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Title Fractal Modulation and Anti-Jamming Performance Evaluation under the Partial-Band Noise Jamming
Degree MS
Author Jihoon, Kim
Advisor Kiseon Kim
Graduation Date 2015.02.25 File
    Date 2017-03-06 10:47

Electronic warfare (EW) is army action that defense adversary’ s electronic attack for friendly communication, and attack to disturb enemy’ s communication using electronic energy during war. Especially, we live in information era, this EW is one of very important war. EW has distinct categories, electronic attack (EA), electronic protect (EP), and electronic support (ES). Electronic attack (EA) refers to attempting to deny an adversary access to his or her information by radiating energy into their receivers. Electronic protect (EP) involves activities undertaken to prevent an adversary from successfully conducting electronic support or EA on friendly forces. Electronic support (ES) is comprised of those measures taken to collect information about an adversary by intercepting radiated emissions.

Electronic attack uses jamming technique to attack enemy’ s signal and communication system to disturb adversary’ s communication. It uses electromagnetic signal which is called jamming signal. Jamming has two distinct types called noise jamming and tone jamming. Noise jamming employs jamming signal similar with white Gaussian noise to increase noise power to decrease signal-to-noise ratio to make difficult to adversary’ s communication. Noise jamming has three categories called broad-band noise jamming, partial-band noise jamming (PBNJ), and narrow-band noise jamming. Tone jamming uses signal similar with enemy’ s signal. This thesis mainly focused on PBNJ is one of the noise jamming.

To ensure friendly communication system communicates, communication equipment

employs EP techniques. Among EP techniques, spread spectrum technique uses

in general, it has three categories that are direct-sequence spread spectrum (DSSS),frequency-hopping spread spectrum (FHSS), and time-hopping spread spectrum (THSS).

DSSS spread one symbol using certain sequence, this method can send signal power under the noise power. FHSS uses total spread bandwidth using hopping carrier frequency to hide signal. It could evade PBNJ or narrow-band noise jamming. THSS uses arbitrary rule to adjust duty cycle of pulse and length of signal to make signal low detective probability. FHSS is selected to counter PBNJ in this thesis.

Existing anti-jamming (AJ), FHSS could evade PBNJ, however, it has only possibility. Adversary jammer can find out signal during transferring it through FHSS, and

jammer send jamming signal to the signal, then it means that enemy success disturbing our communication. However, we can win or defeat because of electronic warfare, we should always success our communication even though there is adversary’s jamming attack. Hence to make our communication perfectly under enemy’ s PBNJ attack, we need new type of EP technology. To this objective fractal modulation will be introduced to protect our signal from PBNJ in this thesis.

Fractal modulation uses wavelet transform to generate fractal signal which is proposed by G.W.Wornell in 1991. Synthesis of wavelet transform is employed to modulate signal from transmitter, analysis of wavelet transform is employed to demodulation signal from receiver. To generate signal, wavelet basis should have orthogonal property, and modulator get input as same and iterative data to be transferred to obtain selfsimilarity. Same data is used for making fractal signal, it is a type of spread spectrum signal. With self-similarity and spread spectrum property, fractal signal could be employed as a AJ signal to counter PBNJ.

In this thesis, noise jamming is introduced to help understand jamming. To help understand fractal modulation, overview of wavelet transform is introduced and equation of generated fractal signal is derived. Also the bit error rate (BER) under the additive white Gaussian noise of fractal signal is derived, and it is verified using simulation results and its before works of others. Last, BER performance of fractal signal under the PBNJ is observed through simulation, and it will be compared with that of FHSSBFSK to show how performance is improved.

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