Network aware P2P multimedia streaming: capacity or locality?

P2P content providers are motivated to localize traffic within Autonomous Systems and therefore alleviate the tension with ISPs stemming from costly inter-AS traffic generated by geographically distributed P2P users. In this paper, we first present a new three-tier framework to conduct a thorough study on the impact of various capacity aware or locality aware neighbor selection and chunk scheduling strategies. Specifically, we propose a novel hybrid neighbor selection strategy with the flexibility to elect neighbors based on either type of network awareness with different probabilities. We find that network awareness in terms of both capacity and locality potentially degrades system QoS as a whole and that capacity awareness faces effort-based unfairness, but enables contribution-based fairness. Extensive simulations show that hybrid neighbor selection can not only promote traffic locality but lift streaming quality and that the crux of traffic locality promotion is active overlay construction. Based on this observation, we then propose a totally decentralized network awareness protocol, equipped with hybrid neighbor selection. In realistic simulation environments, this protocol can reduce inter-AS traffic from 95% to 38% a locality performance comparable with tracker-side strategies (35%) under the premise of high streaming quality. Our performance evaluation results provide valuable insights for both theoretical study on selfish topologies and real-deployed system design. © 2011 IEEE.published_or_final_versionThe 2011 IEEE International Conference on Peer-to-Peer Computing (P2P 2011), Kyoto, Japan, 31 August-2 September 2011. In Proceedings of P2P, 2011, p. 54-6

Trust management schemes for peer-to-peer networks

Peer-to-peer (P2P) networking enables users with similar interests to exchange, or obtain files. This network model has been proven popular to exchange music, pictures, or software applications. These files are saved, and most likely executed, at the downloading host. At the expense of this mechanism, worms, viruses, and malware find an open front door to the downloading host and gives them a convenient environment for successful proliferation throughout the network. Although virus detection software is currently available, this countermeasure works in a reactive fashion, and in most times, in an isolated manner. A trust management scheme is considered to contain the proliferation of viruses in P2P networks. Specifically, a cooperative and distributed trust management scheme based on a two-layer approach to bound the proliferation of viruses is proposed. The new scheme is called double-layer dynamic trust (DDT) management scheme. The results show that the proposed scheme bounds the proliferation of malware. With the proposed scheme, the number of infected hosts and the proliferation rate are limited to small values. In addition, it is shown that network activity is not discouraged by using the proposed scheme. Moreover, to improve the efficiency on the calculation of trust values of ratio based normalization models, a model is proposed for trust value calculation using a three-dimensional normalization to represent peer activity with more accuracy than that of a conventional ratio based normalization. Distributed network security is also considered, especially in P2P network security. For many P2P systems, including ad hoc networks and online markets, reputation systems have been considered as a solution for mitigating the affects of malicious peers. However, a sybil attack, wherein forging identities is performed to unfairly and arbitrarily influence the reputation of peers in a network or community. To defend against sybil attack, each reported transaction, which is used to calculate trust values, is verified. In this thesis, it is shown that peer reputation alone cannot bound network subversion of a sybil attack. Therefore, a new trust management framework, called Sybildefense, is introduced. This framework combines a trust management scheme with a cryptography mechanism to verify different transaction claims issue by peers, including those bogus claims of sybil peers. To improve the efficiency on the identification of honest peers from sybil peers, a k-means clustering mechanism is adopted. Moreover, to include a list of peer’s trustees in a warning messages is proposed to generate a local table for a peer that it is used to identify possible clusters of sybil peers. The defensive performance of these algorithms are compared under sybil attacks. The performance results show that the proposed framework (Sybildefense) can thwart sybil attacks efficiently

A scheme for efficient peer-to-peer live video streaming over wireless mesh networks

Peers in a Peer-to-Peer (P2P) live video streaming system over hybrid wireless mesh networks (WMNs) enjoy high video quality when both random network coding (RNC) and an efficient hybrid routing protocol are employed. Although RNC is the most recently used method of efficient video streaming, it imposes high transmission overhead and decoding computational complexity on the network which reduces the perceived video quality. Besides that, RNC cannot guaranty a non-existence of linear dependency in the generated coefficients matrix. In WMNs, node mobility has not been efficiently addressed by current hybrid routing protocols that increase video distortion which would lead to low video quality. In addition, these protocols cannot efficiently support nodes which operate in infrastructure mode. Therefore, the purpose of this research is to propose a P2P live video streaming scheme which consists of two phases followed by the integration of these two phases known as the third phase to provide high video quality in hybrid WMNs. In the first phase, a novel coefficients matrix generation and inversion method has been proposed to address the mentioned limitations of RNC. In the second phase, the proposed enhanced hybrid routing protocol was used to efficiently route video streams among nodes using the most stable path with low routing overhead. Moreover, this protocol effectively supports mobility and nodes which operate in infrastructure mode by exploiting the advantages of the designed locator service. Results of simulations from the first phase showed that video distortion as the most important performance metric in live video streaming, had improved by 36 percent in comparison with current RNC method which employs the Gauss-Jordan Elimination (RNC-GJE) method in decoding. Other metrics including frame dependency distortion, initial start-up delay and end-to-end delay have also improved using the proposed method. Based on previous studies, although Reactive (DYMO) routing protocol provides better performance than other existing routing protocols in a hybrid WMN, the proposed protocol in the second phase had average improvements in video distortion of l86% for hybrid wireless mesh protocol (HWMP), 49% for Reactive (Dynamic MANET On-Demand-DYMO), 75% for Proactive (Optimized Link State Routing-OLSR), and 60% for Ad-hoc on-demand Distance Vector Spanning-Tree (AODV-ST). Other metrics including end-to-end delay, packet delay variation, routing overhead and number of delivered video frames have also improved using the proposed protocol. Finally, the third phase, an integration of the first two phases has proven to be an efficient scheme for high quality P2P live video streaming over hybrid WMNs. This video streaming scheme had averagely improved video distortion by 41%, frame dependency distortion by 50%, initial start-up delay by 15% and end-to-end delay by 33% in comparison with the average introduced values by three other considered integration cases which are Reactive and RNC-GJE, Reactive and the first phase, the second phase and RNC-GJE

Trust management in cloud computing: A critical review

Cloud computing has been attracting the attention of several researchers both in the academia and the industry as it provides many opportunities for organizations by offering a range of computing services.For cloud computing to become widely adopted by both the enterprises and individuals, several issues have to be solved.A key issue that needs special attention is security of clouds, and trust management is an important component of cloud security.In this paper, the authors look at what trust is and how trust has been applied in distributed computing. Trust models proposed for various distributed system has then been summarized.The trust management systems proposed for cloud computing have been investigated with special emphasis on their capability, applicability in practical heterogonous cloud environment and implementabilty. Finally, the proposed models/systems have been compared with each other based on a selected set of cloud computing parameters in a table

IETF standardization in the field of the Internet of Things (IoT): a survey

Smart embedded objects will become an important part of what is called the Internet of Things. However, the integration of embedded devices into the Internet introduces several challenges, since many of the existing Internet technologies and protocols were not designed for this class of devices. In the past few years, there have been many efforts to enable the extension of Internet technologies to constrained devices. Initially, this resulted in proprietary protocols and architectures. Later, the integration of constrained devices into the Internet was embraced by IETF, moving towards standardized IP-based protocols. In this paper, we will briefly review the history of integrating constrained devices into the Internet, followed by an extensive overview of IETF standardization work in the 6LoWPAN, ROLL and CoRE working groups. This is complemented with a broad overview of related research results that illustrate how this work can be extended or used to tackle other problems and with a discussion on open issues and challenges. As such the aim of this paper is twofold: apart from giving readers solid insights in IETF standardization work on the Internet of Things, it also aims to encourage readers to further explore the world of Internet-connected objects, pointing to future research opportunities

Network overload avoidance by traffic engineering and content caching

The Internet traffic volume continues to grow at a great rate, now driven by video and TV distribution. For network operators it is important to avoid congestion in the network, and to meet service level agreements with their customers. This thesis presents work on two methods operators can use to reduce links loads in their networks: traffic engineering and content caching. This thesis studies access patterns for TV and video and the potential for caching. The investigation is done both using simulation and by analysis of logs from a large TV-on-Demand system over four months. The results show that there is a small set of programs that account for a large fraction of the requests and that a comparatively small local cache can be used to significantly reduce the peak link loads during prime time. The investigation also demonstrates how the popularity of programs changes over time and shows that the access pattern in a TV-on-Demand system very much depends on the content type. For traffic engineering the objective is to avoid congestion in the network and to make better use of available resources by adapting the routing to the current traffic situation. The main challenge for traffic engineering in IP networks is to cope with the dynamics of Internet traffic demands. This thesis proposes L-balanced routings that route the traffic on the shortest paths possible but make sure that no link is utilised to more than a given level L. L-balanced routing gives efficient routing of traffic and controlled spare capacity to handle unpredictable changes in traffic. We present an L-balanced routing algorithm and a heuristic search method for finding L-balanced weight settings for the legacy routing protocols OSPF and IS-IS. We show that the search and the resulting weight settings work well in real network scenarios

Bibliographic Review on Distributed Kalman Filtering

In recent years, a compelling need has arisen to understand the effects of distributed information structures on estimation and filtering. In this paper, a bibliographical review on distributed Kalman filtering (DKF) is provided.\ud The paper contains a classification of different approaches and methods involved to DKF. The applications of DKF are also discussed and explained separately. A comparison of different approaches is briefly carried out. Focuses on the contemporary research are also addressed with emphasis on the practical applications of the techniques. An exhaustive list of publications, linked directly or indirectly to DKF in the open literature, is compiled to provide an overall picture of different developing aspects of this area

Distributed Algorithms for Location Based Services

Real-time localization services are some of the most challenging and interesting mobile broadband applications in the Location Based Services (LBS) world. They are gaining more and more importance for a broad range of applications, such as road/highway monitoring, emergency management, social networking, and advertising. This Ph.D. thesis focuses on the problem of defining a new category of decentralized peer-to-peer (P2P) algorithms for LBS. We aim at defining a P2P overlay where each participant can efficiently retrieve node and resource information (data or services) located near any chosen geographic position. The idea is that the responsibility and the required resources for maintaining information about position of active users are properly distributed among nodes, for which a change in the set of participants causes only a minimal amount of disruption without reducing the quality of provided services. In this thesis we will assess the validity of the proposed model through a formal analysis of the routing protocol and a detailed simulative investigation of the designed overlay. We will depict a complete picture of involved parameters, how they affect the performance and how they can be configured to adapt the protocol to the requirements of several location based applications. Furthermore we will present two application scenarios (a smartphone based Traffic Information System and a large information management system for a SmartCity) where the designed protocol has been simulated and evaluated, as well as the first prototype of a real implementation of the overlay using both traditional PC nodes and Android mobile devices

Intelligent search in social communities of smartphone users

Social communities of smartphone users have recently gained significant interest due to their wide social penetration. The applications in this domain,however, currently rely on centralized or cloud-like architectures for data sharing and searching tasks, introducing both data-disclosure and performance concerns. In this paper, we present a distributed search architecture for intelligent search of objects in a mobile social community. Our framework, coined SmartOpt, is founded on an in-situ data storage model, where captured objects remain local on smartphones and searches then take place over an intelligent multi-objective lookup structure we compute dynamically. Our MO-QRT structure optimizes several conflicting objectives, using a multi-objective evolutionary algorithm that calculates a diverse set of high quality non-dominated solutions in a single run. Then a decision-making subsystem is utilized to tune the retrieval preferences of the query user. We assess our ideas both using trace-driven experiments with mobility and social patterns derived by Microsoft’s GeoLife project, DBLP and Pics ‘n’ Trails but also using our real Android SmartP2P3 system deployed over our SmartLab4 testbed of 40+ smartphones. Our study reveals that SmartOpt yields high query recall rates of 95%, with one order of magnitude less time and two orders of magnitude less energy than its competitors