Interactive applications as online games and mobile devices have grown in popularity. From their combination, new and interesting cooperative services could be generated. For instance, gamers endowed with Augmented Reality (AR) visors, connected as wireless nodes in an ad-hoc network, can interact with each other while immersed in the game. To enable this vision, we discuss here a hybrid architecture enabling game play in ad-hoc mode instead of the traditional client-server setting. In our architecture, one of the player nodes also acts as the server of the game, whereas other backup server nodes are ready to become active servers in case of network disconnection, ie, due to low energy level of the currently active server. This allows to have a longer gaming session before a disconnection occurs due to energy exhaustion. In this context, the server election strategy with the aim of maximizing network lifetime is not so straightforward. To this end, we have analyzed this issue through a Mixed Integer Linear Programming (MILP) model considering static network topologies and both numerical and simulation-based analysis shows that the backup servers solution fulfills its design objective. Contemplating for mobility, we present a simulation study employing actual packet routing protocols and discuss the tradeoffs that emerge.
KEYWORDSbackup server, MANET, mixed integer linear programming, online game
INTRODUCTIONIn recent years, interactive applications such as online games and mobile devices have become more and more popular, generating a huge market.This success is also accompanied by tough technical challenges that have attracted the interest of researchers and practitioners all around the world.Indeed, although online games require only a little amount of bandwidth, their performance is subject to strict per-packet delay requirements and to scalability issues that can be solved only through specific solutions and architectures. 1-3The combination with wireless-enabled mobile devices fosters new gaming scenarios. For instance, think of a multiplayer game based on the user position and proximity, ie, a game that is played outside, on the street, or in courtyards, or close to cultural heritage sites. 4 Players may gather around a certain spot and start a gaming session on their mobile devices, exploiting the device features (eg, connectivity, GPS, gyroscope, etc), rendering the game play more attractive. These applications may be coupled with Augmented Reality (AR), or even with Virtual Reality (VR), through helmets and wireless connectivity so as to enable players to interact with the AR/VR world and with each other (eg, see Figure 1). [5][6][7][8] In these envisioned scenarios, players will be engaged in an outdoor, connectivity-, and proximity-based game. However, in order to enable this scenario, we have to address at least three main issues. First, the main model for networked games is client-server, with the client run by the player's PC and the server located remotely in the Internet. 9-11 Clearly, we could ha...