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Title:An Information-Theoretic Study of Ratio-Threshold Antijam Techniques
Author(s):Chang, Li Fung
Department / Program:Mathematics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Abstract:The performances of ratio-threshold (R/T) antijam communication systems in the presence of different jamming strategies are studied. Frequency hopping spread spectrum (FH/SS) binary frequency-shift-keying (FSK) modulation is used for the transmitted signal. Comparisons with a hard decision receiver are made. Channel capacity, cutoff rate and coded bit error probability are used to measures of the performance.
We first form a game-theoretic problem with two players, transmitter and jammer. The transmitter can choose either fixed threshold or random threshold as its strategy. The jammer with fixed finite power has either one dimensional jamming or partial band jamming as its strategy. The payoff function of the game is channel capacity or cutoff rate.
We find that by using R/T technique, performance considerably superior to that possible with a hard decision receiver vs. one dimensional jamming channel or partial band jamming channel can be obtained. Moreover, the effect of the one dimensional jammer on the R/T channel is not as serious as it is on the channel with R/T technique. The performance of a standard rate 1/2, constraint length 7 convolutional code used on an R/T channel vs. different jamming strategies is calculated. Coded bit error probabilities are calculated.
We also investigate the performance of Rayleigh R/T fading channel vs. partial band jammer. We find that the worst-case partial band jamming is full band jamming, and against full band jamming the best threshold to maximize the pay-off function is the fixed (i.e. nonrandom) threshold. Repetition codes are used to neutralize the effect of Rayleigh fading.
Issue Date:1985
Description:114 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.
Other Identifier(s):(UMI)AAI8521736
Date Available in IDEALS:2014-12-16
Date Deposited:1985

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