Improving VoIP quality through path switching

Abstract

The current best-effort Internet cannot readily provide the service guarantees that VoIP applications often require. Path switching can potentially address this problem without requiring new network mechanisms, simply by leveraging the robustness to performance variations available from connectivity options such as multi-homing and overlays. In this paper, we evaluate the effectiveness and benefits of path switching in improving the quality of VoIP applications, and demonstrate its feasibility through the design and implementation of a prototype gateway. We argue for an application-driven path switching system that accounts for both network path characteristics and application-specific factors (e.g., codec algorithms, playout buffering schemes). We also develop an application path quality estimator based on the ITU-T E-model for voice quality assessment, and an application-driven path switching algorithm that dynamically adapts the time scales over which path switching decisions are made to maximize voice quality. Through network emulation and experiments over a wide-area multi-homed testbed, we show that, with sufficient path diversity, path switching can yield meaningful improvements in voice quality. Hence by exploiting the inherent path diversity of the Internet, application-driven path switching is a viable option in providing quality-of-service to applications.

Quantum Key Distribution

“…Finding alternative routes that can provide a service with a higher degree of quality and quick rerouting in the case of interrupt detection or using multipath communications are key features of the overlay network approach. The use of multipath connections is an often suggested solution for improving network workloads through protecting against network failures, network load balancing, large bandwidth implementation, low-delay time selection, and more [83][84][85][86]. Studies have shown that at least four link-disjoint paths between large ISPs are present in 90% of point-of-presence pairs [87,88].…”

A Border-friendly, Non-overlay Mechanism for Inter-domain QoS Support in the Internet

“…In [14,11,10] the authors show a measurable increase in QoS, when having control over the selected AS-path between two end-points. Clearly, fixed paths are a key to maintaining QoS and possibly as important as any other employed QoS technologies and protocols.…”

Autonomic QoS Optimization of Real-Time Internet Audio Using Loss Prediction and Stochastic Control

“…This is in contrast to our packet loss prediction mechanism, where we identify variation of delays relative to degree of congestion, and delay trends to estimate the likelihood of loss in next packet train. In Tao et al (2005) the authors used an adaptive diversity only path switching algorithm by measuring actual quality of the paths and switching to an alternate path whenever the alternative path quality exceeded the original path quality by a constant value. In contrast, we measure projected quality based on Loss Predictor, and combine FEC and path diversity in a single mechanism.…”

“…Active probing to evaluate alternate path conditions is a commonly used technique in path diversity (Andersen, Balakrishnan, Kaashoek, & Morris, 2001;Tao et al, 2005). In a multi-path transport, we need a predictor for each path to estimate loss probability on each path.…”

“…In particular, packet dispersion is significantly beneficial to reduce the effect of high degree of burst loss (Zlatokrilov & Levy, 2004). But compared to FEC, path diversity is a relatively costly solution, since it can incur more sudden changes in one-way delay (Tao et al, 2005), disrupting a smooth playback. Thus the challenge is to provide an error control solution that adaptively combines the benefits of both FEC and dispersion techniques under different network conditions in order to provide optimal quality.…”