Multipath routing with adaptive playback scheduling for Voice over IP in Service Overlay Networks

Voice over IP (VoIP) quality of service provision over the best effort Internet remains a challenging task since an interactive level conversation has strict delay, loss and delay jitter requirements. The ITU-T E-model [1] defines R-factor to measure the subjective quality of VoIP phone calls. Multipath routing and adaptive playback scheduling have been proposed to improve the quality of VoIP phone calls. However, it is still not clear how to select a multipath at the sender so that the best quality is achieved for voice signals. We propose a novel mechanism to select the optimal multipath that provides the best R-factor for VoIP phone calls with adaptive playback scheduling being applied at the receiver. We evaluate the VoIP quality for the proposed mechanism by comparing the R-factor of the VoIP calls sent through the optimal multipath with that of the VoIP calls sent through the direct path (the shortest hop path decided by the underlying network). The results show that the proposed method can raise the VoIP quality and provide much more stable quality for VoIP calls.