A Measurement Study of P2P Live Video Streaming on WLANs

P2P live video streaming (P2PLVS) has become a very popular and successful service on Internet. As one of the most successful commercial P2PLVS systems, PPStream has attracted millions of users all over the world. Meanwhile, more and more WiFi access points present opportunity for enhancing the experience on watching Fl Grand Prix and vocal concerts with the help of P2PLVS on WiFi networks (WLANs). However, applying P2PLVS on such last-hop WLANs is still a challenge due to the characteristics of both WLANs and P2PLVS. Therefore, understanding principles, characteristics and limitations of P2PLVS under WLANs is important to the design and optimization of future systems. In this paper, real trace analysis is performed to reveal the detailed proprietary communication protocol and communication characteristics of PPStream. Moreover, the traffic model of PPStream is proposed based on our understanding of its protocol. In order to find the bottleneck caused by P2PLVS on WLANs, this model is simulated on network simulator version2 (NS-2) which excludes the impact of the network problems outside the WLAN. Our simulation results clearly show that the increase of effective neighbors and uploading traffics will severely affect the playback performance.