Showing papers in "IEEE Network in 2010"

A generic quantitative relationship between quality of experience and quality of service

Abstract: Quality of experience ties together user perception, experience, and expectations to application and network performance, typically expressed by quality of service parameters. Quantitative relationships between QoE and QoS are required in order to be able to build effective QoE control mechanisms onto measurable QoS parameters. Against this background, this article proposes a generic formula in which QoE and QoS parameters are connected through an exponential relationship, called IQX hypothesis. The formula relates changes of QoE with respect to QoS to the current level of QoE, is simple to match, and its limit behaviors are straightforward to interpret. It validates the IQX hypothesis for streaming services, where QoE in terms of Mean Opinion Scores is expressed as functions of loss and reordering ratio, the latter of which is caused by jitter. For web surfing as the second application area, matchings provided by the IQX hypothesis are shown to outperform previously published logarithmic functions. We conclude that the IQX hypothesis is a strong candidate to be taken into account when deriving relationships between QoE and QoS parameters.

Toward publicly auditable secure cloud data storage services

Abstract: Cloud computing is the long dreamed vision of computing as a utility, where data owners can remotely store their data in the cloud to enjoy on-demand high-quality applications and services from a shared pool of configurable computing resources. While data outsourcing relieves the owners of the burden of local data storage and maintenance, it also eliminates their physical control of storage dependability and security, which traditionally has been expected by both enterprises and individuals with high service-level requirements. In order to facilitate rapid deployment of cloud data storage service and regain security assurances with outsourced data dependability, efficient methods that enable on-demand data correctness verification on behalf of cloud data owners have to be designed. In this article we propose that publicly auditable cloud data storage is able to help this nascent cloud economy become fully established. With public auditability, a trusted entity with expertise and capabilities data owners do not possess can be delegated as an external audit party to assess the risk of outsourced data when needed. Such an auditing service not only helps save data owners? computation resources but also provides a transparent yet cost-effective method for data owners to gain trust in the cloud. We describe approaches and system requirements that should be brought into consideration, and outline challenges that need to be resolved for such a publicly auditable secure cloud storage service to become a reality.

Adaptive intervehicle communication control for cooperative safety systems

Abstract: Vehicular ad hoc networks play a critical role in enabling important active safety applications such as cooperative collision warning. These active safety applications rely on continuous broadcast of self-information by all vehicles, which allows each vehicle to track all its neighboring cars in real time. The most pressing challenge in such safety-driven communication is to maintain acceptable tracking accuracy while avoiding congestion in the shared channel. In this article we propose a transmission control protocol that adapts communication rate and power based on the dynamics of a vehicular network and safety-driven tracking process. The proposed solution uses a closed-loop control concept and accounts for wireless channel unreliability. Simulation results confirm that if packet generation rate and associated transmission power for safety messages are adjusted in an on-demand and adaptive fashion, robust tracking is possible under various traffic conditions.

User measures of quality of experience: why being objective and quantitative is important

Abstract: This article develops the concept of quality of user experience by focusing on requirements for its measurement and communication for use in industry Whereas more typical work involves either modeling media quality based on technical measures or user subjective assessment of media quality, it is argued that QoE measurement should include objective measures of the process and outcomes of usage Also, subjective measures should be collected as quantitative data rather than qualitative data as is currently common, because quantitative data enables combined analyses of objective and subjective measures for deriving global QoE ratings Global ratings are important for optimizing the communicability of results to target audiences Examples of measures and scales are provided A structured approach to defining and measuring QoE in relation to QoS is explained and illustrated

Privacy and security for online social networks: challenges and opportunities

Abstract: Online social networks such as Facebook, Myspace, and Twitter have experienced exponential growth in recent years. These OSNs offer attractive means of online social interactions and communications, but also raise privacy and security concerns. In this article we discuss the design issues for the security and privacy of OSNs. We find there are inherent design conflicts between these and the traditional design goals of OSNs such as usability and sociability. We present the unique security and privacy design challenges brought by the core functionalities of OSNs and highlight some opportunities of utilizing social network theory to mitigate these design conflicts.

Exploration of adaptive beaconing for efficient intervehicle safety communication

Abstract: In the future intervehicle communication will make driving safer, easier, and more comfortable. As a cornerstone of the system, vehicles need to be aware of other vehicles in the vicinity. This cooperative awareness is achieved by beaconing, the exchange of periodic single-hop broadcast messages that include data on the status of a vehicle. While the concept of beaconing has been developed in the first phase of research on VANETs, recent studies have revealed limitations with respect to network performance. Obviously, the frequency of beacon messages directly translates into accuracy of cooperative awareness and thus traffic safety. There is an indisputable trade-off between required bandwidth and achieved accuracy. In this work we analyze this trade-off from different perspectives considering the consequences for safety applications. As a solution to the problem of overloading the channel, we propose to control the offered load by adjusting the beacon frequency dynamically to the current traffic situation while maintaining appropriate accuracy. To find an optimal adaptation, we elaborate on several options that arise when determining the beacon frequency. As a result, we propose situation-adaptive beaconing. It depends on the vehicle's own movement and the movement of surrounding vehicles, macroscopic aspects like the current vehicle density, or microscopic aspects.

Broadcasting safety information in vehicular networks: issues and approaches

Abstract: A primary goal of intelligent transportation systems is to improve road safety. The ability of vehicles to communicate is a promising way to alleviate traffic accidents by reducing the response time associated with human reaction to nearby drivers. Vehicle mobility patterns caused by varying traffic dynamics and travel behavior lead to considerable complexity in the efficiency and reliability of vehicular communication networks. This causes two major routing issues: the broadcast storm problem and the network disconnection problem. In this article we review broadcast communication in vehicular communication networks and mechanisms to alleviate the broadcast storm problem. Moreover, we introduce vehicular safety applications, discuss network design considerations, and characterize broadcast protocols in vehicular networks.

Stuxnet, the real start of cyber warfare? [Editor's Note]

Abstract: In recent years, the press has been banging the drums about the prospects of cyber warfare between nations. It makes a good story. In the imagined scenario, national governments are gathering and training elite teams of computer hackers prepared to infiltrate or take down the computer network of an enemy nation. Every nation has the weapons ? computers and software ? to be a major threat without having to be a superpower. Any David can take on a Goliath, and in fact the most industrialized countries might be the most network- dependent and vulnerable.

Sharing location in online social networks

Abstract: Online social networks (OSNs) have become important media for information sharing among Internet users. In particular, several OSNs provide mechanisms to facilitate sharing of the users' location, which is gaining increased popularity due to the growth of GPS-equipped smartphones. These location-based OSNs (LSNs) bridge users' physical and social worlds, allowing users to know where their friends are and enabling location-based information access and user interactions. In this article we first introduce several LSNs and compare their location-sharing related features. A user's location, however, is sensitive and personal information that may raise significant privacy concerns. To understand real-world users' location-sharing behavior, we collected 21 months of data traces from a commercial LSN and analyzed its users' location-sharing updates. We found that the characteristics of the users' privacy protection behavior is correlated with their age, gender, mobility, and geographic region. In addition, friends tend to have similar privacy protection patterns. To the best of our knowledge, this article is the first large-scale empirical study of a modern LSN.

Biologically inspired consensus-based spectrum sensing in mobile Ad Hoc networks with cognitive radios

Abstract: Cognitive radios, which are capable of sensing their surrounding environment and adapting their internal parameters, have been considered in mobile ad hoc networks. Secondary users can cooperatively sense the spectrum to detect the presence of primary users. In this article we present a novel biologically inspired consensus-based cooperative spectrum sensing scheme in CR-MANETs. Our scheme is based on recent advances in consensus algorithms that have taken inspiration from self-organizing behavior of animal groups such as birds, fish, ants, honeybees, and others. Unlike the existing cooperative spectrum sensing schemes, such as the OR-rule or the 1-out-of-N rule, there is no need for a common receiver to do the data fusion for reaching the final decision. A secondary user needs only to set up local interactions without a centralized node in CR-MANETs. Simulation results are presented to show the effectiveness of the proposed scheme.

Smart grids, smart cities need better networks [Editor's Note]

Abstract: Near the end of October 2009, U.S. President Obama announced $3.4 billion in federal stimulus grants for 100 projects related to the smart grid, as part of the American Reinvestment and Recovery Act, with another $4.7 billion expected to be matched by companies. The smart grid refers to a modernization of the existing power grid, which is characterized by unidirectional energy distribution, centralized energy generation, fixed consumer tariffs, and relatively simple meters. Most electricity meters are not capable of communications and must be read manually. Some meters are more advanced with communications capability, but the vast majority of them can only transmit data for remote reading and cannot receive data.

Quadrant of euphoria: a crowdsourcing platform for QoE assessment

Abstract: Existing quality of experience assessment methods, subjective or objective, suffer from either or both problems of inaccurate experiment tools and expensive personnel cost The panacea for them, as we have come to realize, lies in the joint application of paired comparison and crowdsourcing, the latter being a Web 20 practice of organizations asking ordinary unspecific Internet users to carry out internal tasks We present in this article Quadrant of Euphoria, a user-friendly Web-based platform facilitating QoE assessments in network and multimedia studies, which features low cost, participant diversity, meaningful and interpretable QoE scores, subject consistency assurance, and a burdenless experiment process

Social network analysis concepts in the design of wireless Ad Hoc network protocols

Abstract: This article presents a survey of ad hoc networking protocols that have used concepts such as centrality metrics and community formation from the area of social network analysis, which is seen as a network measurement task that deals with structural properties of the network graph. We recognize the synergy among social network analysis and ad hoc networking as a fertile research area that can provide significant advances for the design of network protocols, especially in environments where the communication is opportunistic in nature and therefore cannot be easily or efficiently described as an optimization problem, and other systematic approaches like cross-layer optimization are more difficult to apply.

Using social network theory for modeling human mobility

Abstract: Human mobility modeling plays an essential role in accurately understanding the performance of data forwarding protocols in mobile networks and has been attracting increasing research interest in recent years. People's movement behaviors are strongly affected by their social interactions with each other, which, however, are not sufficiently considered in most existing mobility models. Recent studies in social network theory have provided many theoretical and experimental results, which are useful and powerful for modeling the realistic social dimension of human mobility. In this article we present a novel human mobility model based on heterogeneous centrality and overlapping community structure in social networks. Instead of extracting communities from artificially generated social graphs, our model manages to construct the k-clique overlapping community structure which satisfies the common statistical features observed from distinct real social networks. This approach achieves a good trade-off between complexity and reality. The simulation results of our model exhibit characteristics observed from real human motion traces, especially heterogeneous human mobility popularity, which has significant impact on data forwarding schemes but has never been considered by existing mobility models.

Measuring user behavior in online social networks

Abstract: The users' role is crucial in the development, deployment and the success of online social networks. Despite this fact, little is known and even less has been published about user activities in operating OSNs. In this article we present a large-scale measurement analysis of user behavior in some popular OSNs: Bebo, MySpace, Netlog, and Tagged. A measurement framework has been created in order to observe user activity: more than 500 PlanetLab nodes across the globe have been used for our measurement, monitoring more than 80,000 users for six weeks by downloading more than 100 million profile pages. Based on the measurements, we address two key issues of online social networks: characterization of user activities and usage patterns in the examined OSNs. The main findings of the article include that users' online time spending can be modeled with Weibull distributions; soon after subscribing, a fraction of users tend to lose interest surprisingly fast; and the duration of OSN users' online sessions shows power law distribution characteristics.

Betweenness centrality and resistance distance in communication networks

Abstract: In this article we report on applications and extensions of weighted graph theory in the design and control of communication networks. We model the communication network as a weighted graph and use the existing literature in graph theory to study its behavior. We are particularly interested in the notions of betweenness centrality and resistance distance in the context of communication networks. We argue that in their most general form, the problems in a communication network can be converted to either the optimal selection of weights or optimal selection of paths based on the present values of weights in a graph. Motivated by this, we propose a two-loop general architecture for the control of networks and provide directions to design appropriate control algorithms in each control loop. We show that the total resistance distance (network criticality) of a graph has very useful interpretations in the context of communication networks; therefore, we propose to use network criticality as the main objective function, and we provide guidelines to design the control loops to minimize network criticality. We also discuss the development of new directed weighted graph models and their application to communication networks.

G-Sense: a scalable architecture for global sensing and monitoring

Abstract: The pervasiveness of cellular phones combined with Internet connectivity, GPS embedded chips, location information, and integrated sensors provide an excellent platform to collect data about the individual and its surrounding environment. As a result, new applications have recently appeared to address large-scale societal problems as well as improve the quality of life of the individual. However, these new applications, recently called location-based services, participatory sensing, and human-centric sensing, bring many new challenges, one of them being the management of the huge amount of traffic (data) they generate. This article presents G-Sense, for Global-Sense, an architecture that integrates mobile and static wireless sensor networks in support of location-based services, participatory sensing, and human-centric sensing applications. G-Sense includes specific mechanisms to control the amount of data generated by these applications while meeting the application requirements. Furthermore, it creates a network of servers organized in a peer-to-peer architecture to address scalability and reliability issues. An example prototype application is presented along with some basic results and open research issues.

Could Skype be more satisfying? a QoE-centric study of the FEC mechanism in an internet-scale VoIP system

Abstract: The phenomenal growth of Skype in recent years has surpassed all expectations. Much of the application's success is attributed to its FEC mechanism, which adds redundancy to voice streams to sustain audio quality under network impairments. Adopting the quality of experience approach (i.e., measuring the mean opinion scores), we examine how much redundancy Skype adds to its voice streams and systematically explore the optimal level of redundancy for different network and codec settings. This study reveals that Skype's FEC mechanism, not so surprisingly, falls in the ballpark, but there is surprisingly a significant margin for improvement to ensure consistent user satisfaction.

Online social networks

Abstract: The popularity and complexity of online social networks (OSNs) continues to grow unabatedly with the most popular applications featuring hundreds of millions of active users. Ranging from social communities and discussion groups, to recommendation engines, tagging systems, mobile social networks, games, and virtual worlds, OSN applications have not only shifted the focus of application developers to the human factor, but have also transformed traditional application paradigms such as the way users communicate and navigate in the Internet. Indeed, understanding user behavior is now an integral part of online services and applications, with system and algorithm design becoming in effect user-centric. As expected, this paradigm shift has not left the research community unaffected, triggering intense research interest in the analysis of the structure and properties of online communities.

Content delivery networks: a bridge between emerging applications and future IP networks

Abstract: With the rapid development of network applications, the Internet has evolved from a content-based communication infrastructure to a social-based community network. The emerging applications require the Internet to preserve not only the existing advantages of simplicity and scalability, but also demand varying amounts of capability, availability, reliability, flexibility, and differentiated quality of service. Therefore, it is of paramount importance to bridge the gap between these applications and the IP networks which were originally designed and developed for supporting one-size-fits-all functionality. An efficient solution is to build a virtual network on top of a generic IP transport layer in order to provide additional functionality and flexibility. The content delivery networks technique is one of the successful virtual networks rapidly developed over the last decade with the specific advantage of optimizing the Internet. Nowadays, the CDN has become one of the most important parts of the Internet architecture for content distribution. In this article we highlight the innovative technologies in CDNs and present their evolution triggered by ever newer emerging applications. By presenting in-depth discussion about the architecture, challenges, and applications of CDNs, we demonstrate their importance for the future Internet.

Improvement of vehicular communications by using 3G capabilities to disseminate control information

Abstract: Cellular networks have gained a lot of popularity in the context of vehicular communication within the last few years. Existing reference architectures such as CALM already consider them to provide enhanced connectivity to vehicles for data communication. Their capabilities, especially 3G and next-generation, translate into great potential in the vehicular environment, far beyond the provision of data connectivity. In this context we present a solution that uses 3G cellular networks not only as a backup for data communication among vehicles, but also and especially as an efficient mechanism for the dissemination of relevant control information for multiple applications, services, and protocols. Our simulation results demonstrate that by using our 3G-based solution to disseminate connectivity information, vehicular ad hoc routing protocols improve their route selections, which results in a higher packet delivery ratio in urban scenarios.

Resilient secure aggregation for vehicular networks

Abstract: Innovative ways to use ad hoc networking between vehicles are an active research topic and numerous proposals have been made for applications that make use of it. Due to the bandwidth-limited wireless communication medium, scalability is one crucial factor for the success of these future protocols. Data aggregation is one solution to accomplish such scalability. The goal of aggregation is to semantically combine information and only disseminate this combined information in larger regions. However, the integrity of aggregated information cannot be easily verified anymore. Thus, attacks are possible resulting in lower user acceptance of applications using aggregation or, even worse, in accidents due to false information crafted by a malicious user. Therefore, it is necessary to design novel mechanisms to protect aggregation techniques. However, high vehicle mobility, as well as tight bandwidth constraints, pose strong requirements on the efficiency of such mechanisms. We present new security mechanisms for semantic data aggregation that are suitable for use in vehicular ad hoc networks. Resilience against both malicious users of the system and wrong information due to faulty sensors are taken into consideration. The presented mechanisms are evaluated with respect to their bandwidth overhead and their effectiveness against possible attacks.

Attractor selection and perturbation for robust networks in fluctuating environments

Abstract: The heterogeneity of connected devices, technologies, and protocols anticipated in future-generation information and communication networks also requires the development of new approaches for robust and self-adaptive systems. Recently, methods observed from biological phenomena have gained much attention as viable alternatives or inspiration for the solution of networking problems. The main advantages of such dynamic mechanisms inspired by biology lies in their self-organizing properties, scalability to numbers of connected devices, simplicity in terms of control rules, as well as adaptability and robustness to changing and fluctuating environments. Dealing with fluctuations plays a key role in maintaining the stability of the system. In this article we propose a new framework for selecting among different networks and services based on the robustness of each network?s performance metrics. The selection is only based on observations of the system's responsiveness to inherent fluctuations. This method is derived from biological experiments where the speed of fluorescence evolution of proteins in bacteria is observed to have a positive correlation with the phenotypic fluctuation of fluorescence over clone bacteria. Due to the explicit utilization of the inherent fluctuations in the system, the proposed selection scheme can operate smoothly to select the most suitable and robust network.

In-network services for customization in next-generation networks

Abstract: The design of the current Internet lacks in adaptability to accommodate novel network uses and functional requirements. It is therefore important to explore how new services can be introduced into the network infrastructure. We present a novel network architecture that can accommodate the deployment and custom instantiation of such network services. We discuss the motivation for our design and several of the research challenges that arise in this context.

Sizing up online social networks

Abstract: While the size of popular online social networks such as MySpace and Twitter has been reported to be in the tens or hundreds of millions of users (and growing), little is known about the fraction of users who have either deleted or abandoned their accounts. Therefore, the growth of an OSN's overall user population and, more important, its population of active users cannot easily be determined. In this article we describe a measurement technique to infer the fine-grained growth in the total number of allocated accounts for a class of OSNs that include MySpace and Twitter and are characterized by two features. First, they assign numerical user IDs using a format and allocation strategy that can be determined. Second, a fraction of their users have abandoned these OSNs shortly after creating their accounts, and these short-lived users (called 'tourists') are scattered across the ID space. By exploiting these two properties, we are able to determine the growth in total and valid user accounts for MySpace and Twitter since their inception. For valid user accounts, we also derive the fraction of active users in the system at the time of our experiment, where we define the activity of a user in terms of the recency of her last visit to the OSN. In the case of MySpace and Twitter, our results show that the active population of these OSNs is typically an order of magnitude smaller than the reported (total) population.

Understanding the behavior of malicious applications in social networks

Abstract: The World Wide Web has evolved from a collection of static HTML pages to an assortment of Web 2.0 applications. Online social networking in particular is becoming more popular by the day since the establishment of SixDegrees in 1997. Millions of people use social networking web sites daily, such as Facebook, My-Space, Orkut, and LinkedIn. A side-effect of this growth is that possible exploits can turn OSNs into platforms for malicious and illegal activities, like DDoS attacks, privacy violations, disk compromise, and malware propagation. In this article we show that social networking web sites have the ideal properties to become attack platforms. We introduce a new term, antisocial networks, that refers to distributed systems based on social networking web sites which can be exploited to carry out network attacks. An adversary can take control of a visitor's session by remotely manipulating their browsers through legitimate web control functionality such as image-loading HTML tags, JavaScript instructions, and Java applets.

A biologically inspired networking model for wireless sensor networks

Abstract: Wireless sensor networks have emerged in strategic applications such as target detection, localization, and tracking, where the large scale renders centralized control prohibitive In addition, the finite batteries of the nodes demand energy aware network control In this article we propose an energy-efficient topology management model inspired by biological intercell signaling schemes, which allows sensor nodes to form clusters around imminent targets in a purely distributed and autonomous fashion In particular, nodes in the target vicinity collaborate to form a cluster according to their relative observation quality values, based on a bioinspired lateral induction process Subsequently, the clustered nodes compete according to their energy levels until some of them gain active status while the rest remain idle, based on a bio-inspired lateral inhibition process A final phase of the model has the active cluster members compete until one of them becomes the cluster head, again based on the lateral inhibition process We examine the behavior of such a network control flow in both finite-size and infinite-size networks Specifically, we show that the proposed model is inherently stable and discuss its convergence for networks of finite size Furthermore, we discuss the asymptotic behavior when the number of nodes goes to infinity, where we study the average number of active cluster members

Network science: A new paradigm shift

Abstract: We argue that we are witnessing a paradigm shift in science, which could be referred to as network science. Some of the fundamental findings and open problems in network science are reviewed. Since most questions are still largely open, it is expected that the network science will still attract researches with different background: mathematics, physics, biology, electrical and computer engineering, and sociology, to mention only a few.

Application-specific resource provisioning for wide-area distributed computing

Abstract: Some modern distributed applications require cooperation among multiple geographically separated computing facilities to perform intensive computing at the end sites and large-scale data transfers in the wide area network. It has been widely recognized that WDM networks are cost-effective means to support data transfers in this type of data-intensive applications. However, neither the traditional approaches to establishing lightpaths between given source destination pairs nor the existing application-level approaches that only consider computing resources but take the underlying connectivity for granted are sufficient. In this article we identify key limitations and issues in existing systems, and focus on joint resource allocation of both computing resources and network resources in federated computing and network systems. A variety of resource allocation schemes that provide modern distributed computing applications with performance and reliability guarantees are presented.

A multiple failure propagation model in GMPLS-based networks

Abstract: In this article, a new model to simulate different failure propagation scenarios in GMPLS-based networks is proposed. Several types of failures and malfunctions may spread along the network following different patterns (hardware failures, natural disasters, accidents, configuration errors, viruses, software bugs, etc.). The current literature presents several models for the spreading of failures in general networks. In communication networks, a failure affects not only nodes but also the connections passing through those nodes. The model in this article takes into account GMPLS node failures, affecting both data and control planes. The model is tested by simulation using different types of network topologies. In addition, a new method for the classification of network robustness is also introduced.