摘要
Mobile devices are getting increasingly popular all over the world. Mobile users in developing countries, however, rarely have Internet access, which puts them at economic and social disadvantages compared to their counterparts in developed countries. We propose mBridge: a distributed system to disseminate multimedia content to mobile users with intermittent Internet access and opportunistic ad-hoc connectivity. By disseminating various multimedia content, such as news reports, notification messages, targeted advertisements, movie trailers, and TV shows, mBridge aims to eliminate the digital divide. We formulate an optimization problem to compute personalized distribution plans for individual mobile users, to maximize the overall user experience under various resource constraints. Our formulation jointly considers the characteristics of multimedia content, mobile users, and intermittent networks. We present an efficient distribution planning algorithm to solve our problem, and we develop several online heuristics to adapt to the system and network dynamics. We implement a prototype system and demonstrate that our algorithm outperforms the existing algorithms by up to 206%, 472% and 188% in terms of user experience, disk efficiency, and energy efficiency, respectively. In addition, we conduct trace-driven simulations to rigorously evaluate the proposed system in different environments and for large-scale deployments. Our simulation results demonstrate that the proposed algorithm substantially outperforms the closest ones in the literature in all performance measures. We believe that mBridge can allow multimedia content providers to reach out to more mobile users, and mobile users to access multimedia content without always-on Internet access.