Behind the VoLTE Curtain, Pt. 4

You Can't Ride in my Little Red Wagon ... Because it is Being Used to Lug Around Test Equipment to Measure the Performance of VoWI-FI

08/10/2015 | 47 pages
Price: $1,395.00

We conducted an independent performance analysis of T-Mobile's VoWi-Fi service. Spirent Communications provided us with its Nomad User Experience Analytics System to conduct the call quality tests. We used Accuver Americas XCAL-M drive test solution and XCAP post processing software to analyze the lower layer interactions of the smartphones with the cellular network.

Our summary-level conclusion is that VoWi-Fi is as good or as bad as the underlying Wi-Fi network.  We obtained results which suggest the typical consumer would never notice the difference when switching from VoLTE to VoWi-Fi, let along the actual handover itself.  Conversely, we also documented results which weren’t as favorable.  In many, but not all, of these instances, we believe that other factors were involved.

We answer 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 which might detract from an otherwise favorable user experience or give operators cause for concern?