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August 2009 | Volume 12 / Number 8
Feature Story

Guaranteeing Quality of Service

By: Richard “Zippy” Grigonis

In telecom, Quality of Service (QoS) refers to the measurement and reporting of metrics regarding such packet-switched network impairments packet loss, delay and “jitter” (variability of packet arrival times). It can also include not just the detection but ways of mitigating and or eliminating such impairments, all of which degrade the quality of voice, video, data and multimedia communications. Quality of Experience (QoE), on the other hand, relates to overall customer satisfaction. No one cares about perfect IPTV (News - Alert) video if it takes too long to change channels, or if a user doesn’t perceive enough value to pay for a service subscription.

QoS and QoE became a big deal in the packet-switched network world when real-time, multimedia communications moved over to IP from the old circuit-switched networks of the PSTN. Initially, IP networks such as the Internet had not been designed to handle voice calling, PBX (News - Alert)/Centrex services, presence with instant voice or video calling/conferencing, multimedia collaboration, video conferencing, distance learning, interactive Customer/Supplier Relationship Management (C/SRM), multimedia customer care web sites, and demand end-to-end monitoring of QoS.

Moreover, QoS and QoE is such a big concern in IP networks not just because of real-time communications, but also because such communications must traverse multiple IP networks (wireline, wireless, cable) while satisfying security, service assurance and law enforcement requirements. Phone calls also had to pass through corporate firewalls. All of this led to the development of the Session Border Controller (SBC), made by such companies as Acme Packet (News - Alert).

Acme Packet’s Jonathan Zarkower, director of product marketing, says: “Particularly in the enterprise, we find that many people are still associating SBCs with VoIP security, and not a whole lot of time is spent discussing the various capabilities or functional areas where SBCs play a role. Our tagline is, ‘Trusted, first-class communications’. The ‘first-class’ part speaks to the whole notion of QoS and QoE – basically high-quality IP communications. The SBC plays a critical role in helping to deliver that. If I had to break it down, I’d talk about it in terms of three different levels. The first level is more of a ‘mission control’ function. That can involve setting policy-based constraints on a per-user or per-network basis, or on session agents. It just assures that there are resources available from a bandwidth standpoint, but also because there are resources available relative to the infrastructure; i.e., the IP PBXs, UC server infrastructure, and so forth. SBCs are unique in that they have the ability to not only monitor bandwidth usage and apply policies and impose bandwidth constraints, but they also have the ability to proactively monitor upstream elements such as PBXs, so they know, for instance, how busy those devices may be. And then we can control the rate of, say Session Initiation Protocol (News - Alert) (SIP)-registrations to that particular element. We can set limits based on session rate capacity. We can police registration rates and set burst rate limits, and things like that.”

“The second key level involves traffic management – transport management, really,” says Zarkower. “So that basically involves detecting failures and rerouting, or QoS-based marking and routing, or mapping based on specific networks or applications. It’s about controlling transport and media flows. The third level has more to do with the feedback loop, or our ability to monitor such things as QoS, answer-seizure ratios, packet latency, jitter and loss, and do routing based on that. Or, at the very least, provide reporting back to the end-users so they can, say, hold their SIP trunking providers to the Service Level Agreements [SLAs].”

Just Imagine

Imagine Communications’ Imagine ICE Video Platform employs a combination of next-gen video processing, variable bit rate coding and statistical multiplexing to enable up to 50 percent more streams over existing infrastructure (be it digital cable, satellite, the Internet or mobile video) and yet the Imagine ICE-Q video quality measurement algorithms are able to ensure the highest video quality at any given bit rate. As a result, Imagine Communication’s content providers and system operator customers have dramatically expanded their premium services, such as HDTV, VOD, and even HD-VOD – while at the same time offering subscribers excellent picture quality. ICE supports various applications, including IPTV, wireless video, and “over-the-top” Internet video, paving the way for Imagine’s vision of “PersonalizedTV” on every screen.




Imagine Communications’ CEO, Jamie Howard, says: “There’s a movement toward giving consumers the ultimate choice in their TV and video habits. We call that PersonalizedTV. When we leave the push mode experience of traditional and legacy broadcast TV and video, and move toward the Personalized TV experience, where the consumer initiates the ‘pull’ of content coming to any device, this opens up both the needs and opportunities for an unprecedented QoS requirement. What we’re all about is enabling PersonalizedTV with the best video quality and QoS. This is our ‘sweet spot.’”

“There are several trends and challenges that we need to take into consideration as we examine the situation,” says Howard. “Probably the most central trend is that the proliferation of IP-enabled devices with increased computing power, improved displays and greater battery capability, is rapidly changing how consumers access and experience video. There’s a cultural revolution going on that’s really driving this change from the push model to the pull model, which means that networks have to be a lot more flexible, adaptable and scalable to achieve efficient network resource utilization to really deliver quality of experience. Imagine’s technology addresses that.”

“There are both opportunities and challenges associated with what’s happening today, and Imagine’s technology is designed to deal with this transformation,” says Howard. “First, we give the consumer control over the experience while enabling the network service provider and content provider to maintain control over their video assets. We have to do that as we enable the operator to deliver a TV-like viewing experience, which in QoS terms means no stuttering or jerky video frames, which we’ve seen in the past with Internet video. After all, broadcast video over cable, satellite or teleco arrives in a pretty steady manner, notwithstanding those occasional times when there may be a cable plant outage or a sunspot that disrupts a satellite transmission. For the most part, you turn on your TV and tune to a certain channel, and you experience uninterrupted video. On the public Internet however, the available bandwidth varies owing to traffic congestion, and a stuttering or ‘freeze-framing’ effect can take place, making it a less than compelling experience. So one challenge is to overcome that and deliver a TV-like viewing experience with a steady-stream play-through.”

Howard continues: “Another challenge is that because these devices in our homes have evolved and have IP connections, not to mention improved microprocessors and display capabilities, people want both HD video and sound quality for the content they want to experience, whether it’s being streamed to them through traditional broadcast or on-demand technologies, or even over the Internet. Look at services such as Hulu, Apple (News - Alert) TV and Netflix. You can download HD movies and TV episodes and events over the Internet. Managing the quality of video and the quality of sound is another challenge associated with QoE.”

“Then there’s the dimension of experience that has to do with the feel of the interaction between your content choice and the delivery of that choice,” says Howard. “I’m referring to things such as content discovery. When you have 500 choices among video and audio services, how do you search and discover the content that is really relevant to you? When you add the Internet to that dimension, where there’s a nearly infinite number of possibilities of content choice. How do you really easily sift through those choices to get to the content that’s most relevant to you?”

“Then there’s time-shifting and place-shifting, which involves content portability from device to device and network-to-network so that there’s a ‘TV anywhere’ type of experience. This is the new world of QoS. New technologies open up great opportunities, but it also carries a lot of challenges that technology companies such as Imagine Communications are working very hard to solve for the tier-1 service provider market and the top content providers.”

The Customer is Always Right

InfoVista enables managed service providers, mobile operators, broadband operators and enterprise IT organizations to cost-effectively ensure the quality and availability of the services they deliver, empowering these organizations to successfully make the transformation from infrastructure providers to service providers.

InfoVista’s Director of Product Marketing, Steve Hateley, explains: “QoS from our perspective is very much related to the implementation on the network. We refer to QoS in terms of how you implement the treatment of different traffic flows through equipment from the enterprise – CPE device – and then how the different types of traffic in different classes of service are apportioned at that CPE device to be then sent across the service provider’s network. That’s really how we see QoS. As for QoE, we view it as a measure of the end user’s experience, of their applications, really. This involves things such as putting an agent on a cell phone to monitor the performance of the received application on a mobile device. Or if something is sitting on your desktop which is monitoring the performance of a received application on your PC, which can be affected by multiple touch points throughout the network. A poor user QoE could be the result of a deficiency in the network, or it could be something to do with a long server response time that’s degrading your experience of the application. There are many things that could be degrading the QoE.”

“They way you monitor and maintain QoE is to use both active and passive probing techniques,” says Hately, “or it could be something as simple as getting customer feedback, and how you interpret that feedback.”

Thus, service providers may be armed with all sorts of interesting QoS tools, but ultimately, QoE is more of an art than a science. IT

Richard Grigonis is executive editor of TMC (News - Alert)’s IP Communications Group.

 

The following companies were mentioned in this article:

Acme Packet - (www.acmepacket.com)

Imagine Communications - (www.imaginecommunications.com)

InfoVista - (www.infovista.com)

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