι απαραίτητο, παρέχουμε αποτελέσματα προσομοίωσης που επαληθεύουν την ακρίβεια αυτών των μοντέλων. Πραγματικά ίχνη δικτύου χρησιμοποιούνται όπου θέλουμε να υποστηρίξουμε περαιτέρω τη λογική για την πρόταση ενός συγκεκριμένου σχήματος. Ένα βασικό εργαλείο για τη μοντελοποίηση και την ανάλυση των προβλημάτων συνεργασίας σε δίκτυα με αυτόνομους κόμβους είναι η θεωρία παιγνίων, η οποία χρησιμοποιείται σε μερικά τμήματα αυτής της διατριβής για να βοηθήσει στην εξακρίβωση της δυνατότητας διατήρησης της συνεργασίας μεταξύ των κόμβων στο δίκτυο. Με την αξιοποίηση των κοινωνικών χαρακτηριστικών των κόμβων, μπαίνουμε επίσης στον τομέα της ανάλυσης των κοινωνικών δικτύων, και χρησιμοποιούμε σχετικές μετρικές και τεχνικές ανάλυσης.This thesis contributes to the literature by proposing and modeling novel algorithms and schemes that allow the tasks of information dissemination and retrieval – and more generally of content management – to be performed more efficiently in a modern networking environment. Apart from information dissemination and retrieval, other aspects of content management we examine are content storage and classification. The most important challenge that will preoccupy many of the proposed schemes is the need to manage the autonomy of nodes while preserving the distributed, as well as the open nature of the system. In designing distributed mechanisms in networks with autonomous nodes, an important challenge is also to develop incentives for nodes to cooperate while performing communication tasks. A novel characteristic of most of the proposed schemes is the exploitation of social characteristics of nodes, focusing on how common interests of nodes can be used to improve communication efficiency. In order to evaluate the performance of the proposed algorithms and schemes, we mainly develop mathematical stochastic models and obtain numerical results. Where it is deemed necessary, we provide simulation results that verify the accuracy of these models. Real network traces are used where we want to further support the rationale for proposing a certain scheme. A key tool for modeling and analyzing cooperation problems in networks with autonomous nodes is game theory, and it is used in parts of this thesis to help identify the feasibility of sustaining cooperation between nodes in the network. By exploiting social characteristics of nodes, we also enter the field of social network analysis, and use related metrics and techniques

    CAMF: Context-Aware Message Forwarding in Mobile Social Networks

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    In mobile social networks (MSN), with the aim of conserving limited resources, egotistic nodes might refuse to forward messages for other nodes. Different from previous work which mainly focuses on promoting cooperation between selfish nodes, we consider it from a more pragmatic perspective in this paper. Be specific, we regard selfishness as a native attribute of a system and allow nodes to exhibit selfish behavior in the process of message forwarding. Apparently, selfishness has a profound influence on routing efficiency, and thus novel mechanisms are necessary to improve routing performance when self-centered nodes are considered. We first put forward a stateless approach to measure encounter opportunities between nodes, and represent forwarding capabilities of nodes by combining the acquired encounter opportunities with node selfishness.We then quantify receiving capabilities of nodes based on their available buffer size and energy. Taking both forwarding and receiving capabilities into account, we finally present a forwarding set mechanism, which could be deduced to a multiple knapsack problem to maximize the forwarding profit. Consequently, we take all the above studies into the design of a context-aware message forwarding algorithm (CAMF). Extensive trace-driven simulations show that CAMF outperforms other existing algorithms greatly. In fact, it achieves a surprisingly high routing performance while consumes low transmission cost and resource in MSN
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