Quality of service in VoIP over WLANs

Abstract

Voice over Internet Protocol (VoIP) uses the existing data networks to support voice services. It has abroad appeal in that it is currently unregulated and calls can be placed fixed fee to any part of the globe. The integration of voice traffic with data traffic opens up opportunities for new revenue stream for Internet Service Providers.

Therefore, it have to deal with both voice and data traffic. In this thesis, it assesses the suitability of IEEE 802.11 networks to carry real-time voice traffic using Internet Protocol (IP) network.

Thesis works were performed over IEEE 802.11 Wireless LANs in both ad-hoc and infrastructure modes and focused on the four major VoIP Quality of Service metrics: Packet loss, Delay time, Jitter, and Mean Opinion Score (MOS). The environmental factors such as the attenuation and the different radio channel models between Sender and Receiver nodes were recorded wherever possible. Furthermore, the effect of TCP traffic competing was also analyzed.

In this thesis found that IEEE 802.11 networks can support the requirements of real-time voice communication when there is clear to the peer node or when communicating nodes are close. Attenuation and Radio channel models proved to cause packet loss and delay time, whilst TCP traffic competing increased Delay time leading to worse quality. All experimental data was recorded in a repository of laboratory for further study.