Transient analysis of queues for peer-based multimedia content delivery

Consider a firm that sells online multimedia content. In order to manage costs and quality of service, this firm maintains a peer network that allows new users to download files from their peers who have previously downloaded the required files. The scenario can be modeled as a queueing system where the number of servers varies over time. Analytical models are developed that are based on fluid and diffusion approximations and allow analysis of transient system performance. The same approximations are used to analyze the steady-state behavior of this network. It is shown that the existing fluid and diffusion approximations are inaccurate for transient analysis. To address this shortcoming, a novel Gaussian-based adjustment is proposed and it significantly improves the accuracy of the approximations. Furthermore, the models used in this research can be extended seamlessly to the case of time-varying system parameters (e.g., arrival rates and service rates). Several numerical examples are provided that show how the proposed adjusted models work for the analysis of transient phenomena.