vMOS Aims to Give Telcos a Clear Picture of Video Quality

Today more than half of YouTube and Facebook users watch video from their platforms on mobile devices, with the GSMA estimating that 70% of all mobile network data will be video by 2021. Mobile operators must optimize their networks, but the usual capacity- and coverage-related KPIs don't correlate well for video, while neglecting the subjective elements of what the user actually sees.

A unified industry standard is needed.

The ITU-T has long been researching, developing and evaluating assessment models for video quality assessment, reference models, These evaluation methods include objective and subjective assessment methods, with the objective model defining the conditions for objective experiments, as well as the relevant measurement methods and objective evaluation standards, while the subjective assessment model is an algorithm that defines a set of parameters based on objective inputs to estimate multimedia quality. This cross-pollination methodology has helped drive Huawei to propose a methodology for a new generation of mean opinion score (MOS) for video, or vMOS.

Huawei's vMOS candidate is built on Huawei Technologies Co. Ltd. mLab-partnered research with Oxford and Beijing University where consumers evaluated video qualitatively, leading to the development of three indicators affecting video experience -- video resolution, initial buffering delay and stalling ratio. Combining these indicators with other objective and subjective perceptual data, a mobile scenario-based computational formula was developed, with scoring spanning the same range and relative quality as the MOS test score (from one to five).

Huawei has put its vMOS candidate to work for Etisalat , which has the top-rated mobile network in the UAE (as rated by Ookla), but its mobile video experiences were only middle-of-the-pack, and they needed to know why. Testing was carried out at one of the largest shopping hubs in the country -- the Dubai Mall.

The mall's local area network (LAN) was divided into 50m x 50m grids, and testing revealed that 40% of these grids were performing below the target range for video, with subsequent evaluation revealing the causes as high user number, high interference and weak 4G coverage (leading to 3G fallback). But after Etisalat implemented the proper countermeasures, the percentage of low performers dropped to less than 10%, with LAN data consumption shooting up over 30% over the next three months relative to non-optimized areas.

Current status of vMOS standardization
In terms of the broader standardization process, progressive download streaming and adaptive streaming (TCP-based) is incorporated into the International Telecommunication Union, Standardization Sector (ITU-T) Study Group 12 P.NATS phase 1 (Parametric non-intrusive assessment of TCP-based multimedia streaming quality) standards research work. Huawei's proposed vMOS standards have been selected into the winning group for ITU-T P.NATS phase 1, and Huawei will participate in the standard documentation and code merging work. P.NATS phase 1 supports H.264 encoding and 1080p resolution video, and is planned for release in October 2016.

In addition, Huawei's proposals for 2K/4K resolution and H.265/VP9 encoding has been included in the scope of ITU-T P.NATS phase 2 work-item, which was agreed upon in January.