共查询到19条相似文献,搜索用时 125 毫秒
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对于独立同分布的瑞利衰落信道,Grassmann码本可以取得良好的系统性能,但是当MIMO信道存在空间相关性时,该码本不可避免的带来性能损失,本文针对空间相关的MIMO信道,通过用发送相关矩阵的平方根对传统Grassmann码本进行旋转,然后再量化,得到适用于空间相关信道下的新码本,并通过实验仿真阐释了新得到的码本对于传统码本在误码率和信道容量方面等方面的性能优势。 相似文献
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在多天线无线通信系统中,发射机利用来自接收机有限反馈的信道方向信息,能够提高系统容量和降低误码率.有限反馈的关键是码本设计,本文综述了近年来这一领域的研究成果.码本设计主要包括基于Grassmann流形中子空间包和基于信源编码中向量量化的两种方案,涉及对象包括不同类型的多天线信道和发射数据流模式.详细介绍了这两种方案的原理和相应算法,并比较了它们的异同点。 相似文献
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考虑到大规模多输入多输出(Multiple Input Multiple Output, MIMO)阵列尺寸及外形等因素的限制,本文提出了一种适用于基站采用交叉极化天线面阵的大规模MIMO(Massive MIMO)码本设计方法。该方法综合考虑交叉极化信道的对角化特点和相邻天线之间的相关性,首先设计出与采用交叉极化线阵匹配的码本,进而利用垂直维度天线间的相关性对其进行扩展,最终生成与交叉极化面阵相匹配的码本。仿真结果表明该码本设计方法可使大规模MIMO系统的传输速率和误码率性能得到明显地提升。 相似文献
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为了提高协作分集系统的信道容量,该文在多中继节点协作背景下提出了基于注水算法的中继节点功率分配方案。首先,对空时矩阵的列序号提出了一种新的映射方案,该方案能够提升中继节点发射信号间的正交性。对于采用线性正交解码算法的GABBA码,列序号重新排布后能够降低误码率。然后,通过对接收信噪比与中继节点发射功率的分析,针对信道容量最大化问题提出了一种应用注水算法的两步求解方案。该文对瑞利平坦慢衰落信道下采用GABBA码的协作分集系统进行仿真,仿真结果表明,与中继节点发射功率均分方案相比,该文提出的功率分配方案能够提升系统抗误码性能,达到满分集增益NtNr。该文提出的方案在不同的仿真条件下对信道容量均有提升,并且信道容量与min{NtNr}log2M成正比。 相似文献
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提出一种基于码本旋转的自适应码本设计方法,在不改变现有的码本基础矩阵的基础上,根据误码率(BER)和信干噪比(SINR)的统计和估计结果,生成一组新的旋转矩阵码本,并结合反馈开销考虑与原来基础码本矩阵构成双码本矩阵,根据信道的实时变化及时地调整码本的精度,从而能够在有限反馈的情况下更加有效地提高预编码的性能。 相似文献
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有限反馈MISO-OFDM系统中基于误码率的波束成形 总被引:1,自引:1,他引:0
该文提出了一种在有限反馈条件下多入单出正交频分复用(MISO-OFDM)系统中基于误码率的波束成形方案。将OFDM符号的所有子载波分成若干簇,从码本中选择能够最小化该簇每个子载波的平均误码率的码字,作为该簇的波束成形向量。此方案既能降低反馈量,又能取得较低误码率。同时,为避免所提方案中探求最优解时的穷尽搜索,还基于簇内不同子载波信道频响之间的相关性提出了一种简化的次优算法。仿真结果表明,在典型参数设置下,所提方案能够以较低计算复杂度取得比其他已有方案更好的误码率性能。 相似文献
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随着互联网终端海量接入,传统正交多址接入(orthogonal multiple access,OMA)技术接入效率低, 5G NR 系统面临拥塞及高时延问题,并且在高速场景下,基于正交频分复用(orthogonal frequency-division multiplexing,OFDM)的系统由于多普勒效应性能严重恶化。为满足6G在高速移动场景下低时延、高可靠、海量接入需求,首先,结合正交时频空间(orthogonal time frequency space,OTFS)和图样分割多址接入(pattern division multiple access,PDMA)技术,提出了一种OTFS-PDMA联合方案;然后,推导PDMA传输码字在时延-多普勒(delay-Doppler,DD)域采用不同分配方式的系统输入-输出关系;最后,提出了一种基于期望传播算法(expectation propagation algorithm,EPA)的低复杂度接收机。仿真结果表明,OTFS-PDMA较传统的OTFS-OMA技术能够显著提升误码率性能;对于规则码本,不同码字分配方案性能相似,而对于非规则码本,发送信号采用集中式扩频优于离散式扩频,且对于离散式扩频,PDMA 扩频信号沿多普勒轴分配,系统可取得较好性能;此外EPA接收机性能优于其他传统接收机。 相似文献
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针对MIMO时变信道下,有限反馈发射预编码存在反馈延迟的问题,提出将多数据流空间复用传输的MIMO信道的主右奇异矩阵的列空间建模于n维复欧氏空间上p维子空间的集合Grassmannian流形Gn,p上,利用Grassmannian流形的测地线对时变信道进行跟踪预测,以补偿反馈延迟对于系统性能的影响。在此基础上,从Grassmannian流形的几何特性入手,针对Grassmannian流形的切空间提出了一种高分辨率动态聚焦的多维切空间码本。计算机仿真表明,Grassmannian流形上基于高分辨率动态聚焦码本的有限反馈预测预编码的系统性能明显优于存在反馈延迟的无记忆有限反馈预编码和采用固定码本的有限反馈预测预编码。 相似文献
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本文主要对预编码的反馈方式进行研究。首先介绍了预编码技术,然后分别对离散傅里叶变换码本反馈法和格拉斯曼码本反馈方式进行介绍和分析。最后在Mat lab上对系统误码率进行仿真,比较不同反馈方式对于预编码性能的影响。格拉斯曼码本反馈法的性能好于离散傅里叶变换码本的性能,但是格拉斯曼码本反馈更复杂。 相似文献
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Suen A.-N. Wang J.-F. Yao T.-C. 《Vision, Image and Signal Processing, IEE Proceedings -》1995,142(1):52-58
The authors present a new classified dynamic partial search structure for the stochastic codebook of the FS1016 CELP coder to replace the fixed partial search for selecting the best excitation vector of the stochastic codebook. In the proposed scheme, the conventional one-stage stochastic codebook search is substituted with a two-stage dynamic method for reducing the computational complexity without degrading the voice quality. The establishment of this structure is based on two classifiers, one for the line spectrum pairs (LSP) of the input signals, and the other for the autocorrelation coefficients (AC) of the stochastic codebook search target. In addition, the stochastic codebook is classified into K subcodebooks, and with these two classifiers it is possible to determine dynamically which subcodebook needs to be searched. This method achieves a reduction in the search procedure by a factor of 2-8. The efficiency of these two classifiers is discussed and the comparison of the performance between the fixed partial search and the proposed technique is also addressed 相似文献
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Next-state functions for finite-state vector quantization 总被引:1,自引:0,他引:1
The finite-state vector quantization scheme called dynamic finite-state vector quantization (DFSVQ) is investigated with regard to its subcodebook construction. In the DFSVQ, each input block is encoded by a small codebook called the subcodebook which is created from a much larger codebook called supercodebook. Each subcodebook is constructed by selecting, using a reordering procedure, a set of appropriate code-vectors from the supercodebook. The performance of the DFSVQ depends on this reordering procedure; therefore, several reordering procedures are introduced and their performance are evaluated. The reordering procedures investigated, are based on the conditional histogram of the code-vectors, index prediction, vector prediction, nearest neighbor design, and the frequency usage of the code-vectors. The performance of the reordering procedures are evaluated by comparing their hit ratios (the number of blocks encoded by the subcodebook) and their computational complexity. Experimental results are presented and it is found that the reordering procedure based on the vector prediction performs the best when compared with the other reordering procedures. 相似文献
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Cheol Mun 《Communications, IEEE Transactions on》2008,56(5):838-846
In this paper, for spatial multiplexing with limited feedback, a quantized principal component selection (QPCS) precoding scheme is proposed that achieves comparable capacity to the closed-loop multiple-input multiple-output (MIMO) and furthermore adapts to various fading channel conditions without any additional feedback bits and transmit channel state information (CSI). We propose a systematic design method for a codebook consisting of a finite number of unitary matrices based on a maximizing minimum distance criterion in the one- dimensional angular domain and show that the method outperforms the Grassmannian subspace packing method in various fading channel conditions. The proposed QPCS precoding scheme allows for adjustment of the precoding matrix based on limited feedback information on the principal vectors approximating a MIMO channel in the angular domain according to various channel conditions. Furthermore, for practical implementation of the QPCS precoding scheme, we propose a structured precoder optimization procedure and show that the proposed procedure induces a negligible capacity loss compared with the exhaustive precoder optimization, even with considerably reduced complexity. 相似文献
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Transmit beamforming has been widely adopted for wireless systems with multiple transmit antennas. For a block fading channel, the Grassmannian beamformer has been shown to provide very good performance for finite rate feedback. However, the original Grassmannian beamformer does not take the time domain correlation of the channel fading into consideration. In this paper, based on a first-order autoregressive (AR1) dynamic fading model, we develop two new classes of beamforming algorithms that exploit the interframe correlations in the channel fading. We first introduce an algorithm based on a standard predictive vector quantization (PVQ) approach, and the resulting PVQ beamformer accomplishes superior power delivery at the receiver. However, the error performance of the PVQ beamformer is not satisfactory at high signal-to-noise ratios, and it also has a high implementation complexity. To resolve these issues, we then develop a novel successive beamforming (SBF) algorithm. The new SBF scheme uses the knowledge of the previous fading blocks to aid the beamforming codebook design of the current fading block. The beamforming codebook is constructed based on the successive partition of the surface of a spherical cap. The new SBF scheme accomplishes nearly the same performance as that of the PVQ beamformer, and it has a much simpler implementation. Through numerical simulations, we demonstrate that the proposed beamformers outperform the other previously proposed beamformers at various fading scenarios 相似文献
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Vector quantization of images raises problems of complexity in codebook search and subjective quality of images. The family of image vector quantization algorithms proposed in this paper addresses both of those problems. The fuzzy classified vector quantizer (FCVQ) is based on fuzzy set theory and consists basically in a method of extracting a subcodebook from the original codebook, biased by the features of the block to be coded. The incidence of each feature on the blocks is represented by a fuzzy set that captures its (possibly subjective) nature. Unlike the classified vector quantizer (CVQ), in the FCVQ a specific subcodebook is extracted for each block to be coded, allowing a better adaptation to the block. The CVQ may be regarded as a special case of the FCVQ. In order to explore the possible correlation between blocks, an estimator for the degree of incidence of features on the block to be coded is included. The estimate is based on previously coded blocks and is obtained by maximizing a possibility; a distribution that intends to represent the subjective knowledge on the feature's possibility of occurrence conditioned to the coded blocks is used. Some examples of the application of a FCVQ coder to two test images are presented. A slight improvement on the subjective quality of the coded images is obtained, together with a significant reduction on the codebook search complexity and, when applying the estimator, a reduction of the bit rate 相似文献