Field Test of Mobile Terminals in a Wireless City

Abstract

A rising question today is whether or not wireless networks and terminals are at the border of being able to compete with the cellular phone service. A variety of terminals are available and citywide wireless networks are either already deployed or under deployment in many cities worldwide. Although voice over wireless networks already is up and running in many office buildings and hospitals, few have experimented with and tested the use of voice over IP in public wireless networks. In this thesis, a series of field experiments are conducted in ''Wireless Trondheim'', a city-sized wireless network. Through tests gathering information on voice quality, network capacity and other metrics critical for a voice service, differences between terminals and the state of the technology is presented. Using the network analysis tool IxChariot a selection of Wi-Fi enabled mobile terminals from Qtek and HTC are tested under different conditions and network loads. The tests unveil vast differences among the tested terminals. While some terminals are capable of handling multiple conversations at once (e.g. call waiting and teleconference functionality) others have trouble keeping the quality of a single conversation good enough for it to be of any value. Allover, the achieved voice quality for the tested terminals in the Wireless Trondheim network lies well below the quality of the GSM service. The radios on the mobile Wi-Fi terminals are strongly affected by interference in a densely populated outdoor environment, which makes it difficult to maintain good voice quality. The results obtained in the thesis indicate that the tested mobile terminals are not yet ready to deliver telephony over a shared outdoor wireless network with sufficient voice quality.