共查询到16条相似文献,搜索用时 109 毫秒
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针对脉冲噪声下盲均衡器难以快速收敛并有效抑制噪声的问题,该文提出一种基于Renyi熵的分数低阶双模盲均衡算法。该算法将Renyi熵与分数低阶统计量相结合并用作代价函数来更新盲均衡器权向量,利用Renyi熵提高算法的收敛速度,利用分数低阶统计量增强算法对脉冲噪声的抑制能力。为了提升系统稳健性,该文进一步提出双阈值加权判决法,通过设置双阈值并引入非线性加权函数,使得两种代价函数之间的切换更为平滑。在不同脉冲性噪声、不同信道环境下进行仿真实验,结果表明,该文算法既能有效抑制脉冲噪声,又具有较快的收敛速度。 相似文献
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摘 要:信道失真和多径衰落特性会造成符号间串扰,从而导致系统性能下降。以QAM信号为对象,研究提高信号盲自适应均衡性能的算法,该算法利用联合MCMA DD的误差函数并结合分集合并技术运用到非线性结构的判决反馈均衡器中形成一种混合盲算法来均衡QAM信号。混合算法中同时利用两误差函数对系数进行更新以提高QAM信号的均衡适应能力,利用空间分集减少衰落的影响和利用非线性结构适应频响起伏大的信道。从仿真结果看,与其他算法相比该混合算法加快了收敛速度、减小了稳态误差并且纠正了相位旋转,有效性得到验证。 相似文献
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基于对常数模判决反馈算法(CMDFE)进行分析,提出了一种能够快速收敛的判决反馈盲均衡算法。该算法中构造了一种与常数模算法不同的、能够快速收敛的误差函数,并利用该误差函数对前向权进行调整,而反馈权的调整仍使用常数模误差项。前向权和反馈权系数的更新取不同的步长值。最后通过水声信道模型仿真,对这几种算法进行了数值分析研究。结果表明:所提出的算法可有效地实现对多途水声信道的均衡,并且其收敛速度高于常数模算法和常模判决反馈算法。 相似文献
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针对深衰落稀疏多径信道下多进制相移键控(Multiple Phase Shift Keying,MPSK)信号的盲均衡问题,提出了一种l0-范数约束的分数间隔稀疏自适应双模式盲均衡算法.该算法借鉴传统的分数间隔双模式盲均衡算法思想,结合稀疏自适应滤波理论,首先利用l0-范数对均衡器抽头系数进行稀疏性约束,构造出一种l0-范数约束的分数间隔双模式最小均方误差代价函数,然后依据梯度下降法推导出盲均衡器抽头系数更新公式,并对迭代步长进行归一化和比例系数化.理论分析和仿真实验表明,与基于门限稀疏化的盲均衡算法、基于分数阶范数的盲均衡算法及分数间隔双模式盲均衡算法相比,本文所提算法在保证较快收敛速度的前提下,能有效降低剩余符号间干扰.本文设计的盲均衡算法为水声通信系统中接收方恢复出发送信号,提供了一种快速有效的方法. 相似文献
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Blind equalization for short burst wireless communications 总被引:4,自引:0,他引:4
In this paper, we propose a dual mode blind equalizer based on the constant modulus algorithm (CMA). The blind equalizer is devised for short burst transmission formats used in many current wireless TDMA systems as well as future wireless packet data systems. Blind equalization is useful for such short burst formats, since the overhead associated with training can be significant when only a small number of bits are transmitted at a time. The proposed equalizer overcomes the common problems associated with classic blind algorithms, i.e., slow convergence and ill-convergence, which are detrimental to applying blind equalization to short burst formats. Thus, it can eliminate the overhead associated with training sequences. Also, the blind equalizer is extended to a two branch diversity combining blind equalizer. A new initialization for fractionally spaced CMA equalizers is introduced. This greatly improves the symbol timing recovery performance of fractionally spaced CMA equalizers with or without diversity, when applied to short bursts. Through simulations with quasi-static or time-varying frequency selective wireless channels, the performance of the proposed equalizer is compared to selection diversity and conventional equalizers with training sequences. The results indicate that its performance is far superior to that of selection diversity alone and comparable to the performance of equalizers with short training sequences. Thus, training overhead can be removed with no performance degradation for fast time-varying channels, and with slight performance degradation for static channels 相似文献
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There are serious intersymbol interference (ISI) and signal attenuation in wireless ultraviolet communication system.Aiming at this problem,an improved constant modulus fractionally spaced equalizer (CMA-FSE) based on signal-to-noise (SNR) estimation was proposed.The algorithm combined the fractionally spaced equalizer (FSE) and constant modulus algorithm (CMA) for blind equalization of wireless ultraviolet channels.The input SNR was measured by the mean square value of the received signal,and it was used to determine the best iterative step to ensure the convergence of the equalization algorithm.Simulation results show that the improved CMA-FSE algorithm can converge rapidly under various SNR,and it can effectively suppress ISI and improve the BER performance of the system.Compared with the existing algorithms,the improved algorithm is more useful in channel tracking and noise suppression. 相似文献
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多径效应造成的符号间干扰是大容量散射传输所遇到的首要问题.根据文献中提出的基于二阶循环统计量的直接盲均衡算法,依据最小均方误差准则,对接收到的信号进行过采样,构造了一个线性的分数间隔均衡器,并用它来均衡对流层散射信道,获得了较好的均衡效果.由于该算法不经过信道盲辨识而直接均衡信道,因此受信道阶教误差的影响较小,且该算法与传统的基于二阶矩的两步均衡算法相比,具有计算简单,精度高的特点. 相似文献
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本文针对恒模算法(CMA)收敛速度较慢、收敛后均方误差较大的缺点,提出一种新的双模式盲均衡算法。先采用T/4分数间隔采样的盲均衡算法,由于采用了过采样技术,避免了因欠采样引起的频谱混叠,然后在算法收敛后切换到判决引导(DD-LMS)算法,减少误码率。计算机仿真表明,本文提出的新算法有较快的收敛速度、较小的稳态误差和较低的误码率。 相似文献