共查询到19条相似文献,搜索用时 62 毫秒
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支持向量机作为一种新的模式分类方法是建立在统计学习理论的VC维理论和结构风险最小原理基础上。论文将支撑向量应用到DS-CDMA系统的多址干扰抑制中,并采用SMO算法构建非线性的检测接收器,理论推导和系统仿真表明该多用户检测接收器在高斯信道中具有非常好的性能,并通过分析影响系统性能的关键因素,指出了基于SMO算法的多址干扰抑制今后研究突破的方向。 相似文献
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分析了ST-OFDM系统中载波间干扰的具体内容,提出了一种ST-OFDM系统中载波间干扰线性抑制技术,利用连续发射已知ST-OFDM符号来估计ST-OFDM中各个子载波对其他子载波的干扰,然后通过特定的线性运算达到ST-OFDM载波间干扰的抑制。仿真结果表明,使用与不使用载波干扰抑制技术ST-OFDM系统可获得至少4dB性能增益,而且选择6~10个相邻子载波干扰系数可以使ST-OFDM系统在性能和运算量上获得最佳。莱斯衰落信道下该线性抑制方法可较有效克服ST-OFDM系统的载波间干扰。 相似文献
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测试系统的干扰及其抑制 总被引:3,自引:0,他引:3
阐述了检测系统中的各类干扰,并对其产生的原因作了较详细的分析。针对干扰的特性,指出了它们的危害范围及程度,提出了检测系统抗干扰的方法和措施。 相似文献
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《计算机应用与软件》2013,(5)
针对超宽带多址干扰问题,采用高斯7阶导脉冲作为UWB原始脉冲,使用厄米特矩阵特征向量分解算法设计UWB正交脉冲序列,采用Logistic混沌序列作为跳时码进行混沌跳时-脉位调制,生成混沌超宽带脉冲,从而达到抑制多址干扰的目的。最后,分析CTH-PPM UWB系统的抗多址干扰性能。仿真结果表明CTH-PPM UWB系统抗多址干扰性能明显优于TH-PPM UWB系统,具有更强的抗多址干扰能力。 相似文献
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OFDM-CDMA系统中,在多径传播和其他同频干扰存在时,接收机会收到多个恒模信号,针对这种情况,文章提出一种基于线性约束恒模算法(LCCMA)的盲抗干扰方法,该方法结合了通常的旁瓣消除器和恒模算法,用于消除多址干扰对系统的影响。分别对不同用户数目的系统进行计算机仿真,结果表明,采用本算法后,能有效地抑制多址干扰,极大地提高了系统的性能。 相似文献
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在直接序列扩频/码分多址(DS/CDMA)系统中由于各用户之间的影响而使其容量受到很大限制。通常这种用户之间的影响是作为噪声来处理的。本文讨论了多址干扰问题,从另一不同的角度出发,即把用户之间的影响作为有用信息,对多个用户的数据信息进行联合判决,提出了提高判决准确性的方案。 相似文献
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A structure was proposed for multiple-input-multiple-output multicarrier code divi- sion multiple access (MIMO MC-CDMA) uplink transmission system. Linear zero- forcing V-BLAST (ZF V-BLAST) algorithm and maximum ratio combining (MRC) scheme was applied to the receivers. The average bit error rate (BER) expression was derived on condition that the number of receive antennas was larger than that of transmit antennas and it was verified by simulations. Numerical results show that the number of transmit and receive antennas, as well as the number of sub- carriers, all exert significant effects on the BER performance. The space diversity and frequency diversity show different abilities to improve the BER performance. The MIMO MC-CDMA system based on linear ZF V-BLAST algorithm is capable of achieving better BER performance than that of the conventional MC-CDMA system by reducing the number of transmit antennas or increasing the number of receive antennas. 相似文献
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Tsui-Tsai LinFuh-Hsin Hwang 《Expert systems with applications》2012,39(3):3145-3152
This paper presents a simple scheme, which speeds the estimation of carrier frequency offset (CFO) as well as reducing the estimation complexity for multicarrier code-division multiple-access (MC-CDMA) uplink. Based on the concept of bisection method, the CFO is efficiently estimated by way of locating the peak value in the output power spectrum of the minimum output energy (MOE) detector. Complexity reduction results from the proposed data vector partition associated with an innovative data processing technique for the MOE detector. Simulation results show that the expected advantage of the proposed scheme can be achieved at the expense of a reasonable performance loss even in the presence of a large CFO. 相似文献
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多载波码分多址(MC-CDMA)系统的微小载频偏移将破坏子载波之间的正交性,恶化系统性能,因此需要载频偏移估计和补偿;各个载频偏移的最大似然估计是个多维的全局搜索过程,计算复杂。提出一种MC-CDMA系统上行链路的基于粒子群算法的多用户频偏估计算法,降低了频偏估计方法的计算复杂度。仿真结果表明,基于粒子群算法的MC-CDMA系统多用户频偏估计方法的估计性能好,其均方误差小于基于虚拟子载波的多用户频偏估计的均方误差。 相似文献
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To improve the capacity of initial ranging (IR) users simultaneously accessing into network and enhance the performance of the IR, a novel IR algorithm is presented for the orthogonal frequency division multiple access systems with the smart antenna. The beamforming weight vectors provided by the antenna array are introduced for the IR users, and the procedures of the multiuser parameter estimation and the interference cancellation are designed. The proposed method can improve the accuracy of the channel estimation of active paths and efficiently reduce the residual multiple access interference. Simulation results show that the proposed method has a much better performance than the available successive multiuser detection and interference cancellation algorithm and accommodates more active ranging users simultaneously accessing into a cell. 相似文献
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N. Kumaratharan 《Computers & Electrical Engineering》2010,36(1):224-233
Multiple-input Multiple-output (MIMO) multi-carrier code division multiple access (MC-CDMA) is a strong candidate for the downlink of future mobile communications to obtain high data rates. Nevertheless, during any transmission over fading channel, performance of MC-CDMA systems are highly degraded due to the presence of multiple access interference (MAI). Multi-user detection (MUD) and channel estimation play a major role in overcoming MAI and characterising the channel, respectively. In this paper, space time serial interference cancellation (STSIC) detection using random and Gold codes and turbo aided iterative channel estimation (ICE) techniques are extended for MC-CDMA system MIMO channels to overcome MAI. Simulation results show STSIC outperforms optimal MUD and linear MUD techniques in mitigating MAI and turbo aided ICE surpasses ICE in characterising the channel with reduced error rates. 相似文献
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地铁中的对讲系统是乘客信息系统的重要组成部分.在实际应用中,由于地铁运行环境嘈杂及硬件设备的限制,使得全双工免提对讲过程中存在很大的声学回声,啸叫现象也时有发生.因此目前地铁中的对讲系统基本都在半双工状态下运行.基于此,本文提出了一种结合啸叫抑制的归一化最小均方算法,来解决全双工对讲回声控制中出现的声学回声及啸叫问题,并通过仿真及地铁项目中的实际应用表明了该算法的有效性. 相似文献
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为了找到一种适合于全球定位系统(GPS)接收机抗压制性干扰的方法,在介绍自适应数字波束形成的基础上,研究了直接矩阵求逆(SMI)和GS自适应算法的基本原理,在GS算法的基础上进行了改进,在均匀线阵中对各算法进行仿真,比较了各算法的优缺点,在运算量小和抗干扰性能稳定的前提下,认为改进的GS算法是适宜于工程实现的一种好方法. 相似文献
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空时编码(STC)与正交频分复用多址(OFDM)结合形成的STC-OFDM系统,虽然有效弥补了正交频分复用多址系统中符号间干扰(ISI)和频率选择性衰落等不足,但依然存在如何有效抑制因多天线传输在接收端产生的相互干扰如同频干扰(CCI)等问题。为此,在充分利用STC-OFDM已有优点基础上,给出了一种结合自适应波束赋形和哈达玛转换(WHT)来抑制CCI的算法。通过理论分析与计算机仿真表明,该算法能进一步改善系统误符号率(SER)而抑制STC-OFDM中的同频干扰。 相似文献