共查询到17条相似文献,搜索用时 218 毫秒
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脉冲干扰是宽带接入网上行信道数据传输性能受限的因素之一,基于对脉冲噪声干扰影响宽带接入网上行信道特性的研究,推导了其特征函数模型。建立了脉冲噪声干扰下的系统仿真模型,在16进制QAM调制下,仿真得到了载噪比与误码率的曲线,并对系统模型的BER仿真曲线结果进行了分析。为提高宽带接入网系统性能和故障诊断提供了有效的理论依据。 相似文献
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基于电力线信道的改进LDPC码译码算法研究 总被引:2,自引:1,他引:1
脉冲噪声是电力线通信中存在的最大障碍,造成信号的误码率(BER)高,必须考虑采用复杂的信道编码技术.低密度奇偶检验码(LDPC)是无线通信系统中最接近香农极限的纠错码,译码算法是针对无线信道的干扰而设计的.针对电力线信道存在的脉冲噪声,用A脉冲类噪声电力线信道模型,提出了一种改进的LDPC码译码算法.通过对改进的算法进行仿真,表明改进的LDPC算法大大提高了系统编码增益,可用于电力线宽带通信系统. 相似文献
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超宽带通信系统窄带干扰变换域抑制方法 总被引:1,自引:0,他引:1
结合UWB系统的工作特点,对信道中信号的频谱特性进行分析,在变换域(频域,或时间-尺度域)中设计出最佳脉冲波形,使其与周围电磁环境中含有干扰的变换域相互正交,从而有效地避开干扰.通过对环境的周期性重复采样,可使得UwB成为一个自适应抑制干扰的通信系统.仿真结果表明,设计的自适应抑制干扰脉冲比通常使用的Scholtz脉冲的性能更优,抗干扰能力更强.且此方法不需要在整个频段内降低UWB脉冲的功率谱密度,为提高UWB脉冲发射功率,增大UWB系统的通信距离,提供了一种灵活易行的参考型方案. 相似文献
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针对战场环境下复杂传播环境及敌方干扰对无人机通信系统性能的影响,提出了综合信道衰落和干扰共同作用下的无人机通信信道理论模型。在此基础上,基于微波暗室设计实现了无人机通信干扰电磁环境半实物仿真系统。该系统利用硬件现场可编程门阵列(Field Programmable Gate Array,FPGA)实时模拟无人机通信信道和干扰信号,利用微波暗室模拟外场的无线传播环境,并通过天线位置和角度调节装置模拟发射机、干扰机和接收机之间的空间位置特性。实测结果表明,该半实物仿真系统能够真实复现无人机通信干扰电磁环境,可用于无人机数据链抗干扰性能的测试和评估。 相似文献
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对基于SCDMA接入方案的HFC上下行通信系统的发送机进行了功能仿真,为HFC接入网上行信道物理层的硬件实现创造了有利条件。 相似文献
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60 GHz脉冲通信环境中的多径衰落问题使信号能量发生弥散并产生符号间干扰(ISI).针对这一问题,分析了系统中ISI的严重程度,并研究了消除干扰的解决方法.在IEEE 802.15.3c工作组建立的60 GHz无线信道模型基础上,搭建了60 GHz脉冲通信系统仿真平台,对系统中的ISI进行了理论分析与数值仿真,设计了一种Rake接收机联合均衡器的接收方案.研究结果表明,采用两径MRC-Rake接收模块并联合MMSE线性均衡模块,既可获得多径分集增益又能有效处理ISI,在不增加过多复杂度的同时提高了系统性能.为今后60 GHz脉冲通信系统接收方案的设计提供了技术参考. 相似文献
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为了减轻冲激噪声和多径干扰的影响,本文提出了一种基于DS-CDMA同步信道的空时非线性接收机。该接收机联合了线性解相关器和带有基于相关匹配M yriad非线性滤波器的非线性前端的天线阵列。将这种M yriad滤波器合并在一起以消除冲激噪声和阻止其进入系统。所提出的检测器采用了一种结构来估计冲激噪声系数和修正非线性滤波器系数。仿真结果表明,这种空时接收机在空时领域的非线性信号处理方面具有很好的性能。 相似文献
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We demonstrate an overlay of a broadband passive optical network (PON) on the same fiber network as an operating baseband digital system. The baseband system is modeled after current-generation narrowband PONs, and the two PONs can be operated simultaneously. The broadband PON incorporates coarse wavelength division multiplexing to increase the downstream bit rate, and subcarrier multiple access for the upstream upgrade. We examine the RF interference between baseband and subcarrier signals, and provide guidelines on channel spacing and means for accommodating differing power levels for the two signals. The broadband architecture described here provides a graceful upgrade path for providing advanced digital services on a PON without having to modify the network or terminal equipment used for providing narrowband services 相似文献
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In many physical channels where multiuser detection techniques are to be applied, the ambient channel noise is known through
experimental measurements to be decidedly non-Gaussian, due largely to impulsive phenomena. This is due to the impulsive nature
of man-made electromagnetic interference and a great deal of natural noise. This paper presents a robust multiuser detector
for combating multiple access interference and impulsive noise in code division multiple access (CDMA) communication systems.
A new M-estimator is proposed for "robustifying" the detector. The approach is corroborated with simulation results to evaluate
the performance of the proposed robust multiuser detector compared with that of the linear decorrelating detector, and the
Huber and the Hampel M-estimator based detectors. Simulation results show that the proposed detector with significant performance
gain outperforms the linear decorrelating detector, and the Huber and the Hampel M-estimator based detectors. This paper also
presents an improved robust blind multiuser detection technique based on a subspace approach, which requires only the signature
waveform and the timing of the desired user to demodulate that user's signal. Finally, we show that the robust multiuser detection
technique and its blind adaptive version can be applied to both synchronous and asynchronous CDMA channels. 相似文献
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Zi-Wei Zheng 《Wireless Personal Communications》2010,53(1):67-79
In this paper, we consider the receiver design problem for the uplink multiuser code division multiple access (CDMA) communication
system based on the neural network technique. The uplink multiuser CDMA communication system model is described in the form
of space–time domain through antenna array and multipath fading expression. Novel suitable neural network technique is proposed
as an effective signal processing method for the receiver of such an uplink multiuser CDMA system. By the appropriate choice
of the channel state information for the neural network parameters, the neural network can collectively resolve the effects
of both the inter-symbol interference due to the multipath fading channel and the multiple access interference in the receiver
of the uplink multiuser CDMA communication system. The dynamics of the proposed neural network receiver for the uplink multiuser
CDMA communication system is also studied. 相似文献
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目前 ,基于CableModem技术的HFC接入网已得到较为广泛的应用 ,但网络中的漏斗噪声限制了系统带宽的充分利用。着重分析上行信道的噪声特性 ,并根据噪声特性 ,研究了TDMA ,FDMA和CD MA 3种多址接入技术的特点 ,认为TDMA/FDMA混合方案更适合HFC网络上行信道的传输要求 相似文献