Eliya Buyukkaya

VoroGame: A Hybrid P2P Architecture for Massively Multiplayer Games

Peer-to-peer (P2P) architectures have recently become very popular in massively multiplayer games (MMGs). While P2P gaming offers high scalability compared to client/server architectures, it introduces several major issues related to data distribution and game state consistency. In this paper, we report our initial version of VoroGame, a P2P architecture for MMGs that addresses these issues by combining a structured P2P overlay based on a distributed hash table (DHT) for data distribution, with a Voronoi diagram used for virtual game world decomposition and semantic overlay support. The resulting hybrid architecture enables a fully distributed management of data and state information, and ensures efficient dissemination of game state updates to relevant peers.

A spatial publish subscribe overlay for massively multiuser virtual environments

Peer-to-peer (P2P) architectures have become popular for designing scalable virtual environments (VEs) in recent years. However, one question that remains is whether a single overlay can be flexible enough to support different types of VEs. We present S-VON, a P2P overlay that attempts this goal by providing spatial publish/subscribe (SPS) services. Besides flexibility, S-VON also aims to be practical and efficient by utilizing super-peers and considering the physical topology (i.e., network distance) to reduce latencies. Our simulations show that super-peers provide a unique design space where both bandwidth usage and latencies can be effectively reduced, such that even a crowded Second Life region can be hosted with residential ADSL.

A Survey of Peer-To-Peer Overlay Approaches for Networked Virtual Environments

This paper identifies and analyzes the key design approaches that have been proposed over the last decade to construct a peer-to-peer (P2P) networked virtual environment (NVE) systems. We discuss each approach, their advantages and drawbacks, and examine several representative P2P-based NVE systems based on the presented approaches, thus providing the background and literature review of P2P NVEs.

Peer-to-peer visualization of very large 3D landscape and city models using MPEG-4

The recent availability of broadband Internet access and web-based visualization techniques is paving the way for a large scale use of 3D landscape and city models for a great variety of professional and mass market services. To make such services appealing to a large audience, these 3D models must reach a sufficient level of realism and accuracy. Many solutions are now available to automatically generate 3D models of huge urban environments. Geographic Information System (GIS) databases (i.e. terrain elevation grids, ortho photographs, buildings footprint and height) provide a good basis for generating such models at affordable cost with minimum human intervention. However, the growing size of the transmitted data will favour streaming over download-and- play. Moreover, the new market for virtual worlds is likely to be soon demanding in interoperability. The goal of this paper is to show how solutions based on hierarchical LOD models and view-dependent progressive streaming can efficiently be implemented using the MPEG-4 AFX standard in peer-to-peer networks architectures, solving both streaming and interoperability issues.

GROUP: Dual-Overlay State Management for P2P NVE

Peer-to-peer (P2P) architectures have recently become a popular design choice to build scalable Networked Virtual Environments (NVEs). While P2P architectures offer better scalability than server-based architectures, efficient distribution and management of avatar and object states remains a highly challenging issue. In this paper, we propose GROUP, a fully-distributed P2P architecture for NVEs that addresses this issue by combining a structured P2P overlay, used for object state management, with a Voronoi-based overlay, used for avatar state and group membership management. The resulting dual overlay architecture enables efficient and fully distributed management of state updates for P2P-based NVEs.

Peer-to-peer live streaming for Massively Multiplayer Online Games

One of the most attractive features of Massively MuItiplayer Online Games (MMOGs) is the possibility for users to interact with a large number of other users in a variety of collaborative and competitive situations. Garners within an MMOG typically become members of active communities with mutual interests, shared adventures, and common objectives. This demonstration presents a peer-to-peer live video system that enables MMOG players to stream screen-captured video of their game. Players can use the system to show their skills, share experience with friends, or coordinate missions in strategy games.

Level-Based Peer-to-Peer Live Streaming with Rateless Codes

We propose a peer-to-peer system for streaming user-generated live video. Peers are arranged in levels so that video is delivered at about the same time to all peers in the same level, and peers in a higher level watch the video before those in a lower level. We encode the video bit stream with rate less codes and use trees to transmit the encoded symbols. Trees are constructed to minimize the transmission rate for the source while maximizing the number of served peers and guaranteeing on-time delivery and reliability at the peers. We formulate this objective as a height bounded spanning forest problem with nodal capacity constraint and compute a solution using a heuristic polynomial-time algorithm. We conduct ns-2 simulations to study the trade-off between used bandwidth and video quality for various packet loss rates and link latencies.

Resource allocation in underprovisioned multioverlay peer-to-peer live video sharing services

Multioverlay peer-to-peer live video streaming systems face the problem of finding a suitable peer upload bandwidth allocation among concurrent overlays. So far, no efficient solution has been proposed for the important case where the overall system is underprovisioned, that is, when peers do not have enough upload bandwidth to ensure video distribution at full quality. We design various objective functions for this upload bandwidth allocation problem and show how optimal solutions can be computed using a bipartite flow network. Simulation results show that our solutions improve on existing algorithms in terms of video quality.

Resource allocation in underprovisioned multioverlay live video sharing services

In a multioverlay live video sharing service consisting of multiple independent peer-to-peer live video streaming systems, a user can simultaneously watch multiple live video streams. A major challenge for such services is the inter-overlay bandwidth competition problem, which is to find an upload bandwidth allocation between the overlays each peer has subscribed to. So far, no solution has been proposed in the literature for the important case where the overall system is underprovisioned, that is, when peers do not have enough upload bandwidth to ensure a distribution of videos at full quality. We show that an allocation of upload resources that minimizes the wastage of resources (i.e., minimizes the upload bandwidth allocated to overprovisioned overlays) can be computed in polynomial time. Then we present a generic model that allows the design of different strategies for the management of the resource deficit in underprovisioned systems. Finally, we provide relevant simulation results to demonstrate the gains in video quality resulting from the implementation of our solutions.

A flexible connectivity architecture for avatar management in P2P virtual environments

The present paper addresses the efficient management of avatar states in P2P virtual environments (VEs) by building on our previously proposed Relaxed Triangulation (RT) overlay, designed to accommodate the dynamic nature of VEs by drastically reducing the maintenance cost inherent to the well-known Delaunay construct. Given that our RT overlay no longer supports greedy routing, we propose in this paper to complement our RT overlay with a message routing algorithm that guarantees message delivery on top of RT.