Blind audio watermarking mechanism based on variational Bayesian learning by Xin TANG, Zhao-feng MA, Xin-xin NIU, Yi-xian YANG

“…In order to improve the performance of audio watermarking detection,a blind audio watermarking mechanism using the statistical characteristics based on MFCC features of audio frames was proposed.The spread spectrum watermarking was embedded in the DCT coefficients of audio frames.MFCC features extracted from watermarked audio frames as well as un-watermarked ones were trained to establish their Gaussian mixture models and to estimate the parameters by vatiational Bayesian learning method respectively.The watermarking was detected according to the maximum likelihood principle.The experimental results show that our method can lower the false detection rate compared with the method using EM algorithm when the audio signal was under noise and malicious attacks.Also,the experiments show that the proposed method achieves better performance in handling insufficient training data as well as getting rid of over-fitting problem.…”
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New techniques of intra-satellite communication and ranging/time synchronization for autonomous formation flyer by LI Xue, ZHANG Qi-shan, XU Yong, WANG Ce

“…The principle of two-way noncoherent ranging mode about direct sequence spread spectrum（DSSS） was presented for intersatallite ranging/time synchronization in AFF FDMA/ CDMA networks,concerned equations were constructed and two iteration compupting algorithms were derived. …”
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Multiple access based on three-stage modulation in multi-band OFDM-UWB system by BAO Zhi-hua, ZHANG Shi-bing, ZHANG Guo-an, QIN Jin-jing

“…According to the characteristics of multi-band orthogonal frequency-division multiplexing ultra-wideband（OFDM-UWB） system,a multiple access based on three-stage modulation（TSM-MA） was proposed.It combined multi-carrier code division multiple access（MC-CDMA） with orthogonal frequency division multiple access（OFDMA） and frequency hopping multiple access（FHMA）,carried out the advantages of the three multiple access techniques.It reduced the multiple access interference and made full use of the available resource of the channel.The two-stage spread spectrum and two-stage frequency hopping were used to the TSM-MA for reducing the complexity of receiver.Simula-tion results showed that TSM-MA has obvious advantages in bit error rate（BER） performance over time frequency code multiple access（TF-MA） about 3 dB and lower complexity than that of TF-MA.…”
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Upper processing gain bound of the spreading signal in multipath fading channels by Wan-zhi MA, Jun WANG, You-xi TANG

“…Using the joint algorithm of coherent detection and non-coherent detection,the upper processing gain bound of the spreading signal,which is two-dimensional spread spectrum signal relative to BPSK and transmitted in rich scattering multipath fading channel,was sought.Firstly,the expression of the processing gain of the spreading signal was calculated.Secondly,with increasing signal bandwidth or symbol period unlimitedly,the processing gain was bounded.At last,it was obtained that the upper processing gain bound is determined by the channel parameters and signal noise io.By analysis and simulation,the processing gain of the spreading signal,relative to BPSK and transmits in rich scattering multipath fading channel,is not more than 30dB,when the signal noise ratio is 20dB,the maximum doppler shift is 100Hz,and the negative exponential factor is 5×10<sup>−6</sup>.…”
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Underwater acoustic communications based on differential chaos shift keying by Hongying DAI, Menglei CHEN, Weikai XU

“…As the most stringent and complicated channel,underwater acoustic (UWA) channels are featured by high multipath interference,time-frequency doubly spread,high noise,and narrow bandwidth.Due to time varying of underwater acoustic,it is difficult to trance and estimate channel state information (CSI).The underwater acoustic communication techniques based on orthogonal frequency division multiplex (OFDM) and spread spectrum were reviewed.Then,the characteristic of differential chaos shift keying (DCSK) was analyzed,and two multicarrier differential chaos shift keying modulations were proposed.Finally,over time-frequency doubly spread channel and underwater acoustic channel,the bit errors rate (BER) performances for two proposed schemes were presented and analyzed.Numerical results show that the proposed schemes own good robustness over underwater acoustic channels.…”
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Construction method of type-Ⅱ even-length Z-complementary pair with large zero correlation zone width by Xiaoyu CHEN, Lianfeng SUN, Yihan ZHANG

“…The construction method of Type-Ⅱ even-length Z-complementary pair (ZCP) was proposed by using the inter-leaving technique.The basic framework of interleaving structure with Golay complementary pair (GCP) and its mate as the basic sequences was proposed.Furthermore, the necessary conditions were given for the framework in order that the resulting ZCP could have large zero correlation zone (ZCZ) width.The main parameter form of the constructed ZCP was((2k+1)N,(2k+1)N-k)-ZCP, where N was the length of the chosen GCP.Although not all even lengths can be covered, the constructed ZCP has the ZCZ width that can achieve or approach the upper bound of Type-Ⅱ even-length binary ZCP, and has small peak-to-mean envelope power ratio whose value is less than or equal to 4.The resultant sequences can be applied to multi-carrier spread spectrum system to eliminate more asynchronous interference and reduce nonlinear distortion.…”
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Blind source separation communication anti-jamming technology and practice by Fuqiang YAO, Miao YU, Pengcheng GUO, Miaomiao GU

“…Aiming at the threat of broad frequency band suppressing jamming and the inherent contradiction between spectrum resources and communication anti-jamming ability, a method was proposed to add the statistics domain dimension on the basis of spread spectrum anti-jamming, which promoted the transformation of communication anti-jamming from hard anti-jamming to accommodate the jamming.The statistical characteristics difference between communication signal and jamming signal was utilized by blind source separation (BSS) communication anti-jamming technology to separate signals, which could improve the communication anti-jamming ability without increasing spectrum resources.To understand and improve the development process of BSS communication anti-jamming (BSSCA) from theory and algorithm to engineering practice, the basic principle of BSSCA was described, the key technologies such as multi-channel BSS and single channel BSS were emphasized.The main characteristics and existing problems of BSSCA were analyzed.Finally, the development priorities of this field were pointed out.…”
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A robust audio steganography algorithm based on differential evolution by Zhaopin SU, Chaoyong SHEN, Guofu ZHANG, Feng YUE, Donghui HU

“…Audio steganography is to hide secret information into the audio carrier and has become a research hotspot in the field of information hiding.Most of the existing studies focus on minimizing distortion at the expense of steganography capacity, and it is often difficult for them to extract secret information correctly after some common signal processing attacks.Therefore, based on the spread spectrum technology, firstly, the relationship between steganography parameters (i.e., segmented scaling parameters and steganography capacity) and imperceptibility as well as robustness was analyzed.Next, a multi-objective optimization model of audio steganography was presented, in which segmented scaling parameters and steganography capacity were decision variables, imperceptibility and steganography capacity were optimization objectives, and the signal-to-noise ratio was a constraint.Then, a robust audio steganography algorithm based on differential evolution was proposed, including the corresponding encoding, fitness function, crossover and mutation operators.Finally, comparative experimental results show that the proposed steganography algorithm can achieve better robustness against common signal processing attacks on the premise of ensuring imperceptibility and anti-detection.…”
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Index modulation aided frequency hopping anti-jamming and encryption method based on rotation scrambling by Xinjin LU, Jing LEI, Yuxin SHI

“…In order to improve the anti-jamming ability and security of the wireless communication system， an index frequency-hopping anti-interference encryption method based on rotation scrambling was designed， which could be simply called encrypted index modulation frequency hopping spread spectrum （EIM-FHSS）.Firstly， the wireless secret key was used to control multiple orthogonal frequency hopping patterns to determine the available frequencies at the current moment.The index of the active frequency （the frequency point with the modulation symbol） was used to transmit the bit information.Secondly， the secret key was used to employ scrambling encryption on the mapping table between information bits and the indexes， to ensure the security of the index bits.Finally， constellation rotation encryption was used on the symbols transmitted on the active frequency in the scheme， which ensured the security of symbol bits.Theoretical analysis and simulation results show that the proposed EIM-FHSS method has stronger security and anti-jamming abilities than the traditional IM-FHSS methods.…”
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A signal design method for LEO satellite communication and navigation integration based on optimized CCSK modulation by ZHU Min, ZHAO Yafei, ZHANG Yuman, PENG Mugen

“…A signal design method was proposed for communication and navigation integration,utilizing optimized cyclic code shift keying (CCSK) as communication spread spectrum modulation. The positive value of the cross-correlation function of the communication signal aligns with the peak value of the autocorrelation function of the navigation signal to overcome the cross-correlation interference and enhence the communication rate. …”
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Research on end hopping and spreading for active cyber defense by Leyi SHI, Hongbin GUO, Xiao WEN, Jianlan LI, Yuwen CUI, Mengfei MA, Hui SUN

“…Inspired by the spread spectrum technology for communications,the concept of end spreading was proposed to represent a piece of information of the data transmission with a sequence of multiple end information,of which each piece of end information was irrelevant to the information it conveys.Thus the covert data transmission can be performed.Further,an active cyber defense model of end information hopping and spreading was presented,in which the hopping strategy was separated from the synchronization strategy.The synchronization was accomplished by means of end information spreading for synchronous authentication of both parties,which can solve the high-speed hopping synchronization problem with high concealment requirements.The mode of generation,transmission and authentication of the spreading sequence,and the data migration strategy in the end hopping and spreading model were described in detail,and the security performance and synchronization performance were analyzed and verified experimentally.Theoretical analysis and experimental results show that the cyber defense model of end information hopping and spreading has improved the availability and confidentiality of network services under high-speed hopping and has good anti-attack performance,which is of great significance for the proactive defense application of high intensity confrontation.…”
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A Simplified Multiband Sampling and Detection Method Based on MWC Structure for Mm Wave Communications in 5G Wireless Networks by Min Jia, Xue Wang, Xuemai Gu, Qing Guo

“…Moreover, MWC structure has the ability to apply to different bands used in mm wave communications by mixed processing, which is similar to spread spectrum technology.…”
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Evaluation of Selected Modulation Techniques in Underwater Multipath Channel by Agnieszka Czapiewska, Andrzej Luksza, Ryszard Studanski, Lukasz Wojewodka, Andrzej Zak

“…In this paper, a comparison is made between two well-known modulation techniques used in radio communication: the widely used BPSK (Binary Phase Shift Keying) modulation and CSS (Chirp Spread Spectrum) technique used in LoRa (Long Range communication) system. …”
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Clamshell Inductive Current Coupler for Online Cable Condition Monitoring by Samuel W. Glass, Jonathan R. Tedeschi, Muthu Elen, Mychal P. Spencer, Jiyoung Son, Leo S. Fifield

“…This document describes the adaptation of a clamshell inductive current coupler for online reflectometry testing (both frequency-domain reflectometry and spread spectrum time-domain reflectometry) to evaluate cable anomalies. …”
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