Publication details

During the past few years we have been seeing an increasing popularity of Wireless VoIP (Voice over IP) services, mostly due to the increasing availability of the software driven smartphones running Google Android and Apple iOS, where VoIP applications can be downloaded and installed on to the mobile device and then simply start using it similar to how you would have done in front of a computer. However there are still many major challenges with regard to quality that need to be overcome in order to offer customer an excellent service. In this paper we provide a detailed analysis on the performance of Skype’s SILK speech codec. We setup a wireless VoIP test bed on an Android driven mobile platform and investigate the impact of packet-loss and background traffic, on the performance of SILK. We used recommended speech samples from the ITU-T database, and three different experiments were conducted. We used data extraction and reporting tools, to measure and evaluate the network performance parameters such as jitter, inter-arrival time, packet loss, and variation of bit rate on all these experiments. A relationship between packet loss vs. jitter and inter arrival time were seen. With increasing levels of packet loss jitter and inter-arrival time were affected badly. It was seen for 5% and 10% packet loss jitter can be tolerated as shown by the MOS score of 4.44 and 3.88 respectively. Informal subjective quality measurements showed SILK was able to tolerate packet loss of up to 10% before it showed signs of degradation. We believe that this study can be helpful for the research community who are currently doing performance analysis on SILK.

Karawita A, Sun L