Importance of Cross-Correlation of QoS metrics in Network Emulators to Evaluate QoE of Video Streaming Applications

Abstract

Most of the existing studies on mapping of Quality of Service (QoS) to Quality of Experience (QoE) ignores any correlation between the QoS metrics. Network emulators such as NetEm that are used to study various network situations, have similar limitations. NetEm's inability to emulate realistic long-tail packet latency and correlation between QoS metrics may have already resulted in doubtful QoS to QoE functions. In this paper, we analysed real-time cellular QoS metrics data, and observed that there is significant correlation between several QoS parameters. We used them to create bespoke distributions for NetEm using different statistical methods such as maximum likelihood estimation and cumulative distribution functions. These distributions were used to modify NetEm to address the lack of representative packet waiting-time distributions. In addition, the bespoke distributions were also used to provide a way to emulate correlated packet delay and loss in NetEm. This bespoke emulator was then used to observe the impact of correlated delay-loss metric on end user QoE of video streaming applications using PSNR, SSIM and VMAF objective evaluation techniques. The emulation results showed that bespoke emulator gives better QoE compared to default NetEm configuration for same Packet Loss Ratio (PLR). In this paper, we analysed real-time cellular QoS metrics data, and observed that there is significant correlation between several QoS parameters. We used them to create bespoke distributions for NetEm using different statistical methods such as maximum likelihood estimation and cumulative distribution functions. These distributions were used to modify NetEm to address the lack of representative packet waiting-time distributions. In addition, the bespoke distributions were also used to provide a way to emulate correlated packet delay and loss in NetEm. This bespoke emulator was then used to observe the impact of correlated delay-loss metric on end user QoE of video streaming applications using PSNR, SSIM and VMAF objective evaluation techniques. The emulation results showed that bespoke emulator gives better QoE compared to default NetEm configuration for same Packet Loss Ratio (PLR).