Performance of Digital Communications Over Selective Fading Channels
Garber, Frederick Dwight
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https://hdl.handle.net/2142/69276
Description
Title
Performance of Digital Communications Over Selective Fading Channels
Author(s)
Garber, Frederick Dwight
Issue Date
1983
Department of Study
Electrical Engineering
Discipline
Electrical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Abstract
The performance of digital communications over selective wide-sense-stationary uncorrelated-scattering (WSSUS) fading channels is investigated. The emphasis is on the evaluation of the performance of binary differential phase-shift keyed (DPSK) and binary frequency-shift keyed (FSK) communications with primary emphasis on the effects of intersymbol interference produced by the frequency-selective character of WSSUS fading channels.
The error probabilities of DPSK and FSK are evaluated for several models of WSSUS frequency-selective fading channels. The analysis if focused on the performance evaluation of Rayleigh fading channels. The expressions for the probability of error for these systems are formulated in a way that allows the identification of the key parameters of the communication system.
The performances of DPSK and FSK are evaluated for several signaling formats. The design parameters considered are the shapes of the basic data-pulse waveforms for both DPSK and FSK, the modulation index, and the relative phase between successive transmitted signals for FSK. It is shown that the system error probability is highly dependent on these system parameters.
The interaction between the various elements of the communication system is examined. We show that the average error probability can be approximated in terms of one or two rms type channel measurements. A technique for obtaining bounds on system performance in terms of the key system and channel parameters is described and applied to the evaluation of both DPSK and FSK systems for several channel models and signaling formats. A method of approximating the performance of systems employing complicated pulse shapes and channels which are difficult to fully characterize is discussed. It is shown that the techniques for obtaining bounds and approximations for Rayleigh channels are easily applied to the more general frequency-selective Rician fading channels.
The applicability of adaptive equalization techniques to digital communications over WSSUS frequency-selective fading channels is discussed. We describe the characteristics of adaptive equalizers that are commonly employed for fading-channel communications. It is found that adaptive equalizers can be used to establish a coherent communications environment as well as to reduce the effects of ISI. The results of cited simulation and experimental studies are compared to the analytical results for the error probabilities of the DPSK and FSK systems. We develop a method of obtaining estimates of adaptive equalizer performance for practical systems.
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