A class of reduced-complexity hybrid precoding algorithms for MU-MISO OFDM transmission

Cornelis, Sander; Noels, Nele; Moeneclaey, Marc

doi:10.1109/scc53769.2021.9768339

Cited by 2 publications

(12 citation statements)

References 10 publications

(19 reference statements)

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“…Although variablegain amplifiers can also be avoided without imposing a UM constraint by adopting a double-phase-shifter implementation [5], [6], the UM constraint gives rise to a singlephase-shifter implementation, which requires only half the number of phase shifters compared to the double-phaseshifter implementation. The connectivity constraint further reduces the number of required RF components by limiting the number of connections between the antennas and RF chains, i.e., each antenna is connected to only a subset of RF chains [6], [7], [8], [9], [10].…”

Section: Introduction a Motivationmentioning

confidence: 99%

Weighted Sumrate Maximizing Hybrid Precoder for MU-MISO-OFDM

Cornelis,

Noels,

Moeneclaey

2024

IEEE Access

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In multi-antenna transceivers with all-digital beamforming, the number of radio frequency (RF) chains necessarily equals the number of antennas, which entails a large hardware complexity and power consumption when deploying large antenna arrays. Hybrid beamforming, which splits the beamforming into an analog part operating at RF and a digital part operating at baseband, allows using as few RF chains as the number of data streams. A further reduction in the RF hardware cost is achieved by imposing additional constraints on the analog beamformer, such as single-phase-shifter implementation and limited connectivity between the RF chains and antennas. In this contribution we consider a downlink multi-user MISO OFDM communication system and present a novel approach for obtaining the linear hybrid precoder that maximizes the weighted sumrate (WSR) under the above constraints on the analog part. Unlike the WSR maximizing hybrid precoders from the literature, our approach exploits the uplink-downlink duality and performs a gradient-based optimization over a suitable manifold which describes the search space as determined by the imposed constraints. The proposed approach gives rise to a WSR maximizing precoder with a better trade-off between performance and computational complexity compared with WSR maximizing precoders from the literature. From this WSR maximizing precoder, two reduced-complexity heuristic precoders are derived, which outperform state-of-the-art heuristic precoders from the literature, in terms of spectral efficiency and/or computational complexity. The performance of the WSR maximizing precoder provides a useful theoretical benchmark for any heuristic precoder with the same constraints on the analog part.

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Section: Introduction a Motivationmentioning

confidence: 99%

Weighted Sumrate Maximizing Hybrid Precoder for MU-MISO-OFDM

Cornelis,

Noels,

Moeneclaey

2024

IEEE Access

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“…The optimization of A over the complex circle manifold, referred to as manifold optimisation (MO), has also been performed in the context of hybrid beamforming for scenarios involving intelligent reflective surfaces [9] and relay networks [10]. Other hybrid beamforming designs under the UM constraint avoid the complexity of manifold optimization by making use of a convexication of the optimization problem [4], [9], [11] or by heuristically applying phase extraction (PE) to determine A [2], [6], [7], [12]- [15]. The rate resulting from AltMin manifold optimization in the case of SC modulation turns out to be close to the performance of the all-digital beamformer; therefore, the former rate has been considered as a performance benchmark for UM-constrained hybrid precoders [2].…”

Section: Introductionmentioning

confidence: 99%

“…To further reduce the number of RF components (at the expense of an additional loss in performance), the connectivity of the analog part of the hybrid beamformer can be constrained, i.e., each antenna is connected to only a subset of RF chains [2], [6], [7], [12]. In [7], three different connectivity constraints are defined: full connectivity (FC), group connectivity (GC), and partial connectivity (PC).…”

Section: Introductionmentioning

confidence: 99%

“…An important conclusion is that, for 𝑁 rf equal to or slightly in excess of 𝐾, the SE is significantly higher for the WSRmax precoder than for MD-type ZF precoders, whereas some of the latter precoders are much more avantageous in terms of computational complexity. Related work on hybrid precoders that aim to directly maximize the WSR or SE can be found in [12], [11], [9]. For a MU-MISO-OFDM system with ZF hybrid precoding and a power loading that imposes the same SNR on all subcarriers for all users, the numerical results obtained from the maximization of the SE (which simplifies to the maximization of the common SNR) over the analog and digital parts of the hybrid precoder are used as a performance benchmark in [12].…”

Section: Introductionmentioning

confidence: 99%

“…Related work on hybrid precoders that aim to directly maximize the WSR or SE can be found in [12], [11], [9]. For a MU-MISO-OFDM system with ZF hybrid precoding and a power loading that imposes the same SNR on all subcarriers for all users, the numerical results obtained from the maximization of the SE (which simplifies to the maximization of the common SNR) over the analog and digital parts of the hybrid precoder are used as a performance benchmark in [12]. In a different context, the authors of [11] have maximized a convexication of the mutual information (between the RX antenna signals and the transmitted symbols) over the hybrid precoder under a total TX power constraint and a UM constraint on the analog part, for a SU-MIMO-SC system; as the hybrid precoder is not rank-deficient, the resulting maximized mutual information is very close to the rate associated with the optimum all-digital precoder.…”

Section: Introductionmentioning

confidence: 99%

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Rate-Maximizing Zero-Forcing Hybrid Precoder for MU-MISO-OFDM

2023

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Hybrid precoders, consisting of an analog hardware-constrained part operating at radio frequency (RF) and a digital part operating at baseband, reduce the RF implementation complexity and power consumption of multi-antenna transceivers, at the expense of some rate loss compared to an all-digital precoder. The analog and digital parts of the hybrid precoder are commonly designed by performing a constrained matrix decomposition (MD) of the all-digital precoder, which aims to minimize the Euclidean distance between the matrices corresponding to the hybrid and the all-digital precoder. In contrast, in this contribution we determine the zero-forcing (ZF) hybrid precoder that directly maximizes the weighted sumrate of a MU-MISO-OFDM communication system, taking into account various hardware constraints on the analog part. The resulting maximum rate serves as a useful benchmark for comparison with other ZF hybrid precoders. In a multi-carrier massive MIMO scenario, the rate-maximizing ZF precoders show a considerable performance advantage over MD-type hybrid precoders, indicating that the latter precoders are far from optimum. This contribution also investigates the trade-off between performance and computational complexity. Because of the iterative nature of the rate-maximizing ZF hybrid precoders, their superior performance comes with a large computational complexity. When this complexity cannot be afforded, one should revert to the MD-type precoders, at the expense of a considerable performance penalty; among the MD-type precoders, the non-iterative ones have only a slightly worse performance but a significantly smaller computational complexity, in comparison with the iterative ones.

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A class of reduced-complexity hybrid precoding algorithms for MU-MISO OFDM transmission

Cited by 2 publications

References 10 publications

Weighted Sumrate Maximizing Hybrid Precoder for MU-MISO-OFDM

Weighted Sumrate Maximizing Hybrid Precoder for MU-MISO-OFDM

Rate-Maximizing Zero-Forcing Hybrid Precoder for MU-MISO-OFDM

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