Context-Aware P2P Over Opportunistic Networks

Context-Aware P2P Over Opportunistic Networks

Marco Conti (IIT Institute – CNR, Pisa, Italy), Franca Delmastro (IIT Institute – CNR, Pisa, Italy) and Andrea Passarella (IIT Institute – CNR, Pisa, Italy)
DOI: 10.4018/978-1-60566-715-7.ch021
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Abstract

Recently, the popularity of p2p computing paradigm has been increasing, especially in the mobile environments, due to the large use of mobile devices as tools to generate and share content among users. Several works have been proposed in ad hoc networks literature to optimize legacy p2p systems over a mobile environment, mainly relying on the necessity of a stable path between pairs of nodes wishing to communicate. However, in the last few years, resources limitations and high mobility of users have introduced a new networking paradigm characterized by intermittent connectivity and frequent partitioning: the opportunistic networks. In such a dynamic environment, where systems must exploit all communication opportunities to enable the users to get in touch and exchange data, the authors propose a novel definition of mobile p2p, which exploits context information to enhance distributed services. In addition, they present a Context-aware opportunistic File Sharing application as a practical example of an optimized p2p service over opportunistic networks.
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Introduction

In the last few years mobile p2p computing is increasingly emerging as an important paradigm for building next generation distributed mobile applications. The main motivation is the increasing use of mobile devices as tools to generate and share content among users according to the Web 2.0 model. Until now, this paradigm has been supported by the legacy client/server model (e.g., through web sites such as YouTube). In a pervasive mobile environment, the p2p paradigm is conceptually closer (with respect to the client/server paradigm) to Web 2.0 content generation and sharing models. In p2p systems users directly communicate with each other without any intermediate entity such as a server. They can join and leave dynamically equally sharing the load of communication and data management. Unfortunately, p2p systems in mobile environments are not (yet) as successful as the legacy p2p systems for the wired Internet are. This is essentially due to the difficulties of running efficient p2p systems in resource-scarce and possibly challenged networking environments, which is the typical case of mobile pervasive environments. However, there is no reason not to foresee that p2p system will play a fundamental role to support data sharing in mobile environments as well, as – in principle – they represent a very efficient and natural solution.

Recently a lot of studies on p2p over self-organizing ad hoc networks have been conducted providing optimized solutions for mobile users (see (Conti, Delmastro, & Turi, 2007) as an example) but they are essentially based on the assumption that there always exists a stable path between pairs of nodes wishing to communicate. Actually, while it’s foreseeable that users’ devices be able to communicate wirelessly with each other, it’s not realistic to envision a single, well-connected, ad hoc network including all devices. A pervasive network made up of a large number of mobile devices is intrinsically disconnected. Due to nodes’ mobility, clouds of connected devices appear, disappear, and re-configure dynamically. Some of these clouds can include devices connected to the legacy Internet (e.g., Wi-Fi Access Points), while some others can be (temporarily) disconnected from the rest of the network. This scenario can be supported by the new communication paradigm called opportunistic networking (Pelusi, Passarella, & Conti, 2006). It fits well the behavior of mobile users who need to exchange data while they are moving even in areas without the Internet coverage. In this case nodes must be enabled to communicate even if a route connecting them never exists. Mobile nodes are not supposed to possess or acquire any knowledge about the network topology, which instead is necessary in traditional routing protocols for mobile ad hoc networks (MANETs).

In opportunistic networks routes are built dynamically, hop by hop, while data flows towards the destination(s). In this way any possible node can opportunistically be used as next hop, provided its probability to bring the message closer to the final destination is sufficiently high. In this scenario nodes must exploit all the available opportunities to get in touch and communicate. In this type of networks the topological information about the network states is often unreliable and not precise. Therefore, data-centric communication paradigms should be preferred with respect to conventional topology-based paradigms. Furthermore, as the network is very dynamic and possibly unstable, context information should be exploited to complement the inaccurate knowledge provided by topological information alone. This makes an outstanding case for the use of context-aware p2p systems in opportunistic networks, as p2p systems are one of the most natural ways of supporting data-centric communication. Available systems designed for ad hoc networks are not directly applicable in such an environment, and network protocols and services must be enhanced to exploit all possible opportunities to deliver messages on the network. However, characteristics of p2p systems for MANETs must be considered as a basis for designing data-centric services for opportunistic networks.

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Editorial Advisory Board
Table of Contents
Acknowledgment
Boon-Chong Seet
Chapter 1
Raphaël Kummer, Peter Kropf, Pascal Felber
The most important characteristics of mobile ad-hoc networks (MANETs) such as broadcast and multihop communication, limited resources (particularly... Sample PDF
P2P Information Lookup, Collection, and Distribution in Mobile Ad-Hoc Networks
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Chapter 2
Thomas Repantis, Vana Kalogeraki
In this chapter the authors study the problems of data dissemination and query routing in mobile peerto- peer networks. They provide a taxonomy and... Sample PDF
Data Dissemination and Query Routing in Mobile Peer-to-Peer Networks
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Chapter 3
Jie Feng, Lisong Xu, Byrav Ramamurthy
With the evolution of wireless technologies, mobile networks can provide much more interesting services and resources to users than before.... Sample PDF
Overlay Construction in Mobile Peer-to-Peer Networks
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Chapter 4
Thomas Kunz, Abdulbaset Gaddah, Li Li
Peer-to-Peer computing is a popular, relatively new, distributed computing paradigm. It allows for a flexible set of participants to coordinate... Sample PDF
Mobility Support in a P2P System for Publish/Subscribe Applications
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Chapter 5
Leonardo B. Oliveira, Isabela G. Siqueira, Daniel F. Macedo, José M. Nogueira, Antonio A.F. Loureiro
Both Mobile Ad hoc Networks (MANETs) and Peer-to-Peer (P2P) networks are decentralized self-organizing networks with a dynamic topology, used to... Sample PDF
P2P over MANETs: Application and Network Layers' Routing Assessment
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Chapter 6
Fotis Loukos, Helen Karatza
Mobile Peer-to-Peer networks are an emerging topic in networking. One of the major usages is the cooperation between peers. The aim of this chapter... Sample PDF
Enabling Cooperation in MANET-Based Peer-to-Peer Systems
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Chapter 7
Tobias Hoßfeld, Daniel Schlosser, Kurt Tutschku, Phuoc Tran-Gia
The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often... Sample PDF
Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Selfishness and Heterogeneity
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Chapter 8
Tobias Hoßfeld, Michael Duelli, Dirk Staehle, Phuoc Tran-Gia
The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often... Sample PDF
Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks: Considering Mobility and Heterogeneity
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Chapter 9
Wei Wu, Kian-Lee Tan
Caching and prefetching are two effective ways for mobile peers to improve access latency in mobile environments. With short-range communication... Sample PDF
Peer-Based Collaborative Caching and Prefetching in Mobile Broadcast
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Chapter 10
Mark Kai-Ho Yeung, Yu-Kwong Kwok
The widespread deployment of competing wireless technologies has created new research opportunities. In particular, the authors consider media... Sample PDF
Wireless Peer-to-Peer Media Streaming: Incentives and Resource Management Issues
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Chapter 11
Panayotis Antoniadis
The goal of this chapter is to analyze the incentive issues that arise in multi-hop ad hoc networks when their nodes are potentially mobile devices... Sample PDF
Incentives for Resource Sharing in Ad Hoc Networks: Going Beyond Rationality
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Chapter 12
Johann van der Merwe, Dawoud Dawoud
Group communication in mobile ad hoc networks (MANETs) generally occurs in the form of dynamic peer groups (DPGs). This chapter reviews the existing... Sample PDF
Key Management for Dynamic Peer Groups in Mobile Ad Hoc Networks
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Chapter 13
James Walkerdine, Peter Phillips, Simon Lock
The growth of mobile devices with near PC equivalent capabilities has brought with it the possibility of mobile Peer-to-Peer (P2P) systems. However... Sample PDF
A Tool Supported Methodology for Developing Secure Mobile P2P Systems
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Chapter 14
Spyridon L. Tompros
Enabled by the emergence of high-speed Internet access in last mile communications, P2P systems have witnessed significant growth in the recent... Sample PDF
Integration and Interworking of Fixed and Mobile P2P Systems
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Chapter 15
Erkki Harjula, Jani Hautakorpi, Nicklas Beijar, Mika Ylianttila
Due to the increasing popularity of Peer-to-Peer (P2P) computing, the information technology industry and standardization organizations have started... Sample PDF
Peer-to-Peer SIP for Mobile Computing: Challenges and Solutions
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Chapter 16
Kurt Tutschku, Andreas Berl, Tobias Hossfeld, Hermann de Meer
The telecommunication industry has recently seen two areas with very high growth rates: cellular networks, for example, GSM (Global System for... Sample PDF
Mobile P2P in Cellular Mobile Networks: Architecture and Performance
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Chapter 17
Norihiro Ishikawa, Hiromitsu Sumino, Takeshi Kato, Johan Hjelm, Shingo Murakami, Kazuhiro Kitagawa, Nobuo Saito
Compared with traditional Internet technologies, peer-to-peer technologies has functions to realize resource discovery, resource sharing, and load... Sample PDF
Peer-to-Peer Networking Platform and Its Applications for Mobile Phones
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Chapter 18
Raphaël Kummer, Peter Kropf, Jean-Frédéric Wagen, Timothée Maret
Many innovative P2P algorithms designed for mobile ad-hoc networks (MANETs) have been designed to scale smoothly when handling a very large number... Sample PDF
Evaluation Platform for Large Scale P2P Mobile Ad-hoc Networks
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Chapter 19
Alf Inge Wang
This chapter presents the Peer2Me mobile peer-to-peer framework, Peer2Me applications, and discusses the experiences from using the Peer2Me... Sample PDF
Mobile Peer-to-Peer Collaborative Framework and Applications
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Chapter 20
Antônio Tadeu A. Gomes, Artur Ziviani, Luciana S. Lima, Markus Endler
This chapter surveys the approaches to service discovery that are relevant to mobile peer-to-peer systems in a variety of scenarios. More... Sample PDF
Service Discovery Approaches to Mobile Peer-to-Peer Computing
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Chapter 21
Marco Conti, Franca Delmastro, Andrea Passarella
Recently, the popularity of p2p computing paradigm has been increasing, especially in the mobile environments, due to the large use of mobile... Sample PDF
Context-Aware P2P Over Opportunistic Networks
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About the Contributors