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High-Sensitivity Acquisition of Ultrahigh Dynamic Direct Sequence Spread Spectrum Signals in Space Communications 被引量:2
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作者 徐颖 袁洪 《China Communications》 SCIE CSCD 2013年第10期26-36,共11页
According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the ... According to the requirements of the high-sensitivity acquisition of Direct Sequence Spread Spectrum(DSSS) signals under ultrahigh dynamic environments in space communications, a three-dimensional joint search of the phase of Pseudo-Noise-code(PN-code),Doppler frequency and its rate-of-change is presented to achieve high sensitivity in sensing high-frequency dynamics. By eliminating the correlation peak loss caused by ultrahigh Doppler frequency and its rate-of-change offset,the proposed method improves the acquisition sensitivity by increasing the non-coherent accumulation time. The validity of the algorithm is proved by theoretical analysis and simulation results. It is shown that signals with a carrier- to-noise ratio as low as 39 dBHz can be captured with high performance when the Doppler frequency is up to ±1 MHz and its rate-of-change is up to ±200 kHz/s. 展开更多
关键词 direct sequence spread spectrum signals space communications ACQUISITION high sensitivity ultrahigh dynamic
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New Acquisition Algorithm for Direct Sequence Spread Spectrum Signals 被引量:1
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作者 王永庆 吴嗣亮 《Journal of Beijing Institute of Technology》 EI CAS 2009年第4期468-472,共5页
Aiming at improving acquisition performance for direct sequence spread spectrum (DSSS) signals, a new acquisition algorithm based on fast Fourier transform (FFT) is proposed. The code phases are parallel searched ... Aiming at improving acquisition performance for direct sequence spread spectrum (DSSS) signals, a new acquisition algorithm based on fast Fourier transform (FFT) is proposed. The code phases are parallel searched throughout the Doppler frequency domain. Since the influence of Doppler frequency errors on peak-to- average ratios of correlation power shows a pattern similar to the sinc function, it is our belief that by judging on peak-to-average ratios for different Doppler frequency errors false alarm probabilities should be lowered. Analyses have supported the underlying principle of this new algorithm. Simulation results have also indicated that the new algorithm can effectively improve the acquisition performance for DSSS signals. 展开更多
关键词 direct sequence spread spectrum dsss ACQUISITION false alarm probability
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Research on Estimator and Testing Acquisition Schemes in Direct Sequence Spectrum Spreading Systems 被引量:1
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作者 陈岩 黄其华 +1 位作者 安建平 罗伟雄 《Journal of Beijing Institute of Technology》 EI CAS 2004年第1期5-9,共5页
Serveral methods for the pararrel acquisition of a PN sequence in a baseband direct sequence spread spectrum system are investigated. Four different kinds of schemes are considered: the optimal estimation scheme, the ... Serveral methods for the pararrel acquisition of a PN sequence in a baseband direct sequence spread spectrum system are investigated. Four different kinds of schemes are considered: the optimal estimation scheme, the locally optimal estimation scheme, the optimal testing searches and the locally optimal testing scheme. In the four kinds of parallel acquisition schemes, the expressions for the probability of error are given and compared with the actual error probabilities obtained via Monte Carlo simulation. We also outline a technique that can be suboptimal because of a large amount of hardware and computation when using the parallel acquisition schemes. 展开更多
关键词 direct sequence spectrum spreading systems parallel acquisition SYNCHRONIZATION
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Several Modulation in Direct-Sequence Spectrum-Spread Systems
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作者 Wang Yi, Zhao Ming, Zhang Zhongpei & Yao Yan State Key Lab. on Microwave & Digital Communication, Tsinghua University, Beijing 100084, P.R.China 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2002年第1期53-58,共6页
Performances of BPSK, balanced quaternary modulation, dual quaternary modulation and complex quaternary modulation in direct sequence spectrum spread (DS SS) system are discussed in this paper. Based on the crit... Performances of BPSK, balanced quaternary modulation, dual quaternary modulation and complex quaternary modulation in direct sequence spectrum spread (DS SS) system are discussed in this paper. Based on the criterion the power of original signal is the same, it is shown that complex quaternary modulation has the best performance, and dual quaternary modulation degrades 2dB. Moreover, the frequency efficient of the two modulations is 2bit/Hz. Balanced quaternary has the same performance as BPSK with frequency efficient 1bit/Hz. 展开更多
关键词 MODULATION direct sequence spectrum spread Frequency efficient.
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Low complexity method for spreading sequence estimation of DSSS signal in non-cooperative communication systems 被引量:10
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作者 Chang Liang Wang Fuping Wang Zanji 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第1期41-49,共9页
It is a necessary step to estimate the spreading sequence of direct sequence spread spectrum (DSSS) signal for blind despreading and demodulation in non-cooperative communications. Two innovative and effective detec... It is a necessary step to estimate the spreading sequence of direct sequence spread spectrum (DSSS) signal for blind despreading and demodulation in non-cooperative communications. Two innovative and effective detection statistics are proposed to implement the synchronization and spreading sequence estimation procedure. The proposed algorithm also has a low computational complexity with only linear additions and modifications. Theoretical analysis and simulation results show that the algorithm performs quite well in low SNR environment, and is much better than all the existing typical algorithms with a comprehensive consideration both in performance and computational complexity. 展开更多
关键词 direct sequence spread spectrum detection statistic low complexity.
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Fast method for spreading sequence estimation of DSSS signal based on maximum likelihood function 被引量:12
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作者 Yanhua Peng Bin Tang Ming Lv 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第6期948-953,共6页
To estimate the spreading sequence of the direct sequence spread spectrum (DSSS) signal, a fast algorithm based on maximum likelihood function is proposed, and the theoretical derivation of the algorithm is provided. ... To estimate the spreading sequence of the direct sequence spread spectrum (DSSS) signal, a fast algorithm based on maximum likelihood function is proposed, and the theoretical derivation of the algorithm is provided. By simplifying the objective function of maximum likelihood estimation, the algorithm can realize sequence synchronization and sequence estimation via adaptive iteration and sliding window. Since it avoids the correlation matrix computation, the algorithm significantly reduces the storage requirement and the computation complexity. Simulations show that it is a fast convergent algorithm, and can perform well in low signal to noise ratio (SNR). 展开更多
关键词 direct sequence spread spectrum dsss signal spreading sequence maximum likelihood estimation (MLE).
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Non-Supervised Learning for Spread Spectrum Signal Pseudo-Noise Sequence Acquisition
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作者 Hao Cheng Na Yu Tai-Jun Wang 《Journal of Electronic Science and Technology》 CAS CSCD 2015年第1期83-86,共4页
An idea of estimating the direct sequence spread spectrum(DSSS) signal pseudo-noise(PN) sequence is presented. Without the apriority knowledge about the DSSS signal in the non-cooperation condition, we propose a s... An idea of estimating the direct sequence spread spectrum(DSSS) signal pseudo-noise(PN) sequence is presented. Without the apriority knowledge about the DSSS signal in the non-cooperation condition, we propose a self-organizing feature map(SOFM) neural network algorithm to detect and identify the PN sequence. A non-supervised learning algorithm is proposed according the Kohonen rule in SOFM. The blind algorithm can also estimate the PN sequence in a low signal-to-noise(SNR) and computer simulation demonstrates that the algorithm is effective. Compared with the traditional correlation algorithm based on slip-correlation, the proposed algorithm's bit error rate(BER) and complexity are lower. 展开更多
关键词 Blind estimation direct sequence spread spectrum signal non-supervised learning pseudo-noise sequence
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Neural network approach to blindestimation of PN spreading sequence in lower SNR DS/SS signals 被引量:6
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作者 Zhang Tianqi Lin Xiaokang Zhou Zhengzhong 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第4期756-760,共5页
An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extr... An approach based on discrete Karhunen-Loeve transformation of the DS/SS signals is proposed to estimate PN sequence in lower S/N ratio DS/SS signals. Characteristics of self-organization and principle components extraction of unsupervised neural networks are exploited adequately. Theoretical analysis and experimental results are provided to show that this approach can work well on the lower S/N ratio input signals. 展开更多
关键词 discrete Karhunen-Loeve transformation neural networks direct sequence spread spectrum (DS/SS) signal PN sequence.
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A Neural Network Approach to Blind Estimation of PN Spreading Sequence in DS/SS Signals 被引量:1
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作者 张天麒 周正中 《Journal of Electronic Science and Technology of China》 2004年第2期1-6,共6页
In this paper, a new approach is proposed to estimate pseudo noise(PN) sequence in the lower SNR DS/SS signals blindly. This method utilizes the characteristics of self-organization, principal components analysis and ... In this paper, a new approach is proposed to estimate pseudo noise(PN) sequence in the lower SNR DS/SS signals blindly. This method utilizes the characteristics of self-organization, principal components analysis and extraction of unsupervised neural networks adequately, in addition to its higher-speed operation ability, successfully solve the difficult problem about PN sequence blind estimation. The theoretic analysis and experimental results show that this approach can work very well on lower SNR input signals. 展开更多
关键词 neural networks direct sequence spread spectrum signal PN sequence
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一种突发DQPSK-DSSS信号解调方法 被引量:1
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作者 李楠 纪恺悦 +1 位作者 王天雄 田资 《长江信息通信》 2023年第3期82-84,共3页
为了解决通信测控系统可靠性通信的问题,提出了一种将直接序列扩频和DQPSK相结合的通信方法。文章通过对突发信号的捕获、DQPSK解调两方面仿真和分析,验证了算法的性能。文章通过Vivado等工具进行了基于FPGA的硬件代码开发,在工程中实测... 为了解决通信测控系统可靠性通信的问题,提出了一种将直接序列扩频和DQPSK相结合的通信方法。文章通过对突发信号的捕获、DQPSK解调两方面仿真和分析,验证了算法的性能。文章通过Vivado等工具进行了基于FPGA的硬件代码开发,在工程中实测,验证了算法的可行性,该方法具有很高的应用前景。 展开更多
关键词 直接序列扩频 突发信号捕获 DQPSK解调
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Approach to blind estimation of the PN sequence in DS-SS signals with residual carrier 被引量:8
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作者 Tianqi Zhang Shaosheng Dai +2 位作者 Guoning Ma Wei Zhang Pu Miao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2010年第1期1-8,共8页
This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) dire... This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise (PN) sequence estimation in low signal to noise ratios (SNR) direct sequence spread spectrum (DS-SS) signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR. 展开更多
关键词 direct sequence spread spectrum (DS-SS) signal pseudo-noise (PN) sequence blind estimation singular value de-composition digital phase lock loop residual carrier.
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Radar-Communication Integration Based on MSK-LFM Spread Spectrum Signal 被引量:4
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作者 Zheng Dou Xiaokang Zhong Wenxu Zhang 《International Journal of Communications, Network and System Sciences》 2017年第8期108-117,共10页
At present, with the progress and innovation of technology, the radar communication dual function wave has become a hot research at home and abroad. Excellent integrated waveform can make full use resources of combat ... At present, with the progress and innovation of technology, the radar communication dual function wave has become a hot research at home and abroad. Excellent integrated waveform can make full use resources of combat platform, reduce the size of equipment, and realize the actual functionality of the reality of the battle-field without affecting the radar communication func-tion. The MSK-LFM dual-function wave is a typical representative;it is based on LFM, through the MSK modulation to achieve the integration function. This paper proposes a scheme of combining the spread spectrum technology with the MSK-LFM waveform based on the previous literature. The simulation results show that the waveform envelope is more stable and the energy is more concentrated. With the introduction of spread-spectrum technology, the new waveform ambiguity function graph is much closer to the thumbtack than the traditional MSK-LFM waveform. 展开更多
关键词 Radar-Communication INTEGRATION direct sequence spread spectrum Ambiguity Function MSK-LFM
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Narrow-band interference excision in spread-spectrum systems using new N-sigma algorithm based on fuzzy threshold 被引量:4
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作者 Feng Jining Wu Siliang Wang Ju 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第1期20-26,共7页
The key to narrow-band interference excision in frequency domain is to determine the excision thresh- old in direct-sequence spread-spectrum (DS-SS) systems. The excision threshold is a non-linear function related t... The key to narrow-band interference excision in frequency domain is to determine the excision thresh- old in direct-sequence spread-spectrum (DS-SS) systems. The excision threshold is a non-linear function related to the number and the power of interference, and attempting to get the exact relation of threshold related to the number and the power of interference is almost impossible. The N-sigma algorithm determines the excision threshold using subsection function; however, the excision threshold determined by this method is not exact. A new method to determine the threshold of N-sigma algorithm is proposed. The new method modifies the scale factor N by use of the membership function. The threshold determined by this method is consecutive and smooth, and it is closer to the fact than that of the initial N-sigma algorithm. The GPS signal and single-tone (CW) interference (that is, typical narrow-band interference) are implemented in the simulation, and the results are presented to demonstrate the validity of the new algorithm. 展开更多
关键词 direct-sequence spread-spectrum systems adaptive frequency domain interference suppression fuzzyfunction GPS signal.
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Frequency Hopping Spread Spectrum Security Improvement with Encrypted Spreading Codes in a Partial Band Noise Jamming Environment 被引量:1
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作者 Amirhossein Ebrahimzadeh Abolfazl Falahati 《Journal of Information Security》 2013年第1期1-6,共6页
Frequency Hopping Spread Spectrum (FHSS) system is often deployed to protect wireless communication from jamming or to preclude undesired reception of the signal. Such themes can only be achieved if the jammer or unde... Frequency Hopping Spread Spectrum (FHSS) system is often deployed to protect wireless communication from jamming or to preclude undesired reception of the signal. Such themes can only be achieved if the jammer or undesired receiver does not have the knowledge of the spreading code. For this reason, unencrypted M-sequences are a deficient choice for the spreading code when a high level of security is required. The primary objective of this paper is to analyze vulnerability of linear feedback shift register (LFSRs) codes. Then, a new method based on encryption algorithm applied over spreading codes, named hidden frequency hopping is proposed to improve the security of FHSS. The proposed encryption security algorithm is highly reliable, and can be applied to all existing data communication systems based on spread spectrum techniques. Since the multi-user detection is an inherent characteristic for FHSS, the multi-user interference must be studied carefully. Hence, a new method called optimum pair “key-input” selection is proposed which reduces interference below the desired constant threshold. 展开更多
关键词 FREQUENCY HOPPING spread spectrum KEY Distribution Centre KEY Encryption KEY Linear Feedback Shift REGISTER FREQUENCY HOPPING Code Division Multiple Access direct sequence spread spectrum
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Combinatory Spread-Spectrum Multiple-Access Based on Residue Number System:System and Performance 被引量:1
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作者 Yang Lieliang Li Chengshu(Northern Jiaotong University,Beijing 100044) 《通信学报》 EI CSCD 北大核心 1995年第4期79-88,共10页
CombinatorySpread-SpectrumMultiple-AccessBasedonResidueNumberSystem:SystemandPerformanceYangLieliang;LiCheng... CombinatorySpread-SpectrumMultiple-AccessBasedonResidueNumberSystem:SystemandPerformanceYangLieliang;LiChengshu(NorthernJiaot... 展开更多
关键词 扩频通信 多径访问 直接序列 余数数系
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Rapid Coherent Acquisition for PN Sequence UsingOptimum Search Algorithm
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作者 宋阳 胡光锐 《Journal of Shanghai University(English Edition)》 CAS 2005年第4期339-343,共5页
An optimun search algorithm for the coherent acquisition in direct-sequence spread-spectrum (DSSS) receivers is proposed and analyzed in this paper. The system consists of two major parts: a phase region estimator ... An optimun search algorithm for the coherent acquisition in direct-sequence spread-spectrum (DSSS) receivers is proposed and analyzed in this paper. The system consists of two major parts: a phase region estimator and a phase alignment detector. We use an auxiliary sequence to correlate the incoming signal in the phase region estimator. Since the cross-correlation value between the auxiliary sequence and the incoming PN signal has linear magnitude, and can provide the direction for the phase updating, an optimum search algorithm, try and error method, can be adopted to obtain the phase region information of the incoming signal. The mean acquisition time is derived through the signal flow graph theory. The time is compared with that of the conventional serial search scheme, and the results show that the proposed scheme can achieve coarse acquisition significantly faster than the conventional scheme. 展开更多
关键词 auxiliary signal direct-sequence spread-spectum(dsss PN sequence try and error synchronization.
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复杂环境下的DSSS信号抗均匀频谱干扰研究
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作者 刘芳 李成旺 贡胜男 《沈阳理工大学学报》 CAS 2023年第5期29-32,39,共5页
随着直接序列扩频(DSSS)信号的广泛应用,复杂环境下的DSSS信号抗干扰研究尤为重要。以直扩系统中常见的均匀频谱信号为例,进行信号抗干扰研究。首先分析均匀频谱信号特性,进而设计直扩信号同步环路模型,通过均匀频谱信号带宽、中心频偏... 随着直接序列扩频(DSSS)信号的广泛应用,复杂环境下的DSSS信号抗干扰研究尤为重要。以直扩系统中常见的均匀频谱信号为例,进行信号抗干扰研究。首先分析均匀频谱信号特性,进而设计直扩信号同步环路模型,通过均匀频谱信号带宽、中心频偏、能量的有机配置,研究均匀频谱信号对DSSS信号同步环路的影响,给出不同条件下最佳抗干扰方案,为通信接收机抗干扰及保障技术提供理论基础。 展开更多
关键词 直接序列扩频 均匀频谱 同步环路 信号抗干扰
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星间链路通信收发一体化系统设计
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作者 鲍爱达 候世豪 +2 位作者 郭鑫 崔鹤 张鑫哲 《计算机测量与控制》 2024年第8期280-286,共7页
随着卫星制造发射成本的降低以及全球通信需求的增加,低轨星间链路技术成为研究热点;星间链路可将多颗卫星互联,建立具有导航和通信功能的自主运行系统,可靠的通信技术是当前的研究重点;为了适应外太空具有较大多普勒频移的高动态环境,... 随着卫星制造发射成本的降低以及全球通信需求的增加,低轨星间链路技术成为研究热点;星间链路可将多颗卫星互联,建立具有导航和通信功能的自主运行系统,可靠的通信技术是当前的研究重点;为了适应外太空具有较大多普勒频移的高动态环境,设计了星间链路通信收发一体化系统;发射端采用UQPSK直接序列扩频技术,双通道架构可同时完成不同速率的导航与通信数据的发射,再运用LDPC编码技术提升数据发射速率与稳定性;接收端采用改进的PMF-FFT分段捕获算法与归一化最小和LDPC译码算法,以快速准确捕获星间信息;在FPGA硬件平台经过多次测试,该系统均可在高动态环境下,正确快速捕获到多普勒频移高达±341 kHz的信号,捕获算法时间均可保持在200 ms以内,符合实际应用中的性能需求。 展开更多
关键词 星间链路 UQPSK直接序列扩频技术 PMF-FFT LDPC FPGA
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基于可逆元胞自动机加密的扩展码索引调制方案
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作者 赵耿 黄思婕 +2 位作者 马英杰 董有恒 吴锐 《计算机科学》 CSCD 北大核心 2024年第6期416-422,共7页
针对直接序列扩频系统伪随机(Pseudo Noise,PN)码资源有限且码索引调制系统误码率性能下降的问题,提出了一种基于可逆的初等元胞自动机加密的扩展码索引调制方案。首先,针对PN码资源有限的问题,提出使用混沌规则的初等元胞自动机对PN码... 针对直接序列扩频系统伪随机(Pseudo Noise,PN)码资源有限且码索引调制系统误码率性能下降的问题,提出了一种基于可逆的初等元胞自动机加密的扩展码索引调制方案。首先,针对PN码资源有限的问题,提出使用混沌规则的初等元胞自动机对PN码进行迭代的方案,从而实现扩展PN码的目的;其次,针对码索引调制误码率性能下降的问题,提出了一种可逆元胞自动机加密的码索引调制方案,在发射端,把信息比特切割成调制比特和映射比特,并分别映射为调制符号和扩频码索引,使用对应索引的扩频码对同相分量进行扩频,同时使用可逆元胞自动机对映射比特进行加密,加密后的映射比特为调制符号的正交分量选取对应索引的扩频码进行扩频。仿真与分析结果表明,在相同频谱效率条件下,在加性高斯白噪声信道中,当误码率为10-5时,扩展码索引调制方案的误码率性能优于码索引调制和广义码索引调制方案约2~4 dB,优于非正交码移键控码索引调制方案约0.5 dB。 展开更多
关键词 直接序列扩频 码索引调制 初等元胞自动机 误比特率
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An underwater acoustic direct sequence spread spectrum communication system using dual spread spectrum code 被引量:2
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作者 Lan-jun LIU Jian-fen LI +4 位作者 Lin ZHOU Peng ZHAI Hao ZHAO Jiu-cai JIN Zhi-chao LV 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2018年第8期972-983,共12页
With the goal of achieving high stability and reliability to support underwater point-to-point communications and code division multiple access(CDMA) based underwater networks, a direct sequence spread spectrum based ... With the goal of achieving high stability and reliability to support underwater point-to-point communications and code division multiple access(CDMA) based underwater networks, a direct sequence spread spectrum based underwater acoustic communication system using dual spread spectrum code is proposed. To solve the contradictions between the information data rate and the accuracy of Doppler estimation, channel estimation, and frame synchronization, a data frame structure based on dual spread spectrum code is designed. A long spread spectrum code is used as the training sequence, which can be used for data frame detection and synchronization, Doppler estimation, and channel estimation. A short spread spectrum code is used to modulate the effective information data. A delay cross-correlation algorithm is used for Doppler estimation, and a correlation algorithm is used for channel estimation. For underwater networking, each user is assigned a different pair of spread spectrum codes. Simulation results show that the system has a good anti-multipath, anti-interference, and anti-Doppler performance, the bit error rate can be smaller than 10^(-6) when the signal-to-noise ratio is larger than-10 dB, the data rate can be as high as 355 bits/s, and the system can be used in the downlink of CDMA based networks. 展开更多
关键词 Underwater acoustic communication direct sequence spread spectrum Doppler estimation and compensation Channel estimation and equalization Gold code Single carrier Code division multiple access
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