Jaehee Lee

Date of Award


Document Type


Degree Name

Master of Science in Electrical Engineering


Department of Electrical and Computer Engineering

First Advisor

Richard A. Raines, PhD


Recently, many Low Earth Orbit (LEO) satellite systems have been proposed for the purpose of global communication and one of those systems is planned to start the commercial service in 1998. These LEO satellite systems are providing most of current communication services (voice, fax, data, paging, and even real time video service) without any limitation on place and time. However, little is published about their detail system methodology on user tracking and managing schemes. This thesis presents two user location tracking algorithms in a LEO environment. One (Gateway Approach) is the most likely approach under present system proposals, while the other (Satellite Approach) requires more risk in implementing the proposed scheme. These two approaches are compared via computer simulation in an Iridium-like satellite network system environment. Comparative measures of call setup delay and number of hops needed to establish initial call request are examined, and minimum requirements for the Satellite Approach are discussed. It is concluded that the Satellite Approach performs better than the Gateway Approach when the memory space and computational ability of each satellite can satisfy the minimum conditions discussed in this paper. Also, the Satellite Approach experienced well balanced message distribution than the Gateway Approach. Moreover, as far as system survivability and service continuity, the Satellite Approach showed more advantageous factors than the Gateway Approach.

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DTIC Accession Number