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QIM digital watermarkingbased on LDPC code and messagepassingunder scalingattacks
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作者 崔鑫 颜斌 +1 位作者 贾霞 王亚菲 《Journal of Measurement Science and Instrumentation》 CAS 2014年第1期37-40,共4页
Watermarking system based on quantization index modulation (QIM) is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronizati... Watermarking system based on quantization index modulation (QIM) is increasingly popular in high payload applications,but it is inherently fragile against amplitude scaling attacks.In order to resist desynchronization attacks of QIM digital watermarking,a low density parity check (LDPC) code-aided QIM watermarking algorithm is proposed,and the performance of QIM watermarking system can be improved by incorporating LDPC code with message passing estimation/detection framework.Using the theory of iterative estimation and decoding,the watermark signal is decoded by the proposed algorithm through iterative estimation of amplitude scaling parameters and decoding of watermark.The performance of the proposed algorithm is closer to the dirty paper Shannon limit than that of repetition code aided algorithm when the algorithm is attacked by the additive white Gaussian noise.For constant amplitude scaling attacks,the proposed algorithm can obtain the accurate estimation of amplitude scaling parameters.The simulation result shows that the algorithm can obtain similar performance compared to the algorithm without desynchronization. 展开更多
关键词 digital watermarking quantization index modulation (QIM) message passing algorithm based on factor graph low density parity check (LDPC) code amplitude scaling attack
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A New Service Based on CDMA Short Message System-Roaming Advertisement
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作者 Shen Guoqiang (ZTE Corporation,Shenzhen 518057,China) 《ZTE Communications》 2003年第1期8-10,共3页
Through the comparison of the features of GSM and CDMA short message services,the paper shows that the CDMA short message center has stronger service capability and provides more value- added services.
关键词 CDMA as from ISP ICP it HLR A New Service based on CDMA Short message System-Roaming Advertisement on
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