共查询到20条相似文献,搜索用时 15 毫秒
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针对WCDMAFDD下行链路,提出了一种接收机结构。与传统接收机不同,该结构是根据多径来拉动(延时)输入信号,即根据多径把各径的信号延时对齐,而本地码的相位只需一个,来对多径支路解扩,并直接合并输出。该结构可进一步通过串行方法实现,大大减少硬件资源。由于采用全硬件技术,因此,便于ASIC集成。 相似文献
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本文提出将KM 序列用作RAKE型CDMA系统的扩频码.基于一个RAKE接收机模型,分析了CDMA系统性能并提出了适于作RAKE型CDMA系统扩频码的PN序列的特性.接着,分析了KM 序列作RAKE型CDMA系统扩频码的优劣.最后,运用计算机仿真,比较了m序列和KM 序列的互相关特性以及在相干接收机和RAKE接收机下,这两种序列和Gold序列对应的系统平均误码率,从而证实了KM 序列作为扩频码的可行性. 相似文献
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J. Zhang R. A. Kennedy T. D. Abhayapala 《International Journal of Wireless Information Networks》2003,10(4):193-200
In this paper, the conditions and performance of ideal RAKE reception for time hopping Ultra-Wideband (UWB) investigated. Owing to the complex propagation phenomena and specific structure of UWB signals, new problems relevant to the operation of RAKE receivers arise. This motivates us to reconsider the conditions under which a RAKE receiver can work effectively with negligible interference between fingers. Key findings are that the conditions not only relate to the property of time hopping codes, but also modulation methods. An analytical technique is introduced to derive explicit expressions of RAKE performance for various combining methods for a lognormal fading channel. Numerical results show that RAKE reception can largely improve the performance, and equal gain combining has comparable performance to maximum ratio combining. 相似文献
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In this paper, we present a simple interference cancellation technique for the downlink of wideband code‐division multiple‐access (WCDMA) systems in multipath environment. With the same knowledge required by a RAKE receiver, the present method acts as an equalizer and cancels the interfering multipath signals from the received signal to retrieve the orthogonality property of the received signal. The present receiver has a simple structure and it has significant performance gain against the RAKE receiver. In addition, the noise enhancement is negligible when there is a line of sight path or the channel power delay profile has an exponential decaying form. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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为了充分利用瑞克(RAKE)接收机的多径能量利用效果和智能天线(SA)的定向收发作用,研究了RAKE接收机和智能天线的联合使用,提出了基于智能天线的定向二维(2D)RAKE接收机模型,给出了定向2D-RAKE接收机分别在射频、中频和基带的实现框图、工作原理和输出信号表达式,并对它们的性能以及工程实现做了分析讨论。指出基带定向二维RAKE接收机由于可以在基带上通过幅度加权来实现信号的定向收发,其优点是可以利用目前比较成熟的基带信号处理技术,但是由于不能利用相干解调作用来抑制多径干扰(MPI)和多用户干扰(MAI),存在噪声放大问题;射频定向二维RAKE接收机的信噪比增益最大,但工程实现难度较大;中频定向二维RAKE接收机则具有较高的性价比。 相似文献
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DS-CDMA中基于MMSE相关器的RAKE接收机 总被引:1,自引:0,他引:1
该文研究了DS-CDMA中用于频率选择性多径信道RAKE接收机的限阶MMSE相关器的性能,这种基于CSA(Correlations Subtractive Architecture)结构的MMSE相关器很适用于频率选择性多径信道。通过用MMSE柑关器取代普通多用户RAKE接收机的传统相关器,可以达到与扩展到多个码元的MMSE接收机相近的BER性能。CSA产生MMSE相关器不需要矩阵的逆变换,降低了运算复杂度,有利于直接取代普通RAKE接收机的相关器。 相似文献
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利用逐次干扰抵消多用户检测结构,结合空时RAKE接收机,提出一种空时逐次干扰抵消多用户检测算法.仿真结果表明,该算法相比传统空时RAKE接收机有近5 dB的增益,误码率有了相当的改进. 相似文献
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在实际环境中RAKE接收机在接收信号时都要进行信道系数估计,以便进行相干合并。文章研究了不采用导频信号与采用导频信号两种估计器,具有估计误差情况下,在相关Nakagami信道下的RAKE接收机的性能,并且通过特征函数法得到了误码率公式的闭合表达式。比较了两种估计器对系统性能的影响,最后给出了数值结果,可以看出,当导频信号能量与信号能量相等,且导频数目比较多时(大于5),采用导频信号的系统性能优于直接估计信道系数的系统。直接估计信道系数的系统性能在信噪比大于5dB后,其性能远远优于导频信号的估计系统。 相似文献
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CDMA系统反向信道RAKE接收的研究 总被引:1,自引:0,他引:1
本文研究了码分多址系统反向链路上的正交调制非相干RAKE接收机,介绍了接收机模型,并对最强径搜索、逐位输出软判量度、天线分集等问题进行了讨论,最终给出了相应的仿真结果。 相似文献
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A receiver of simple structure for antenna array CDMA systems 总被引:3,自引:0,他引:3
In code division multiple access systems, the two-dimensional (2-D) RAKE structure had been proposed using multiple antennas to increase the capacity. It consists of multiple fingers of a beamformer and a correlator. In this paper, we consider a simpler receiver structure. We only use one finger, which consists of one pair of spatial and temporal filters to combine signals. It is shown that the performance of the receiver system is comparable with that of the 2-D RAKE receiver. Furthermore, it is observed that the proposed receiver and the 2-D RAKE receiver have limited near-far resistance by the generation of the space domain due to antenna arrays 相似文献
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This paper investigates the application of super-orthogonal convolutional codes (SOCC) to a direct-sequence based ultra- wideband
(DS-UWB) system under a realistic environment including inter-symbol interference (ISI) and multiuser interference (MUI).
The effect of MUI and ISI on the performance of SOCC is analyzed by using both maximum ratio combining (MRC) RAKE receiver
and minimum mean-squared error (MMSE) RAKE receiver followed by matched filter receiver. The analysis shows that in the case
of employing simple MRC-RAKE receiver, the performance of SOCC is ffected by MUI and ISI because of the short length of the
spreading sequence. In order to combat MUI and ISI, a code-hopping scheme is proposed in conjunction with SOCC. The results
show that SOCC scheme outperforms the higher-rate conventional convolutional coded scheme for multipath and multiple access
channels. Furthermore, the use of MMSE-RAKE receiver to suppress interference is analyzed and the subsequent increase of the
system capacity is observed. 相似文献
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宽带衰落信道中慢衰落信号的实时测量 总被引:2,自引:0,他引:2
本文研究了宽带衰落信道中慢衰落信号的实时测量,通过将测量误差描述为高斯分布的随机变量量化分析了利用RAKE接收机实时测量慢衰落信号的误差,结果表明,采用RAKE接收机进行测量可以显著提高测量的准确性,同时,讨论了没条件下测量滤波器的设计 。 相似文献
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