# A Study on Design Requirement Development and Satisfaction for Future Virtual World Systems
## 2 Trend Analysis
### Implications  
The changes in investment, value, population, and consumption show the industrial/market adoption of each virtual-world-related technology. Following technology changes, we believe user and market expectations towards future virtual worlds will change along with their underlying technologies, resulting in new system design requirements. Thus, the implications of trends towards virtual world system development are studied, mainly from two perspectives: computing and content. From the computing perspective, the mobility trend implies the capability limitation of client-end devices for running virtual world applications. Compared with desktop computers and game consoles, mobile devices are not configured with equally high computing power (e.g., graphic processing power), storage, and bandwidth resources. In terms of floating-point arithmetic computation, for example, the performance of Nintendo Switch (2017, portable mode) and Samsung Galaxy S10 (2019) is 157 GFLOPS and 899 GFLOPS, respectively, while Sony PlayStation 4 already reached 4197.8 GFLOPS in 2014. On the other hand, the immersion and intelligence trends imply the increase of rendering complexity and computing tasks to run a high-fidelity virtual world with massive copresent user and software agents to promote users' sense of social presence [50] and satisfaction [51], such as World of Warcraft. The conflict between the limited client-end resources and the rapid increase of computational complexity implies that mobile clients may have limited capability to provide large-scale immersive rendering and intelligent computing functions [52]. Thus, computing resource sufficiency is the first emerging requirement. Moreover, a single mobile device is more subject to failure than a desktop computer for two reasons [52; 53]. First, a connection to remote services through a wireless network is less stable than through a wired network, as the former relies on signal quality. Second, mobile devices have limited battery life and battery quickly depletes for resource-hungry applications, such as virtual world, leading to device failure. A poorly connected or highly congested network will even cause extra power consumption, due to communication overhead increase [54]. Since unstable connections will corrupt users' gaming experience, and device failure may cause game state loss, computing reliability is another new requirement. The above issues bring mobile cloud gaming [55] to virtual world development. From the content perspective of virtual world development, diversity implies that more content will be generated by users, including user-created virtual objects and virtual wealth generated in gaming [56]. Meanwhile, interconnectivity implies that more user information will be stored in virtual worlds, including the user data collected from multiple peripheral (i.e., wearable and IoT) devices and the relationships built from users' online social networks. For simplicity, the content, including user-generated objects, virtual wealth, user data, and social connections, which virtually belong to a user, are uniformly called user content. The increase and importance of user content have two questions drawing our attention. First, intuitively, will users suffer content loss in the case of virtual world application failures, such as infrastructure failure or service discontinuation? To avoid content loss, this question brings the persistency requirement to system design. Besides content storage, users may also care more than ever about how a system will treat their content. With the increase of personal data and social connections, data security is gradually becoming a great concern to users, especially the security of privacy-sensitive information, including personal identification, personal (i.e., religion, race, health, sexual orientation, financial, biometric, etc.) information, collected data, and device traceable information.