Wireless Video Transmission over Multiuser MIMO Systems with Fair Power Allocation With the spread of mobile devices, image and video transmission is in great demand. The use of multiuser multipleinput multipleoutput (MUMIMO) systems, where multiple data can be sent to multiple users, is highly expected. This paper proposes a novel power allocation scheme for MUMIMO systems, which minimizes the variance of channel capacities of each spatial stream of all users to achieve user fairness in terms of video quality. In addition to the user fairness, we make the spatial streams which convey visually more important information be highquality for achieving high video quality. Simulation results show that the proposed power allocation enables to equalize video quality even if the distances between a transmitter and users are different.

PowerEfficient Video Streaming on Mobile Devices Using Optimal Spatial Scaling This paper derives optimal spatial scaling and rate control parameters for powerefficient wireless video streaming on portable devices. A video streaming application is studied, which receives a highresolution and highquality video stream from a remote server and displays the content to the enduser. We show that the resolution of the input video can be adjusted such that the qualitypower tradeoff is optimized. Making use of a power model from the literature and subjective quality evaluation using a perceptual metric, we derive optimal combinations of the scaling factor and the ratecontrol parameter for encoding. For HD sequences, up to 10% of power can be saved at negligible quality losses and up to 15% of power can be saved at tolerable distortions. To show general validity, the method was tested for WiFi and a mobile network as well as for two different smartphones.