The effect of packet dispersion on voice applications in IP networks

Abstract

Abstract-Delivery of real time streaming applications, such as voice and video over IP, in packet switched networks is based on dividing the stream into packets and shipping each of the packets on an individual basis to the destination through the network. The basic implicit assumption on these applications is that shipping all the packets of an application is done, most of the time, over a single path along the network. In this study we present a model in which packets of a certain session are dispersed over multiple paths, in contrast to the traditional approach. The dispersion may be performed by network nodes from various reasons such as load-balancing, or implemented as a mechanism to improve quality, as will be presented in this work. To study the effect of packet dispersion on the quality of Voice over IP (VoIP) applications , we focus on the effect of the network loss on the applications, where we propose to use the Noticeable Loss Rate (NLR) as a measure (negatively) correlated with the voice quality. We analyze the NLR for various packet dispersion strategies over paths experiencing memory-less (Bernoulli) or bursty (Gilbert model) losses, and compare them to each other. Our analysis reveals that in many situations the use of packet dispersion reduces the NLR and thus improves session quality. The results suggest that the use of packet dispersion can be quite beneficial for these applications 12 .

ViSQOL: an objective speech quality model

“…All three factors stem from the nature of a packet network, which provides no guarantee that a packet of speech data will arrive at the receiving end in time, or even that it will arrive at all [6]. Packet losses can occur both in routers in the network or at the end point when packets arrive too late to be played out.…”

Exploiting the Path Propagation Time Differences in Multipath Transmission with FEC

“…We denote by Immediate the schedule S imm = (T imm , R imm ) that represents the approach used in [4]- [7,9,10]. As the name suggests, Immediate sends the data packets as soon as they are generated, i.e., every time interval T .…”

“…. .=n R , then this boils down to a simple round-robin schedule applied in [4,6,7,9]. In contrast, when the rates differ, a more elaborate approach should be used.…”

“…It got more attention recently, e.g., in [4]- [7,9,10]. Multipath was also studied in the context of Multiple Description Coding [11].…”

“…As in [4,9,10,22] we assume the paths to be independent. This can be achieved by detecting correlated paths in endto-end measurements [23] and treating them as one.…”