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排序方式: 共有338条查询结果,搜索用时 15 毫秒
101.
在多用户大规模多输入多输出(MIMO)系统中,针对传统方案受限于集中式部分连接结构和固定匹配相控算法而未能充分利用空间资源的问题,提出一种基于分布式部分连接结构的低复杂度相控迫零混合预编码方案.所提方案设计了多于射频链路数的逻辑天线子阵列,以使每个射频链路能连接多个分布子阵列,从而提供更高的空间分集增益.进一步通过分析... 相似文献
102.
We present an efficient precoding method by using generalized singular value decomposition (GSVD) and vector perturbation in the downlink of multi-user MIMO. Linear precoding/decoding matrices are explicitly computed through the GSVD algorithm, avoiding any matrix inversion or squaring operation. Accordingly, the computational complexity can be drastically reduced compared to the conventional iterative algorithms. In addition, by considering the inter-user interference, we derive a new perturbation vector that minimizes system-wide mean-squared-error of detected symbols. We also show that the proposed precoding scheme is suitable to update the precoding weights efficiently when the channel is newly updated, rather than recomputing the precoding weights for all users from scratch. 相似文献
103.
Ji-Sung Jung Won-Seok Lee Yeong-Rong Lee Jaeho Kim Hyoung-Kyu Song 《计算机、材料和连续体(英文)》2021,67(3):3057-3070
Massive multiple input multiple output (MIMO) has become essential for the increase of capacity as the millimeter-wave (mmWave) communication is considered. Also, hybrid beamforming systems have been studied since full-digital beamforming is impractical due to high cost and power consumption of the radio frequency (RF) chains. This paper proposes a hybrid beamforming scheme to improve the spectral efficiency for multi-user MIMO (MU-MIMO) systems. In a frequency selective fading environment, hybrid beamforming schemes suffer from performance degradation since the analog precoder performs the same precoding for all subcarriers. To mitigate performance degradation, this paper uses the average channel covariance matrix for all subcarriers and considers an iterative algorithm to design analog precoder using approximation techniques. The analog precoder is iteratively updated for each column until it converges. The proposed scheme can reduce errors in the approximating process of the overall spectral efficiency. This scheme can be applied to fully-connected and partially-connected structures. The simulation results show that spectral efficiency performance for the proposed scheme is better than the conventional schemes. The proposed scheme can achieve similar performance with full-digital beamforming by using a sufficiently large number of RF chains. Also, this paper shows that the proposed scheme outperforms other schemes in the frequency selective fading environment. This performance improvement can be achieved in both structures. 相似文献
104.
This paper investigates user scheduling in multi-user MIMO broadcast channel. We propose a leakagebased user scheduling scheme,
in which a user’s leakage power to other users is an important factor to determine whether the user should be selected. The
accuracy of closed-form solution of SLNR (signal to leakage plus noise ratio) makes the proposed scheme outperform the traditional
scheduling method based on SINR (signal to interference plus noise ratio). The proposed algorithms can work in case of perfect
or limited feedback of CSI (channel state information) at transmitter, and the advantage is verified with numerical results.
A tradeoff relation among feedback bits number, active user number and transmit/receive antennas number is analyzed, which
serves as a system design guideline. 相似文献
105.
106.
Heng Liu Siyuan Yang Xin Liu Gang Liu Zheng Ma Pingzhi Fan 《International Journal of Communication Systems》2024,37(8):e5745
The orthogonal time frequency space (OTFS) transmission scheme was shown to outperform orthogonal frequency division multiplexing (OFDM) under the doubly dispersive channel. In this paper, the linear precoding is studied for multiple-input and multiple-out (MIMO) OTFS systems, in which a spatial-Doppler domain singular value decomposition (SVD) precoding scheme is proposed. At the transmitter, the Doppler domain symbols from different spatial streams are precoded before projected onto multiple antennas for transmission. At the receiver, multipath components of the transmitted symbols in the delay-Doppler grid are combined by using maximal ratio combining (MRC) strategy, so as to achieve the multipath diversity gain and increase the reception reliability. The achievable rate and complexity of the proposed scheme are analyzed, revealing that it can increase the achievable rate while reducing the detector complexity as well. The simulation results confirm that the SVD-based precoding significantly enhances the error performance of the MIMO-OTFS with MRC-based detector. 相似文献
107.
108.
Enhancing secrecy capacity of multi‐relay wiretap systems with partial channel state information 下载免费PDF全文
Hang Long Wei Xiang Jing Wang Xiaoli Zhang Wenbo Wang 《International Journal of Communication Systems》2015,28(12):1847-1861
Distributed precoding has provento be capable of enhancing the secrecy capacity of the multi‐relay wiretap system. An iterative distributed precoding and channel state information (CSI) sharing scheme can be used to reduce the CSI overhead at each relay node. However, in practical applications, the CSI of each relay node cannot be perfectly known to themselves, especially that of the relay‐eavesdropper channels. Thus, partial CSI for the relay‐eavesdropper links is assumed, and the corresponding distributed precoding and CSI sharing schemes are investigated. Under the assumption that the average value of the relay‐eavesdropper channel is known at each relay node, an extended iterative distributed precoding and CSI sharing scheme is proposed. Simulation results demonstrate that with the increase of the power ratio of the constant part to the random part of the relay‐eavesdropper channels, the proposed scheme with partial CSI performs increasingly close to the one with perfect CSI in secrecy capacity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
109.
提出了一种能高效利用多用户分集和空分复用增益的有限反馈空分多址(SDMA,space division multiple access)方法。首先利用子空间扰动的方法构造了一种具有分簇结构的多用户预编码码本。基于该码本,进一步给出了一种新型的多用户机会调度算法,该算法利用码本的簇结构实现对信道条件匹配的用户组进行快速的机会调度,同时确定被调度用户的首选码字。仿真结果表明,在蜂窝网络中,与传统的有限反馈SDMA方法相比,所提方法可以在不明显增加反馈开销的前提下显著提高系统吞吐量。 相似文献
110.
第三代移动通信系统长期演进(3G LTE)系统的下行链路传输中,基站端无法获知完全的信道状态信息(CSI),需要根据终端反馈的预编码序号从已有的码本中挑选合适的预编码矩阵进行信号处理。研究了多小区场景下基于有限信息反馈的码本选择算法,提出了一种单双流自适应的码本选择方案,分析了2×2天线情况下所提预编码算法的性能,通过计算机仿真给出了不同多天线预编码方案的性能对比。 相似文献