Dynamic Reduction of Rollbacks in Wireless Multi-user Virtual Environments

In distributed virtual environments such as multiplayer games, where many users interact in real time while communicating through a network, the users may have an inconsistent view of the game world because of the communication delays across the network. Consistency maintenance algorithms must be used to have a uniform view of the game world. The majority of these algorithms use rollback mechanisms to correct the inconsistencies that occur because of the disorder of the arrival of update messages. These rollbacks are very costly, especially when playing a game, using high-latency wireless networks, on mobile terminals which have limited memory and processing speed. In this paper, we present a dynamic and adaptive approach for reducing the number of rollbacks in distributed virtual environments on wireless mobile devices. This approach takes into account the underlying network latency and the semantics of the game virtual world to dynamically decide whether a rollback is needed in case inconsistencies have occurred or can be possibly avoided. We evaluate our approach on a simplified version of a Football game on hand-held devices and show that this dynamic rollbacks’ reduction approach improves the responsiveness of the game and maintains consistency of the game state while limiting the use of processing power and memory space.