Title page for ETD etd-5048131259631631


Type of Document Master's Thesis
Author Vasavada, Yash M.
URN etd-5048131259631631
Title Performance Evaluation of a Frequency modulated Spread-Spectrum System
Degree Master of Science
Department Electrical and Computer Engineering
Advisory Committee
Advisor Name Title
Sweeney, Dennis G.
Woerner, Brian D.
Reed, Jeffrey Hugh Committee Chair
Keywords
  • none
Date of Defense 1996-05-01
Availability unrestricted
Abstract
Analog frequency modulated (FM) systems offer advantages of reliable speech

quality and simplicity, whereas code division multiple access (CDMA) systems

promise high capacity, resistance to multipath fading, and simplified frequency

planning. In this thesis, we investigate the performance of a wireless local loop

(WLL) system that uses the frequency modulation with the CDMA technique.

The performance of the FM CDMA system is affected by the choice of the

frequency demodulation method. Performance of different state-of-art DSP

based FM demodulators is evaluated. Design improvements with threshold

extension, pre-deemphasis, and voice companding techniques are explored, and

the limitations of the DSP based FM demodulation methods are identifed.

The transmitter, the channel, and the receiver of the FM CDMA system are

simulated for particular values of FM bandwidth and spread-spectrum processing

gain. The capacity supported by the FM CDMA sysem is estimated with different

levels of orthogonal as well as non-orthognal multiple access interference. The

performance of the FM CDMA system in AWGN, multipath fading, Doppler

spread, and nonlinear signal processing effects is predicted. A power control

algorithm for the FM CDMA system is proposed, and its effect on the system

performance is studied.

The capacity of the FM based wireless system may saturate as the system evolves.

An adaptive FM CDMA interference cancelation technique and a digital

modulation with CDMA are two approaches investigated as ways to improve

system capacity.

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