 | Issue: | EMEA 2009 |
| Article no.: | 14 | |
| Topic: | VoIP and video conferencing – does quality of service cut it? | |
| Author: | Joe Frost | |
| Title: | VP Marketing | |
| Organisation: | Psytechnics | |
| PDF size: | 188KB |
About author
Joe Frost is Psytechnics’ Vice President of Marketing; he has nearly 30 years’ experience in the IT and networking industry. Mr Frost has spent his entire career working in IT, starting as an engineer and networking consultant at Digital Equipment, then moving into product management and marketing roles at 3Com, Cisco Systems, Inktomi and JacobsRimell.
Article abstract
Despite the great advances in telecommunications technology, technical problems users are often dissatisfied with the quality of service (QoS) received and the quality of experience (QoE) perceived. Businesses use video conferencing to eliminate travel, but picture quality is often so bad they must revert to a voice-only call. Most carriers use management tools that tell if the signal arrived – the QoS. Few as of yet can monitor the quality of the signal, the QoE, for each and every call.
Full Article
The rise of IP telephony and IP video conferencing has transformed the way that many of us do business, allowing us to make voice and video calls to the other side of the world at very low cost. But how often have you phoned a company or colleague only to find that you cannot properly hear the person on the other end of the line? How many times have you tried to have a video conference only to find that the picture quality is so poor or the synchronisation between voice and video so bad that you have to revert to an audio only call? Big players across the globe and in the Middle East such as Microsoft, Cisco and IBM are now offering increasingly popular Unified Communications (UC) packages for the enterprise. Frost & Sullivan predicts the EMEA Unified Messaging and Communication Market to be worth €539.5m in 2012. Nevertheless, while business users are keen to take advantage of the heightened convenience these tools can offer, they can still experience quality problems with voice or video calls on IP networks. When it comes to IP voice calls, business users typically complain about call distortion, echo, and noise. With IP video calls it is picture blocking, distortion or loss of lip-sync that cause complaints, despite the care taken, pre- and post- deployment, to test the network’s ability to carry real-time communications traffic. The majority of IP telephony and network management software vendors offer Quality of Service (QoS) based management and monitoring, but in reality the QoS based tools just don’t cut it. For real-time visibility of what the users actually experience, a new approach is needed. Traditional operating procedures and tools focus inwardly on the network, devices, bandwidth, and traditional network (QoS) measurements and cannot provide the information the support team requires to cope with the users’ needs. Vendors and Managed Service Providers (MSPs) must provide the capability to monitor and manage both network and application performance to make their integrated communications systems meet acceptable performance standards. We are not saying that QoS shouldn’t be implemented and measured, but QoS measures only do what they say on the tin – control the way network traffic is carried and prioritized, enabling applications to work as effectively as possible when competing for network resources. QoS may give the green light in terms of carrying and prioritizing different streams of network traffic; unfortunately, this alone is not enough to guarantee users’ experience or service levels for real-time communications applications such as voice and video. To put this in perspective, think about buying a new car; let’s compare this to the IP QoS mechanism. You place your order for the car and agree to collect it at a certain time. The car manufacturer manages the production line and your car arrives at the dealer as agreed. However, you wouldn’t be very happy if your new car arrived looking exactly as expected but – when you got in it – there was no steering wheel, and the gearbox was from a different model. Applying this analogy to an IP network, QoS-based management tools can make sure all voice and video data being carried across the network arrives at its designated end point (suitably prioritised because voice and video are real-time applications) and then turn the ‘green light’ on. What QoS cannot do, however, is ensure that the actual voice conversation, or the video signal carried within the data stream, was intelligible and undamaged, meaning that it cannot give any real indication of whether the end user experience was acceptable. Existing network and VoIP management tools do their job of managing network performance and availability, typically reporting an ‘IP MOS’ (mean opinion score) as their indicator of voice performance. However, these measures bear no relation to the users’ actual call experience, leaving operations and support without a way to ‘see’ and diagnose call quality problems. The ability to measure the user experience termed ‘Quality of Experience’ (QoE) – as well as network-related QoS is fundamental to a consistent and acceptable IP telephony and video conferencing user experience; it also enables efficient and profitable operations and support. It is the combination of QoS and QoE monitoring and reporting that makes a good IP voice and video applications performance management strategy. If we look at the difference between QoS and QoE we can see why they are both needed and where they are significantly different. QoS enables you to provide better service for specific traffic by changing the relative priorities of the traffic on a real-time basis. QoS based congestion-management tools raise the priority of more ‘important’ flows using queuing mechanisms, and servicing these queues with different priorities and traffic management mechanisms. Traffic policing and shaping effectively prioritise a flow by limiting the throughput of other flows, reducing the impact of jitter, packet loss and latency on the prioritised flow. QoE is significantly different and complementary to QoS. QoE is a purely subjective measure, based on the user’s perspective of the overall value or quality of the service used. It is influenced by the type of device the user is using, and is typically represented by a different set of MOS scores that accurately reflect the user experience based on the service level achieved. Whereas QoE relies on the network’s QoS capabilities, it additionally adds a significantly increased degree of visibility. QoE monitoring does look at QoS characteristics, but on a more granular, per stream basis. For QoE, every phone call is monitored in both directions simultaneously; in contrast, network-based QoS typically looks at flows by traffic type and reports all voice traffic as one flow, which does not help one judge the QoE for specific calls. If we apply our car analogy again, QoS ensures that the car ordered is delivered to the right place at the right time; QoE, on the other hand, ensures that the customer gets what they ordered with the right fittings and accessories, all working, clean and shiny. QoE monitoring, to be accurate, should also take into account any capabilities that the end device may have to mask network based problems from the user, or not, as the case may be for lower cost terminal equipment in some cases. For example, if jitter is detected on a particular call, this may have an impact on the quality of the voice in the call. But if the end device (handset, soft client, or video conferencing station) has been characterised as having advanced jitter handling built into it, then there is no need to raise an alarm because this instance of jitter has not impacted on the user. Using our car analogy again, if the car dealer knows that one of his new car customers is tolerant of a delivery delay he can push that car to the back of the pre-delivery workshop and concentrate on those customers that he/she knows will be impatient and get their car prepped first. Using this process he/she keeps all his customers happy even though there was a slight delivery delay. Lastly, QoE based monitoring also looks at how the signal – the voice analogue signal carried inside the IP packets – carried by the network is performing. This provides the ability to detect in real time whether the voice conversation has been impacted by background noise, or has become distorted, or indeed whether there are other artefacts introduced (such as echo) that may contribute to a poor call experience. These QoE measurement techniques are now defined by the International Telecommunications Union (ITU) and recognised throughout the industry. So, user QoE monitoring provides more granular visibility for each and every call: QoE monitoring looks at the quality of the payload or voice signals being carried by the IP network to detect and report any factors that are known to impact users’ perception of quality. This additional level of visibility allows operations and support teams to work much more effectively and fix problems correctly the first time. The widespread use of IP telephony, IP video conferencing and eventually UC gives businesses advanced communications features that, with application integration, increase productivity and reduce capital and call costs. Unacceptable call quality, however, can mean the loss of business, and result in a substantial loss of customer confidence and brand reliability for the company as a whole. The importance of call quality and user confidence cannot be underestimated. Customer-service focused companies can win and lose customers, revenue and staff through frustration with call quality. By taking a purely ‘network-centric’ view of a UC deployment and ongoing operations, using existing or traditional network and IP telephony management tools that focus on IP QoS and network and device availability, there is no ability to focus on the user or the customer experience, and support and operational costs go unchecked. As UC, IP telephony and IP video conferencing roll out across organisations on a larger scale, it is the proactive monitoring of the system at both the network and the application level, that is, the user’s perception of quality that becomes the key factor in controlling operating costs, and maintaining a consistent and acceptable user experience.
