共查询到18条相似文献,搜索用时 78 毫秒
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基于量子遗传算法的CDMA多用户检测技术 总被引:2,自引:0,他引:2
多用户检测技术的最优解在常规条件下是个NP难解问题,利用量子态并行计算特性和量子纠缠特性能有效获得多用户检测的最优解,现提出了一种基于量子计算理论和遗传算法理论相结合的量子遗传算法的多用户检测技术.仿真结果表明,此方法在误码率方面具有良好的性能并且其抗多址干扰能力和抗远近效应能力明显优于经典遗传算法多用户检测器和传统检测器. 相似文献
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基于传统遗传算法的多用户检测器易陷入局部最优解且收敛较慢,影响实时性。本文利用混沌优化算法的优势来弥补遗传算法的这一缺陷,使两种算法优势互补,同时采用具有“迁移策略”的并行搜索机制,提出了一种新的次优多用户检测方法———并行混沌遗传混合算法(PCGA),并在同步CDMA系统中对其性能进行了研究。仿真结果表明,我们提出的这种算法能有效克服传统遗传算法易陷入局部极小的问题,计算量小,收敛速度快,在抗干扰与克服“远-近”效应方面均有明显的优势。 相似文献
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提出一种基于蚁群优化算法(ant colony optimization algorithm)的CDMA多用户检测(MUD)的方法。该方法在基本蚁群算法的基础上,应用一种新的相遇和搜索分区的策略,来解决最佳多用户检测的组合优化问题,可提高搜索的质量和效率,通过分析以及仿真表明,该方法具有多项式的计算复杂度,并可以得到较好的误码率性能,为寻求新的多用户检测方法提供了思路。 相似文献
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基于Hopfield神经网络的DS—CDMA多用户检测 总被引:3,自引:0,他引:3
从新的角度研究DS-CDMA(直接序列码分多址)系统中的多用户检测,将多用户检测的优化问题映射为Hopfield神经网络(HNN)“能量”函数的最小化问题,利用连续HNN固有的快速下降特性,实现了坟对CDMA(码分多址)系统的多用户检测。与现有各种方案比较,具有运算量小、抗远近效应强、实时性好等优点。 相似文献
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多用户检测(MUD)是有效地抑制多址干扰(MAI)的关键技术。本文在对各种现有MUD算法的特点进行认真分析的基础上,提出了将最小均方误差(MMSE)横式滤波器与并行干扰对消(PIC)相结合的联合检测结构。计算机仿真结果表明,该算法计算复杂度不高,性能明显优于传统的MUD算法,具有一定的实际应用价值。 相似文献
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本文介绍了一种将正交频分复用(OFDM)技术和码分多址(CDMA)技术相结合的多载波CDMA (MC-CDMA)系统,分析了MC-CDMA系统的发射端和接收端的结构,建立了MC-CDMA系统的信号模型,详细分析了MC-CDMA中的多址干扰形式,以及针对MC-CDMA系统的多用户检测原理,提出了一种基于最小误码率准则的多用户检测算法。理想的基于最小误码率准则的多用户检测算法在实际中难于实现,本文采用估计概率密度函数的方法,推导出了一种自适应实现的最小误码率多用户检测算法。仿真结果表明,该算法能够有效抑制多址干扰,降低误码率,同时,该算法还具有比基于最小均方误差准则的多用户检测器更低的误码率的优点。 相似文献
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Zoran Zvonar 《Wireless Personal Communications》1995,2(4):373-392
Multipath fading severely limits the performances of conventional code division multiple-access (CDMA) systems. Since every signal passes through an independent frequency-selective fading channel, even modest cross-correlations among signature sequences may induce severe near-far effects in a central multiuser receiver. This paper presents a systematic approach to the detection problem in CDMA frequency-selective fading channels and proposes a low complexity linear multiuser receiver, which eliminates fading induced near-far problem.We initially analyze an optimal multiuser detector, consisting of a bank of RAKE filters followed by a dynamic programming algorithm and evaluate its performance through error probability bounds. The concepts of error sequence decomposition and asymptotic multiuser efficiency, used to characterize the optimal receiver performance, are extended to multipath fading channels.The complexity of the optimal detector motivates the work on a near-far resistant, low complexity decorrelating multiuser detector, which exploits multipath diversity by using a multipath decorrelating filter followed by maximal-ratio combining. Analytic expressions for error probability and asymptotic multiuser efficiency of the suboptimal receiver are derived that include the effects of multipath fading, multiple-access interference and signature sequences correlation on the receiver's performance.The results indicate that multiuser detectors not only alleviate the near-far problem but approach single-user RAKE performance, while preserving the multipath diversity gain. In interference-limited scenarios multiuser receivers significantly outperform the RAKE receiver.This paper was presented in part at the Twenty-Sixth Annual Conference on Information Sciences and Systems, Princeton, NJ, March 1992 and MILCOM'92, San Diego, CA, October 1992. This work was performed while author was with the Department of Electrical and Computer Engineering, Northeastern University, Boston, USA. 相似文献
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CDMA移动通信中的判决反馈多用户信号检测器 总被引:4,自引:0,他引:4
本文推导了一种具有线性计算复杂度的同步DS—CDMA系统多用户检测算法,由此形成的判决反馈检测器在性能上优于解相关检测器,与两级多用户检测器的性能相当,而实现起来则更为简单。数值结果表明,当接收到的干扰信号能量比有用信号能量高4dB以上时,判决反馈检测器的性能将接近单用户系统的性能,因而该检测器可有效地克服CDMA移动通信中的远近影响。 相似文献
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最优多用户检测方法具有最优性能,但复杂度高,利用优化算法求解可以降低实现复杂度。粒子群算法是一种简单有效的新型群智能优化算法,研究了一种Socialcognition模型简化粒子群算法,并应用于大用户量CDMA多用户检测问题,主要考虑降低算法复杂度,提高算法的实现效率。分析及仿真表明该方法在系统用户数量较大时具有较好性能。 相似文献
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In this paper, we propose a sub-optimum multiuser detection technique in multicarrier code division multiple access (MC-CDMA)
communication systems based on missing parameter expectation maximization (MPEM) algorithm. In the proposed detection procedure,
first initial values for the bits of all users are estimated from received signal. Then, the proposed MPEM based algorithm
uses outputs of carries’ demodulators to improve the accuracy of the initial estimates of the bits. In this paper, the expectation
and maximization steps’ functions of the MPEM algorithm for MC-CDMA multiuser detection are derived and the performance of
the proposed algorithm is analyzed. Our presented numerical results demonstrate the efficiency of the proposed detection algorithm
both in bit error rate performance and computational complexity points of view.
Paeiz Azmi was born in Tehran, Iran, on April 17, 1974. He received the B.Sc., M.Sc., and Ph.D. degrees in electrical engineering from
Sharif University of Technology (SUT), Tehran, Iran, in 1996, 1998, and 2002, respectively. Since September 2002, he has been
with the Electrical and Computers Engineering Department of Tarbiat Modarres University, Tehran, Iran. From 1999 to 2001,
he was with Advanced Communication Science Research Laboratory at Iran Telecommunication Research Center (ITRC), Tehran, Iran.
From 2002 to 2005, he was with Signal Processing Research Group at ITRC. His current research interests include modulation
and coding techniques, digital signal processing, and optical CDMA communications. 相似文献