Amgad Naiem

On the feasibility of centrally-coordinated Peer-to-Peer live streaming

In this paper we present an exploration of central coordination as a way of managing P2P live streaming overlays. The main point is to show the elements needed to construct a system with that approach. A key element in the feasibility of this approach is a near real-time optimization engine for peer selection. Peer organization in a way that enables high bandwidth utilization plus optimized peer selection based on multiple utility factors make it possible to achieve large source bandwidth savings and provide high quality of user experience. The benefits of our approach are also seen most when NAT constraints come into play.

MyP2PWorld: Highly Reproducible Application-Level Emulation of P2P Systems

In this paper, we describe an application-level emulator for P2P systems with a special focus on high reproducibility. We achieve reproducibility by taking control over the scheduling of concurrent events from the operating system. We accomplish that for inter- and intra- peer concurrency. The development of the system was driven by the need to enhance the testing process of an already-developed industrial product. Therefore, we were constrained by the architecture of the overlying application. However, we managed to provide highly transparent emulation by wrapping standard/widely-used networking and concurrency APIs. The resulting environment has proven to be useful in a production environment. At this stage, it started to be general enough to be used in the testing process of applications other than the one it was created to test.

On the Optimality and Speed of the Deep Greedy Switching Algorithm for Linear Assignment Problems

The Deep Greedy Switching algorithm is a fast heuristic for solving large instances of the linear sum assignment problem whilst sacrificing very little in terms of optimality. In this paper we explore the worst case performance aspects of the algorithm. We prove that the algorithm is finite and analyze its computational complexity. We also discuss a number of simplified variations of the algorithm that shed some light on how the algorithm works. The basic algorithm is also extended to problems involving partial assignment. Computational results on a number of problem types show that the solutions reached by our algorithm are only slightly worse than those obtained by the auction algorithm. A parallelized version of the basic algorithm is presented. Our algorithm is significantly faster than other methods with approaching a comparable quality of solution.

Project Portfolio Exploration and Visualization using Self-Organizing Maps

When dealing with portfolio analysis and assessment, decision makers often have to select a portfolio of a subset of proposed projects with varying levels of investment. The process involves comparing large sets of project portfolios across many dimensions. A tool that would make such comparisons cognizable would greatly facilitate portfolio selection. We tackle this challenge by visualizing the set of candidate portfolios using a self-organizing map (SOM). We adopt and modify the matching and updating steps of the SOM to work with project portfolio data. Our approach is based on content aware distance calculation between the data and codebook vectors as well as a novel process of updating the codebooks when dealing with project portfolio data.

NAT Constraints Management in Tree-Based P2P Live Streaming Systems

In this paper we present an approach for organizing peers in a centralized tree-based P2P live streaming system in order to minimize peer connectivity failures due to network address translation (NAT) constraints. The centralized coordinator in our system optimizes peers position according to their upload bandwidth to reach maximum P2P contribution and optimizes the position of each single peer to avoid incompatible NAT connectivity between peers which can cause a decrease in the systems performance. A network optimization technique is used to reach the optimal peer placement in the tree to satisfy the download demands of as many peers as possible.