Date of Award

1997

Document Type

Thesis

Publisher

Edith Cowan University

Degree Name

Bachelor of Engineering Honours

Faculty

Faculty of Science, Technology and Engineering

First Supervisor

Dr Tadeusz Wysocki

Abstract

This report outlines the multipath fading phenomenon and its relationship to wireless system design. The work was conducted for the academic year of 1996. This report provides the reader with an insight into the phenomenon called fading and its relevance when designing wireless systems. Fading is an important consideration when wireless systems are to be designed. Because fading is very unpredictable and it cannot to totally eliminated in a wireless system, systems engineers have a hard time trying to design and commission efficient communication systems for a particular environment. Over the years, there has been a existing need worldwide to design wireless systems which perform efficiently under fading conditions which is introduced into the propagation channel. As Wireless Local Area Networks (WLAN) and Wireless Private Branch Exchanges (WPBX) have become increasingly popular, along with a whole other range of wireless systems such as Personal Communication Systems and cellular systems, the need to provide effective and efficient systems which perform well under fading conditions and also other conditions which degrade a system, has been the utmost challenge faced by systems and communications engineers. With all this research going into designing efficient systems for communication being conducted worldwide, when the opportunity was presented by my supervisor to conduct similar research into indoor wireless systems within the microwave region. I was very excited as to the prospect of conducting research in these field of interest. This report outlines the background theory, which the reader will find most helpful and then presents the measurements conducted, and finally the results and analysis of the conducted measurements and its important relationship to wireless systems design within the ISM band of 2.4 to 2.5 GHz. This study investigates the various aspects of fading which affect a wireless channel under the introduction of controlled motion for a set measurement period. The empirical data base consists of twenty five 20 second recordings of the continuos wave envelope fading waveforms with both antennas in a stationary position. Measurements were conducted in a cluttered laboratory setting at 2.4 GHz with two quarter wave monopole antennas with transmitter and receiver separation ranging from 2 to 5 meters. Effects of controlled degrees of motion with 2 individuals walking briskly around the antennas was investigated. The report results are presented with statistical properties such a the number of crossings at a particular level, the level crossings rates and the average duration of fades being investigated on the fading envelopes of the measurements. These results and statistical analysis can be used in designing wireless computer communication applications, such as WLAN's and also the results can be used to simulate wireless channels which use intelligent antenna systems to reduce fading.

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