This thesis is a study of multiple access schemes for satellite land
mobile systems that provide a domestic or regional service to a large
number of small terminals.
Three orbit options are studied, namely the geostationary, elliptical
(Molniya) and inclined circular orbits. These are investigated for
various mobile applications and the choice of the Molniya orbit is
justified for a U. K. system.
Frequency, Time and Code Division Multiple Access (FDMA, TDMA and
CDMA) are studied and their relative merits in the mobile environment
are highlighted. A hybrid TDMA/FDMA structure is suggested for a
large system.
Reservation ALOHA schemes are appraised in a TDMA environment and an
adaptive reservation multiple access protocol is proposed and analysed
for a wide range of mobile communication traffic profiles. The system
can cope with short and long data messages as well as voice calls.
Various protocol options are presented and a target system having
100,000 users is considered. Analyses are presented for the steady
state of protocols employing pure and slotted ALOHA and for the
stabilty of the slotted variant, while simulation techniques were
employed to validate the steady state analysis of the slotted ALOHA
protocol and to analyse the stability problem of the pure ALOHA
version.
An innovative technique is put forward to integrate the reservation
and the acquisition processes. It employs the geographical spread of
the users to form part of the random delay in P-ALOHA.
Finally an economic feasibility study is performed for the spacesegment.
For costs of capital (r) less than 23 % the discounted
payback period is less than the project's lifetime (10 years). At r-
8% the payback period is about 5.6 years, while the internal-rate-of-return
is 22.2 %. The net present value at the end of the projects
lifetime is £M 70 at r-8%.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/5028 |
| Date | January 1987 |
| Creators | Fenech, Hector T. |
| Contributors | Watson, P.A., Gardiner, John G. |
| Publisher | University of Bradford, Postgraduate School of Studies in Information Systems Engineering |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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