A Lifetime-limited Causal Order Control Method in Asynchronous DVE System

Distributed virtual environment(DVE) is a computer-generated virtual space that simulates the real world. Therefore, in a DVE, causal order consistency is required to be preserved in real time, which means the causal events must be delivered within the lifetime of the result event. However, due to the network latency, part of causal events may not arrive the receiving node in time especially in large-scale DVE, and then the causality between the arrived causal events and the result event can not be maintained within the lifetime of it. In related work, some do not consider the causality with lifetime limitation based on the presumption that all events can arrive in time, while others require accurate synchronous simulation clock and their control overhead is closely-coupled with the system scale so that causal control efficiency becomes very low in large-scale DVE. In this paper, we propose a novel lifetime-limited causal order (LCO) control method that can compare asynchronous time of different nodes, conclude the ending condition of multi-path causal order control information selection and dynamically adapt the causal control information according to network latency variation. Thus even when part of causal events can’t arrive in time, the causality among arrived events can be preserved within lifetime limitation using causal control information selected by LCO. The experiment results demonstrate that LCO can effectively preserve causal order consistency within lifetime and the overhead of the causal control information is irrelevant with system scale.