Optimal Mobile Content Downloading in Device-to-Device Communication Underlaying Cellular Networks

With the emerging demands for local area services of popular content downloading, device-to-device (D2D) communication is conceived as a vital technological component for next-generation cellular communication networking to increase the spectral efficiency and to enhance the system capacity. Targeting the application of mobile content downloading, we investigate the fundamental problems of how D2D communication improves the system performance of cellular networks and what is the potential effect of D2D communication, with the aid of the optimal solutions for the system resource allocation and mode selection obtained under the realistic user and mobility conditions. Specifically, by formulating a max-flow optimization problem that maximizes the content downloading flows from all the cellular base stations to the content downloaders through any possible ways of transmission, we obtain the theoretical upper bound to system content-downloading performance. Using realistic mobility model and trace driven simulations, we evaluate the effects of the different system settings on the performance of the mobile content-downloading system, and reveal the fundamental influence of D2D communication.