70 research outputs found
SVM-Based Channel Estimation and Data Detection for One-Bit Massive MIMO systems
The use of low-resolution Analog-to-Digital Converters (ADCs) is a practical solution for reducing cost and power consumption for massive Multiple-Input-Multiple-Output (MIMO) systems. However, the severe nonlinearity of low-resolution ADCs causes significant distortions in the received signals and makes the channel estimation and data detection tasks much more challenging. In this paper, we show how Support Vector Machine (SVM), a well-known supervised-learning technique in machine learning, can be exploited to provide efficient and robust channel estimation and data detection in massive MIMO systems with one-bit ADCs. First, the problem of channel estimation for uncorrelated channels is formulated as a conventional SVM problem. The objective function of this SVM problem is then modified for estimating spatially correlated channels. Next, a two-stage detection algorithm is proposed where SVM is further exploited in the first stage. The performance of the proposed data detection method is very close to that of Maximum-Likelihood (ML) data detection when the channel is perfectly known. We also propose an SVM-based joint Channel Estimation and Data Detection (CE-DD) method, which makes use of both the to-be-decoded data vectors and the pilot data vectors to improve the estimation and detection performance. Finally, an extension of the proposed methods to OFDM systems with frequency-selective fading channels is presented. Simulation results show that the proposed methods are efficient and robust, and also outperform existing ones
DNN-based Detectors for Massive MIMO Systems with Low-Resolution ADCs
Low-resolution analog-to-digital converters (ADCs) have been considered as a
practical and promising solution for reducing cost and power consumption in
massive Multiple-Input-Multiple-Output (MIMO) systems. Unfortunately,
low-resolution ADCs significantly distort the received signals, and thus make
data detection much more challenging. In this paper, we develop a new deep
neural network (DNN) framework for efficient and low-complexity data detection
in low-resolution massive MIMO systems. Based on reformulated maximum
likelihood detection problems, we propose two model-driven DNN-based detectors,
namely OBMNet and FBMNet, for one-bit and few-bit massive MIMO systems,
respectively. The proposed OBMNet and FBMNet detectors have unique and simple
structures designed for low-resolution MIMO receivers and thus can be
efficiently trained and implemented. Numerical results also show that OBMNet
and FBMNet significantly outperform existing detection methods.Comment: 6 pages, 8 figures, submitted for publication. arXiv admin note: text
overlap with arXiv:2008.0375
Linear and Deep Neural Network-based Receivers for Massive MIMO Systems with One-Bit ADCs
The use of one-bit analog-to-digital converters (ADCs) is a practical
solution for reducing cost and power consumption in massive
Multiple-Input-Multiple-Output (MIMO) systems. However, the distortion caused
by one-bit ADCs makes the data detection task much more challenging. In this
paper, we propose a two-stage detection method for massive MIMO systems with
one-bit ADCs. In the first stage, we propose several linear receivers based on
the Bussgang decomposition, that show significant performance gain over
existing linear receivers. Next, we reformulate the maximum-likelihood (ML)
detection problem to address its non-robustness. Based on the reformulated ML
detection problem, we propose a model-driven deep neural network-based
(DNN-based) receiver, whose performance is comparable with an existing support
vector machine-based receiver, albeit with a much lower computational
complexity. A nearest-neighbor search method is then proposed for the second
stage to refine the first stage solution. Unlike existing search methods that
typically perform the search over a large candidate set, the proposed search
method generates a limited number of most likely candidates and thus limits the
search complexity. Numerical results confirm the low complexity, efficiency,
and robustness of the proposed two-stage detection method.Comment: 12 pages, 10 figure
A Reduced Complexity Ungerboeck Receiver for Quantized Wideband Massive SC-MIMO
Employing low resolution analog-to-digital converters in massive
multiple-input multiple-output (MIMO) has many advantages in terms of total
power consumption, cost and feasibility of such systems. However, such
advantages come together with significant challenges in channel estimation and
data detection due to the severe quantization noise present. In this study, we
propose a novel iterative receiver for quantized uplink single carrier MIMO
(SC-MIMO) utilizing an efficient message passing algorithm based on the
Bussgang decomposition and Ungerboeck factorization, which avoids the use of a
complex whitening filter. A reduced state sequence estimator with bidirectional
decision feedback is also derived, achieving remarkable complexity reduction
compared to the existing receivers for quantized SC-MIMO in the literature,
without any requirement on the sparsity of the transmission channel. Moreover,
the linear minimum mean-square-error (LMMSE) channel estimator for SC-MIMO
under frequency-selective channel, which do not require any cyclic-prefix
overhead, is also derived. We observe that the proposed receiver has
significant performance gains with respect to the existing receivers in the
literature under imperfect channel state information.Comment: This work has been submitted to the IEEE for possible publication.
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A comparative study of STBC transmissions at 2.4 GHz over indoor channels using a 2 Ă— 2 MIMO testbed
In this paper we employ a 2×2 Multiple-Input Multiple-Output (MIMO) hardware platform to evaluate, in realistic indoor scenarios, the performance of different space-time block coded (STBC) transmissions at 2.4GHz. In particular, we focus on the Alamouti orthogonal scheme considering two types of channel state information (CSI) estimation: a conventional pilot-aided supervised technique and a recently proposed blind method based on second-order statistics (SOS). For comparison purposes, we also evaluate the performance of a Differential (non-coherent) space-time block coding (DSTBC). DSTBC schemes have the advantage of not requiring CSI estimation but they incur in a 3dB loss in performance. The hardware MIMO platform is based on high-performance signal acquisition and generation boards, each one equipped with a 1GB memory module that allows the transmission of extremely large data frames. Upconversion to RF is performed by two RF vector signal generators whereas downconversion is carried out with two custom circuits designed from commercial components. All the baseband signal processing is implemented off-line in MATLAB®, making the MIMO testbed very flexible and easily reconfigurable. Using this platform we compare the performance of the described methods in line-of-sight (LOS) and non-line-of-sight (NLOS) indoor scenarios.This work has been supported by Ministerio de Educación y Ciencia of Spain, Xunta de Galicia and FEDER funds of the European Union under grant numbers TEC2004-06451-C05-02, TEC2004-06451-C05-01, PGIDT05PXIC10502PN, and FPU grants AP2004-5127 and AP2006-2965
On The Performance Of 1-Bit ADC In Massive MIMO Communication Systems
Massive multiple-input multiple-output (MIMO) with low-resolution analog-to-digital converters is a rational solution to deal with hardware costs and accomplish optimal energy efficiency. In particular, utilizing 1-bit ADCs is one of the best choices for massive MIMO systems. This paper investigates the performance of the 1-bit ADC in the wireless coded communication systems where the robust channel coding, protograph low-density parity-check code (LDPC), is employed. The investigation reveals that the performance of the conventional 1-bit ADC with the truncation limit of 3-sigma is severely destroyed by the quantization distortion even when the number of antennas increases to 100. The optimized 1-bit ADC, though having substantial performance gain over the conventional one, is also affected by the quantization distortion at high coding rates and low MIMO configurations. Importantly, the investigation results suggest that the protograph LDPC codes should be re-designed to combat the negative effect of the quantization distortion of the 1-bit ADC
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