共查询到14条相似文献,搜索用时 0 毫秒
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We propose the use of soft feedback estimates for the PIC detector in aDS-CDMA system with FEC. The soft estimates are computed by the a posterioriof the log-MAP decoder. We compare this method with the conventional methodof using tentative hard decisions to perform interference cancellation at eachstage. Simulations under AWGN and multipath asynchronous channels areperformed for comparison. We supply a suitable a posteriori for the log-MAPdecoder, and obtain a suitable soft feedback from the decoder. 相似文献
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根据宽带码分多址( WCDMA) 系统的特点,提出并分析了一种导频符号辅助干扰删除多用户检测器(PSAIC),分析结果表明,该方法充分利用了WCDMA系统中的帧结构,在不增加物理信道的情况下,实现接收信号的相干解调,并与多址干扰删除器相连,可以大大提高系统的性能,增加系统的容量,当干扰删除器的级数为2 时,其性能有较大的改善,复杂度也不高 相似文献
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It is well known that the iterative method is used for solving a set of linear equations corresponding to linear interference cancellation structures. An ideal computation of the decorrelating or the linear minimum mean-squared-error (LMMSE) detector requires order K
3 flops, where K is the number of users. To alleviate the computational complexity, iterative decorrelating and the LMMSE detectors are proposed. In this paper, the symmetric successive over relaxation (SSOR) preconditioning scheme is applied to the conjugate gradient (CG) method. The performance of the detectors is investigated and it is found that the SSOR preconditioned CG (PCG) method can provide significantly faster convergence than CG method. 相似文献
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为了利用多用户检测和并行干扰对消克服WCOMA系统的多址干扰和远近效应,文中建立了WCDMA系统模型并由此推导了一种用于WCDMA上行系统的并行干扰对消算法,并在E-DPDCH信道验证了算法的性能。将干扰用户发射信噪比固定为14dB,当两个用户到达同一吞吐量时,采用PIC有1.5dB的信噪比增益。最后针对基于CCSS平台的仿真结果提出了几种优化方案。 相似文献
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Gang Xu Sridhar Rajagopal Joseph R. Cavallaro Behnaam Aazhang 《The Journal of VLSI Signal Processing》2002,30(1-3):21-33
The multistage detection algorithm has been proposed as an effective interference cancellation scheme for next generation Wideband Code Division Multiple Access (W-CDMA) base stations. In this paper, we propose a real-time VLSI implementation of this detection algorithm in the uplink system, where we have achieved both high performance in interference cancellation and computational efficiency. When interference cancellation converges, the difference of the detection vectors between two consecutive stages is mostly zero. Under the assumption of BPSK modulation, the differences between the bit estimates from consecutive stages are 0 and ±2. Bypassing the zero terms saves computations. Multiplication by ±2 can be easily implemented in hardware as arithmetic shifts. However, the convergence of the algorithm is dependent on the number of users, the interference and the signal to noise ratio and hence, the detection has a variable execution time. By using just two stages of the differencing detector, we achieve predictable execution time with performance equivalent to at least eight stages of the regular multistage detector. A VLSI implementation of the differencing multistage detector is built to demonstrate the computational savings and the real-time performance potential. The detector, handling up to eight users with 12-bit fixed point precision, was fabricated using a 1.2 m CMOS technology and can process 190 Kbps/user for 8 users. 相似文献
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依据自适应旁瓣相消原理,着重分析了宽带干扰信号对旁瓣相消性能的影响,针对宽带干扰影响下,主辅天线间的波程差、主辅天线通道频率特性的不一致性以及主天线旁瓣的频率敏感特性等引起的自适应旁瓣相消系统的主辅天线2通道信号的去相关作用,采用了主天线通道均衡和子带自适应相消2种方法改善带宽特性,并通过MATLAB仿真验证,仿真结果表明该两种方法均可明显改善系统的相消性能,达到良好效果。 相似文献
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本文提出的一种新颖的基于多用户反馈的判决反馈均衡器,解决了在CDMA多用户检测中传统自适应判决反馈均衡器误码率高、系统容量小的缺点.它由具有误差反馈滤波器的判决反馈均衡器(Decision Feedback Equalizer with Error Feedback Filter,DFE-EFF)构成,并在判决后反馈多用户数据抵消多址干扰(多用户反馈干扰抵消).文中给出其结构图,分析各种判决反馈均衡算法.理论证明,具有误差反馈滤波器的多用户反馈干扰抵消判决反馈均衡器(多用户反馈干扰抵消DFE-EFF)较各种判决反馈均衡器为最优,它能同时有效处理ISI,MAI和噪声的干扰.仿真结果表明,在误码率性能和系统容量两方面,多用户反馈干扰抵消DFE-EFF比DFE、DFE-EFF均有较大改善. 相似文献
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The bootstrap separator for multiuser signals is principally composed of cancelers, each one using the output of the other cancelers to facilitate control of its adaptive weight. In fact, such a structure performs as a signal separator rather than an interference canceler. Since for its separation there is no need for a reference signal (as in LMS cancelers), it is sometimes justifiably called a Blind Separator. However, for its operation the bootstrap separator requires a signal distinguisher termed discriminator. The algorithm was used in the past in applications such as dually polarized satellite communications and microwave terrestrial links. It was particularly reported for multiuser CDMA signal separating, with the signum function as discriminator. Especially for QAM signals, complex presentation is important. Therefore, we will concentrate in this report on what we call the Complex Bootstrap Algorithm. It is an extension to the previously reported bootstrap structure of [5]. We will examine its performance and emphasize the hardware saving in its implementation, and the ease of using it in simulation. 相似文献
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1xEV-DO[1]是CDMA2000 1x针对数据业务的增强系统.为提高数据传输速率,其前向链路用16个并行的码道传输调制符号,各码道由正交码-Walsh码隔离.但是这种正交性却被多径衰落信道破坏,产生了多码道干扰[2],严重影响了系统在高速传输数据时的性能.本文在1xEV-DO前向链路中引入了一种符号级迭代多用户检测器,用于消除多码道干扰.仿真结果表明,符号级迭代多用户检测器的性能好于Rake接收机和码片级均衡器,能够较好地解决系统在多径衰落信道中高速数据传输的问题. 相似文献
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Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) transmission can improve both the transmission
capacity and performance due to diversity gain. However, when the antennas are close to each other in a MIMO-OFDM system,
the diversity order will be decreased because of channel correlation. In the paper performance of various detection methods
for space–time block code (STBC) MIMO-OFDM with channel correlation are evaluated, including the conventional Alamouti full
matrix detection, the modified diagonal matrix detection, the least square-zero forcing (LS-ZF) detection, and the successive
interference cancellation (SIC). The paper also verify that the SIC detection can still keep excellent detection performance
under large channel correlation.
相似文献
Shyue-Win WeiEmail: |