Characterizing the UHF factory multipath channel
Abstract
Futuristic flexible manufacturing facilities will likely use radio to provide portable communications and mobile robot control. In the factory environment, deleterious effects caused by reflections and refractions of the transmitted signal from the surrounding building structure and inventory cause inter-symbol interference and signal fading, thus limiting radio system performance. A portable UHF factory multipath measurement apparatus which uses pulsed and CW transmissions has been developed and used to measure narrow band fading and multipath power delay profiles to 10 ns resolution in five large factories throughout Indiana. Four distinct factory geographies common to all manufacturing facilities have been identified and characterized by extensive multipath measurements. Results indicate that multipath distributions are similar in shape to the urban mobile radio channel, with delay spreads ranging from 50-150 ns in line of sight (LOS) paths to 100-250 ns for obstructed paths. Path loss is largely dependent upon surrounding clutter and varies with distance as d$\sp{1.5}$ to d$\sp{2.8}$. Shadowing effects of common factory machinery are presented, along with distributions on spatial and temporal fading. The data indicates large scale path losses are log-normally distributed, small scale fading is primarily Rayleigh (although log-normal and Rician distributions fit some of the data well), and temporal fading is Rician with K = 10 dB. A simple multipath statistical model, based in principle on a model recently proposed by Saleh and Valenzuela for office buildings, is suggested here. This thesis provides measurements and results for an indoor radio channel not considered previously in the open literature.
Degree
Ph.D.
Advisors
McGillem, Purdue University.
Subject Area
Electrical engineering
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