3G networks are currently overloaded, due to the increasing popularity of various applications for smartphones. Offloading mobile data traffic through opportunistic communications is a promising solution to partially solve this problem, because there is almost no monetary cost for it. We propose to exploit opportunistic communications to facilitate information dissemination in the emerging Mobile Social Networks (MoSoNets) and thus reduce the amount of mobile data traffic. As a case study, we investigate the target-set selection problem for information delivery. In particular, we study how to select the target set with only k users, such that we can minimize the mobile data traffic over cellular networks. We propose three algorithms, called Greedy, Heuristic, and Random, for this problem and evaluate their performance through an extensive trace-driven simulation study. Our simulation results verify the efficiency of these algorithms for both synthetic and real-world mobility traces. For example, the Heuristic algorithm can offload mobile data traffic by up to 73.66 percent for a real-world mobility trace. Moreover, to investigate the feasibility of opportunistic communications for mobile phones, we implement a proof-of-concept prototype, called Opp-off, on Nokia N900 smartphones, which utilizes their Bluetooth interface for device/service discovery and content transfer.

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Mobile Data Offloading through Opportunistic Communications and Social Participation

The emerging Internet-of-Things (IoT) are vulnerable to Sybil attacks where attackers can manipulate fake identities or abuse pseudoidentities to compromise the effectiveness of the IoT and even disseminate spam. In this paper, we survey Sybil attacks and defense schemes in IoT. Specifically, we first define three types Sybil attacks: SA-1, SA-2, and SA-3 according to the Sybil attacker’s capabilities. We then present some Sybil defense schemes, including social graph-based Sybil detection (SGSD), behavior classification-based Sybil detection (BCSD), and mobile Sybil detection with the comprehensive comparisons. Finally, we discuss the challenging research issues and future directions for Sybil defense in IoT.

Sybil Attacks and Their Defenses in the Internet of Things

We say that a network coding scheme is strongly 1-secure if a source node s can multicast n field elements {m1, · · · ,mn} to a set of sink nodes {t1, · · · , tq} in such a way that any single edge leaks no information on any S ⊂ {m1, · · · ,mn} with |S| = n − 1, where n = mintimax-flow(s, ti) is the maximum transmission capacity. We also say that a strongly h-secure network coding scheme is strongly (h + 1)secure if any h + 1 edges leak no information on any S ⊂ {m1, · · · ,mn} with |S| = n − (h + 1). In this paper, we show the first explicit algorithm which can construct strongly k-secure network coding schemes. In particular, it runs in polynomial time for fixed k.

Information Theoretic Security

Making new connections according to personal preferences is a crucial service in mobile social networking, where the initiating user can find matching users within physical proximity of him/her. In existing systems for such services, usually all the users directly publish their complete profiles for others to search. However, in many applications, the users' personal profiles may contain sensitive information that they do not want to make public. In this paper, we propose FindU, the first privacy-preserving personal profile matching schemes for mobile social networks. In FindU, an initiating user can find from a group of users the one whose profile best matches with his/her; to limit the risk of privacy exposure, only necessary and minimal information about the private attributes of the participating users is exchanged. Several increasing levels of user privacy are defined, with decreasing amounts of exchanged profile information. Leveraging secure multi-party computation (SMC) techniques, we propose novel protocols that realize two of the user privacy levels, which can also be personalized by the users. We provide thorough security analysis and performance evaluation on our schemes, and show their advantages in both security and efficiency over state-of-the-art schemes.

FindU: Privacy-preserving personal profile matching in mobile social networks

Keywords: LTS3 Reference LTS-ARTICLE-2004-019 Record created on 2006-06-14, modified on 2016-08-08

Introduction to the special issue on multimedia implementation », IEEE Trans. On Circuits and Systems for Video Technology

Small talk is an important social lubricant that helps people, especially strangers, initiate conversations and make friends with each other in physical proximity. However, due to difficulties in quickly identifying significant topics of common interest, real-world small talk tends to be superficial. The mass popularity of mobile phones can help improve the effectiveness of small talk. In this paper, we present E-SmallTalker, a distributed mobile communications system that facilitates social networking in physical proximity. It automatically discovers and suggests topics such as common interests for more significant conversations. We build on Bluetooth Service Discovery Protocol (SDP) to exchange potential topics by customizing service attributes to publish nonservice-related information without establishing a connection. We propose a novel iterative Bloom filter (IBF) protocol that encodes topics to fit in SDP attributes and achieves a low false positive rate. We have implemented the system in Java ME for ease of deployment. Our experiments on real-world phones show that it is efficient enough at the system level to facilitate social interactions among strangers in physical proximity. To the best of our knowledge, E-SmallTalker is the first distributed mobile system to achieve the same purpose.

/pdf/e-smalltalker-a-distributed-mobile-system-for-social-3or41td7f8.pdf

E-SmallTalker: A Distributed Mobile System for Social Networking in Physical Proximity

Nowadays, an increasing number of objects can be represented by their wireless electronic identifiers. For example, people can be recognized by their phone numbers or their phones' WiFi' MAC addresses and products can be identified by their RFID numbers. Localizing objects with electronic identifiers is increasingly important as our lives become increasingly "digitalized". However, traditional wireless localization techniques cannot meet the fast growing needs of accurate and cost efficient localization. Some of these techniques require expensive hardware to achieve high accuracy, which is impractical for massive deployment. Others, such as WiFi RSSI based localization, are inaccurate and not robust to environmental noise. In this paper, we propose a new localization technique called EV-Loc. In EV-Loc, we use visual signals to help improve the accuracy of wireless localization. Our technique fully leverages visual signals' high accuracy and electronic signals' pervasiveness. To effectively couple these two signals, we design an E-V match engine to find the correspondence between an object's electronic identifier and its visual appearance. We implement our technique on mobile devices and evaluate it in real-world scenarios. The localization error is less than 1 m. We also evaluate our approach using large scale simulations. The results show that our approach is accurate and robust.

EV-Loc: integrating electronic and visual signals for accurate localization

Nowadays, more and more objects can be represented with electronic identifiers, e.g., people can be recognized from their laptops' MACs, and products can be identified by their RFID numbers. Localizing electronic identifiers is more and more important for a fully digitalized life. However, traditional wireless localization techniques are not satisfactory in performance to determine these electronic identifiers' positions. Some of them require costly hardware to achieve high accuracy and, hence, are not practical. The others are inaccurate and not robust against environmental noises, e.g., RSSI-based localization. Therefore, an accurate and practical approach for localizing electronic identifiers is needed. In this paper, we propose a new localization technique called EV-Loc. In EV-Loc, we make use of visual signals to help improve the accuracy of wireless localization. Our technique fully takes advantage of the high accuracy of visual signals and pervasiveness of electronic signals. To effectively couple these two signals together, we have designed an E-V match engine to find the correspondence between an object's electronic identifier and its visual appearance. We have implemented our technique on mobile devices and evaluated it in the real world. The localization error is less than 1 m. We have also evaluated our approach using large-scale simulations. The results show that our approach is accurate and robust.

/pdf/ev-loc-integrating-electronic-and-visual-signals-for-3yrwolq8vg.pdf

In this paper, we propose E-Shadow, a distributed mobile phone-based local social networking system. E-Shadow has two main components: (1) Local profiles. They enable EShadow users to record and share their names, interests, and other information with fine-grained privacy controls. (2) Mobile phone based local social interaction tools. E-Shadow provides mobile phone software that enables rich social interactions. The software maps proximate users' local profiles to their human owners and enables user communication and content sharing. We have designed and implemented E-Shadow on mobile phones. In our E-Shadow system, we allow users to perform dynamic and layered information publishing, making use of interpersonal relevance. Our system also provides a mechanism to help users perform direction-driven localization of an E-Shadow and match it with its owner. Experiments on real world Windows Mobile phones and large-scale simulations show that our system disseminates information efficiently and helps receivers find the direction of a specific E-Shadow with accuracy. We believe our E-Shadow concept and system can lead to a more tightly-knit temporary community in one's physical vicinity.

E-Shadow: Lubricating Social Interaction Using Mobile Phones

In this paper, we propose E-Shadow, a distributed mobile phone-based local social networking system. E-Shadow has two main components: (1) Local profiles. They enable E-Shadow users to record and share their names, interests, and other information with fine-grained privacy controls. (2) Mobile phone based local social interaction tools. E-Shadow provides mobile phone software that enables rich social interactions. The software maps proximate users’ local profiles to their human owners and enables user communication and content sharing. We have designed and implemented E-Shadow on mobile phones. In our E-Shadow system, we allow users to perform dynamic and layered information publishing, making use of interpersonal relevance in space and time. Our system also provides a mechanism to help users perform direction-driven localization of an E-Shadow and match it with its owner. Experiments on real world Windows Mobile phones and large-scale simulations show that our system disseminates information efficiently and helps receivers find the direction of a specific E-Shadow with accuracy. We believe our E-Shadow concept and system can lead to a more tightly-knit temporary community in one’s physical vicinity.

Boying Zhang

Papers

E-SmallTalker: A Distributed Mobile System for Social Networking in Physical Proximity

EV-Loc: integrating electronic and visual signals for accurate localization

EV-Loc: integrating electronic and visual signals for accurate localization

E-Shadow: Lubricating Social Interaction Using Mobile Phones

E-Shadow: Lubricating Social Interaction Using Mobile Phones