Real-time joint rate and protection allocation for multi-user scalable video streaming

In this paper, we present a real-time joint bit-rate and error protection allocation scheme for multiple scalable video streams sharing a single downlink channel. High speed downlink packet access (HSDPA) systems allow for multiple live video streams to share a common downlink channel among multiple mobile users. However, the unreliable nature of the wireless link results in packet losses and fluctuations in the available channel capacity. This calls for flexible error protection and rate control strategies implemented at the video encoders that can respond to the variation in channel conditions. In this paper, we formulate a global optimization problem, which is solved at every frame transmission instant and minimizes the expected sum of the video frame distortions of all users by adjusting the encoding quality at the base- and enhancement-layers as well as the application layer error protection overhead used to combat packet losses. We consider frame-level unequal erasure protection (UXP) as the application layer forward error correction scheme. Performance evaluations show that compared with existing schemes our proposed scheme delivers far superior decoded video quality averaging 1.2 dB in PSNR.