# A Study on Design Requirement Development and Satisfaction for Future Virtual World Systems
## 6 Conclusions  
We have studied the trends of the virtual-world-related technologies and their implications for future virtual worlds, mainly from the perspectives of revenue, investment, population, and consumption over the platform, application, peripheral and social connection, immersive technologies, and AI. The importance of trend analysis lies in the proposal of new requirements that have not been commonly recognized in the virtual world community for two reasons: First, our trend analysis and requirement development covers a wide range of virtual-world-related technologies, while existing virtual world communities only focuses on a subset of them, e.g., platform, immersive techniques, or game AI, depending on the discipline of a community. Second, these technologies are still evolving, which leads to the change of design requirements derived from them. Therefore, to the best of our knowledge, there is no comprehensive and timely requirement study for virtual world system design. Based on the trends and implications, we have discussed the emerging requirements of virtual world systems' design in detail. These requirements, including the design issues and criteria, provide a complete requirement space for design reference. We have also thoroughly examined the existing virtual world architectures and discussed their satisfiability and limitations to the new requirements. A complete list of requirement satisfaction examples has been provided for function implementation reference. Then, the comparison between architectures shows that none of the existing architectures can fully satisfy all requirements. The detailed comparison results and a new architecture design provide new avenues for virtual world system development. The main contributions of this paper include the development of new virtual world system design requirements, the requirement satisfaction analysis of existing virtual world architectures, and the possible approach to satisfying new design requirements. We hope that the results of this study, the surveyed content, and the analysis can lay a solid foundation and research avenue for future virtual world development.  
For the future of work, we intend to build a prototype virtual world based on the complete Virtual Net design to validate requirement satisfaction with a real system. Based on the prototype, the feature of sufficiency and reliability can be straightforwardly evaluated with mobile clients, such as smartphones. Persistency and credibility, however, cannot be simply evaluated with a close system. They, especially credibility, are more determined to users' subjective feelings, such as user-perceived security and trust in content storage. Thus, they have to be studied by opening the system to human users and collecting user perceptions with a survey or questionnaire.  
The source data collection can be retrieved from [[https://sunniel.github.io/VirtualNet/post/trend-analysis/Supplemental_Material.pdf](https://sunniel.github.io/VirtualNet/post/trend-analysis/Supplemental_Material.pdf)]([https://sunniel.github.io/VirtualNet/post/trend-analysis/Supplemental_Material.pdf](https://sunniel.github.io/VirtualNet/post/trend-analysis/Supplemental_Material.pdf))  
Methodology and conceptualization, B.S. and J.G.; software, formal analysis, and writing--original draft preparation, B.S.; validation and investigation, H.C.; writing--review and editing, W.T.; supervision, funding acquisition, and project administration, J.G. Validation and resources, B.W. and S.Z. All authors have read and agreed to the published version of the manuscript.  
This research is partially supported by the University of Macau Research Grant No. MYRG2017-00091-FST, and the Macau University of Science and Technology Faculty Research Grant (FRG).  
The authors declare no conflicts of interest.