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Quality of experience (QoE), particularly as it is measured in the WLAN space, can be a difficult concept to wrap your head around.
Of course, QoE isn't a single parameter, but more of a measure of how a given service "feels" as it's delivered over the network -- whether wired or wireless. As a long-time creator and administrator of wireless networks, I generally consider acceptable quality of experience to be achieved via Wi-Fi when not a single user needs to contemplate signal strength, data rate, throughput or connection security because, well, everything just works. That's hardly a scientific or quantitative measure, but then again, QoE is more about perception than it is measureable value. At the same time, certain measurable values are among the building blocks that contribute to acceptable QoE, and by extension, a satisfactory mobile user experience. Put in another way, there is some precision that contributes to the imprecise science of QoE.
QoS is one thing; QoE is something else entirely
Almost every network engineer understands quality of service (QoS). The same really can't be said for quality of experience. Here's one barometer to gauge the overall awareness of QoS versus QoE: Simply do an Internet search on both terms. Inputting them both into Google returned around 400,000 articles for QoE, but around 140 million for QoS.
Before we dig deeper, let's establish that QoE is not the same as QoS (although reckless tech writers will sometimes equate one with the other). Remember that quality of experience is a subjective end-user paradigm, while QoS covers a range of specific and distinct network configurations that can impact how network traffic performs (both for better and for worse).
I can manipulate QoS settings such as protocol priority and defined bandwidth caps to improve the response time of one application over the others traveling in the same pipe. I can also add bandwidth, change codecs and manipulate other components to complement QoS. The goal: improved QoE and a better mobile user experience.
Here's the main difference. QoS is something you configure, while QoE is something your end users experience. On the wired side, you can come close to actually measuring QoE on links of specific capacity, but Wi-Fi is incredibly variable, sporting multiple data rates in use per cell, and vulnerable to performance-impacting factors like interference.
So, does the loose construct of QoE -- combined with the situational variability of Wi-Fi -- mean measuring wireless QoE is a lost cause? Thankfully, the answer is no. But again, remember you are dealing with imprecision, subjectivity and the overall goal of wanting Wi-Fi to work well enough that your users don't have to think about it. To make sense of what potentially sounds incredibly fickle, we can think in terms of thresholds and measurements that either exceed those thresholds or fall below them as the pass/fail mark for wireless QoE. Some toolmakers call this concept service assurance, and it's worth mentioning a couple from the growing ranks of similar products.
Tools that can help you measure quality of experience
One of my favorite utilities for approximating Wi-Fi quality of experience is Fluke Networks' AirCheck for Windows and Android. Within the suite of tools is an application performance module that checks and logs the performance of Web traffic, streaming video and audio, file transfers, and important network services like Dynamic Host Configuration Protocol, domain name system (DNS) and round-trip ping times to configurable destinations. Thresholds and target test endpoints are also configurable. As delivered, AirCheck lets even non-engineers take a legitimate shot at determining whether a given WLAN location should be expected to give acceptable QoE -- and, thus, an improved mobile user experience -- by measuring the performance of a key battery of services.
Where AirCheck is portable and tactical in nature, a company called 7signal provides strategic, holistic and continuous measurements of hundreds of key performance indicators that automate the prediction of acceptable quality of experience from deployed sensors. 7signal is a pricey overlay, but it is also an incredibly powerful option when Wi-Fi QoE simply can't lapse. Part of 7signal's value is the ability to recommend WLAN config changes to optimize system performance in reaction to how it reads the environment.
In addition to these vendors' tools, many network management systems have simple utilities that can help administrators verify critical basics that contribute to QoE. Whether testing authentication server response times, DNS behavior, or network paths, the built-ins have a place, if for no other reason than to identify problem services that diminish QoE when they are not up to par.
Is Wi-Fi a victim of its own success?
Wi-Fi is quickly becoming the user access method of choice, but it's also -- in many ways -- a victim of its own popularity. Poorly designed WLAN systems, consumer-grade Wi-Fi gadgets that have infiltrated the enterprise and performance inconsistencies all contribute to poor Wi-Fi quality of experience. Even the purchase of top-grade WLAN hardware is no guarantee that users will be happy using the network. It's critical that those designing and engineering Wi-Fi understand quality of experience, how it can be affected in the WLAN space, and how you can measure whether your Wi-Fi is working well enough that users simply don't even think about it. The concept may be imprecise, but the need to pay attention to Wi-Fi quality of experience is crystal clear.
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