Spirent Communications and Signals Research Group (SRG) have revealed their collaboration on the next chapter in the multi-part study of all things VoLTE. With the current industry buzz around VoWi-Fi as the vehicle for carriers to deliver seamless voice coverage, the ability to provide a great user experience has been called into question.
This report, “Behind The VoLTE Curtain, Part 4” addresses the immediate concerns around the ability of VoWi-Fi to deliver a favorable user experience and a seamless interaction with the macro cellular network.
SRG worked with Spirent to analyze VoWi-Fi call quality using both residential and public venue access points, such as a major convention center 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. In this report, SRG leveraged 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, the President of Signals Research Group. “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 favorable 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.