LiveShift: mesh-pull P2P live and time-shifted video streaming

The popularity of video sharing over the Internet has increased significantly. High traffic generated by such applications at the source can be better distributed using a peer-to-peer overlay. LiveShift combines both live and on-demand video streaming -- while video is transmitted through the peer-to-peer network in a live fashion, all peers participate in distributed storage. This adds the ability to replay time-shifted streams from other peers in a distributed and scalable manner. This technical report describes an architecture, a mesh-pull protocol, and a set of policies that support the envisioned use case enable. User-focused evaluation results show its effectiveness and limits in terms of quality of experience

LiveShift: Mesh-pull live and time-shifted P2P video streaming

The popularity of video sharing over the Internet has increased significantly. High traffic generated by such applications at the source can be better distributed using a peer-to-peer (P2P) overlay. Unlike most P2P systems, LiveShift combines both live and on-demand video streaming while video is transmitted through the peer-to-peer network in a live fashion, all peers participate in distributed storage. This adds the ability to replay time-shifted streams from other peers in a distributed and scalable manner. This paper describes an adaptive fully-distributed mesh-pull protocol that supports the envisioned use case and a set of policies that enable efficient usage of resources, discussing interesting trade-offs encountered. User-focused evaluation results, including both channel switching and time shifting behavior, show that the proposed system provides good quality of experience for most users, in terms of infrequent stalling, low playback lag, and a small proportion of skipped blocks in all the scenarios studied, even in presence of churn

Search for Neutral Supersymmetric Higgs Bosons in ppˉp\bar{p} Collisions at s=1.8\sqrt{s}=1.8 TeV

We present the results of a search for neutral Higgs bosons produced in association with $b$ quarks in $p\bar{p}\to b\bar{b} \phi\to b\bar{b}b\bar{b}$ final states with $91 \pm 7$ pb$^{-1}$ of $p\bar{p}$ collisions at $\sqrt{s}=1.8$ TeV recorded by the Collider Detector at Fermilab. We find no evidence of such a signal and the data is interpreted in the context of the neutral Higgs sector of the Minimal Supersymmetric extension of the Standard Model. With basic parameter choices for the supersymmetric scale and the stop quark mixing, we derive 95% C.L. lower mass limits for neutral Higgs bosons for \tb values in excess of 35.Comment: 2 tex files 3 figure

Preparing construction supply chains for blockchain technology:An investigation of its potential and future directions

Blockchain, a peer-to-peer, controlled, distributed database structure, has the potential to profoundly affect current business transactions in the construction industry through smart contracts, cryptocurrencies, and reliable asset tracking. The construction industry is often criticized for being slow in embracing emerging technologies and not effectively diffusing them through its supply chains. Often, the extensive fragmentation, traditional procurement structures, destructive competition, lack of collaboration and transparency, low-profit margins, and human resources are shown as the main culprits for this. As blockchain technology makes its presence felt strongly in many other industries like finance and banking, this study investigates the preparation of construction supply chains for blockchain technology through an explorative analysis. Empirical data for the study were collected through semistructured interviews with 17 subject experts. Alongside presenting a strengths, weaknesses, opportunities, and threats analysis (SWOT), the study exhibits the requirements for and steps toward a construction supply structure facilitated by blockchain technology

Game theoretical analysis of incentives for large-scale, fully decentralized collaboration networks

One of the key challenges in peer-to-peer networks is the design of incentives to encourage peers to share their resources. Incentives are necessary in order to exploit the full potential of these systems. The tit-for-tat incentive scheme, as used in BitTorrent for example, has proven to be a successful approach in P2P file sharing systems, where peers have direct relations and share the same kind of resources. However, in P2P systems where different kind of resources are shared between peers with non-direct relations, the design of incentives remains a challenge. In this paper, a large-scale, fully decentralized P2P collaboration network is shown, where peers share not only bandwidth and storage space, but also contribute by editing articles and voting for or against changes. A new incentive scheme is proposed which supports non-direct relations and provides incentives for sharing different kind of resources. The incentive scheme is based on a reputation system that assigns a reputation value to every peer reflecting its previous behavior in the network. Based on this value, the service level is differentiated, i.e. the higher a peer's reputation the better the quality of service it can get from the network. The service differentiation has been analyzed and simulated with rational, irrational and altruistic peers based on game theory concepts

PeerCollaboration

Increasing traffic due to increased bandwidth or the number of users calls for scalable systems, which can be built with peer-to-peer (P2P) mechanisms. Scalability is a key issue for systems that rely on many participants, such as large-scale collaboration system. This paper introduces PeerCollaboration, a fully decentralized P2P collaboration system for documents, which is robust against malicious behavior, provides an efficient content search, and offer mechanisms for distributed control. Typical tasks in PeerCollaboration are searching, retrieving, creating, changing, and maintaining documents in a collaborative manner. Three problem areas are investigated within this system. The first problem focuses on similarity search on top of existing P2P networks and highlights a novel algorithm, which outperforms compared approaches. The second problem deals with incentive schemes, which work with indirect reciprocity. Thus, the novel and robust incentive scheme finds more reciprocities than with compared approaches. The third problem focuses on user-based voting mechanisms