Subjective evaluation of multi-user rate allocation for streaming heterogeneous video contents over wireless networks

Multi-user rate allocation is essential for preventing multiple simultaneous video streaming sessions from congesting a time- shared wireless network. Although the problem fits naturally within an optimization framework, it remains unclear which objective function to optimize, especially for video streams with heterogeneous resolutions, frame rates and content complexity. To address this issue, we have conducted subjective tests and have collected viewers' opinion scores for various quality combinations of high-definition (HD) and standard-definition (SD) video snapshots. The test results yield a simple subjective quality model, useful for comparing performance of several rate allocation schemes. It is shown that the subjectively preferred allocation can be closely approximated by minimizing weighted or equal-weight sum of mean-squared-error (MSE) distortion of all streams. Significant performance gains can be achieved over media-unaware TCP-friendly allocation, up to 1.5 in MOS, when network resources are limited.