Networked games can be seen as forerunners of all kinds of participatory entertainment applications delivered through the Internet. Physically dispersed players are immersed in a common virtual environment where they interact in real time. When a user performs an action, other users must be made aware of that action. Otherwise, there is a discrepancy in the perceptions of participants about the overall state of the virtual world. This discrepancy could lead to undesirable and sometimes paradoxical outcomes. In particular, first-person shooter, and to a lesser extent role-playing games impose stringent constraints on responsiveness and consistency. Disciplines Physical Sciences and MathematicsPublication Details

This article evaluates network and server infrastructure requirements to support real-time flows associated with networked entertainment applications. These include the state information flow to update the status of the virtual environment and immersive communication flows such as voice, video, gesture, and haptics communication. The article demonstrates that scaling these applications to large geographical spreads of participants requires distribution of computation to meet the latency constraints of the applications. This latency-driven distribution of computation is essential even when there are no limitations on the availability of computational resources in one location. The article provides detailed results on distributed server architectures for two of these real-time flows, state information and immersive voice communication. It also identifies a generic set of requirements for the underlying network and server infrastructure to support these applications and propose a new design, called switched overlay networks, for this purpose.

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This paper investigates the assignment of audio mixing operations to a geographically distributed set of servers to provide an immersive audio communication environment for massively multiplayer online games. The immersive audio communication service enables each avatar to hear a realistic audio mix of the conversations in its audible range. There are three primary delivery architectures for this service, namely, peer-to-peer, central server and distributed servers. We focus on the distributed server architecture, which partitions the virtual world into regions or locales and then assigns the computation associated with the creation of audio scenes for all avatars in each locale to a server. Our aim is to find the optimal way to partition the virtual world into locales and then choose the locale servers in such a way that reduces the total delay perceived by all avatars. We have produced a mathematical formulation for the optimal partitioning and server assignment and developed a heuristics approach based on a graph algorithm. We have developed a simulation environment that creates both the physical world (geographic distribution of participants and the Internet topology model) and the virtual world (distribution of avatars based on different avatar aggregation behaviors). We have solved the problem exactly as well as using the heuristics algorithm for a range of simulated virtual and physical worlds. In many cases, the heuristics results were within 5% of the optimal. Our algorithms and simulation study will be of benefit to future immersive audio communication service providers in the design of a cost effective delivery architecture for this service. Disciplines Physical Sciences and Mathematics Publication DetailsThis article was originally published as: Nguyen, CD, Safaei F & Boustead, P, A distributed server architecture for providing immersive audio communication to massively multiplayer online games, Proceedings 12th IEEE International Conference on Networks (ICON 2004), 16-19 November 2004, vol 1, 170-176. Copyright IEEE 2004 This conference paper is available at Research Online: http://ro.uow.edu.au/infopapers/184 Abstma-This paper investigates the assignment of audio mixing operations to a geographically distributed set of servers to provide an immersive audio communicafion environment for massively multi-player online games. The immersive audio communication senice enables each avatar to hear a realistie audio mix of the conversations in its audible range. There are three primary delivery architectures for this service, namely, peer-to-peer, central server and distributed servers. We focus on the distributed server architecture, which partitions the virtual world into regions or locales and then assigns the Computation associated with the c-tion of audio scenes for all avatars in each locale to a server. Our aim is to find the optimal way to partition the virtual world into lodes and then choose the locale servers in such a way that d u c e s the total delay perceived by all avatars. A DISTRI...

Playability and fairness are crucial elements of an enjoyable online game experience. The unavoidable propagation time introduced by the geographical distance between participants can deteriorate the game responsiveness and playability. Also, differences in these delays can provide unfair advantages and/or disadvantages to different players. This paper explores the causal relationships between propagation time, inconsistencies, playability and fairness in online multiplayer games. It clearly defines causes of unfairness and introduces a theoretical quantification supported by an experimental technique to evaluate it in simulations. It also demonstrates through simulations the impact of changes in network architecture and topology on playability and fairness. Disciplines Physical Sciences and Mathematics Publication DetailsThis article was originally published as: Brun, J, Safaei, Abstract-Playability and fairness are crucial elements of an enjoyable online game experience. The unavoidable propagation time introduced by the geographical distance between participants can deteriorate the game responsiveness and playability. Also, differences in these delays can provide unfair advantages and/or disadvantages to different players. This paper explores the causal relationships between propagation time, inconsistencies, playability and fairness in online multiplayer games. It clearly defines causes of unfairness and introduces a theoretical quantification supported by an experimental technique to evaluate it in simulations. It also demonstrates through simulations the impact of changes in network architecture and topology on playability and fairness.