VoLTE call quality “excellent”; further tests for motion, contention required
Telia Sonera’s Finnish LTE network delivered a peak download of 48Mbps in tests carried out by British network test company Epitiro. The tests also showed mean latency of 23 milliseconds meaning that the LTE network would be well suited, at present, to services such as HD video and online gaming.
John Curley, CTO of Epitiro, said that although the company did not know when the LTE service was experiencing peak demand, download speeds of 10-15Mbps were recorded at times, suggesting there was some evidence of service contention. The mean download speed measured was 36.1Mbps.
Epitiro said that LTE upload speeds averaged 1.7Mbps, which meets Skype’s recommendations for Basic video calling (0.3Mbps), HD video calling (1.5Mbps) and Group video calling (0.5Mbps).
Testing was completed over a 5 day period in March 2011 with over 20,000 data points being collected. A 3G test probe also measured services to enable direct comparison to 4G LTE services. Average results for 3G tests over the same period showed a mean download speed of 4Mbps and latency of 117 milliseconds, Epitiro said.
The company also tested VoLTE VoIP quality, terminating a call originating in Finland over a Samsung USB device to a test probe on BT’s 21CN network. Curley said that it showed quality to be “excellent”, scoring ITU-T PESQ MOS (Mean Opinion Score) values of 4.2 or 4.3, from a theoretical maximum score of 5. Tests were carried out using SIP control and the G.711 CODEC.
The Call Setup Times recorded using the 4G LTE services were approximately 0.6 seconds, whichi Epitiro described as exceptionally fast, especially considering the call was originating in Finland and terminating in the UK. These setup times reflect the minimal network latency using LTE within Finland.
Epitiro said that further examination of how the service performs as subscriber numbers increase would be of interest, as additional subscribers could cause congestion at the point of access or in the backhaul. In-motion measurements will also be of interest to see how real-time applications perform with challenges unique to those situations, including cell handoff.
Tests were carried out from March 21st to March 25th 2011, with network measurement probes conducting testing at 30 minute intervals. Each test consisted of Epitiro’s automated mobile broadband test probes connecting to both 4G and 3G services and collecting a series of key performance indicators through active test sequences. Testing was conducted from environmentally controlled locations in Turku, Finland where strong radio signals were available. Genre Mobile Ltd provided the in-country logistics.