The Experts below are selected from a list of 226587 Experts worldwide ranked by ideXlab platform
Jay Y Guo - One of the best experts on this subject based on the ideXlab platform.
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matrix normalization based zf hybrid precoded multi user mimo mmwave systems with massive array
Vehicular Technology Conference, 2018Co-Authors: Thomas Q Wang, Xiaojing Huang, Jay Y GuoAbstract:The superiority of exploring millimeter wave (mmWave) frequencies for future wireless communication systems has pushed forward the development of large-scale antenna arrays for achieving sufficient array gain and high spectral efficiency. In this paper, we study the matrix normalization (MN) based zero-forcing (ZF) hybrid precoding in multi-user multi-input-multi-output (MU-MIMO) mmWave systems. We derive the upper bounds of the achievable rate for two representative hybrid array Structures, i.e., fully-Connected Structure and partially-Connected Structure. Analytical and simulation results validate the tightness of the proposed performance upper bounds for both hybrid Structures using massive array, and provide a comparison of the achievable rate using MN and vector normalization (VN).
Björn Ottersten - One of the best experts on this subject based on the ideXlab platform.
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Energy-Efficient Hybrid Symbol-Level Precoding for Large-Scale mmWave Multiuser MIMO Systems
IEEE Transactions on Communications, 2026Co-Authors: Alireza Haqiqatnejad, Farbod Kayhan, Björn OtterstenAbstract:We address the symbol-level precoding design problem for the downlink of a multiuser millimeter wave (mmWave) multiple-input multiple-output (MIMO) wireless system where the transmitter is equipped with a large-scale antenna array. The high cost and power consumption associated with the massive use of radio frequency (RF) chains prohibit fully-digital implementation of the precoder, and therefore, we consider a hybrid analog-digital architecture where a small-sized baseband precoder is followed by two successive networks of analog on-off switches and variable phase shifters according to a fully-Connected Structure. We jointly optimize the digital baseband precoder and the states of the switching network on a symbol-level basis, i.e., by exploiting both the channel state information (CSI) and the instantaneous data symbols, whereas the phase-shifting network is designed only based on the CSI due to practical considerations. Our approach to this joint optimization is to minimize the Euclidean distance between the optimal fully-digital and the hybrid symbol-level precoders. Remarkably, the use of a switching network allows for power-savings in the analog precoder by switching some of the phase shifters off according to the instantaneously optimized states of the switches. Our numerical results indicate that, on average, up to 50 percent of the phase shifters can be switched off. We provide an analysis of energy efficiency by adopting appropriate power dissipation models for the analog precoder, where it is shown that the energy efficiency of precoding can substantially be improved thanks to the phase shifter selection approach, compared to the fully-digital and the state-of-the-art hybrid symbol-level schemes.
Thomas Q Wang - One of the best experts on this subject based on the ideXlab platform.
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matrix normalization based zf hybrid precoded multi user mimo mmwave systems with massive array
Vehicular Technology Conference, 2018Co-Authors: Thomas Q Wang, Xiaojing Huang, Jay Y GuoAbstract:The superiority of exploring millimeter wave (mmWave) frequencies for future wireless communication systems has pushed forward the development of large-scale antenna arrays for achieving sufficient array gain and high spectral efficiency. In this paper, we study the matrix normalization (MN) based zero-forcing (ZF) hybrid precoding in multi-user multi-input-multi-output (MU-MIMO) mmWave systems. We derive the upper bounds of the achievable rate for two representative hybrid array Structures, i.e., fully-Connected Structure and partially-Connected Structure. Analytical and simulation results validate the tightness of the proposed performance upper bounds for both hybrid Structures using massive array, and provide a comparison of the achievable rate using MN and vector normalization (VN).
Dacheng Yang - One of the best experts on this subject based on the ideXlab platform.
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hybrid precoding for mmwave massive mimo systems with partially Connected Structure
IEEE Access, 2017Co-Authors: Zaixue Wei, Hongwen Yang, Xin Zhang, Dacheng YangAbstract:Hybrid precoding is widely studied in millimetre-wave (mmWave) massive MIMO systems due to low cost as well as low power consumption. In general, there are two kinds of hybrid precoding Structures: one is fully Connected Structure (FCS), where each radio frequency (RF) chain is Connected to all antennas, and the other is partially Connected Structure (PCS), where each RF chain is Connected to a sub-array. In this paper, we investigate the optimal hybrid precoder design problem for mmWave massive MIMO systems based on PCS, since this kind of Structure is more practical for antenna deployment. We first focus on the optimization of analog precoder (AP) and propose two AP design schemes for high signal-to-noise ratio (SNR) condition and low SNR condition, respectively. For each of the schemes, the original optimization problem is reformulated to single-stream optimal transmitter beamforming problem with per-antenna power constraint, which has an optimal solution. Then, the optimal digital precoder is obtained by water-filling algorithm after AP is determined. Moreover, upper bounds of the achievable data rate for the proposed schemes with closed-form expression are derived.
Khaled Ben Letaief - One of the best experts on this subject based on the ideXlab platform.
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doubling phase shifters for efficient hybrid precoder design in millimeter wave communication systems
Journal of Communications and Information Networks, 2019Co-Authors: Jun Zhang, Khaled Ben LetaiefAbstract:Hybrid precoding is a cost-effective approach to support directional transmissions for millimeter-wave (mmWave) communications, but its precoder design is highly complicated. In this paper, we propose a new hybrid precoder implementation, namely the double phase shifter (DPS) implementation, which enables highly tractable hybrid precoder design. Efficient algorithms are then developed for two popular hybrid precoder Structures, i.e., the fully- and partially-Connected Structures. For the fully-Connected one, the RF-only pre-coding and hybrid precoding problems are formulated as a least absolute shrinkage and selection operator problem and a low-rank matrix approximation problem, respectively. In this way, computationally efficient algorithms are provided to approach the performance of the fully digital one with a small number of radio frequency (RF) chains. On the other hand, the hybrid precoder design in the partially-Connected Structure is identified as an eigenvalue problem. To enhance the performance of this cost-effective Structure, dynamic mapping from RF chains to antennas is further proposed, for which a greedy algorithm and a modified K-means algorithm are developed. Simulation results demonstrate the performance gains of the proposed hybrid precoding algorithms over existing ones. It shows that, with the proposed DPS implementation, the fully-Connected Structure enjoys both satisfactory performance and low design complexity while the partially-Connected one serves as an economic solution with low hardware complexity.
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Alternating Minimization Algorithms for Hybrid Precoding in Millimeter Wave MIMO Systems
IEEE Journal of Selected Topics in Signal Processing, 2016Co-Authors: Xianghao Yu, Juei Chin Shen, Jinfeng Zhang, Jun Zhang, Khaled Ben LetaiefAbstract:Millimeter wave (mmWave) communications has been regarded as a key enabling technology for 5G networks, as it offers orders of magnitude greater spectrum than current cellular bands. In contrast to conventional multiple-input-multiple-output (MIMO) systems, precoding in mmWave MIMO cannot be performed entirely at baseband using digital precoders, as only a limited number of signal mixers and analog-to-digital converters can be supported considering their cost and power consumption. As a cost-effective alternative, a hybrid precoding transceiver architecture, combining a digital precoder and an analog precoder, has recently received considerable attention. However, the optimal design of such hybrid precoders has not been fully understood. In this paper, treating the hybrid precoder design as a matrix factorization problem, effective alternating minimization (AltMin) algorithms will be proposed for two different hybrid precoding Structures, i.e., the fully-Connected and partially-Connected Structures. In particular, for the fully-Connected Structure, an AltMin algorithm based on manifold optimization is proposed to approach the performance of the fully digital precoder, which, however, has a high complexity. Thus, a low-complexity AltMin algorithm is then proposed, by enforcing an orthogonal constraint on the digital precoder. Furthermore, for the partially-Connected Structure, an AltMin algorithm is also developed with the help of semidefinite relaxation. For practical implementation, the proposed AltMin algorithms are further extended to the broadband setting with orthogonal frequency division multiplexing modulation. Simulation results will demonstrate significant performance gains of the proposed AltMin algorithms over existing hybrid precoding algorithms. Moreover, based on the proposed algorithms, simulation comparisons between the two hybrid precoding Structures will provide valuable design insights.