共查询到19条相似文献,搜索用时 78 毫秒
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跳时序列对UWB系统多址性能的影响 总被引:2,自引:0,他引:2
通过变换超宽带(UWB)无线电通信系统的信号模型,分析了该通信系统的多址性能,给出了跳时序列与其所产生的多址干扰之间的关系,从而明确了跳时序列的相关性能对该通信系统误码率的影响。 相似文献
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跳频码分多址系统中混沌跳频序列的优选与仿真 总被引:1,自引:1,他引:0
根据跳频码分多址系统的特点,总结了跳频序列的性能分析准则,并据此提出了混沌跳频序列的优选方法。通过对大量不同初值的混沌序列进行筛选,得到了性能优异的混沌跳频序列组。与改进型Lempel—Greenberger(L-G)序列相比,优选混沌跳频序列数目多,完全消除频隙滞留现象,而且平均汉明相关特性与之非常接近。为了验证优选混沌序列的性能,在AWGN信道下在跳频异步码分多址系统中进行了仿真,结果证明优选混沌序列的抗多址干扰能力逼近改进型L-G序列。 相似文献
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着眼于抗干扰通信的军事应用研究,通过对UWB MC-DS-CDMA的分析改进,得到了一种新型应用于超短波的UWB信号,分析了该信号的抗干扰性能,并与UWB MC-DS-CDMA信号进行了比较,然后使用安捷伦公司的ADS仿真软件进行了仿真验证,得出了该新型UWB信号具有极强的抗干扰性能的结论。 相似文献
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设计了一款基于低温共烧陶瓷(LTCC)技术的新型超宽带(UWB,)带通滤波器.该款滤波器结合了半集总高通结构与缺陷地(DGS)结构,利用半集总结构实现截止频率为3.1GHz的高通滤波器,再结合DGS在高端产生阻带,从而实现通带为3.1~ 10.6GHz的带通滤波器,尺寸仅为3.2mm×1.6mm×1.2mm.实测结果表明:插入损耗<1.5dB,反射损耗<12dB,群时延<0.8ns,带外抑制>15dB(11.5~17GHz).测试与仿真结果较为吻合.此种LTCC滤波器结构具有尺寸小、插损小、群时延小等优点,而且结构简单,带宽和中心频率容易控制,相对带宽可做到150%以上,特别适合用于极宽带通信系统的频率选择. 相似文献
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Multiuser detection of time-hopping PPM UWB system in the presence of multipath fading 总被引:2,自引:0,他引:2
Ultra-wideband (UWB) impulse radio (IR) systems are currently being considered for several applications due to their attractive features that include low-power carrierless and ample multipath diversity. Among the various modulation and multiple-access schemes, time-hopping (TH) pulse position modulation (PPM) is a popular technique in application. Most past works rely on strict power control and perform single-user detection (matched filtering) on the desired signal. This paper aims to apply multiuser detection techniques in binary PPM (BPPM) UWB IR multiple-access systems. Moreover, we consider frequency-selective multipath fading channels to account for the wireless cellular environment. A class of linear multiuser detectors (LMDs) is applied to extract the information bits while eliminating multiuser interference (MUI) in the presence of multipath fading. Simulation results are provided to compare the performance of different LMDs. 相似文献
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Wei-Chiang Wu 《Circuits, Systems, and Signal Processing》2008,27(1):65-80
Ultra wideband impulse radio systems have attracted great attention for their promised applications in high-speed short-range
indoor wireless communication systems. Among the various modulation and multiple access schemes, this paper deals with time-hopping
(TH) antipodal pulse amplitude modulation operating in the presence of a multipath fading downlink channel. We first employ
a constrained optimization technique to design a batch mode blind (without exploiting training sequences and undesired users’
time-hopping (TH) codes) mobile station receiver. To reduce the computational complexity, we propose a blind adaptive receiver
that is based on the criterion of maximizing the receiver’s minimum possible output energy. The algorithm jointly and iteratively
optimizes the weight vector and channel impulse response to improve system performance. Simulation results show that the proposed
adaptive receiver converges to the optimum batch mode receiver. Moreover, the algorithms are shown to be robust to multi-user
interference and near-far problems. 相似文献
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本文研究多带正交频分复用瑞利衰落信道中,空时网格编码发射天线间空间相关性的分集性能.空时网格编码将单个输出的编码符号转换成多个编码符号,并通过多个发射天线传输,在接收端,Viterbi优化软判决算法用于译码.我们分析了MB-OFDM系统在quasi-static和interleaved两种信道中相关空间衰落对误码率的影响.在空间相关性较小时,分集阶数能得到保持;而在空间相关性较大时,interleaved信道能保持分集阶数,quasi-static信道的分集阶数将减小.空时编码总体上对空间相关性表现出鲁棒性. 相似文献
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本文针对动态信噪比环境超宽带(UWB, Ultra WideBand)信号的非相干捕获,提出了一种基于遗传算法的信号捕获方案.以遗传算法结合在线估计接收信噪比,搜索积分窗口长度与定时位置的参数组合,实现系统要求的比特错误概率.该方法解决了传统捕获方案在未知信噪比条件下积分长度无法择优选取以及捕获门限难于设定的问题.仿真结果表明,基于遗传算法的二维参数捕获方法与传统Look and Jump by K steps算法相比有效的提高了未知信噪比条件下的系统捕获性能,拓展了UWB非相干系统的应用范围. 相似文献