Low-Complexity and Robust Hybrid Beamforming Design for Multi-Antenna Communication Systems (original) (raw)
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Alternating Hybrid Beamforming Design using GMD Decomposition for mmWave MIMO-OFDM Systems
2022
Since millimeter wave (mmWave) communications have wideband channels, mmWave signal corruptions increase due to radio-channel frequency selectivity. In this case, the combination of the orthogonal frequency division multiplexing (OFDM) with the mmWave MIMO system is envisioned as a candidate technique to address the degradation of communication. As hybrid analog/digital architecture offers potential energy and spectral efficiency for the mmWave MIMO device. Matrix factorization formulation with singular value decomposition (SVD) is the most used method for designing the hybrid precoder/combiner. However, using SVD decomposition in precoding/combining designing requires power allocation schemes due to the different signal-to-noise ratios (SNRs) of different subchannels. To achieve a high wireless communications capacity, we propose in this work an alternating minimization algorithm based on a manifold optimization technique using the geometric mean decomposition (GMD) (called MO-AltMin-GMD) to derive unconstrained optimal precoders and combiners from the channel state information (CSI). The main advantage is that the proposed hybrid design avoids any allocation schemes in order to reduce the hybrid architecture complexity. Numerical simulations show that the proposed hybrid design provides high results compared to the existing methods in terms of spectral efficiency. Index Terms-MmWave MIMO OFDM system, hybrid precoder/combiner design, MO-AltMin algorithm, geometric mean decomposition, wideband channels.
IEEE Transactions on Communications
Hybrid beamforming (HB) has been widely studied for reducing the number of costly radio frequency (RF) chains in massive multiple-input multiple-output (MIMO) systems. However, previous works on HB are limited to a single user equipment (UE) or a single group of UEs, employing the frequency-flat first-level analog beamforming (AB) that cannot be applied to multiple groups of UEs served in different frequency resources in an orthogonal frequency-division multiplexing (OFDM) system. In this paper, a novel HB algorithm with unified AB based on the spatial covariance matrix (SCM) knowledge of all UEs is proposed for a massive MIMO-OFDM system in order to support multiple groups of UEs. The proposed HB method with a much smaller number of RF chains can achieve more than 95% performance of full digital beamforming. In addition, a novel practical subspace construction (SC) algorithm based on partial channel state information is proposed to estimate the required SCM. The proposed SC method can offer more than 97% performance of the perfect SCM case. With the proposed methods, significant cost and power savings can be achieved without large loss in performance. Furthermore, the proposed methods can be applied to massive MIMO-OFDM systems in both time-division duplex and frequency-division duplex.
Hybrid MIMO-OFDM Beamforming for Wideband mmWave Channels Without Instantaneous Feedback
IEEE Transactions on Signal Processing, 2018
In this paper, we consider the design of statistical multiple-input-multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) beamformers for millimeter wave (mmWave) channels. The transmitter designs the subcarrier beamformers based on the statistics of the channel, without instantaneous channel information. To overcome the radio frequency (RF) limitation in mmWave application, the subcarrier beamformers are implemented in a hybrid structure, which imposes constraints on the design of subcarrier beamformers. We analyze the unconstrained statistical subcarrier beamformers using spectral analysis of the subcarrier channels. The analysis shows that, for each subcarrier channel, the optimal statistical beamformer is approximately a linear combination of optimal statistical beamformers for some appropriately defined narrowband single-cluster subchannels. The result suggests a design of the subcarrier beamformers that can be readily implemented in a hybrid structure. Furthermore, a hybrid design for the receiver is proposed based on the concept of vector quantization. Simulations are given to show that the use of a hybrid beamforming structure incurs a minor degradation in transmission rate. With three RF chains, the performance is close to that of all digital statistical beamforming. Index Terms-Hybrid precoding, wideband mmWave, statistical precoding, hybrid multiple-input-multiple-output orthogonal frequency division multiplexing (MIMO-OFDM). I. INTRODUCTION T HE performance of a MIMO system is known to improve with the number of antennas at the transmitter and receiver. Recent advances show that it is feasible to pack a large number of antennas in a small area, particularly in mmWave communication systems that use small wavelengths [1]. However cost and power constraints often prohibit having one dedicated RF chain for each antenna [2]. A promising technique to overcome the RF limitation is the so called hybrid scheme [3], [4], in which analog processing of RF signals is combined with digital processing in the baseband. Analog RF processing, due to power and complexity consideration, is typically implemented using phase shifters and the elements of the analog precoder are of unit modulus [5], [6]. Recently, it is shown in [7]-[9] that if two
Generalized Singular Value Decomposition for Coordinated Beamforming in MIMO Systems
2010 IEEE Global Telecommunications Conference GLOBECOM 2010, 2010
In this paper we examine the use of generalized singular value decomposition (GSVD) for coordinated beamforming in MIMO systems. GSVD facilitates joint decomposition of a class of matrices arising inherently in source-to-2 destination MIMO broadcast scenarios. GSVD allows two channels of suitable dimensionality to be jointly diagonalized, i.e. to be reduced to non-interfering virtual broadcast channels, through the use of jointly determined transmit precoding and receiver reconstruction matrices.
Hybrid Beamforming Analysis Based on MIMO Channel Measurements at 28 GHz
Hybrid beamforming systems represent an efficientarchitectural solution to realize massive multiple-input multiple-output (MIMO) communication systems in the centimeter wave (cmW) and millimeter wave (mmW) region. These hybrid beamforming systems separate the beamforming process into a digital and analog beamforming network. The analog beamforming networks can be realized by different architectural solutions, which demand dedicated algorithms to determine the complex weighting factors in the digital and analog domain. To date, novel hybrid beamforming architectures and algorithms are solely compared in numerical simulations based on statistical channel models. These abstract channel models simplify the complicated electromagnetic propagation process, thereby not exactly reconstructing the wireless channel. Within this work, we present a measurement-based evaluation of hybrid beamforming algorithms and compare them with numerical results gained from a statistical path-based MIMO chan...
Multi-antenna techniques and beamforming for communication systems
2011
Reconfigurability, efficiency, and power consumption are key areas for improvement in future communication systems. The frequency spectrum is becoming more crowded and the spatial density of users is increasing. It becomes interesting for a communication system to use temporary freedom in the spatial and spectral domain. In this paper, we provide an overview of multi-antenna techniques, which can exploit the spatial degree of freedom, thereby addressing the challenges of flexibility and reconfigurability of front-ends in communication systems. Starting with a general qualification of multi-antenna techniques, their benefits and their goals, we will focus on beamsteering and beamforming techniques and their possible application for communication systems.
Low-Complexity Hybrid Beamforming for Massive MIMO Systems in Frequency-Selective Channels
IEEE Access
Hybrid beamforming for frequency-selective channels is a challenging problem as the phase shifters provide the same phase shift to all of the subcarriers. The existing approaches solely rely on the channel's frequency response and the hybrid beamformers maximize the average spectral efficiency over the whole frequency band. Compared to state-of-the-art, we show that substantial sum-rate gains can be achieved, both for rich and sparse scattering channels, by jointly exploiting the frequency and time domain characteristics of the massive multiple-input multiple-output (MIMO) channels. In our proposed approach, the radio frequency (RF) beamformer coherently combines the received symbols in the time domain and, thus, it concentrates signal's power on a specific time sample. As a result, the RF beamformer flattens the frequency response of the "effective" transmission channel and reduces its root mean square delay spread. Then, a baseband combiner mitigates the residual interference in the frequency domain. We present the closedform expressions of the proposed beamformer and its performance by leveraging the favorable propagation condition of massive MIMO channels and we prove that our proposed scheme can achieve the performance of fully-digital zero-forcing when number of employed phase shifter networks is twice the resolvable multipath components in the time domain. INDEX TERMS Frequency-selective channels, hybrid analog-and-digital beamforming, massive MIMO.
Sparse Array Receiver Beamformer Design for Multi-Functional Antenna
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Planning sensor locations can potentially economize the receiver cost by minimizing the hardware and computational needs, while satisfying a predetermined design criterion. In this paper, we consider a sparse array receive beamformer design approach for Multi-Functional Antennas (MFA), operating in different frequency bands. In this approach, antenna positions are selected from uniformly spaced locations that are served by a limited number of transceiver chains. The design objective is to maximize the beamformer output Signal-to-Interference-plus-noise-ratio (MaxSINR) for desired sources with disjoint frequency bands operating in a wideband jamming environment. The problem is solved efficiently through alternating direction method of multipliers (ADMM) and simplified to parallel quadratically constraint quadratic programs (QCQP) with a single associated constraint. The re-weighted group sparsity is adopted to ensure a common sparse configuration across all frequency bands. The effic...
Subspace Beamforming for Near-Capacity MIMO Performance
IEEE Transactions on Signal Processing, 2008
A subspace beamforming method is presented that decomposes a MIMO channel into multiple pairs of subchannels. The pairing is done based on singular values such that similar channel capacity is obtained between different subchannel pairs. This new capacity balancing concept is key to achieving high performance with low complexity. We apply the subspace idea to geometric mean decomposition (GMD) and maximum likelihood (ML) detection. The proposed subspace GMD scheme requires only two layers of detection/decoding, regardless of the total number of subchannels, thus alleviating the latency issue associated with conventional GMD. We also show how the subspace concept makes the optimization of ML beamforming and ML detection itself feasible for any K × K MIMO system. Simulation results show that subspace beamforming performs nearly as well as optimum GMD performance, and to within only a few dB of the Shannon bound.