Network Latency in On-Line Gaming: An Engineering or a Psychological Problem?

Ongoing research attempts to find engineering-based solutions to the problem of network latency in multiplayer computer games. However, few studies have been conducted to examine the end-users' experience of latency from a psychological perspective. The current study examines the roles of network latency and game complexity on the subjective experience of participants playing a specially designed computer game. Results suggest that participants prefer complex over simple games, regardless of the level of latency experienced. These findings suggest the possibility of a psychological solution to some of the negative effects of network latency. It is suggested that by manipulating Relational Complexity, it may be possible to maintain a satisfactory gaming experience in the presence of latency

Examining User Performance in the presence of Latency and Jitter in Distributed Interactive Applications

Latency and jitter inherently limit the maintenance of consistency in Distributed Interactive Applications such as computer games, distributed whiteboards and real-time, collaborative environments. Although there has been much research into methods for maintaining consistency, there is a distinct lack of research exploring the connection between latency, jitter and the end user experience in Distributed Interactive Applications. We have developed an application that allows us to conduct trials under controlled latency and jitter conditions. This provides data, which can be analysed to characterise how people adapt to various degrees of latency and jitter. We present results that highlight how an increase in latency and jitter affect the end-user experience, thus confirming the need for techniques to combat latency and jitter in Distributed Interactive Applications. We alsoe note that the effects of jitter are significantly greater than those of latency

Does Reducing Packet Transmission Rates Help to Improve Consistency within Distributed Interactive Applications?

Networked games are an important class of distributed systems. In order for such applications to be successful, it is important that a sufficient level of consistency is maintained. To achieve this, a high level of network traffic is often required. However, this can cause an increase in network latency due to overloaded network hardware, which, ironically, can have a negative impact on consistency. Entity state prediction techniques aim to combat this effect by reducing network traffic. Although much work has focused on developing predictive schemes, there has been little work to date on the analysis of their true impact on the consistency of the system overall. In this paper, we identify an important performance-related characteristic of packet reduction schemes. It is demonstrated that there exists an optimal packet transmission region. Increasing or decreasing network traffic above or below this level negatively impacts on consistency. Based on this characteristic, it is proposed that predictive schemes exploit this optimal point in order to maximise consistency by efficiently utilising the available resources

Building Real-World Ad-Hoc Networks to Support Mobile Collaborative Applications: Lessons Learned

Mobile collaboration is required in several work scenarios, i.e. education, healthcare, business and disaster relief. The features and capabilities of the communication infrastructure used by mobile collaborative applications will influence the type of coordination and collaboration that can be supported in real work scenarios. Developers of these applications are typically unaware of the constraints the communication infrastructure imposes on the collaborative system. Therefore, this paper presents an experimental study of how ad-hoc networks can effectively support mobile collaborative work. The article analyzes several networking issues and it determines how they influence the collaborative work. The paper also presents the lessons learned and it provides recommendations to deal with the networking issues intrinsic to adhoc networks.Postprint (published version

On Consistency and Network Latency in Distributed Interactive Applications: A Survey—Part I

This paper is the first part of a two-part paper that documents a detailed survey of the research carried out on consistency and latency in distributed interactive applications (DIAs) in recent decades. Part I reviews the terminology associated with DIAs and offers definitions for consistency and latency. Related issues such as jitter and fidelity are also discussed. Furthermore, the various consistency maintenance mechanisms that researchers have used to improve consistency and reduce latency effects are considered. These mechanisms are grouped into one of three categories, namely time management, Information management and system architectural management. This paper presents the techniques associated with the time management category. Examples of such mechanisms include time warp, lock step synchronisation and predictive time management. The remaining two categories are presented in part two of the survey

Measurement of Remote Response Delay in Multi-Synchronous Collaborative Editing

In this study we examine the performance consequences of simulated network delay in collaborative document editing. Related studies suggest that while delay in the distribution of an individual's work to the team is a potential influence on performance, the impact is a function of strategy and task. However, a dearth of quantitative research in the domain of document editing makes it difficult to evaluate either concern for delay or the efficacy of compensatory strategies. The present study measures performance on an artificial document editing task with a time constant and metrics for process and outcome suitable for experimental study. Results suggest that strategy in the distribution of work influences task outcome at least as much as delay in the distribution of work in progress. However, a paradoxical interaction between delay and strategy emerged, in which the more generally effective, but highly coupled strategy was also more sensitive to delay

How Do User Groups Cope with Delay in Real-Time Collaborative Note Taking

International audienceA property of general interest of real-time collaborative editors is delay. Delays exist between the execution of one user's modification and the visibility of this modification to the other users. Such delays are in part fundamental to the network, as well as arising from the consistency maintenance algorithms and underlying architecture of collaborative editors. Existing quantitative research on collaborative document editing does not examine either concern for delay or the efficacy of compensatory strategies. We studied an artificial note taking task in French where we introduced simulated delay. We found out a general effect of delay on performance related to the ability to manage redundancy and errors across the document. We interpret this finding as a compromised ability to maintain awareness of team member activity, and a reversion to independent work. Measures of common ground in accompanying chat indicate that groups with less experienced team members attempt to compensate for the effect of delay. In contrast, more experienced groups do not adjust their communication in response to delay, and their performance remains sensitive to the delay manipulation

Reducing the effect of network delay on tightly-coupled interaction

Tightly-coupled interaction is shared work in which each person’s actions immediately and continuously influence the actions of others. Tightly-coupled interaction is a hallmark of expert behaviour in face-to-face activity, but becomes extremely difficult to accomplish in distributed groupware. The main cause of this difficulty is network delay – even amounts as small as 100ms – that disrupts people’s ability to synchronize their actions with another person. To reduce the effects of delay on tightly-coupled interaction, I introduce a new technique called Feedback-Feedthrough Synchronization (FFS). FFS causes visual feedback from an action to occur at approximately the same time for both the local and the remote person, preventing one person from getting ahead of the other in the coordinated interaction. I tested the effects of FFS on group performance in several delay conditions, and my study showed that FFS substantially improved users’ performance: accuracy was significantly improved at all levels of delay, and without noticeable increase in perceived effort or frustration. Techniques like FFS that support the requirements of tightly-coupled interaction provide new means for improving the usability of groupware that operates on real-world networks

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