Improving the Subscriber's Quality of Experience

As broadband has evolved and grown, WiFi has seen massive deployment in both residential and business settings. Creating a new reality for service providers around the globe, the edge of their network is actually a WiFi connection. This makes WiFi performance a key driver of their subscribers' quality of experience (QoE).

For those unfamiliar with the term, QoE is a measure or score of the subscriber's perception of the network performance. For example, in a setting with a large number of WiFi stations, all competing for "airtime" along with negative impactors like other interfering wireless networks, a subscriber is just as likely to say, "My Internet connection stinks" as they are to say, "I'm having wireless network issues." In both cases, you can extract two axioms: first, poor wireless performance leads to poor QoE scores and, second, poor QoE scores leads to subscriber complaints.

The challenge is how to ensure wireless systems meet the subscriber's expectations when deployed into the edge of the broadband network. As with all network performance testing, the first step is understanding the items that impact the network's performance. In WiFi, we can break this down into five categories: range, fairness, noise, operation, and interoperability. Thoroughly testing the WiFi access point, typically provided by the service provider, in each of these areas can detect issues before the devices hit the field. To perform that testing, it's necessary to create an environment that will yield controlled and repeatable results. Key aspects of this test environment are control, repeatability, flexibility and future proof. Control and repeatability of the testing can be addressed using a shielded and cabled environment. Using an emulator instead of open air to establish the multi-path channel between the devices furthers these aspects as well.

WiFi Test Environment & Equipment

In the test lab, new tests -- using the above equipment and environment -- directly address the QoE performance areas. Test cases have been developed to ensure the access points are able to operate under load from multiple stations (devices), including cases where these stations are mobile, moving, and are likely based on differing generations of the wireless standards. Because, like it or not, no subscriber is going to upgrade every device in their network with each new generation of WiFi technology.

Test cases for range use an emulated (controllable) channel to vary the "distance" between the station and the access point, while measuring the performance (throughput and latency) of the wireless link. Forcing the station to a single coding schedule (bit-rate) can provide an estimation of the access point's receiver sensitivity. Performing both measurements using the controlled test setup, allows for apples-to-apples comparisons between devices. Seeing the need and advantage to this approach of testing, the Broadband Forum has kicked off the development of WiFi performance testing, providing the service providers with the much-needed common ground for addressing QoE at the edge of their network.

The UNH-IOL will participate in a webinar on Broadband World News today at 11 a.m. EST, with VIAVI Solutions. Register here. Also catch the recent webinar by The UNH-IOL on WiFi Testing Services, available here.

— Lincoln Lavoie, Senior Engineer for Broadband Technologies, UNH-IOL