| Abstract |
Wireless local area networks are increasingly being deployed to accommodate the user demand for constant connectivity. Wireless networks though often experience periods of severe impairment (PSIs), characterised by significant packet losses in either or both directions between the wireless Access Points (APs) and wireless hosts, increased TCP-level retransmissions, rate reduction, throughput reduction, increased jitter, and roaming effects. The frequency and intensity of PSI events in modern home and enterprise wireless networks is not well understood. Very few studies analyse the impact of PSI events on the quality of user experience.
This research aims to provide a better understanding of the perceived quality of unidirectional, non-interactive VoIP calls under various wireless network conditions, namely handover and high background traffic. Its main contributions include a novel methodology for performing auditory tests, a performance analysis of VoIP, the statistical analysis and identification of the significant network parameters, and a re-examination of various rules-of-thumb in the context of VoIP over wireless networks. Specifically, in this work, we employed the E-model and performed empirical measurements and subjec¬tive auditory tests to analyse the impact of the aforementioned network conditions on the perceived VoIP quality. The reported results show the inability of the E-Model to capture the quality of user experience and the significant impact of various network parameters, such as jitter and packet loss burst inter-arrivals on the perceived quality. Furthermore, this work demonstrates that both the network condition (e.g., roaming, type of background traffic) and the support of Quality of Service (QoS) mechanism exhibit statistically significant differences in terms of their reported opinion score values. The empirical experiments reveal an interesting behaviour of QoS-enabled wireless networks, leading to long packet loss bursts in high-priority flows. Finally, this research proposes a new methodology for performing auditory tests for lengthy VoIP calls.
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A comparative analysis of the perceived quality of VoIP under variouus wireless network conditions
