Loss-aware DR-based update scheduling for improving consistency in DVEs

Abstract

Maintaining a consistent presentation of the virtual world among participants is a fundamental problem in the distributed virtual environment. The problem is exacerbated due to the limited network bandwidth and error-prone transmission. Using the metric of time-space inconsistency (TSI), we analytically derive the impact of message loss on TSI when using a dead reckoning (DR)-based update mechanism. To improve consistency, a naive algorithm and a compensation algorithm for update scheduling are proposed, in which expected spatial difference and expected TSI are, respectively, calculated by taking message loss into account. Using these algorithms, a budget-based mechanism is developed to meet the network bandwidth constraint. We show through experiments using a racing car game that the budget-based mechanism using the compensation algorithm makes the best use of available network bandwidth to reduce the inconsistency and its impact on the participants, and ensures fairness among participants in spite of widely varying message loss rates.

Keywords:

• distributed virtual environment
• consistency
• dead reckoning
• update scheduling
• message loss
• bandwidth constraint

Acknowledgements

This work was supported in part by Nanyang Technological University under Academic Research Fund Tier 1 Grant RG14/08.