| dc.description.abstract | Mobile devices, such as laptops, mobile phones, PDAs and portable game consoles, are equipped with radio modules for wireless access, such as WiFi. These devices can be directly connected to each other to form a one-hop wireless ad hoc network for multiplayer game play. However, such a network can support only a limited number of players distributed over a narrow area. In this paper, we propose a synchronous multihop architecture (SYMA) for wireless ad hoc multiplayer games to support more players distributed over a broader area. In SYMA, devices are assumed to have one-hop neighbor device information, as well as timers synchronized with good accuracy. A player, called game initiator, broadcasts an invitation message to invite other players to join a new game. A joining player issues a message along with its neighborhood information, including the expected transmission time (ETT) for each neighbor node, to reply to the invitation so that the initiator can derive the topology of the participating players. The initiator applies Floyd–Warshall shortest path algorithm, taking the topology and ETT values as input to construct the shortest path spanning tree rooted at each player (or node). It then calculates the expected broadcast time (EBT) for each tree, which is useful to estimate the time for the root node of a tree to broadcast a game state to all tree nodes. Finally, the tree with the smallest EBT is selected as the communication tree and its root is designated as the coordinator, which collects timestamped actions of each player, executes the game logic, and then broadcasts the new game state. By exploiting synchronized timers, the game state consistency is guaranteed, and each node can be scheduled to send/receive game messages without causing collisions. The constructions of communication trees and message schedules are simulated for different scenarios. Compared with the one-hop network architecture, SYMA can support a broader area and a larger number of players with the help of synchronous multihop communication.
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