Following fast growth of cellular networks, more users have drawn attention to the contradiction between dynamic user data traffic and static data plans. To address this important but largely unexplored issue, in this paper, we design a new data plan sharing system named Prometheus, which is based on the scenario that some smartphone users have surplus data traffic and are willing to help others download data. To realize this system, we first propose a mechanism that incorporates LT codes into UDP. It is robust to transmission errors and encourages more concurrent transmissions and forwardings. It also can be implemented easily with low implementation complexity. Then we design an incentive mechanism using a Stackelberg game to choose assistant users ( @math ), all participants will gain credits in return, which can be used to ask for future help when they need to download something. Finally real environment experiments are conducted and the results show that users in our Prometheus not only can manage their surplus data plan more efficiently, but also achieve a higher speed download rate.
Video applications are increasingly popular over smartphones. However, in current cellular systems, the downlink data rate fluctuates and the loss rate can be quite high. We are interested in the scenario where a group of smartphone users, within proximity of each other, are interested in viewing the same video at the same time and are also willing to cooperate with each other. We propose a system that maximizes the video quality by appropriately using all available resources, namely the cellular connections to the phones as well as the device-to-device links that can be established via Bluetooth or WiFi. Key ingredients of our design are: (i) the cooperation among users, (ii) network coding, and (iii) exploiting broadcast in the mobile-to-mobile links. Our approach is grounded on a network utility maximization formulation of the problem. We present numerical results that demonstrate the benefit of our approach, and we implement a prototype on android phones. A promising approach for power reduction in mobile devices is peer-to-peer cooperation. In this paper, we present a testbed system implementation to evaluate the performance of an infrastructure controlled cooperative video streaming architecture. A number of mobile devices in close proximity are connected to the Internet through a wireless access point and are all requesting the same video stream from a dedicated server. Instead of sending the stream independently to each device, the server distributes the video packets among the devices, over a long-range wireless link using WLAN technology; the devices then exchange the received packets among each other over short-range wireless links using Bluetooth technology. The implemented testbed is used to experimentally demonstrate the power reduction gains in mobile devices and to derive an analytical model that relates power consumption to various design and system parameters.