共查询到20条相似文献,搜索用时 31 毫秒
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针对应用干遥控或命令辨别场合的跳码系统,提出了一种新型的非对称跳码算法。该跳码系统的加解密算法基于有限域GF(2^n)上的多项式运算,采用了随机数发生嚣,能够完成汽车电子钥匙等遥控或命令辨别场合的跳码功能,并达到较高的安全性。文章主要介绍了加解密模块及发送端芯片的设计与实现。 相似文献
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在文章中,首先介绍Turbo码的基本编译码结构和它的译码算法MAP。在此基础上,尝试对MAP算法的循环译码的后向递推的起点以及循环译码结构的最终判决条件根据实际应用情况进行改进。将译码的后向递推的起点定义为译码的前向递推的终点,并且将每一轮译码结果进行加权相加,得到最后系统输出。最后,根据MATLAB仿真的结果论证改进后的算法能减少系统的误码率。 相似文献
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Turbo Code译码算法的硬件实现 总被引:1,自引:0,他引:1
并行级联卷积码迭代译码算法(TurboCode)有着非常强的纠错译码能力。但大量的运算给工程实现TC译码器带来相当难度。文章在对MAP软输入软输出算法充分仿真基础上,给出一种简化MAP算法的Turbo译码器方案,此方案适用于FPGA器件实现。 相似文献
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The improved three novel schemes of the super forward error correction(super-FEC) concatenated codes are proposed after the development trend of long-haul optical transmission systems and the defects of the existing FEC codes have been analyzed. The performance simulation of the Reed-Solomon(RS)+Bose-Chaudhuri-Hocguenghem(BCH) inner-outer serial concatenated code is implemented and the conceptions of encoding/decoding the parallel-concatenated code are presented. Furthermore, the simulation results for the RS(255,239)+RS(255,239) code and the RS(255,239)+RS(255,223) code show that the two consecutive concatenated codes are a superior coding scheme with such advantages as the better error correction, moderate redundancy and easy realization compared to the classic RS(255,239) code and other codes, and their signal to noise ratio gains are respectively 2~3dB more than that of the RS(255,239)code at the bit error rate of 1×10 -13 . Finally, the frame structure of the novel consecutive concatenated code is arranged to lay a firm foundation in designing its hardware. 相似文献
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A new family of two-dimensional optical orthogonal code(2-DOOC), namely, modified quadratic congruence code(MQCC )/optical orthogonal code(OOC) is proposed who employs MQCC and OOC as wavelength hopping and time-spreading patterns, respectively. Through analyzing the performance of MQCC/ OOC, we can see that the correlation properties of the MQCC/OOC are still ideal. Simultaneously, our analysis shows that the proposed new code families can get more cardinalities than other codes and can improve the bit error rate(BER) of optical code division multiple access(OCDMA) effectively. 相似文献
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传统的无线密码锁实现方案中,多发送固定的密码,难以对付“拷贝重发”和“扫描跟踪”等入侵手法。文章提出一种基于非线性移位寄存器技术的跳码方案,这种方案能保证钥匙每次发送的密码都是随机的,不重复的,因此能有效避免“拷贝重发”和“扫描”等手法的入侵,基本达到了无法破解的安全性。 相似文献
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提出一种基于改进的Logistic+Tent映射的短波差分跳频转移函数算法。利用该算法构造跳频序列,针对跳频图案进行数值仿真并与原映射进行比较。仿真结果和性能分析表明,该新算法所构造的跳频序列不仅具有更好的随机性、平衡性,均匀性和相关性,符合跳频码的要求,而且具有较高的线性复杂度,因此,基于改进的Logistic+Tent混沌映射构造的跳频序列,具有较强的抗干扰能力和安全保密性。 相似文献
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基于KEELOQ跳码技术的密码系统设计 总被引:3,自引:0,他引:3
以跳码芯片为基础的系统在生活中正得到越来越广泛的应用,尤其是在汽车密码锁方面。早期使用的固定密码方式,具有两个致命的缺陷,即密码是固定的以及密码的可能组合数太少,使得通过码扫描而获得密码成为可能。跳码芯片使用了KEELOQ技术,每次发出的密码独一无二且无法预测,长达66位,可能的密码组合数达64 k(216),成功地解决了密码容易被破译的问题,大大地提高了系统的安全性。 相似文献
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M. P. Fitton A. R. Nix M. A. Beach 《International Journal of Wireless Information Networks》1999,6(4):219-229
In this paper, the suitability of Slow FrequencyHopping Code Division Multiple Access (SFHCDMA) isevaluated for wireless local access applications.Investigations of the wireless channel indicate that frequency hopping mitigates the poorpropagation characteristics associated with low mobilitycommon to fixed wireless applications. Employingstatistical analysis and simulation models, it is shownthat the frequency hopped channel displays inherentfrequency diversity. Consequently, an FH architecture isresilient to the effects of intersymbol interferencearising from significant time dispersion frequently experienced in the wireless channel.Furthermore, interference diversity of SFH-CDMA resultsin a robust air interface technique. With simulationtechniques it is demonstrated that SFH-CDMA can support the medium rate service bearers (approximately1 Mbps) required for wireless local access, whilstproviding high capacity. 相似文献
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Frequency hopping (FH) is a common characteristic of a wide variety of communication systems. On the other hand, software‐defined radio (SDR) is an increasingly utilized technology for implementing modern communication systems. The main challenge when trying to realize an SDR FH system is the frequency tuning time, that is, the higher the hopping rate, the lower the required frequency tuning time. In this paper, significant universal hardware driver tuning options (within GNU Radio software) are investigated to discover the tuning option that gives the minimum frequency tuning time. This paper proposes an improved SDR frequency tuning algorithm for the generation of a target signal (with a given target frequency). The proposed algorithm aims to improve the frequency tuning time without any frequency deviation, thus allowing the realization of modern communication systems with higher FH rates. Moreover, it presents the design and implementation of an original GNU Radio Companion block that utilizes the proposed algorithm. The target SDR platform is that of the Universal Software Radio Peripheral USRP‐N210 paired with the RFX2400 daughter board. Our results show that the proposed algorithm achieves higher hopping rates of up to 5,000 hops/second. 相似文献
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以混沌跳频码预测为背景,针对现有预测方法中存在的缺乏记忆能力导致识别准确率不高以及运算量大等问题,论文提出了基于优化回声状态网络的混沌跳频码预测方法。该方法在继承回声状态网络优良性能的同时,利用改进遗传算法优化网络储备池参数,较好地解决了参数选择问题,使其具有更强的针对性和更好的预测效果。论文以logistic-kent映射、Lorenz系统和Mackey-Glass系统跳频码为样本数据,通过改进遗传算法确定最优储备池参数并进行仿真实验,将仿真结果与其他文献结果作了比较,证明了该预测方法的优越性。 相似文献
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一种基于差分跳频转移函数的短波跳频码 总被引:6,自引:0,他引:6
该文提出了一种基于Logistic映射的短波差分跳频转移函数算法,利用该算法构造跳频图案,并对跳频图案进行了数值仿真和性能检验。研究结果表明:该算法所产生的跳频图案不仅具有较好的随机性、均匀性、平衡性和相关特性,符合短波跳频图案要求,而且,具有大的线性复杂度,因此,基于混沌映射构造的短波跳频序列具有较强的抗干扰能力和安全保密性。 相似文献