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本文采用ML准则得出了适于频率选择性衰落的线性解相关算法。仿真表明本方法性能优于Zvonarr提出的先解相关再最大比值合并的算法;且该方法由于采用等价扩频序列实现,硬件耗费也较少。 相似文献
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我们提出了一种新的基于导频辅助的MC-CDMA系统的信道估计和解相关、解相关干扰消除检测器。这里的基于导频辅助的MC-CDMA系统的信道估计采用了一种新的算法.通过设计每个用户的导频信息.无需增加系统的过多负担,就可以实现较好的信道估计。解相关检测器采用了伪逆算法,解相关干扰消除检测器则用解相关检测器的输出作为一级输入,结合并行干扰消除算法。仿真结果显示了信道估计和多用户检测器的较好性能。 相似文献
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MUSIC算法作为DOA估计的经典算法,在处理高度相关的信号时,算法性能急剧下降甚至完全失效。为了正确地估计出相干信号的DOA,就必须要对相干信号进行解相干。采用前/后向空间平滑技术与修正MUSIC算法是两种估计相关信号DOA的有效方法。通过算法仿真实验,证明了理论的正确性。 相似文献
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提出基于互质阵列的相干与非相干混合目标空间达波方向(DOA)估计算法。首先,基于差协同阵等效的概念,将互质阵列相关矩阵的元素重排形成增广相关矩阵;然后采用矩阵重构对增广相关矩阵进行解相关处理;最后,对解相关的增广相关矩阵进行多重信号分类(MUSIC)空间谱搜索,实现对目标的DOA估计。仿真结果表明,该算法可实现对数目多于互质阵列物理阵元的相干与非相干混合目标的DOA估计。对比矩阵重构、前向空间平滑和前后向空间平滑3种解相关算法,矩阵重构解相关获得了更大的可分辨目标数目,在低信噪比(SNR)下呈现出更佳的估计误差性能,而空间平滑解相关在低快拍情况下具备更优的估计误差性能。 相似文献
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针对多阵元相位干涉仪测向过程中的解模糊概率问题,在相位差误差条件下建立了解模糊概率与基线长度比之间的关系,给出一种相关干涉仪基线设计方法,并研究了相关干涉仪的解模糊条件;提出一种改进的相关干涉仪算法,缩小了相关干涉仪的取值范围,优化了相关函数,该方法最大程度地利用了干涉仪孔径尺寸,保证了测向精度,提升了运算速度,同时具有更强的解模糊稳定性.仿真试验表明,改进的相关干涉仪算法有效可行. 相似文献
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基于小波变换的加权最小二乘相位解缠算法 总被引:2,自引:0,他引:2
提出了一种求解加权最小二乘相位解缠问题的新算法,采用相位导数方差相关图定义了相位数据的初始权重,给出了利用多分辨率小波变换进行相位解缠的具体实现方法.利用离散小波变换,将原线性系统转化成具有较好收敛条件的等价新系统,通过独立求解新系统中的低频部分,加快了系统的收敛速度.仿真实验表明:该算法具有收敛速度快、解缠效果好等特点. 相似文献
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A new multiuser coherent decorrelating detector is proposed for the reverse-link asynchronous channels of DS-CDMA. The main feature of the proposed scheme is that it selects the largest interferences to be decorrelated, using the received power of the users and the crosscorrelation between the users. The proposed preselection-type coherent decorrelating detector offers better bit error rate (BER) performance than the conventional decorrelating detector, especially when the number of the received signals swamps the processing gain 相似文献
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Junqiang Shen Zhi Ding 《Communications, IEEE Transactions on》1999,47(3):438-445
Asynchronous decorrelating detector is a linear multiuser detector in code-division multiple-access (CDMA) environment. It has relatively good performance and low-computational complexity. However, the ideal asynchronous decorrelating detector requires the observation of the entire input bit sequence. Implementation of this ideal detector based on a long bit sequence results in long delays and high computational complexity. In fact, if the observed window does not cover the entire data sequence, the classical asynchronous decorrelating detector is no longer near-far resistant. In this paper, we propose a method using initial decisions on bits for both edges of the finite observed window. These initial decisions are used to assist subsequent decisions of the whole sequence inside the observed window based on the decorrelating method. This new edge decision assisted decorrelator (EDAD) method is shown to be near-far resistant 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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R.S. Chen L. Yang L. Zhao Y.M. Siu K.K. Soo 《International Journal of Electronics》2013,100(12):745-757
An ideal computation of the decorrelating or the linear minimum mean-squared-error (LMMSE) detector requires computational complexity of order K 3 when there K is the number of users. To alleviate the computational complexity, iterative decorrelating and LMMSE detectors are proposed for solving a set of linear equations corresponding to linear interference cancellation structures. Iterative conjugate gradient (CG) method has been used for the linear interference cancellation detectors. Its main advantages are to reduce the order of computation complexity and their suitability to highly parallel implementations. In this paper, the symmetric successive overrelaxation (SSOR) preconditioning scheme is applied to the CG method. The performance of the detectors is investigated and it is found that the SSOR preconditioned CG method can provide significantly faster convergence than CG method. 相似文献
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Jie Luo Pattipati K.R. Willett P. Levchuk G.M. 《Communications, IEEE Transactions on》2004,52(4):632-642
A fast optimal algorithm based on the branch-and-bound (BBD) method is proposed for the joint detection of binary symbols of K users in a synchronous code-division multiple-access channel with Gaussian noise. Relationships between the proposed algorithms (depth-first BBD and fast BBD) and both the decorrelating decision-feedback (DF) detector and sphere-decoding algorithm are clearly drawn. It turns out that decorrelating DF detector corresponds to a "one-pass" depth-first BBD; sphere decoding is, in fact, a type of depth-first BBD, but one that can be improved considerably via tight upper bounds and user ordering, as in the fast BBD. A fast "any-time" suboptimal algorithm is also available by simply picking the "current-best" solution in the BBD method. Theoretical results are given on the computational complexity and the performance of the "current-best" suboptimal solution. 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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We investigate multiuser signal detection with a base-station antenna array for a synchronous DS-CDMA uplink using nonorthogonal codes in Rayleigh fading channels. We have developed a new formulation for a spatial-temporal decorrelating detector using the maximum-likelihood criteria. The detector is shown to be near-far resistant. We propose to implement the spatial-temporal decorrelating receiver iteratively by applying the space-alternating generalized expectation-maximization (SAGE) algorithm. Simulation results show that the SAGE-based decorrelating receiver significantly outperforms the conventional single-user receiver and with performance close to that of a spatial-temporal decorrelating receiver with known channel parameters. We have observed that adding base-station antennas can actually improve convergence of the proposed iterative receiver 相似文献
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van Heeswyk F. Falconer D.D. Sheikh A.U.H. 《Selected Areas in Communications, IEEE Journal on》1996,14(8):1619-1626
The decorrelating detector is a near-far resistant linear joint detector for a code-division multiple-access (CDMA) system. It consists of a bank of matched filters followed by a decorrelating matrix. For proper operation, both the matched filter bank and the decorrelating matrix require knowledge of the delays of all users. The delays are due to the different propagation times from each user to the base station. Delay estimation is a weak link in this system since it is complex and prone to error. The proposed decorrelating detector does not require exact knowledge of the user delays, but instead requires that the delays be bounded to a fraction of a symbol interval. The delays are naturally bounded in this way in many microcell and picocell systems where the round trip propagation time is small compared to the symbol interval. The new delay independent decorrelating detector is shown to be near-far resistant and, through appropriate spreading code selection, to experience a modest 3 dB signal-to-noise ratio (SNR) loss relative to orthogonal access schemes. It is also shown to limit capacity to a maximum of 50% of the spreading gain when the delays are bounded by a single chip interval. The complexity is similar to the conventional correlating receiver which is far less complex than the joint detection schemes proposed to date 相似文献