Coping with inconsistency due to network delays in collaborative virtual environments

Collaborative Virtual Environments (CVEs) are shared virtual spaces designed to enhance collaboration between the - usually remote - participants. The deployment of Collaborative Virtual Environments over wide area networks increases typical network delays, potentially breaking the consistency between the replicated versions of an environment at the participants' sites. This paper presents our qualitative observations of an experiment involving two players engaged in a virtual ball game in the presence of increasing network delays. It also describes how network delay affected the participants' behaviour and produced collaboration breakdowns. We observed that, as the network delay increases, the users modify their playing strategies in an attempt to cope with the situation, presenting several types of adaptation strategy. Knowledge of the presence and effect of delays is a major factor in allowing users to adopt strategies for coping with inconsistencies. We propose that if the participants were made more aware of the behaviour of the system, e.g. the presence of delays, then they might be able to improve their performance. Consequently, we propose a number of techniques to increase the user's knowledge of infrastructural characteristics such as delay.