VoWi-Fi quality determined by underlying Wi-Fi network

Latest study into all aspects of VoLTE by Signals Research Group and Spirent Communications looks at user experience of voice over Wi-Fi

VoWi-Fi quality determined by underlying Wi-Fi network

A new report into the quality of Voice over Wi-Fi (VoWi-Fi) by Spirent Communications and Signals Research Group (SRG) has found that it is largely determined by the quality of the underlying Wi-Fi network.

Residential Wi-Fi generally provides a better quality thanks to the controlled environment it operates in, while public access Wi-Fi delivers a more patchy experience, according to the report, Behind The VoLTE Curtain, Part 4, the latest in a series of studies into all things Voice over LTE (VoLTE) by Spirent and SRG.

The two firms decided to look at VoWi-Fi in their latest report, because of the current industry buzz around it as the vehicle for carriers to deliver seamless voice coverage. They noted that VoWi-Fi’s ability to provide a great user experience has been called into question.

The report therefore addresses the immediate concerns around the ability of VoWi-Fi to deliver a favourable user experience and a seamless interaction with the macro cellular network.

SRG worked with Spirent to analyse VoWi-Fi call quality using both residential and public venue access points, such as a major convention centre and an international airport lounge. These tests included the impacts of network loading and comparisons with VoLTE, 3G HD Voice, and Skype, including test scenarios involving a mix of the aforementioned voice applications.

Finally, the study detailed call hand-offs between VoWi-Fi and VoLTE to determine what, if any, challenges exist with respect to network interoperability. SRG used Spirent’s Nomad User Experience Analytics System to quantify the voice quality using the industry-standard POLQA algorithm for a large number of usage scenarios.

“By and large, we found that VoWi-Fi is as good or as bad as the underlying Wi-Fi network,” said Michael Thelander, president of SRG. “Without question, the call quality was much better and more consistent with a residential Wi-Fi access point in a controlled environment and with minimal network traffic. With public Wi-Fi access points, the consumer needs to be more forgiving, especially in areas where other Wi-Fi users like to congregate.”

“Collaborating with SRG on this live field study gives us the opportunity to evaluate initial deployments of VoWi-Fi devices and services and explore anticipated user experience challenges,” said Kurt Bantle, senior solutions architect at Spirent Communications.

“For the next study, we are looking forward to working with SRG in a controlled lab environment where we can replicate many of the same VoWi-Fi test scenarios. This will provide a more definitive understanding of the potential performance differences in the various VoLTE-enabled devices.”

Part Four in the series of VoLTE reports answers the following questions:

• What is the expected call quality (MOS) of a VoWi-Fi call and how does it compare with VoLTE and 3G HD voice?
• How is the VoWi-Fi MOS impacted by other background traffic on the access point and how does the performance compare with an OTT voice application, such as Skype?
• What are the differences in the call quality between an end-to-end VoWi-Fi call and a voice call which combines VoWi-Fi with either VoLTE, 3G HD voice, or Skype?
• How well do VoWi-Fi to VoLTE handovers and VoLTE to VoWi-Fi handovers work?
• What are the flies in the ointment, such as IMS interoperability and call handovers, which might detract from an otherwise favourable user experience or give operators cause for concern?

Spirent and SRG plan to continue the collaboration with additional VoLTE-related testing, including lab-based studies of VoLTE client performance and VoLTE performance in a multi-operator network.

For a preview of the report in Signals Ahead, Behind The VoLTE Curtain, Part 4 please visit: http://signalsresearch.com/issue/behind-the-volte-curtain-pt-4/



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