Spread-spectrum techniques in optical communication using transform domain processing

ABSTRAKPada studi ini, dilakukan penggabungan metode - metode untuk memperkuat dan meningkatkan sisi keamanan proses pertukaran informasi atau pesan digital. Metode yang digunakan diantaranya adalah metode kriptografi dan metode steganografi. Implementasi pada sistem yang dibangun dilakukan dengan menyandikan pesan pada penerapan metode steganografi citra dalam menyembunyikan pesan tersandi yang dihasilkan ke dalam sebuah citra warna (RGB) dalam domain Discrete Cosine Transform dengan teknik penyisipan Spread Spectrum. Hasil penelitian menunjukan bahwa kualitas dari stego image sangat mirip dengan cover citra yang digunakan, berdasarkan perolehan nilai performansi objektif PSNR diatas 30 db dan subjektif MOS di atas nilai 4.Kata kunci: Steganografi, Discrete Cosine Transform, Spread Spectrum, PSNR, SNR ABSTRACTIn this study, a combination of methods was used to strengthen and enhance the security side of the process of exchanging information or digital messages. The methods used include cryptographic methods and steganography methods. The implementation of the system built is done by encoding the message on the application of the image steganography method in hiding the encrypted message generated into a color image (RGB) in the Discrete Cosine Transform domain with the Spread Spectrum insertion technique. The results of the study show that the quality of the stego image is very similar to the cover image used, based on the acquisition of an objective performance value of PSNR above 30 db and subjective MOS above a value of 4.Keywords: Steganografi, Discrete Cosine Transform, Spread Spectrum, PSNR, SNR

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An Effective Scheme of M-Ary Spread Spectrum System Based on Orthogonal Spread Spectrum and CPSK

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.765-767.2696 ◽

2013 ◽

Vol 765-767 ◽

pp. 2696-2700

Author(s):

Yue Xuan Liu ◽

Shu Jian Liang ◽

Yue Huai Ma ◽

Song Xian Gong

Keyword(s):

Monte Carlo Simulation ◽

Bit Error Rate ◽

Spread Spectrum ◽

Bandwidth Efficiency ◽

Transform Domain ◽

Communication Scheme ◽

System Synchronization ◽

Orthogonal Spread ◽

Simulation Results ◽

Ber Performance

A hybrid M-ary spread spectrum (SS) communication scheme which combined with orthogonal SS and CPSK technique is proposed. Based on dual orthogonal SS, every SS code is treated as original code to adopt CPSK modulation, the unattached synchronous code is chosen to achieve system synchronization. At the receiver, A circular correlator based on transform domain processing is employed to de-spread the received signals. Compared with M-ary SS and CPSK, the proposed scheme is able to obtain higher bandwidth efficiency, stronger anti-intercept capability, and better synchronous performance. The Monte-Carlo simulation results demonstrate that the proposed scheme can achieve better synchronous and bit error rate (BER) performance under additional white gauss noise channel models.

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Interference Suppression for Satellite Navigation Based on Neural Network and Wavelet Packets Transform

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.457-458.1111 ◽

2012 ◽

Vol 457-458 ◽

pp. 1111-1117

Author(s):

Yang Chun Shi ◽

You Bao Liu

Keyword(s):

Neural Network ◽

Spread Spectrum ◽

Simple Structure ◽

Interference Suppression ◽

Direct Sequence Spread Spectrum ◽

Wavelet Packets ◽

Interference Signal ◽

Transform Domain ◽

System A ◽

Data Adaptive

To suppress the interference in the direct sequence spread spectrum (DSSS) system, a transform domain message data adaptive identify (TISI) algorithm is proposed in this paper, based on two improved algorithms: Power distributing predominance wavelet packets transform (PDP-WPT) and extended BP neural network (EBPNN). Firstly, PDP-WPT is presented to track the interference signal effectively, which improves the convergence rate of TISI. Secondly, the message data can be identified in transform domain by adaptability EBPNN, which has simple structure and enhanced numerical robustness. Simulation results show that TISI can improve the capability of interference suppression by 32% compared with widely used conventional algorithms.

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