共查询到20条相似文献,搜索用时 156 毫秒
1.
Massive MIMO技术在垂直维度和水平维度均具备良好的波束赋形能力,有效提升覆盖能力,降低了干扰,增加了覆盖优化的灵活性。本文提出了一种根据覆盖区域内用户话务分布自适应权值优化的方法,通过动态调整同步信号SSB天线波束赋形,实现Massive MIMO小区覆盖与业务分布的实时匹配。 相似文献
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通过洋细分析波束赋形算法及其在LTE系统甲的实现方式,对波束赋形性能以及发射天线数对波束赋形系统性能的影响进行了仿真,仿真结果表明,双流波束赋形适用于小区中心区域SINR高的区域:增加发射天线的数量能够改蓠波束赋形系统的SINR性能,从而提升系统的容量。最后指出了波束赋形技术进一步的研究方向。 相似文献
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利用广播波束赋形技术实现小区覆盖优化是近来智能天线的一个研究热点,但是目前的研究主要集中在65°、90°等常见广播波束赋形应用上。首先介绍了智能天线广播波束赋形的基本方法,在此基础上总结了有特殊广播覆盖需求的几种常见场景,将其作为目标覆盖分析了如何生成对应的广播波束权值,并通过实验验证了特殊广播覆盖场景下权值的赋形效果。 相似文献
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捅要:研究了多用户多输入多输出(MIMO)系统在有限反馈下的一种结合单位预编码与用户调度算法的方案。在该系统中每一用户都具有多个接收天线,该方案具有较大的多用户分集增益和较小的计算复杂度,从而能够减少系统中的用户间干扰。每个用户独立地决定自己的天线合并矢量,并将最优波束矢量以及对应的估计信干噪比通过有限反馈信道反馈给基站,此时基站获取了相应的用户信道信息和用户间干扰信息。基于接收到的反馈信息,基站从预定义的码本中选取和速率最大的最优子集进行系统预编码,然后依照预编码矩阵调度欧氏距离最小的用户且用户个数不超过发送天线的数目。仿真结果显示该方案有效地改善了系统速率,特别是在用户数目较多或者信道环境较好的情况下。 相似文献
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智能天线波束赋形技术能很好地抑制小区间干扰,联合检测只能抑制小区内的多址干扰。在TD-SCDMA系统上行链路实现了智能天线波束赋形与联合检测的算法结合,并按照标准3GPP25.996的信道环境做了仿真,加入小区间干扰,仿真结果表明,智能天线与联合检测的结合能同时抑制小区内多址干扰和小区间干扰。 相似文献
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瞿轶莫建忠王颖恒应瑛樊忠文 《中国新通信》2021,(14):42-44
5G移动通信关键技术在于波束赋形,以及波束多样性带来的垂直角度覆盖增益,配置不同的波束赋形权值,小区水平和垂直覆盖增益各不相同。5G TDD 3.5G频段分配17种波束配置模式,开网默认S0模式垂直波宽小、电子下倾调整范围小、电子方位角不能调整、覆盖局限性大。通过结合城区地域特色结合理论模型搭建、仿真支撑、路测数据验证、室内CQT验证、系统指标同步评估、验证结果合理性整体评估的方法,给出适合城区的5G小区广播波束配置组合模式,提升室内外整体覆盖能力。 相似文献
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波束赋形技术是智能天线在TD-SCDMA系统中的主要应用之一,简要介绍了智能天线波束赋形的原理,并对比了天津地区无线设备厂家和天线厂家的权值设置的波束赋形的仿真效果。在天津TD-SCDMA系统的网络优化中,根据地域信号覆盖特点,通过修改天线权值参数、优化广播信道波速赋形效果达到了改善TD网络信号覆盖的目地。 相似文献
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In this paper, coordinated limited feedback zero‐forcing beamforming multicell system in time‐varying channel is studied. In time‐varying channels, the actual rate loss arising from error in channel quantization of both interuser and intercell inferences is quantified in this work. Using the actual degradation of rate loss, a limited feedback bit allocation is proposed to reduce interuser and intercell interference simultaneously with feedback update period as one of the parameters. Furthermore, the scaling law of bits required to maintain a constant rate loss is formulated in varying channel conditions for a given feedback update period. Simulation results demonstrated the practical feedback requirement in multicell systems in the presence of both intercell and interuser interference over conventional schemes to maintain a constant rate offset. The key finding from the proposed feedback allocation is that practically much higher allocation of feedback bits and feedback scaling are required in time‐varying channels to reduce throughput degradation. 相似文献
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Wonmu Lee Illsoo Sohn Byong Lee Kwang Lee 《Communications Letters, IEEE》2008,12(10):758-760
In this letter, we consider practical downlink multiuser multiple-input multiple-output systems where each user has multiple antennas and codebook-based limited channel feedback is available at base station. We propose a preprocessing scheme for downlink transmission where a unitary beamforming matrix is used. Firstly, we propose how to construct the unitary matrix that maximizes sum rate. Secondly, we propose a codebook-based channel feedback method for the proposed beamforming method. Numerical results show that the proposed scheme outperforms conventional zero-forcing beamforming scheme in terms of sum rate. 相似文献
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Feedback of quantized channel state information (CSI), called limited feedback, enables transmit beamforming in multiple-input-multiple-output (MIMO) wireless systems with a small amount of overhead. Due to its efficiency, beamforming with limited feedback has been adopted in several wireless communication standards. Prior work on limited feedback commonly adopts the block fading channel model where temporal correlation in wireless channels is neglected. In this paper, we consider temporally correlated channels and design single-user transmit beamforming with limited feedback. Analytical results concerning CSI feedback are derived by modeling quantized CSI as a first-order finite-state Markov chain. These results include the information rate of the CSI quantizer output, the bit rate a CSI feedback channel is required to support, and the effect of feedback delay on throughput. In particular, based on the theory of Markov chain convergence rate, feedback delay is proved to reduce the throughput gain due to CSI feedback at least exponentially. Furthermore, an algorithm is proposed for CSI feedback compression in time. Combining the results in this work leads to a new method for designing limited feedback beamforming as demonstrated by a design example. 相似文献
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本文针对有限反馈MIMO-OFDM波束形成系统,研究了基于簇的有限反馈方法。利用簇内相邻子载波信道的频率相干性,提出了一种低复杂度的信道均值分簇法,该方法以平均信道响应在给定码本中选择最佳簇波束形成向量。此外,利用簇波束形成向量之间的剩余相关性,还提出了递归反馈和基于格的反馈两种反馈速率降低方法,即将前一簇码字的邻域内码字作为当前簇的新码本,从而大幅度降低反馈比特数。仿真结果表明信道均值分簇法能以较低的计算复杂度获得较佳的BER性能,反馈降低方法相对传统分簇方法能进一步降低反馈速率,递归反馈方法有一定性能损失,而基于格的反馈方法性能损失可忽略不计。 相似文献
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Wei Dai Youjian Liu Rider B. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(8):3651-3669
We analyze the effect of finite rate feedback on code-division multiple-access (CDMA) signature optimization and multiple-input multiple-output (MIMO) beamforming vector selection. In CDMA signature optimization, for a particular user, the receiver selects a signature vector from a codebook to best avoid interference from other users, and then feeds the corresponding index back to the specified user. For MIMO beamforming vector selection, the receiver chooses a beamforming vector from a given codebook to maximize the instantaneous information rate, and feeds back the corresponding index to the transmitter. These two problems are dual: both can be modeled as selecting a unit norm vector from a finite size codebook to ldquomatchrdquo a randomly generated Gaussian matrix. Assuming that the feedback link is rate limited, our main result is an exact asymptotic performance formula where the length of the signature/beamforming vector, the dimensions of interference/channel matrix, and the feedback rate approach infinity with constant ratios. The proof rests on the large deviations of the underlying random matrix ensemble. Further, we show that random codebooks generated from the isotropic distribution are asymptotically optimal not only on average, but also in probability. 相似文献
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Transmit beamforming and receive combining are simple methods for exploiting spatial diversity in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) system. Optimal beamforming requires channel state information in the form of the beamforming vectors for each OFDM subcarrier. This paper proposes a limited feedback architecture that combines beamforming vector quantization and smart vector interpolation. In the proposed system, the receiver sends a fraction of information about the optimal beamforming vectors to the transmitter and the transmitter computes the beamforming vectors for all subcarriers through interpolation. A new spherical interpolator is developed that exploits parameters for phase rotation to satisfy the phase invariance and unit norm properties of the transmitted beamforming vectors. The beamforming vectors and phase parameters are quantized at the receiver and the quantized information is provided to the transmitter. The proposed quantization system provides only a moderate increase in complexity versus over comparable approaches. Numerical simulations show that the proposed scheme performs better than existing diversity techniques with the same feedback data rate. 相似文献
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The secrecy rate of limited feedback beamforming is studied for a Multiple-Input Single-Output(MISO) wiretap channel with a multi-antenna eavesdropper.We first obtain the secrecy rate of limited feedback beamforming achieved at the legitimate receiver.We then derive a lower bound for the asymptotic secrecy rate in the large system limit.From this bound,we observe a threshold for the ratio of eavesdrop antennas to transmit antennas to obtain a positive secrecy rate.We further show that the secrecy rate loss due to limited feedback decays with the number of feedback bits per transmit antenna. 相似文献
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Limited or finite rate, feedback is an efficient way to implement beamforming in multiple antenna systems using frequency division duplexing. Unfortunately, closed-form performance analysis of limited feedback beamforming has not been investigated. This paper provides an analytical framework for the correlated limited feedback beamforming problem by treating selection of the beamforming vector from the codebook as a multibranch selection problem. 相似文献
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Tae-Sung Kang Hyung-Myung Kim 《Communications Letters, IEEE》2008,12(9):636-638
The throughput performance of orthogonal random beamforming (ORBF) with a finite number of users is limited due to the increasing amount of residual interference. In this letter, we find the optimal beam subset, the optimal user set, and the optimal number of random beams to maximize the sum throughput of the ORBF. The proposed scheme provides the best trade-off between the multiplexing gain and the multiuser interference by the determination of the optimal number of random beams as well as the beam selection diversity gain due to the selection of the optimal beam subset. In addition, two efficient suboptimal schemes are presented to reduce the computational complexity and the feedback overhead of the optimal method. 相似文献
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Jae-Yun Ko Yong-Hwan Lee 《Wireless Communications, IEEE Transactions on》2009,8(10):4998-5002
In this paper, we propose an adaptive beamforming scheme that generates the beam weight using dominant eigenvectors of the spatial covariance matrix. The number of eigenvectors used for the generation of beam weight is determined to maximize the signal-to-noise ratio (SNR) for given feedback constraints (e.g., the amount of feedback information and feedback delay). It is shown that the conventional limited feedback beamforming and eigen-beamforming are special cases of the proposed scheme. Simulation results show that the proposed beamforming scheme can effectively be applied to spatially correlated channels. 相似文献