Analog Versus Hybrid Precoding for Multiuser Massive MIMO With Quantized CSI Feedback

Zhao, Yaqiong; Xu, Wei; Xu, Jindan; Jin, Shi; Wang, Kezhi; Alouini, Mohamed‐Slim

doi:10.1109/lcomm.2020.2999646

Cited by 18 publications

(8 citation statements)

References 14 publications

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“…1) Ultra-large fractional bandwidth: With abundant spectrum resource, the fractional bandwidth of THz UM-MIMO systems can be very large, e.g., 16.7% (50 GHz bandwidth at 300 GHz central frequency). By contrast, the fractional bandwidth at microwave and mmWave systems is usually limited, e.g., 0.83% (20 MHz at 2.4 GHz) and 3.33% (2 GHz at 60 GHz).…”

Section: Severe Beam Squint Caused By Thz Peculiaritiesmentioning

confidence: 99%

Energy-efficient Dynamic-subarray with Fixed True-time-delay Design for Terahertz Wideband Hybrid Beamforming

Liu¹,

Chen²,

Yuan³

2022

Preprint

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Hybrid beamforming for Terahertz (THz) ultra-massive multiple-input multiple-output (UM-MIMO) systems is a promising technology for 6G space-air-ground integrated networks, which can overcome huge propagation loss and offer unprecedented data rates. With ultra-wide bandwidth and ultra-largescale antennas array in THz band, the beam squint becomes one of the critical problems which could reduce the array gain and degrade the data rate substantially. However, the traditional phase-shiftersbased hybrid beamforming architectures cannot tackle this issue due to the frequency-flat property of the phase shifters. In this paper, to combat the beam squint while keeping high energy efficiency, a novel dynamic-subarray with fixed true-time-delay (DS-FTTD) architecture is proposed. Compared to the existing studies which use the complicated adjustable TTDs, the DS-FTTD architecture has lower power consumption and hardware complexity, thanks to the low-cost FTTDs. Furthermore, a lowcomplexity row-decomposition (RD) algorithm is proposed to design hybrid beamforming matrices for the DS-FTTD architecture. Extensive simulation results show that, by using the RD algorithm, the DS-FTTD architecture achieves near-optimal array gain and significantly higher energy efficiency than the existing architectures. Moreover, the spectral efficiency of DS-FTTD architecture with the RD algorithm is robust to the imperfect channel state information.

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Section: Severe Beam Squint Caused By Thz Peculiaritiesmentioning

confidence: 99%

Energy-efficient Dynamic-subarray with Fixed True-time-delay Design for Terahertz Wideband Hybrid Beamforming

Liu¹,

Chen²,

Yuan³

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…For the inaccurate A t [k] and A r [k], the expressions are similar to (27) while the inaccuracy is enforced on the phase since the amplitude of the elements of these two matrices should be fixed as one, as stated in (2). Fig.…”

Section: B Spectral Efficiency and Energy Efficiency Of The Proposed ...mentioning

confidence: 99%

“…Since the overall dimension of the channel matrix in THz UM-MIMO systems is prohibitively large, acquiring partial elements of the channel matrix is sill difficult. The authors of [20], [26], [27] proposed the hybrid beamforming solutions considering the statistical information of the channel. However, due to the lack of well-known general statistical MIMO channel model in the THz band yet, it is also challenging to know the statistical channel information.…”

Section: Introductionmentioning

confidence: 99%

Dynamic-subarray with Fixed Phase Shifters for Energy-efficient Terahertz Hybrid Beamforming under Partial CSI

Liu¹,

Chen²,

Yang³

et al. 2022

Preprint

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Terahertz (THz) communications are regarded as a pillar technology for the 6G systems, by offering multi-ten-GHz bandwidth. To overcome the huge propagation loss while reducing the hardware complexity, THz ultra-massive (UM) MIMO systems with hybrid beamforming are proposed to offer high array gain. Notably, the adjustable-phase-shifters considered in most existing hybrid beamforming studies are power-hungry and difficult to realize in the THz band. Moreover, due to the ultra-massive antennas, full channel-state-information (CSI) is challenging to obtain. To address these practical concerns, in this paper, an energy-efficient dynamic-subarray with fixed-phase-shifters (DS-FPS) architecture is proposed for THz hybrid beamforming. To compensate for the spectral efficiency loss caused by the fixed-phase of FPS, a switch network is inserted to enable dynamic connections. In addition, by considering the partial CSI, we propose a row-successive-decomposition (RSD) algorithm to design the hybrid beamforming matrices for DS-FPS. A row-by-row (RBR) algorithm is further proposed to reduce computational complexity. Extensive simulation results show that, the proposed DS-FPS architecture with the RSD and RBR algorithms achieves much higher energy efficiency than the existing architectures. Moreover, the DS-FPS architecture with partial CSI achieves 97% spectral efficiency of that with full CSI.

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“…Compared with the existing hybrid precoding algorithms based on the single-user system [23][24][25] and the single-antenna multi-user systems [26,27], our work can be applied…”

Section: Computational Complexity Analysismentioning

confidence: 99%

“…In single-antenna multiuser system, it is difficult to jointly consider the changes of user-specific signal quality and multi-user interference. [26] proposed a low-cost hybrid precoding algorithm based on quantized CSI feedback for a single-antenna scenario and revealed that pure analog precoding outperforms hybrid precoding in terms of the ergodic achievable rate under certain conditions, as derived in closed forms with respect to the SNR, the number of users and the number of feedback bits. However, directly quantized feedback still causes a huge amount of overhead to maintain a usable accuracy.…”

mentioning

confidence: 99%

Spectral-efficient hybrid precoding for multi-antenna multi-user mmWave massive MIMO systems with low complexity

Liu

Zhang

et al. 2022

J Wireless Com Network

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Millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO) systems allow for a data transmission rate of gigabits per second owing to the large bandwidth available in the mmWave spectrum and the antenna gains provided by the massive MIMO system. However, hybrid precoding with high complexity and low spectral efficiency cannot address the challenge of high cost and power consumption of RF chains of multi-user systems. In this paper, we propose a low-complexity hybrid precoding scheme for downlink multi-antenna multi-user mmWave massive MIMO systems, aiming to enhance the sum spectral efficiency (SSE) performance. We first extend the dimension of the analog precoding matrix into a square matrix and find the optimal analog combiner by selecting some of the discrete Fourier transform (DFT) bases, which enhances the equivalent baseband channel matrix gain. Then, we directly aggregate the channel gain through the equal gain transmission (EGT) method to ensure the frequency efficiency performance. Finally, we propose an improved BD scheme to design the digital precoder and combiner to reduce the inter-user interference. We consider both the mmWave channel and the Rayleigh channel to evaluate the performance of the proposed algorithm. The simulation results verify that the proposed scheme enjoys near-optimal achievable sum spectrum efficiency and BER performance in both the mmWave channel and Rayleigh channel and performs even better in Rayleigh channel than in the mmWave channel.

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Analog Versus Hybrid Precoding for Multiuser Massive MIMO With Quantized CSI Feedback

Cited by 18 publications

References 14 publications

Energy-efficient Dynamic-subarray with Fixed True-time-delay Design for Terahertz Wideband Hybrid Beamforming

Energy-efficient Dynamic-subarray with Fixed True-time-delay Design for Terahertz Wideband Hybrid Beamforming

Dynamic-subarray with Fixed Phase Shifters for Energy-efficient Terahertz Hybrid Beamforming under Partial CSI

Spectral-efficient hybrid precoding for multi-antenna multi-user mmWave massive MIMO systems with low complexity

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