Characterization and Comparison of Skype Behavior in Wired and Wireless Network Scenarios

This paper analyzes the call quality perceived by Skype users in both fixed and mobile environments. Specifically, LAN, WLAN, ADSL and UMTS network connections are evaluated by means of both PCs and mobile terminals. The end- to-end delay is below 150 ms in all cases, so it does not degrade the call quality (in the case of no echo loss in the path). The traffic patterns of Skype were also studied for uplink/downlink, private/public addresses, which node initiates the call, and what kind of terminal is used. Additionally, PESQ measurements reveal that Skype calls are above the minimum acceptable quality when using PC-based nodes, whereas quality is not acceptable when using mobile terminals. The effect of the CPU load of the mobile terminal on the perceived call quality has also been analyzed.