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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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Body area communication based on quasi-electrostatic field and spread spectrum
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作者 解禹 黄忠华 崔占忠 《Journal of Beijing Institute of Technology》 EI CAS 2011年第1期14-17,共4页
Based on the electrical model of body area communication, the change tendency of chan nel gain in 100 kHz 10 MHz band was experimentally analyzed and verified. Results show that chan nel gain was flat and signal a... Based on the electrical model of body area communication, the change tendency of chan nel gain in 100 kHz 10 MHz band was experimentally analyzed and verified. Results show that chan nel gain was flat and signal attenuation was approximately 43 dB in 1 MHz 10 MHz band. The char acteristics of the channel were taken into account in the design of body area spread spectrum com munication and its multiuser receiver issue. BER Eb/No curves of single user and multiuser were de rived by simulation. The characteristics of body area commutation channel were studied and the fea sibility of introducing spread spectrum theory to body area communication was verified. 展开更多
关键词 spread spectrum technology quasi electrostatic field body area communication
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Modulated Lapped Biorthogonal Transform for Non-orthogonal Narrowband Interference Excision in Spread Spectrum Communications
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作者 朱丽平 胡光锐 +1 位作者 赵海波 朱义胜 《Journal of Shanghai University(English Edition)》 CAS 2005年第3期237-240,共4页
Traditional lapped transform domain excision techniques obtain good performance at the expense of increased processing delay. Extension of transform domain filtering techniques to the lapped biorthogonal transform dom... Traditional lapped transform domain excision techniques obtain good performance at the expense of increased processing delay. Extension of transform domain filtering techniques to the lapped biorthogonal transform domain can help solve the problem. By incorporating biorthogonality into the lapped transforms, more flexibility is obtained in the design of windows. Thus transform bases with better stopband attenuation can be generated by designing windows, but not by increasing the overlapping factor. In this paper, a new modulated lapped biorthogonal transform (MLBT) with optimized windows is introduced for efficient compression of multi-tone interfering signal energy. The bit error rate (BER) performance of the receiver employing the proposed MLBT excision technique is analyzed and compared with that of the lapped transform domain excision-based receivers. Simulation results demonstrate the improved performance and increased robustness of the proposed technique. 展开更多
关键词 modulated lapped biorthogonal transform (MLBT) narrowband interference excision spread spectrum communications.
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THE SCHEME STUDY OF THE APPLICATION OF W-CDMA SPREAD SPECTRUM COMMUNICATION IN MINE MOBILE COMMUNICATION 被引量:4
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作者 杨维 程时昕 孙继平 《Journal of Coal Science & Engineering(China)》 2000年第2期64-68,共5页
For the purpose of making the best use of the mine frequency resource and realizing the instruction idea “to exchange bandwidth for distance" a W-CDMA mine spread spectrum mobile communication scheme based on sp... For the purpose of making the best use of the mine frequency resource and realizing the instruction idea “to exchange bandwidth for distance" a W-CDMA mine spread spectrum mobile communication scheme based on spread spectrum communication technique and the propagation characteristic of electromagnetic wave along laneways is proposed.The structure and make up of the system are studied and the working frequency and channels are assigned.Analysis indicates the scheme is a simple one that can fulfill the mine saying requirement. 展开更多
关键词 CDMA spread spectrum communication MINE mobile communication
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Despreader for Direct Sequence Spread Spectrum System and Its Performance Analysis
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作者 何先灯 裴昌幸 易运晖 《Transactions of Tianjin University》 EI CAS 2010年第4期275-278,共4页
A new type of despreader for direct sequence spread spectrum signal is proposed. Compared with traditional despreaders, the new despreader does not contain hard decision ware or handle binary sequence any more, and th... A new type of despreader for direct sequence spread spectrum signal is proposed. Compared with traditional despreaders, the new despreader does not contain hard decision ware or handle binary sequence any more, and the locally stored spread spectrum signals are pre-modulated baseband signals (such as Gaussian minimum shift keying (GMSK) signals), which are much more similar to the received spread spectrum signals. Moreover, the missed detection probability of the despreader is about one order of magnitude lower than that of traditional ones. Based on the maximum likelihood criterion and phase probability density function of demodulated signal, a new method of ana- lyzing the despreaders’ performance is put forward, which is proved to be more accurate than traditional methods according to the numerical results. Finally, an adaptive despreader under different signal-to-noise ratios is given. 展开更多
关键词 spread spectrum communication matched filter digital matched filter PROBABILITY
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THE STUDY OF A BOCC M-ARY SPREAD SPECTRUM SCHEME
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作者 Chu Zhenyong Ying Xiaofan +1 位作者 Tian Hongxin Yi Kechu 《Journal of Electronics(China)》 2005年第5期449-457,共9页
M-ary spread spectrum technique has been found wide applications in wireless communications, but it needs too many orthogonal spreading codes and its despreading/demodulation is quite complex computationally, which li... M-ary spread spectrum technique has been found wide applications in wireless communications, but it needs too many orthogonal spreading codes and its despreading/demodulation is quite complex computationally, which limit its wider applications. This paper proposes a novel scheme for Code Division Multiple Access (CDMA) communication systems based on M-ary spread spectrum, where only one prototype spreading code is assigned to each user and the codes for different users are orthogonal or quasi-orthogonal with each other. The M spreading codes of each user to represent K bits data are generated by circularly shifting the assigned code and reversing its polarity. The spreading codes generated like that are called as BiOrthogonal Cyclic Codes (BOCCs). At the receiver of the system, a transform domain matched-filter implemented by means of Fast Fourier Transform (FFT) is employed to despread and demodulate the received signals, which has very low computational complexity. The results of simulation experiments and bit-error performance analysis show that the proposed scheme is practical and very useful in many cases. 展开更多
关键词 M-ary spread spectrum BiOrthogonal Cyclic Codes (BOCCs) Satellite communication Transform domain processing
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A High Efficiency Spread Spectrum Scheme Using Approximate Orthogonal Complex Sequences
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作者 Xiaohong SHI 《International Journal of Communications, Network and System Sciences》 2010年第1期79-82,共4页
This paper presents a high efficiency spread spectrum scheme using approximate orthogonal complex (AOC) sequences. In this scheme, the 64 AOC sequences picked up from 84 complex sequences space are employed for spread... This paper presents a high efficiency spread spectrum scheme using approximate orthogonal complex (AOC) sequences. In this scheme, the 64 AOC sequences picked up from 84 complex sequences space are employed for spreading spectrum. In modulation, 6 input bits is used to select one AOC sequence, and the selected sequence is then phase-rotated by another 2 input bits. In demodulator, a complex correlator detects the transmitted AOC sequence. Simulation results show that the proposed scheme has better BER performance than the existing complementary code keying (CCK) modulation scheme. For AOC, additional processing gain of 1.79dB can be obtained when the sequence length is 8. 展开更多
关键词 spread spectrum communications APPROXIMATE ORTHOGONAL COMPLEX (AOC) SEQUENCES Modulation and DEMODULATION
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基于SSCP200的自动抄表系统 被引量:3
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作者 陈轶 潘孟春 吴峻 《电测与仪表》 北大核心 2001年第11期10-12,共3页
简述了扩频载波通信的原理,从应用的角度介绍了一个基于SSCP200的自动抄表系统,实际中取得了较为满意的结果。
关键词 自动抄表 载波通信 扩频通信 电度表
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基于非整数阶SSC盲移频的LFM雷达干扰技术 被引量:5
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作者 赵忠凯 周文彬 李虎 《电子与信息学报》 EI CSCD 北大核心 2021年第10期2824-2831,共8页
传统频谱扩展与压缩(SSC)盲移频干扰的阶数为整数,为了实现精确的位置干扰,需要调整不同的处理延时,在实际应用中存在一定的局限性。该文对整数阶盲移频技术进行了改进,提出了一种基于非整数阶SSC盲移频的LFM雷达干扰技术。该技术在干... 传统频谱扩展与压缩(SSC)盲移频干扰的阶数为整数,为了实现精确的位置干扰,需要调整不同的处理延时,在实际应用中存在一定的局限性。该文对整数阶盲移频技术进行了改进,提出了一种基于非整数阶SSC盲移频的LFM雷达干扰技术。该技术在干扰机处理延时不变的情况下,通过改变SSC盲移频的阶数来实现精确的位置干扰。该文推导了一种高效的非整数阶SSC盲移频干扰实现方法,同时通过Newman序列控制信号的初相来减小压制干扰信号的峰均比(PAPR)。仿真结果表明,该文算法在指定干扰机处理延时的情况下,可以实现假目标欺骗干扰和相参密集压制干扰,能够有效对抗脉冲压缩体制雷达,具有较好的工程应用价值。 展开更多
关键词 LFM雷达 压制干扰 欺骗干扰 频谱扩展与压缩算法 峰均比抑制
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电力线SSC技术在楼宇自动化中的应用
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作者 孙光伟 刘红 牟英峰 《建筑电气》 2002年第3期28-31,共4页
介绍了一种在建筑中应用的扩频载波(SSC)技术,它可以在智能大厦或住宅小区中利用电力线传送管理和控制信号等。实验和分析表明,该技术使电力线载波通信系统的可靠性、实用性有较大提高,并以此为基础设计楼宇自动化通信系统。
关键词 电力线 ssc技术 楼宇 自动化 扩频载波 通信协议
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LDPC Coded DQPSK Modulation with Iterative Detection Method for Underwater Acoustic Communications 被引量:1
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作者 Fang Fu Rui Xue +1 位作者 Dan-Feng Zhao Xiang-Chao Zhou 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2013年第5期25-30,共6页
Aimed at the conventional serial communication system fails when the channel was frequency-selective,long delay and multi-paths effect,resulting in inter-symbol-interference( ISI),an iterative system for underwater ac... Aimed at the conventional serial communication system fails when the channel was frequency-selective,long delay and multi-paths effect,resulting in inter-symbol-interference( ISI),an iterative system for underwater acoustic communication( UWAC) was proposed,which employed iterative differential detection and spread spectrum technique. The proposed scheme adopts π /4-DQPSK soft demodulation to overcome the difficulty of phase ambiguity. For suppression of ISI in UWAC,joint demodulation and decoding iteration was used. The communication scheme has the characteristic of long communication range at low SNR,and the maximum range is up to 100 km. The theoretic analysis and simulation results show that the proposed scheme outperforms traditional serial one. When SNR is- 6 dB,after four joint iterations,compared with serial scheme,BER can decrease from 10- 2to 10- 5. 展开更多
关键词 UNDERWATER acoustic communicationS joint DEMODULATION and DECODING ITERATIVE differential DECODING spread spectrum
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Satellite Communication System Using SSMA Techniques
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作者 Hu Yi and Xu Jinglong(Beijing Institute of Remote Sensing Equipment) 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 1990年第1期71-76,共6页
A satellite communication system consisting of small earth terminals which utilize spread spectrum multiple access (SSMA) techniques is introduced in this paper. Having no master station, the system is distributively ... A satellite communication system consisting of small earth terminals which utilize spread spectrum multiple access (SSMA) techniques is introduced in this paper. Having no master station, the system is distributively controlled. The frequency band used is 6/4GHz. 展开更多
关键词 Satellite communication spread spectrum Earth station communication network.
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An ISS-OFDM based adaptive filtering mechanism for interference suppression in wireless multi-hop communication network
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作者 秦丹阳 Ma Lin +1 位作者 Xu Renheng Ding Qun 《High Technology Letters》 EI CAS 2014年第3期230-236,共7页
The negative impact on communication performance in wireless multi-hop communication net-work caused by limited bandwidth,high bit eror rate (BER),fading,noise and interference is alleviated by an adaptive filtering... The negative impact on communication performance in wireless multi-hop communication net-work caused by limited bandwidth,high bit eror rate (BER),fading,noise and interference is alleviated by an adaptive filtering game based on frequency subbands selection and predetemined threshold.Such threshold is being obtained in Gaussian and multipath fading channel according to the frequency-matching principle and BER performance.The dynamic selection of subbands will obtain high use efficiency without the help of frequency hopping,and propound a new thought to improve band limited communication for wireless multi-hop communication network.The effectiveness of the adaptive filtering method has been verified by interleaving spread spectrum orthogonal frequency division multiplexing (ISS-OFDM) in different interference conditions,and the simulating results based on network simulator 2 (NS2) indicate that system BER can be improved greatly. 展开更多
关键词 multi-hop communication adaptive filtering interleaving spread spectrum orthogonal frequency division multiplexing (ISS-OFDM) interference suppression
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Design of an Acoustic Communication System Based on FHMA for Multiple Underwater Vehicles
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作者 Zixin Zhao Shuxiang Guo 《Wireless Engineering and Technology》 2010年第1期27-35,共9页
This paper designs an underwater acoustic communication system based on tamed spread spectrum and Frequency Hopping Multiple Access (FHMA) for multiple underwater vehicles. In this system, multiple underwater vehicles... This paper designs an underwater acoustic communication system based on tamed spread spectrum and Frequency Hopping Multiple Access (FHMA) for multiple underwater vehicles. In this system, multiple underwater vehicles can communicate with the console on the water surface simultaneously successfully. The communication system is com-posed of tamed spread spectrum modulation and demodulation, frequency hopping modulation and demodulation with synchronization function, 4FSK modulation and demodulation and Rake Receiver. In order to make the system more feasible, underwater channel and the effect of user number on Bit Error Ratio (BER) are also taken into account. The simulation results indicate that it is feasible to use this system to accomplish underwater communication reliably for multiple users due to the low BER. 展开更多
关键词 UNDERWATER ACOUSTIC communication Tamed spread spectrum FHMA Multiple UNDERWATER VEHICLES
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A method of multichannel chaotic phase modulation spread spectrum and its application in underwater acoustic communication 被引量:7
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作者 SHU Xiujun WANG Haibin +1 位作者 WANG Jun YANG Xiaoxia 《Chinese Journal of Acoustics》 CSCD 2017年第1期130-144,共15页
Direct-sequence spread spectrum (DSSS) communication possesses low probability of detection and has been widely used in confidential communications. However, pseudo-noise (PN) sequences, used as spreading code in ... Direct-sequence spread spectrum (DSSS) communication possesses low probability of detection and has been widely used in confidential communications. However, pseudo-noise (PN) sequences, used as spreading code in conventional DSSS communications, possess peri- odic character and binary value. In hostile environments, these distinct characters may lead to some important parameters of signals being estimated accurately, and then lead to the leakage of transmitted information. To solve the problem, we propose the chaotic phase modulation (CPM) sequence alternating the PN sequences. CPM sequence has complex values and constant envelope, and also possesses large quantity and good correlation characteristics. Moreover, it has more hidden features than conventional sequences by modulating its phases using chaotic sequence. To improve the data rate, we apply it into the technique of multichannel communica-tion. Simulation results show this scheme's superior bit error ratio (BER) performance, which demonstrates its feasibility in underwater acoustic communications. 展开更多
关键词 In CPM A method of multichannel chaotic phase modulation spread spectrum and its application in underwater acoustic communication DSSS BER
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A Fine Synchronization Method for Coherent Fast Frequency Hopping
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作者 Xuanhe Yang Weike Zhang +3 位作者 Shixun Luo Chang Li Xiaqing Miao Aihua Wang 《China Communications》 SCIE CSCD 2023年第10期163-184,共22页
Coherent fast frequency hopping(CFFH)is attracting growing attention owing to its good antijamming performance and the coherent combining ability.However,compared with the conventional non-coherent fast frequency hopp... Coherent fast frequency hopping(CFFH)is attracting growing attention owing to its good antijamming performance and the coherent combining ability.However,compared with the conventional non-coherent fast frequency hopping,CFFH requires a more precise system synchronization.In this paper,we propose a new fine synchronization algorithm for CFFH.This algorithm consists two stages,namely,open-loop stage and closed-loop stage.In the openloop stage,a grid-based search parameter estimation method is proposed.In the closed-loop stage,we construct a fully coherent phase-locked loop(PLL)and a delay-locked loop(DLL)with decoding feedback structure to perform further fine estimation of the system clock skew and time delay,respectively.Moreover,we analyze the effect of the search parameter settings on the estimation error and derive the root mean squared error(RMSE)of estimates in the steady state of the closed-loop stage.Finally,through simulation,the RMSE performance are compared with the corresponding Cramer-Rao low bound(CRLB)and conventional code loop estimation to show the effectiveness of proposed algorithm. 展开更多
关键词 fast frequency hopping(FFH) spread spectrum communication fine synchronization
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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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Chaotic Spread- Spectrum Communication using Discrete-Time Synchronization 被引量:1
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作者 Wang Hai and Hu Jiandong (Department of Telecommunications Engineering, Beijing University of Posts and Telecommunications, Beijing 100088, P. R. China) 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 1997年第1期66-69,共4页
The statistic characteristics of chaotic sequences generated by improved logistic map are analyzed and it is found that improved logistic map chaotic sequences have good correlation and they can be used as address ... The statistic characteristics of chaotic sequences generated by improved logistic map are analyzed and it is found that improved logistic map chaotic sequences have good correlation and they can be used as address sequences in spread spectrum communication. The discrete time synchronization of Henon map is immediate. We apply the discrete time synchronization to chaotic spread spectrum communication and propose an original communication scheme. The simulation shows that the application is successful. 展开更多
关键词 chaotic spread spectrum communication discrete time synchronization
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An improved hypothesis-feedback equalization algorithm for multicode direct-sequence spread-spectrum underwater communications
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作者 HAN Jing HUANG Jianguo +1 位作者 SHEN Xiaohong WANG Yu 《Frontiers of Electrical and Electronic Engineering in China》 CSCD 2007年第3期312-316,共5页
In underwater acoustic communication,because the available bandwidth of the channel is severely limited,the direct-sequence spread-spectrum scheme can only be realized at low bit rates.To improve the transmission spee... In underwater acoustic communication,because the available bandwidth of the channel is severely limited,the direct-sequence spread-spectrum scheme can only be realized at low bit rates.To improve the transmission speed,a multicode spread-spectrum scheme is considered.However,in this case,due to the rapid time-variability of the underwater channel,and the influence of inter-symbol interference(ISI)and inter-channel interference(ICI),the conventional rake receiver may fail to function.The hypothesis-feedback equalization algorithm has been proposed for the direct-sequence spread-spectrum system[1].By updating coefficients at chip rate and feeding back hypothesized chips,it can track time-variability and combat ISI effectively.However,for a multicode system,its performance will be degraded by ICI.An improved algorithm is proposed in this paper,which combines parallel interference cancellation(PIC)with hypothesis-feedback equalization(HFE),with the capabilities of tracking the time-varying channel and suppressing the ISI and ICI at the same time.Simulation results prove that the proposed algorithm can significantly improve the performance of a multicode system. 展开更多
关键词 sunderwater communication multicode spread spectrum hypothesis-feedback equalization parallel interference cancellation
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低压电力线载波通信研究与应用现状 被引量:50
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作者 何海波 周拥华 +3 位作者 吴昕 张有兵 J.NGUIMBIS 程时杰 《继电器》 CSCD 北大核心 2001年第7期12-16,共5页
在分析低压电力线载波通信特征的基础上 ,综述了低压电力线载波通信技术研究的发展状况 ,比较了扩频通信 (SSC)技术、多载波正交频分多址 (OFDM)技术和传统低压载波通信技术的性能 ,分析了X - 10、Lon Works、CEBus等多种通信技术标准 ... 在分析低压电力线载波通信特征的基础上 ,综述了低压电力线载波通信技术研究的发展状况 ,比较了扩频通信 (SSC)技术、多载波正交频分多址 (OFDM)技术和传统低压载波通信技术的性能 ,分析了X - 10、Lon Works、CEBus等多种通信技术标准 ,并提出了基于已有技术的低压电力载波通信网络的解决方案及试验研究 ,同时 ,展望了低压电力载波通信技术的发展前景并提出了有待进一步研究解决的问题。 展开更多
关键词 电力线 载波通信 扩频通信 多载波正交频分多址 低压 配电网
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