NCVCS: Network-coding-based video conference system for mobile devices in multicast networks

The user experience has become an important aspect during the design of modern mobile communication devices. The image resolution, fluency and delay are significant factors that affect the user experience during video transmission. To address this issue, this paper proposes a reliable system called NCVCS (Network-Coding-Based Video Conference System) to improve the user experience during video conference with mobile devices. NCVCS is based on network coding, and the coding operation is performed at the intermediate nodes to improve the performance. A coding server is introduced, acting as an intermediate node to perform the coding operation. During the network coding process, NCVCS re-organizes the original data to implement multi-rate multicast such that the heterogeneous devices with different specifications and different locations could join the conference with different resolutions. A real-world testbed consisting of 15 wireless Android devices is implemented to verify whether it is feasible to use network coding in such scenarios. And the performance of NCVCS is evaluated in the testbed. Compared with the traditional multicasting technology, NCVCS could provide higher delivery ratio and better user experience. Especially, when the link quality is poor, our scheme could provide clearer and more fluent media stream.