Hybrid Combining Based on Constant Phase Shifters and Active/Inactive Switches

Bahingayi, Eduard E.; Lee, Kyungchun

doi:10.1109/tvt.2020.2974995

Cited by 10 publications

(24 citation statements)

References 28 publications

(67 reference statements)

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“…where R is the achievable sum rate and P is the power consumption of the architecture. To compare EE, we consider the component power-consumption model in [5], [9], [18]. Table 1 summarizes the power consumption of the components for a reference carrier frequency of f c = 60 GHz.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…Despite successfully designing the lowcomplexity analog combiner, these works still suffer from the degradation in performance. The work in [9] employs constant phase shifters (CPSs) and exploit the per-RF chain antenna-subset selection to maximize the sum rate. However, the employment of a single switch per antenna limits the achievable SE.…”

Section: Introductionmentioning

confidence: 99%

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Hybrid Combining Based on Selective Activation of Double Constant Phase Shifters

2021

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In this paper, we propose a new uplink hybrid beamforming architecture for multi-user multiple-input-multiple-output (MU-MIMO) millimeter-wave (mmWave) systems. The proposed architecture employs constant phase shifters (CPSs) to control the phases of the signals in conjunction with double switches for signal selection in the radio frequency (RF) beamforming part. By using double switches to approximate the optimal double variable phase shifter (VPS)-based scheme, the proposed scheme can achieve near-optimal sum rates when the number of CPSs is large enough. In addition, with the support of the active/inactive switches, it selectively combines the antenna signals, which can further improve the sum rate while reducing power consumption. The simulation results show that the proposed scheme outperforms conventional VPS-based and fully digital combiners in terms of energy efficiency.

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Section: Simulation Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hybrid Combining Based on Selective Activation of Double Constant Phase Shifters

2021

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“…We extend the work in [22], which has been proposed for conventional multi-user massive MIMO, to cell-free massive MIMO systems. We adapt the three low-complexity algorithms proposed in [22] to perform the selection process for the switches at the APs.…”

Section: Introductionmentioning

confidence: 96%

“…Furthermore, because a massive MIMO system can use a large number of receiving antennas, the number of switches necessary to link the antennas to the RF chains is large, and these switches can consume a large amount of power. This problem is overcome in [22] by introducing a new hybrid beamforming architecture for conventional massive MIMO systems whereby each RF chain is connected to a subset of antennas that contribute more to the desired power rather than the interference power. Further, they introduced three low-complexity algorithms compared with the exhaustive search approach to perform the selection process for the switches at the base station.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, we investigate the flexibility of including or excluding the subset of antennas in the signal combining design by extending the proposed algorithms in [22] from conventional multi-user mm-Wave MIMO systems to cell-free mm-Wave massive MIMO systems, especially when there are a large number of APs. Each AP has a large number of antennas.…”

Section: Introductionmentioning

confidence: 99%

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Antenna Selection Based on Matching Theory for Uplink Cell-Free Millimetre Wave Massive Multiple Input Multiple Output Systems

Ayidh

Sambo

Olaosebikan

et al. 2022

Telecom

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In this paper, we propose a hybrid beamforming architecture with constant phase shifters (CPSs) for uplink cell-free millimetre-wave (mm-Wave) massive multiple-input multiple-output (MIMO) systems based on exploiting antenna selection to reduce power consumption. However, current antenna selection techniques are applied for conventional massive MIMO, not cell-free massive MIMO systems. Therefore, the enormous computational complexity of these techniques to optimally select antennas for cell-free massive MIMO networks is caused by numerous randomly distributed access points (APs) in the service area and their large antennas. The architecture proposed in this work solves this issue by employing a low-complexity matching technique to obtain the optimal number of antennas, chosen based on channel magnitude and by switching off antennas that contribute more to interference power than to desired signal power for each radio frequency (RF) chain at each AP, instead of assuming all RF chains at each AP have the same number of selected antennas. Therefore, an assignment optimization problem based on a bipartite graph is formulated for cell-free mm-Wave massive MIMO system uplinks. Then, the Hungarian method is proposed to solve this problem due to its ability to solve this assignment problem in a polynomial time. Simulated results show that, despite several APs and antennas, the proposed matching approach is more energy-efficient and has lower computational complexity than state-of-the-art schemes.

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Energy efficient RF chains selection based on integrated Hungarian and genetic approaches for uplink cell‐free millimetre‐wave massive MIMO systems

Al Ayidh,

Alammar

2024

IET Communications

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The purpose of this work is to explore the decrease of total used power in cell‐free millimetre‐wave (mm‐Wave) massive multiple‐input multiple‐output (MIMO) systems, which can be regarded an essential technology for future wireless generations to improve system performance. One of the most important strategies for reducing total power consumption is to activate and deactivate radio frequency (RF) chains at each access point (AP) in the coverage region. Nonetheless, the optimization issue for this methodology is NP‐hard, and an exhaustive search method may be used to determine the ideal number of RF chains at each AP in the cell‐free network. Unfortunately, the exhaustive searching approach is prohibitively complicated, indicating that it is unworkable when there are a significant number of APs in the service region. Furthermore, present RF chain selection approaches prioritize decreasing consumed power and complexity at the price of system performance in terms of total possible rate. This research solves this issue by introducing a unique RF chain selection approach that combines Hungarian and genetic algorithms. The fact that the genetic algorithm (GA) can readily determine the ideal number of active RF chains, yet this technique generally entails significant complexity in large‐scale cell‐free networks, prompted this notion. As a result, the Hungarian method is used early in the GA to overcome the complexity problem while still retaining system performance. In addition, the suggested system employs a semi‐centralized hybrid beamforming architecture in which all analogue combiners for all APs are operated at a central processing unit using channel state information. In addition, each AP has a fully linked phase shifters network and restricted RF chains connecting to its antennas. Finally, simulation findings reveal that, when compared to state‐of‐the‐art techniques, the suggested approach achieves the maximum attainable rate and overall energy efficiency with a tolerable computational complexity.

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Hybrid Combining Based on Constant Phase Shifters and Active/Inactive Switches

Cited by 10 publications

References 28 publications

Hybrid Combining Based on Selective Activation of Double Constant Phase Shifters

Hybrid Combining Based on Selective Activation of Double Constant Phase Shifters

Antenna Selection Based on Matching Theory for Uplink Cell-Free Millimetre Wave Massive Multiple Input Multiple Output Systems

Energy efficient RF chains selection based on integrated Hungarian and genetic approaches for uplink cell‐free millimetre‐wave massive MIMO systems

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