On the influence of best-effort network conditions on the perceived speech quality of VoIP connections

Abstract

When voice traffic is transported over a packet-based network, a number of conditions different from the ones in the traditional circuit-switched network will have an influence on the quality of the speech signal as perceived by the users. In particular, distortion of the voice signal due to delay jitter and partial loss of signal caused by packet loss will have an important impact. Therefore, in order to determine the influence of delay jitter and packet loss on the perceived quality, an objective speech quality assessment system, called DSLA, is used to predict the Mean Opinion Score for voice connections, which are set up on a test-bed, subject to artificially introduced network conditions. A decomposition of the voice degradation is made into different parts, due to sampling, digitization, encoding/decoding, packet loss and delay jitter, respectively. It Is found that delay jitter has a devastating influence on the perceived quality, when no dejittering buffer is used. However, when the received signal is dejittered, the degradation due to jitter is similar to the one caused by packet loss

On the deployment of VoIP in Ethernet networks: methodology and case study

“…IP phones, or a typical PC or workstation that is VoIP-enabled. A VoIP-enabled workstation runs VoIP software such as IP SoftPhones [6][7][8]. Fig.…”

Performance evaluation of real-time speech through a packet network: a random neural networks-based approach

“…It should be noted that [53] showed that PESQ is not accurate for evaluating voice quality when considering network parameters. LR and jitter effects are studied using subjective data for several codecs in [16]. The effect of packet loss on several speech codecs is evaluated in [9].…”

“…The effects of some of these parameters on speech quality have been the subject of previous research [40,16]. However, those studies normally consider only one or two parameters at once, thus neglecting the effects of their interaction as a whole.…”

Deploying VoIP in Existing IP Networks

“…VoIP requires almost no packet loss. In literature 0.1% to 5% packet loss was generally asserted [8,[23][24][25]. However, in [26] the required VoIP packet loss was conservatively suggested to be less than 10 -5 .…”

“…Other hardware requirements include a VoIP client terminal, which can be a separate VoIP device, i.e., IP phones, or a typical PC or workstation that is VoIP-enabled. A VoIP-enabled workstation runs VoIP software such as IP SoftPhones [8][9][10]. Figure 2 identifies the end-to-end VoIP components from sender to receiver [11].…”