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基于NLMS的CDMA盲自适应多用户检测算法研究 总被引:1,自引:0,他引:1
多用户检测是抑制DS-CDMA系统多址干扰最有效的技术之一。由于所需的先验知识仪有期望用户的地址码,盲多用户检测技术的研究尤受重视。最小输出能量(MOE)准则被广泛用于盲线性多用户检测。目前已提出的该类检测器多采用LMS或RLS算法。本文则研究基于NLMS算法的盲自适应检测技术,并进一步提出盲自适应变步长NLMS检测器和参数可变的盲自适应变步长NLMS检测器。它们具备很好的收敛速度和跟踪能力,以及较高的输出信干比,同时计算复杂度仅为O(3N)或O(4N),非常适合硬件实现。 相似文献
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本文在直接序列/码分多址(DS/CDMA)系统盲检测自适应梯度算法(BAG)的基础上,提出了一种多用户检测盲自适应梯度算法的改进算法(IBAG).BAG算法包括自适应梯度算法(TBAG)和时变自适应梯度算法(TIBAG),TBAG算法的跟踪特性较好,但起始收敛特性不好;TIBAG算法的收敛特性较好,但跟踪特性较差,几乎不具备跟踪能力.本改进算法结合了这两种自适应梯度算法的优点,在不增加算法复杂度的前提下,使其收敛性和跟踪特性较BAG算法有所提高. 相似文献
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子空间方法盲多用户检测技术分析与探索 总被引:1,自引:0,他引:1
着重分析了基于子空间跟踪的盲线性多用户检测算法 ,并对其内部算法模块进行了仿真比较 ,最后对算法性能改善方法提出了自己的新思路 相似文献
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This paper proposes a novel concept of adjusting the hardware size in a multi‐carrier code division multiple access (MC‐CDMA) receiver in real time as per the channel parameters such as delay spread, signal‐to‐noise ratio, transmission rate, and Doppler frequency. The fast Fourier transform (FFT) or inverse FFT (IFFT) size in orthogonal frequency division multiplexing (OFDM)/MC‐CDMA transceivers varies from 1024 points to 16 points. Two low‐power reconfigurable radix‐4 256‐point FFT processor architectures are proposed that can also be dynamically configured as 64‐point and 16‐point as per the channel parameters to prove the concept. By tailoring the clock of the higher FFT stages for longer FFTs and switching to shorter FFTs from longer FFTs, significant power saving is achieved. In addition, two 256 sub‐carrier MC‐CDMA receiver architectures are proposed which can also be configured for 64 sub‐carriers in real time to prove the feasibility of the concept over the whole receiver. 相似文献
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该文研究可变扩频长度(Variable Spreading Length, VSL) 多速率直接序列码分多址(Direct-Sequence Code-Division Multiple-Access, DS-CDMA) 系统中的自适应多用户接收机。利用到相交子空间的迭代投影估计得到包含信道信息的特征矢量,以此构造多用户接收机。借助于子空间跟踪算法的特殊形式,推导了特征矢量估计算法及多用户接收机的一种低复杂度的自适应实现。仿真实验证明,该算法有很好的数值稳定性,与传统算法BER性能相同的情况下,具有更低的计算复杂度。 相似文献
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Multiuser detectors for asynchronous multirate code-division multiple-access (CDMA) systems are considered. A multirate CDMA system model able to fit several system concepts in the same framework is presented. The performance of the multi-code (MC) system with one processing gain and the multiple processing gain (MPG) system is compared. Upper bounds for the expected value of the asymptotic multiuser efficiency of the decorrelating detector for a synchronous multirate CDMA system with three effective users are derived for a system with one and two processing gains. The numerical results show that the performance of the decorrelating detector for MC and MPG systems do not differ significantly. The bit error rates (BER) of the decorrelating, parallel interference canceler (PIC) and groupwise serial interference canceler (GSIC) with either PIC or decorrelator within the group are compared. The results show that the decorrelating and the GSIC detectors yield the best performance. For all interference cancellation schemes the BER saturates at high SNRs due to decision errors degrading the multiple-access interference (MAI) estimates. 相似文献
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多径CDMA信道下最小均方盲空时多用户检测 总被引:1,自引:0,他引:1
本文首先在码片匹配滤波的基础上为多径CDMA信道环境的接收机提出四种数据选择方案,分析了各种数据方案对多址干扰与码间干扰的影响;接着提出了基于Rosen梯度投影实现的最小均方盲空时多用户检测方法并分析了四种数据选择方案对其运算复杂度的影响;最后通过仿真实验结果的分析比较给出较合理的实现方法,该方法在降低运算量具有一定的优势,因而更加具有实用意义. 相似文献
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1 IntroductionMultiuserDetection (MUD)ismainlyappliedinCDMAtocancelthemultiaccessinterference.Thesingle usermatchedfilterorrakereceivertreatstheinterferencefromotherusersasnoise ,butMUDtakesadvantageoftheotheruser’sinterference[1 ].BlindadaptiveMUDhasbeent… 相似文献
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Yonghoon Choi 《ETRI Journal》2014,36(6):953-959
This paper studies the uplink resource allocation for multiple radio access (MRA) in reconfigurable radio systems, where multiple‐input and multiple‐output (MIMO) multicarrier‐code division multiple access (MC‐CDMA) and MIMO orthogonal frequency‐division multiple access (OFDMA) networks coexist. By assuming multi‐radio user equipment with network‐guided operation, the optimal resource allocation for MRA is analyzed as a cross‐layer optimization framework with and without fairness consideration to maximize the uplink sum‐rate capacity. Numerical results reveal that parallel MRA, which uses MC‐CDMA and OFDMA networks concurrently, outperforms the performance of each MC‐CDMA and OFDMA network by exploiting the multiuser selection diversity. 相似文献
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投影近似子空间跟踪算法及其在盲线性多用户检测中的应用 总被引:3,自引:0,他引:3
本文针对CDMA系统中的多用户检测,探讨信号子空间作为一种无约束最小化问题的解这一新的解释,在此基础上分析并研究了一种新的跟踪信号子空间的方法PASTd算法。分析表明,通过适当的投影近似,最小化任务简化为众所周知的指数加权最小二乘问题,从而可以运用递归最小二乘(RLS)方法来有效地跟踪信号子空间。该算法的计算复杂度为O(nr)。计算机仿真结果证明了PASTd算法的有效性,从而该算法对于基于子空间的盲线性多用户检测器的实现具有研究和参考意义。 相似文献
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DS-CDMA通信系统中基于独立分量分析的盲多用户检测 总被引:3,自引:0,他引:3
本文研究了直接序列扩频码分多址(DS-CDMA)通信系统的多用户检测问题,提出了基于独立分量分析(ICA)方法的盲多用户检测算法,实现多用户信号的盲检测。该方法不需知道用户的扩频码就可完成多用户信号的盲检测。仿真结果验证了本文提出的方法的优良性能。 相似文献
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首先分析了CDMA移动通信系统中采用多用户检测的必要性 ,然后介绍了各种多用户检测技术的工作原理 ,对各种多用户检测技术的特点进行了分析比较 ,最后提出了目前多用户检测技术的一些最新发展方向。 相似文献
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Buzzi Stefano Krishnamurthy Vikram Lops Marco Poor H. Vincent 《Wireless Personal Communications》2003,27(4):293-320
The problem of blind adaptive multiuser detection in multirateCDMA systems is considered. Indeed, since symboldetection in multirate CDMA systems requires periodicallytime-varying processing of the observables, classical LMS and RLSadaptive algorithms, which assume that the solution to be trackedis time-invariant or slowly time-varying, are not suited for blindadaptive multiuser detection in a multirate system. While a cyclicRLS algorithm has recently appeared in the literature, thispaper focuses on the development of LMS-based cyclic filteringalgorithms. In particular, cyclic versions of the standard LMSalgorithm, of the LMS algorithm with iterate averaging and of theLMS algorithm with adaptive step-size are derived. Interestingly,the last two algorithms are shown to exhibit a convergence speed close to thatof the cyclicRLS procedure, but with an order of magnitude lower computationalcomplexity.An adaptive procedure for the automatic selection ofthe algorithm periodicity is also presented, which is based on aminimum mean-output-energy criterion, and that obviates theneed for knowledge of the transmitted data-rates from theinterfering signals.Moreover, the case of known multipathfading channels is also examined. In particular, it is shown that theproposed cyclic LMS algorithms can be used to achieve RLS-likeperformance also in the presence of multipath distortion.Extensive computer simulation results, along with some analyticalconvergence results, confirmthat the proposed algorithms are effective and achieve very satisfactoryperformance. 相似文献