QoS involves tracking of jitter, latency and other measurable parameters. It is a series of objective measurements of performance. If the QoS score isn’t good enough, operators can search for the problem and fix it. QoE is a far more subjective measure of how the viewer is judging the audio and video that is being viewed. It is less straight-forward. The closest comparison is the mean opinion score (MOS) that long has been used by carriers to judge the performance of telephone networks.
Standards aimed at helping service providers assess QoE exist. For instance, the International Telecommunications Union – Terrestrial (ITU-T) offers the Perceptual Evaluation of Speech Quality (PESQ), which is used in conjunction with the ITU-T P.800. However, actually automating testing and providing capabilities to the equipment that cable operators use for all the metrics is a gradual process, said Andre Gaynulin, VP of business development for Q'ligent, a maker of platforms to assess network QoE and QoS.
The challenge of calculating QoE is made even greater by the increasing complexity of the cable environment. On one level, over-the-top (OTT) providers demand the ability to measure precisely what their customers are seeing and can complain if they feel that performance is inadequate. At the same time, the fluidity of Docsis 3.0 and, soon, Docsis 3.1 means that the amount and location of bandwidth for any content or application can change in real time.
A key tool in QoE measurements is deep packet inspection (DPI). DPI, as the name implies, is a technique that digs into an Internet packet to determine precisely what it is delivering and how various elements measure up against a predetermined norm. It is a potent technology. However, it remains to be seen how deeply it can be leveraged by operators. The uncertainty about Net Neutrality, which won’t be settled for months or even years, is causing some operators to move a bit more slowly on QoE in general and DPI in particular.
What the Federal Communications Commission – and perhaps the courts – finally determine on Net Neutrality may influence QoE in two ways: The rules will control how spectrum is divvied up between tenants of the network and how deeply operators are allowed to examine the packets flowing through those networks. “Today, operators are not using it as aggressively as possible because they are scared of the FCC and the uncertainly with Net Neutrality,” said Cam Cullen, VP of global marketing at Procera Networks. “If that fear goes away, they could in short order enhance DPI.”
A third issue that makes QoE a difficult challenge is the limitation of CMTS technology that is in place. A key to effective use of DPI is an awareness of the type of content that is traversing the network. The system, in short, needs to know at what it is looking. That capability, Cullen said, is absent in the current generation of CMTSs. “Most [CMTSs] bought and used in cable networks don’t have that level of intelligence,” he said.
In short, the cable industry is struggling with both the technology and regulatory issues surrounding QoE. “Other [world] regions are further along than the U.S.,” said Javier Jimenez, SVP and general manager for the U.S. and Canada for Intraway.
The idea is that such granular assessments of usage and satisfaction generated by QoE married to machine intelligence and big data analytics will produce a tremendous amount of data that will help in a number of ways. The first, of course, is simply to improve audio and video. Beyond that, the placement of sensors in the field and their assessment of QoE at strategic points can help in root cause analysis of problems, aid in the planning of system upgrades and even support sales efforts, said Qligent COO Ted Korte.
The cable industry is aware of the need for QoE, observers say. It is far away from implementing it, however. “In my opinion, [MSOs] have the biggest problem to solve because cable is the predominant carrier of Internet traffic,” Korte said.
Carl Weinschenk is the Senior Editor of Broadband Technology Report. Reach him at [email protected].