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In this paper, we investigate the resiliency to jamming of data protocols, such as IP, over WLAN. We show that, on existing WLAN, an adversary can successfully jam data packets at a very low energy cost. Such attacks allow a set of adversary nodes disseminated over an area to prevent communication, partition an ad hoc network or force packets to be routed over adversary chosen paths. The ratio of the jamming pulses duration to the transmission duration can be as low as 10−4. We investigate and analyze the performance of combining a cryptographic interleaver with various coding schemes to improve the robustness of wireless LANs for IP packets transmission 1 . A concatenated code that is simple to decode and can maintain a low frame error rate (FER) under a jamming effort ratio of 15%. We argue that LDPC codes will be very suitable to prevent this type of jamming. We investigate the theoretical limits by analyzing the performance derived from upper bounds on binary error‐control codes. We also propose an efficient anti‐jamming technique for IEEE802.11b based on Reed–Solomon codes. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Marc Lichtman Jeffrey H. Reed 《International Journal of Satellite Communications and Networking》2016,34(2):195-210
In this paper, we analyze the feasibility of reactive jamming in a satellite communications scenario and propose a countermeasure that takes advantage of the constraints associated with reactive jamming. A reactive jammer is a type of jammer that has the ability to sense a portion of spectrum and immediately transmit a jamming signal when it senses a signal it wants to jam. Thus, a reactive jammer can counter the processing gain associated with frequency hopping spread spectrum. This paper provides a three‐step approach to analyzing the primary constraints associated with reactive jamming, as well as detailed example scenarios (both theoretical and simulated) that demonstrate the feasibility analysis. Additional clarity is provided by splitting the analysis into uplink and downlink jamming. A strategy to mitigate the effects of reactive jamming is presented, which takes advantage of the geometric constraints of reactive jamming by using a coding and interleaving scheme that results in the transmitted bits appearing at the very beginning of each hop. This work demonstrates that reactive jamming is a valid threat to satellite communication systems. The analysis and simulation results suggest that as long as the geographical area around user terminals is free of reactive jammers, substantial mitigation can be achieved using the proposed mitigation strategy. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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为了有效应对频谱弥散干扰(SMSP)和切片组合干扰(C&I)两种新型干扰,提出了一种基于栈式稀疏自编码器的识别算法。该算法首先对干扰与否的雷达接收信号进行双谱分析;然后对双谱特征进行降维,得到高维样本。预训练阶段,构造稀疏自编码器神经网络模型进行无标签样本的预训练;然后根据有标签数据对该模型参数进行有监督微调;最后利用Softmax分类器完成新型干扰的识别。仿真实验证明该方法有较高的识别率,特别是相较于其他文献方法,该方法受信噪比影响最小且识别效果最佳。说明了深度学习方法应用于雷达新型干扰信号识别领域的可行性和优越性。 相似文献
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I. K. Nissopoulos C. E. Dimakis S. S. Kouris 《International Journal of Communication Systems》2001,14(2):199-216
In this paper the performance of a concatenated coding scheme is evaluated over a slow Rayleigh fading HF ionospheric link with additive white Gaussian noise (AWGN). Well‐known Ungerboeck TCM techniques onto an 8‐PSK signal set are used as inner codes and Reed–Solomon block codes as outer codes. The coded/modulated signal is further differentially encoded before transmission to combat random phase changes. Block interleaving techniques are necessary to randomise long bursts of errors caused by the fading channel. The performance of the proposed concatenated coding system is investigated for various Doppler spreads. Significant coding gains are achieved over uncoded, diversity or other conventionally coded systems with a small bandwidth expansion. Finally the interesting effects of interleaving on the behaviour of the proposed systems are analysed. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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In this article, we introduce a new class of product codes based on convolutional codes, called convolutional product codes. The structure of product codes enables parallel decoding, which can significantly increase decoder speed in practice. The use of convolutional codes in a product code setting makes it possible to use the vast knowledge base for convolutional codes as well as their flexibility in fast parallel decoders. Just as in turbo codes, interleaving turns out to be critical for the performance of convolutional product codes. The practical decoding advantages over serially‐concatenated convolutional codes are emphasized. 相似文献
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Q. Wang T. A. Guliver V. K. Bhargava E. B. Felstead 《International Journal of Satellite Communications and Networking》1989,7(3):115-128
Spread-spectrum techniques such as frequency hopping (FH) have been used to reduce the vulnerability of satellite communications to jamming. In such a system, error correcting (EC) codes play an essential role. Thus a knowledge of the performance of various EC codes is necessary in order to choose an EC code and related system parameters in the design of an anti-jam system, this paper examines the performance of various types of error correcting codes under worst case partial band noise jamming and worst case multitone jamming using fast frequency-hopped, non-coherent M-ary frequency-shift keying (NCMFSK) with optimum diversity. A comprehensive study including convolutional codes, binary and non-binary block codes and concatenated codes has been conducted. This paper presents bit error rate (BER) performances of various error correcting codes. New candidate codes with superior anti-jam performance are identified. 相似文献
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数字通信系统通常采用前向纠错编码提高系统可靠性,传统干扰方法针对采用前向纠错编码通信系统的干扰效果较差,为了克服此缺点,提出了通过控制错误分布的脉冲干扰方法。分析了典型卷积码和RS码的纠错能力,根据2种纠错编码的特性分别探讨了干扰信号设计原则和方法。计算机仿真表明,针对不同的编码样式采用特定脉冲干扰参数,能够取得更好的干扰效果。 相似文献
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本文简要介绍了信道编码的关键技术 -交织技术并给出了几种常用的交织器原理与结构。在此基础上着重介绍了适用于Turbo码的几种特殊的交织器。 相似文献
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The coded error probability for direct sequence (DS) BPSK or QPSK spread-spectrum systems, used with or without interleaving, and operating in the presence of pulsed multiple-tone interference, is investigated. We consider the worst-case channel error probability under conditions of pulsed multiple-tone jamming for the various systems, and present coded error probability as a function of interleaving delay for(n, k) block codes with hard-decision decoding. It is shown that when the maximum level of continuous multiple-tone interference does not exceed the level of the desired signal, the duty cycle of the corresponding pulsed interference which yields the worst-case error probability is usually small, and that the smaller the duty factor of the jamming, the more considerable is the performance improvement due to the use of interleaving in conjunction with the coding. 相似文献
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Hua Yang Hang Zhang Jiang Zhang Liu Yang 《International Journal of Satellite Communications and Networking》2019,37(6):527-535
In this paper, an anti‐jamming approach is proposed for the downlink of satellite communication systems when encountering a hostile repeater‐jamming. Based on blind source separation, this approach can eliminate repeater‐jamming by separating the mixtures of the communication signals and the repeater‐jamming. Meanwhile, oversampling method is employed to transform the underdetermined mixing of signals into a determined mixing for facilitating the separation. In the simulations, the symbol error ratio (SER) of the separated communication signals can approximate the theory SER, and the anti‐repeater‐jamming capacity can arrive to nearly 28 dB. 相似文献
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K. H. H. Wong L. Hanzo R. Steele 《International Journal of Satellite Communications and Networking》1989,7(3):143-163
The deployment of channel coding and interleaving to enhance the bit-error performance of a satellite mobile radio channel is addressed for speech and data transmissions. Different convolutional codes (CC) using Viterbi decoding with soft decision are examined with inter-block interleaving. Reed-Solomon (RS) codes with Berlekamp-Massey hard decision decoding or soft decision trellis decoding combined with block interleaving are also investigated. A concatenated arrangement employing RS and CC coding as the outer and inner coders, respectively, is used for transmissions via minimum shift keying (MSK) over Gaussian and Rayleigh fading channels. For an interblock interleaving period of 2880 bits, a concatenated arrangement of an RS(48,36). over the Galois field GF(256) and punctured PCC(3,1,7) yielding an overall coding rate of 1/2, provides a coding gain of 42dB for a BER of 10?6, and an uncorrectable error detection probability of 1–10?9. 相似文献
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自雷达诞生以来,抗干扰能力一直是评价一部雷达性能的关键性指标,特别是随着战场电磁环境的日益复杂,雷达抗干扰问题变得尤其重要。针对抗压制性干扰,改进了传统意义上基于最大信噪比的盲源分离算法,提出了使用干扰重构算法取代滑动平均处理的方法,获得了比传统方法分离出质量更高的雷达信号,输出信号与源信号相关性更强。 相似文献
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删余Turbo码的交织删余的综合设计研究 总被引:1,自引:0,他引:1
删余(Puncturing)是构造高码率Turbo码的主要方法。介绍了删截Turbo码的原理,研究了交织和删余相结合的综合设计删余Turbo码的思想,基于这种思想,设计了一种新颖的交织删余结合的删余Turbo码的设计方案,并给出了实现算法。仿真表明,该综合设计获得了更为优越的性能特性。 相似文献
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本文从最佳遮盖干扰认证的理论出发,得出正态噪声是各种噪声干扰的最佳波形,否定了其为干扰雷达的最佳波形。并提出了一种栅状非噪声压制干扰信号,经过与噪声调幅干扰信号、噪声调频干扰信号相互对比,栅状非噪声压制干扰信号在理论上有较好的干扰效果。 相似文献
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A. Brine P. G. Farrell R. A. Harris 《International Journal of Satellite Communications and Networking》1989,7(3):209-217
A study of reduced complexity concatenated coding schemes, for commercial digital satellite systems with low-cost earth terminals, is reported. The study explored trade-offs between coding gain, overall rate and decoder complexity, and compared concatenated schemes with single codes. It concentrated on short block and constraint length inner codes, with soft decision decoding, concatenated with a range of Reed-Solomon outer codes. The dimension of the inner code was matched to the outer code symbol size, and appropriate interleaving between the inner and outer codes was used. Very useful coding gains were achieved with relatively high-rate, low-complexity schemes. For example, concatenating the soft decision decoded (9,8) single parity check inner code with the CCSDS recommended standard Reed-Solomon outer code gives a coding gain of 4.8dB at a bit error probability of 10?5, with an overall rate of 0-78. 相似文献