Fairness in Multi-Player Online Games on Deadline-Based Networks

The fairness issue in multi-player online games (MOGs) on deadline-based networks is investigated. A particular type of MOGs, namely the first-person-shooter (FPS) game, is examined. Potential unfair scenarios in FPS games due to disparate network delays are analyzed. A fairness definition and two fairness metrics are introduced. Two strategies to achieve fairness in FPS games on a deadline-based network are developed. The first strategy is based on end-system delay compensation; the other is based on the characteristics of the underlying network. The performance of the developed strategies is evaluated by simulation. Experiments show that by employing these two strategies, game fairness can be significantly improved. I. INTRODUCTION Recently, the number of real-time applications running on packet-switched computer networks increased rapidly. They vary from stock quote update and online auction, to audio, video conferencing, Internet telephony, and real-time interac- tive online games. These applications require timely delivery of real-time data across the transport network. In order to support this, quality of service (QoS) support at the transport network is required. Deadline-based network resource management (1) is a new approach to supporting real-time applications in packet- switched networks. In this approach, a pair (size, deadline) is specified for each application data unit (ADU). An ADU can be a file, a state update message in an online game, or an audio or video frame in multimedia applications. The ADU deadline specifies the absolute time at which the ADU should be received by the receiving application. For delivery, an ADU may be fragmented and sent in more than one packet. The ADU deadline is mapped to packet deadlines, which are carried by packets and used by routers for channel scheduling. Deadline-based scheduling is employed in routers. When com- pared to the first-come first-served scheduling, which is used on the classic Internet, deadline-based channel scheduling was shown to yield better performance in terms of the percentage of ADUs that are delivered on time (1). In the literature, the effectiveness of deadline-based scheduling has been evaluated assuming generic real-time traffic rather than traffic from more specific types of real-time applications. In this research, as a step towards real-world application support, we investigate the capability of deadline-based networks in support of MOGs. MOGs are computer games in which multiple game players simultaneously participate in a game session over a computer network. MOGs are increasingly popular on today's Internet. The implementation of MOGs often adopts a client-server architecture in which each game client is connected to a game server via a computer network. State update messages are transmitted between the game clients and the game server. There are various types of MOGs, among which the FPS games often have the most stringent requirement on the delay performance of the underlying network because of the highly interactive nature of such games. Because of its high QoS demand on the network, this research focuses on the support