| Collaborative Virtual Environments (CVEs), such as military training simulations, emergency preparedness exercises, and online games have made a considerable impact on both commercial and academic fields over the last few years. Due to the rapidly increasing usage of personal mobile devices and the need of executing CVE applications in environments that have no previous network infrastructure, Mobile Collaborative Virtual Environments (MCVEs) will become ubiquitous in the future. In such systems, users will share a 3D virtual environment through their mobile devices in an ad-hoc network (MANET) in order to accomplish specific missions. We aspire to develop and deploy CVEs over MANETs using the peer-to-peer model. Both peer-to-peer networks and MANETs exhibit the same features; which include complete decentralization, self-configuration, and self-healing. However, peer-to-peer networks and MANETs operate on different network layers, and may introduce poor performance. Mobile ad-hoc and peer-to-peer networks drive the future of CVEs, and thus form the foundation for this thesis.;Most existing CVE systems are tuned to specific tasks, and their architectures are typically tightly coupled with wired networks and desktop settings, therefore they are not adequate enough for addressing mobile collaborative virtual environments. The evolutionary step in MCVE applications is handling the mobility effect in all its forms, and tackling the poor performance of the ad-hoc network. In this thesis, we explain the main networking issues involved in building scalable MCVEs, and review the most well-known CVE and peer-to-peer systems. We then present a mobility-aware cross-layer approach for MCVE applications; this approach relies on building a dynamic multi-tier overlay network architecture-based Gnutella network. The proposed overlay network will manage mobile devices using a novel rule-based discovery technique, in which users are discovered by their virtual environment interest and proximity. With the help of a caching mechanism and a Gnutella Ultrapeer System to perform a dynamic Ultrapeer selection, we were able to outperform traditional mobile overlay networks, as shown in our simulation results. |
