All Signs Point to Quality — QoS and QoE

Both the importance of quality of service (QoS) and its complexity are increasing in an era of exploding programming streams and operators' desire to appeal to larger commercial clients. There are two main changes afoot. The first is that baseline QoS metrics...

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Qos Feature Image 300x180Both the importance of quality of service (QoS) and its complexity are increasing in an era of exploding programming streams and operators' desire to appeal to larger commercial clients.

There are two main changes afoot. The first is that baseline QoS metrics increasingly are being supplemented by quality of experience (QoE), a set of more subjective measures of what subscribers actually see and hear. Secondly, the move to entice larger business customers is shifting the way QoS and QoE tools are employed.

On the residential side, the most significant trend is the integration of QoS and QoE. The two overlapping approaches enable root cause analysis and prioritization. Jeremy Bennington, senior vice president and general manager for Cheetah, says adding QoE atop QoS enables engineers to drill down to do such things as figure out why a problem exists and whether it is impacting subscribers at that point -- or is likely to in the near future.

"If you look just QoS, you are going to be flooded with data," Bennington notes. "You will see data throughput, loss, delays, things like that ... QoE determines which problem to solve first."

Playing that role -- essentially, being the doctor interpreting the test results -- is the long-established function of QoE. What is changing, Bennington says, is that the measurements are growing more sophisticated and are being automated to continually monitor all channels simultaneously. The CALM Act, which mandates equal audio levels between commercials and other programming, also is pushing operators toward more automated and continual monitoring. The video and audio monitoring tools generally are in the same package.

The industry is tweaking two telephone industry measures -- R-value and mean opinion score (MOS) -- to assess picture quality. Steve Liu, vice president of product management and business development for Tektronix, explains that there are two levels at which video quality is measured. One looks at structural issues that manifest themselves in things such as macro blocking. The other generally is lack of sufficient bandwidth, which shows up as breakdowns in the image during times of intense action, such as during a sporting event.

The industry is starting to learn to the importance of QoE and deploy it more broadly, Bennington says. The next step will be for programmers to use it. That will create a baseline that marks the quality of the video when it enters the cable network. This data will make it easier to determine where the trouble spots are.

QoS and QoE Key in the Enterprise

The other change in the world of QoS is tied to the increasing desire to move into the enterprise space currently dominated by the telcos. The cable industry for many years relied on a very practical way to spot trouble in its HFC networks: Wait for subscribers to call. That fading approach no longer is appropriate for residential or business customers. The move to entice larger enterprises -- and satisfy the service level agreements (SLAs) that they use -- points to a far greater concentration on QoS and QoE.

Bill Dentinger, senior director of business development for test equipment vendor Spirent, says QoS and QoE must continually be measured during turnup, interconnection testing, troubleshooting/sectionalizing and performance monitoring.

Dentinger points to a key difference between deploying QoS/QoE in the commercial services and residential realms. In the business services environment, many connections never enter the headend. Connecting headquarters to a branch office and similar tasks means that QoS and QoE must be established and maintained between two remote locations, Dentinger explains. Indeed, QoS and QoE monitoring requirements often extend outside the system, since a business may be connecting with an end point in another service provider's area.

The industry needs to plan carefully, Dentinger observes. "I think they are in the very early stages of awareness and are plotting a strategy from a solutions standpoint. They know what markets they want to get into and need to figure out how to be effective with it."

The changes will keep coming. Subscribers will increasingly access services over iPads and other mobile devices. While these can be forgiving in terms of QoS -- subscribers are less likely to see impairments on a smaller screen and are more accustomed to glitches over wireless networks -- ways must be found to handle QoS and QoE in the long term.

This is especially difficult in the world of third-party applications, explains Greg Thor, Genband's Solutions Manager for Cable VoIP and Broadband Applications. "What's different today is that when people develop apps, they are assuming someone else is going to figure out how they get supported and maintained," he says. "They are not integrated with any notion of centralized policy."

Carl Weinschenk is a reporter for Broadband Technology Report. Contact him at carl@broadbandtechreport.com.
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