共查询到19条相似文献,搜索用时 72 毫秒
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WCDMA技术是无线宽带通信发展方向之一,其抗干扰技术成为WCDMA系统中的关键技术。本文就DS/CDMA系统的抗干扰性及其干扰抑制进行分析和探讨。 相似文献
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一种低复杂度的Turbo多用户检测技术 总被引:3,自引:0,他引:3
基于Turbo原理,提出了一种适合于同步DS-CDMA系统的迭代多用户接收机结构,它通过在反复迭代的软输入出多用户检测器和一组信道译码之间获得连续的软判决,从而得到一种低复杂度的多用户检测算法-软MMSE干扰消除。 相似文献
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空时编码(STC)技术将天线阵列信号处理和信道编码技术联合起来实现无线信道容量的有效增加。为了抑制空时分组编码(STBC)系统的共道用户干扰,对低复杂度的多用户检测算法进行研究,该文提出了一种STBC系统的迭代(turbo)多用户接收机。该接收机由一个软入软出(SISO)基于均值的软判决多用户检测器(Soft Decision Multi-User Detector, SDMUD)和一组SISO Turbo信道解码器构成。两者之间通过迭代交换外信息,精确地估计用户信号。仿真结果表明这种接收技术经3次迭代后性能改善约2dB,并且系统性能会随着接收天线的增多而得到明显提高,从而大大增加系统容量。 相似文献
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随着移动通信的发展,空时处理技术越来越引起人们的重视.本文首先介绍了DS-CDMA的特点,并在此基础上引入空时处理技术.通过对信号处理的比较,可获得系统性能改善的结论。 相似文献
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研究了Turbo(并行级联码)译码原理及其在CDMA多用户检测中的应用。文中简述了Turbo译码原理及逐符号最大后验算法(symbol-by-symbol MAP),并将Turbo译码原理应用于CDMA系统的多用户检测,提出了基于Turbo译码原理的多用户检测接收机方案,通过计算机仿真验证该方案的性能。结果表明,本文所提出的方案经过4次迭代之后,其误码率接近单用户界,说明这种接收机可去除多址干扰(MAI)的影响。 相似文献
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这篇论文介绍了CDMA的发展概况和相关的标准;论述了DS-CDMA的技术能力,直接序列扩系统的性能和码分多址的优点;举例说明了DS-CDMA在五种通信系统的应用可行性;最后分析比较了CDMA和GSM系统的经济成本和运营收益。 相似文献
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We propose a novel scheme for iterative multiuser detection and turbo decoding. The multiuser detector and single-user turbo decoders are coupled such that after each turbo decoding iteration the extrinsic information of the interfering users is passed to the multiuser detector, and after each multiuser iteration, updated a posteriori probabilities are passed to the single-user turbo decoders as the soft input metrics. In synchronous systems, the proposed detector approaches the multiuser capacity limit within 1 dB in the low signal-to-noise ratio region 相似文献
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Multi-rate multicarrier DS/CDMA is a potentially attractive multiple access method for future wireless communications networks
that must support multimedia, and thus multi-rate, traffic. Several receiver structures exist for single-rate multicarrier
systems, but little has been reported on multi-rate multicarrier systems. Considering that high-performance detection such
as coherent demodulation needs the explicit knowledge of the channel, based on the finite-length chip waveform truncation,
this paper proposes a subspace-based scheme for timing and channel estimation in multi-rate multicarrier DS/CDMA systems,
which is applicable to both multicode and variable spreading factor systems. The performance of the proposed scheme for these
two multi-rate systems is validated via numerical simulations. The effects of the finite-length chip waveform truncation on
the performance of the proposed scheme is also analyzed theoretically. 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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In this paper, a new multiuser detector combining decorrelating detector and multicarrier transmission scheme is proposed and analyzed in a frequency selective Rayleigh fading channel. The bit error probability and asymptotic multiuser efficiency are derived as performance measures. From numerical results, it is shown that the proposed detector achieves better BER performance and lower computational complexity compared to a conventional decorrelating detector. It is also shown that the proposed detector is robust to partial narrowband interference, and alleviates near-far problem effectively. The results in this paper can be applied to design of a wideband CDMA system. 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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An effective multiuser receiver for DS/CDMA systems 总被引:2,自引:0,他引:2
Multiuser detection (MUD) is a key technique for combating multiple access interference (MAI) in CDMA systems. We propose a simple and effective multiuser receiver, which we refer to as the objective function based multiuser detector (OFMUD). This is a successive multistage joint detector based on the statistical optimization of an objective function. Two objective functions are considered in this paper. The first one is based on a maximum likelihood solution, and the second one is based on the least squared error solution. A key feature of the proposed detector is that among all the K user bits, we update the estimate of one and only one bit (the one that is most likely to be wrong) in every stage. Analytical and numerical results show that significant performance improvement can be achieved compared with the conventional DS/CDMA receiver. At the same time, the near-far problem is alleviated. In addition, it is shown that the proposed receiver can outperform the popular multiuser parallel interference cancellation receiver in most cases with a smaller computational cost 相似文献
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H. H. El Morra A. Zerguine A. U. Sheikh 《Wireless Communications and Mobile Computing》2009,9(10):1331-1342
In this work, we present a new multiuser detection (MUD) structure which results from incorporating the tabu search (TS) heuristic algorithm with the local search (LS) heuristic algorithm. The new proposed structure brings much improvement when compared to both the conventional (matched filter) detector and the decorrelating detector. Moreover, the new TS‐LS‐detector proposed here approximates well the performance of the optimal MUD detector but with a very low computational complexity. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献