Spirent Communications is collaborating with Signals Research Group (SRG) to conduct a two-part study that evaluates the VoLTE user experience by analysing VoLTE voice quality, call performance and battery performance.
The recently completed part one of this benchmark study compared VoLTE service to 3G circuit switched voice and over the top (OTT) Skype voice service on the live network of a major US operator. The study revealed VoLTE is worth the wait and successfully delivers on the promise of superior quality of experience (QoE) and efficient use of network resources.
Some key highlights of the study include:
• VoLTE call quality, measured in terms of MOS using the industry-accepted POLQA algorithm, greatly exceeded that of 3G CS voice and was measurably higher than Skype Voice;
• VoLTE performance was considerably better than that of Skype when network loading and background applications were running on the mobile phone and transferring data with the network;
• VoLTE displayed significantly shorter call set up times than circuit-switched fallback (CSFB);
• VoLTE required substantially fewer network resources than Skype which resulted in a far greater network efficiency and a meaningfully-longer estimated mobile battery life.
“Although conceptually I understood the potential benefits of VoLTE, it wasn’t until we analysed the results that we collected with Spirent that I truly appreciated the incremental benefits that VoLTE offers,” commented Michael Thelander, the president of Signals Research Group.
“I am really looking forward to the second part of our study when we have the opportunity to do sensitivity studies and take observations made in the field and confirm them in a tightly-controlled lab environment with Spirent’s test equipment and engineering resources.”
With OTT services such as Skype being readily available to mobile users, the driver behind VoLTE deployment is the opportunity for wireless carriers to realise the full potential of LTE and provide a guaranteed quality of service (QoS) for voice services on their LTE network.
The study results validated that, although both VoLTE and Skype support HD Voice, VoLTE-specific features such as guaranteed bearer (i.e. ability to treat voice calls with higher priority over best-effort data packets) make the difference and deliver a much higher quality voice service to the mobile user.
Additional positive network and user experience implications are expected as carriers push to launch improvements in their LTE deployments and expand LTE coverage.
“It was Spirent’s sincere pleasure to collaborate with SRG on this long-awaited VoLTE study,” said Nigel Wright, VP Spirent Communications. “We have been aggressively working with leading carriers, device and chipset manufacturers for the past several years on testing everything VoLTE and we are delighted to showcase the arrival of a superior experience for the mobile user.”
In this study, the Spirent Nomad User Experience Analytics System was used to measure the call quality (in terms of MOS) of the three voice applications and to control and capture performance data during the call setup and reliability tests.
The Spirent Quantum Battery Life Measurement System was used to measure power consumption, current drain and the implied battery life for the three applications, plus Skype Video. Spirent Datum was used to simulate real world data usage.
The two measurement systems can also be used in a controlled lab environment with data captured from the live network to replicate many of the same test scenarios.
This powerful ability enables the introduction of subtle changes such as different RF conditions and IP impairments to generate a more detailed VoLTE user experience analysis, which will be the focus of a second part of this benchmark study.
For a preview of the report in Signals Ahead, “Behind The VoLTE Curtain, Part 1: Quantifying The Performance of a Commercial VoLTE Deployment” visit the consultancy’s website at www.signalsresearch.com