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作者： DAILYS ARRONDE PEREZ Pontifical Catholic University of Rio de Janeiro

学位级别：硕士

This thesis focuses on the downlink of a multiuser multiple-input multiple-output (MU-MIMO) systems where the Base Station (BS) and the users' stations (UEs) transmit and receive information symbols, respectively, by selected subset of their antennas. The performance of the system is evaluated employing linear precoding techniques as Zero Forcing (ZF) and Minimum Mean Square Error (MMSE). A general model to describe the system and expressions that relate the energy spent in transmission with the energy available for detection at each user are presented. A transmit antenna selection procedure is proposed aiming at the minimization of the detection error probability. A suboptimal search algorithm, called ITES (Iterative Search), able to deliver a performance close to the one resulting from the optimal exhaustive search selection is also proposed. The receive antenna selection is also performed using a similar optimization criterion. Joint antennas selection at the transmitter and receiver contemplates the efficient combination of both strategies, leading to a complexity reduction in BS and UEs. BER performance results, obtained via simulation and semi- analytical approaches, are presented for different scenarios.

关键词： MU-MIMO systems linear precoding Downlink antenna selection Sub-optimal selection algorithms

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SECRECY SUM-RATES WITH REGULARIZED CHANNEL INVERSION precoding UNDER IMPERFECT CSI AT THE TRANSMITTER

SECRECY SUM-RATES WITH REGULARIZED CHANNEL INVERSION PRECODI...

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IEEE International Conference on Acoustics, Speech, and Signal Processing

作者： Giovanni Geraci Romain Couillet Jinhong Yuan Merouane Debbah Iain B. Collings The University of New South Wales Dept. of Telecommunications Alcatel-Lucent Chair on Flexible Radio Supélec France CSIRO ICT Centre Sydney Australia

ISBN: (纸本)9781479903573

In this paper, we study the performance of regularized channel inversion precoding in MISO broadcast channels with confidential messages under imperfect channel state information at the transmitter (CSIT). We obtain an approximation for the achievable secrecy sum-rate which is almost surely exact as the number of transmit antennas and the number of users grow to infinity in a fixed ratio. Simulations prove this anaylsis accurate even for finite-size systems. For FDD systems, we determine how the CSIT error must scale with the SNR, and we derive the number of feedback bits required to ensure a constant high-SNR rate gap to the case with perfect CSIT. For TDD systems, we study the optimum amount of channel training that maximizes the high-SNR secrecy sum-rate.

关键词： Physical layer security limited feedback broadcast channel random matrix theory linear precoding broadcast channels Transmitters transmitting antennas Inversion Channel state information channels Privacy matrix theory Physical layer

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MMSE-Based precoding Designs for Block Diagonalization MIMO Relay Systems with Limited Feedback

MMSE-Based Precoding Designs for Block Diagonalization MIMO ...

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IEEE Global Communications Conference

作者： Xin Gui Li Liu Samsung Research Institute Beijing (SRC-B)

ISBN: (纸本)9781509013296

This paper focuses on linear precoding designs in multi-user multiple-input multiple-output block diagonalization (BD) relay systems with limited feedback. A base station employs spatial multiplexing transmission based on quantized channel state information (CSI) obtained from a relay. Then the relay transmits the received signal to users equipped with multiple antennas. In this paper, we propose a BD precoding scheme based on minimum mean square error (MMSE) criterion, which results in a closed-form solution. We show that the proposed scheme is robust to both noise and channel uncertainties caused by quantization errors. Also, we extend the proposed scheme to the case with CSI feedback delays. Simulation results verify the effectiveness of our proposed schemes.

关键词： linear precoding Multiple-input multiple-output relay Limited feedback Minimum mean square error Mean square error prediction coding Relay systems diagonalization multiple input multiple output systems Quantization Feedback multiple antenna received signal

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Reduced Dimension Minimum BER PSK precoding for Constrained Transmit Signals in Massive MIMO

Reduced Dimension Minimum BER PSK Precoding for Constrained ...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： A. Lee Swindlehurst Hela Jedda Inbar Fijalkowt Center for Pervasive Communications and Computing University of California Irvine Irvine CA 92697 USA Associate Professorship of Signal Processing Dept. of Electrical & Computer Engineering Technical University of Munich Munich 80290 Germany ETIS ENSEA CNRS Universitc Paris-Seine Universite Cergy-Pontoise Cergy F-95000 France

ISBN: (纸本)9781538646595

Recently a number of nonlinear precoding algorithms have been developed for designing a downlink transmit signal that is constrained by some nonlinearity, such as one-bit quantization, power-amplifier saturation or constant modulus. These methods use iterative search algorithms to directly design the signal that is transmitted from each antenna. Since the dimension of the search space equals the number of antennas, the computational complexity of these approaches can be high for massive MIMO scenarios. Thus, in this paper we pose the problem in a smaller dimensional space by constraining the signal prior to the nonlinearity to be the output of a linear precoder. The search is then over the vector of predistorted symbols at the input to the linear precoder, which is typically much smaller than the number of antennas. We focus on algorithms that minimize the bit error rate at the receivers, and show that performance can be obtained that is similar to algorithms that operate directly in the antenna domain.

关键词： one-bit quantization constant modulus massive MIMO linear precoding per-antenna power constraints minimum probability of error precoding

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Minimum probability-of-error perturbation precoding for the one-bit massive MIMO downlink

Minimum probability-of-error perturbation precoding for the ...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： A. Swindlehurst A. Saxena A. Mezghani I. Fijalkow Center for Pervasive Communications and Computing University of California Irvine 92697 USA ETIS UMR 8051 / ENSEA Universite Cergy-Pontoise CNRS F-95000 France

ISBN: (纸本)9781509041183

linear precoders have been shown to perform reasonably well at low SNR when the basestation of a MIMO downlink employs one-bit digital-to-analog converters to quantize the precoder outputs. However, at medium-to-high SNRs, an error floor is encountered due to the coarse quantization. This paper examines methods for slightly perturbing the transmitted signal prior to quantization in an effort to improve downlink performance at higher SNRs. The perturbation is performed with the goal of minimizing the worst-case probability of error among the user terminals, and assumes that the symbols to be transmitted are drawn from a finite alphabet constellation. Two different types of perturbations are studied, and it is found via simulation that the methods can provide dramatic gains in downlink performance.

关键词： one-bit quantization massive MIMO linear precoding perturbation precoding minimum probability of error precoding Downlink perturbation Quantization multiple input multiple output systems user terminal error floor low SNR prediction coding Signs and symbols

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Antenna Selection in the Downlink of Precoded Multiuser MIMO Systems

Antenna Selection in the Downlink of Precoded Multiuser MIMO...

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作者： Dailys Arronde Pérez Pontificia Universidade Catolica do Rio de Janeiro

学位级别：硕士

关键词： MU-MIMO systems linear precoding Downlink antenna selection Sub-optimal selection algorithms

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Closed-Form Power Normalization Methods for a Satellite MIMO System

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SENSORS 2022年第7期22卷 2586页

作者： Segneri, Andrea Baldominos, Alejandro Goussetis, George Mengali, Alberto Fonseca, Nelson J. G. Heriot Watt Univ Inst Sensors Signals & Syst Edinburgh EH14 4AS Midlothian Scotland European Space Agcy Telecom Syst & Tech Sect NL-2201 AZ Noordwijk Netherlands European Space Agcy Antenna & Submillimetre Waves Sect NL-2201 AZ Noordwijk Netherlands

The paper proposes a new set of normalization techniques for precoding/beamforming matrices applicable to broadband multiuser multiple-input multiple-output (MIMO) satellite systems. The proposed techniques adapt known normalization methods to account for the signal attenuation experienced by users due to the degradation of antenna gain and free space losses towards the edge of the coverage. We use, as an example, an array-fed reflector (AFR) antenna onboard a satellite in geosynchronous orbit (GEO), which provides a favorable trade-off between high-directivity, reconfigurability, and the requirement for digital processing, but suffers from high scan losses away from broadside due to optical aberrations when considered for global coverage applications. Three different precoding/beamforming techniques are employed, namely zero forcing (ZF), minimum mean squared error (MMSE), and matched filtering (MF). Low-complexity power normalization techniques digitally applied after the beamformer are introduced that, in the absence of any atmospheric effects, lead to iso-flux-like characteristics whilst satisfying the power constraint per feed. In comparison with other methods reported in the literature, mainly based on iterative algorithms, the proposed techniques consist in closed-form expressions to provide uniform signal-to-noise ratio (SNR) and signal-to-noise plus interference ratio (SNIR) across the users without significant impact on the payload sum rate. Numerical results are presented to comparatively demonstrate the achieved performance in terms of total capacity and distribution of SNR and SNIR at various noise and interference scenarios.

关键词： multiple-input multiple-output satellite communications array-fed reflectors linear precoding power normalization techniques

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linear precoded wavelet OFDM-based PLC system with overlap FDE for impulse noise mitigation

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INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 2017年第17期30卷 e3349.1-e3349.1页

作者： Khan, Arsla Shin, Soo Young Kumoh Natl Inst Technol KIT WENS Lab Dept IT Convergence Engn Sch Elect Engn Gumi South Korea

In recent years, power lines have gained significant interest for their use in high-speed communications because of the already deployed power distribution infrastructure. However, to achieve high data rates with reliability in power line communication (PLC), robust signal processing techniques are required to mitigate channel distortion and noise. Orthogonal frequency division multiplexing (OFDM) as a multicarrier modulation technique has been standardized for PLC;however, to further enhance the quality of communication, wavelet OFDM (WOFDM) has been proposed as a suitable choice. In this article, OFDM-based and WOFDM-based PLC systems are studied, and overlap frequency domain equalization (OFDE) as a robust and efficient equalization technique is presented. Moreover, to enhance the efficiency of the OFDE, linear precoding (LP) is also suggested for fast Fourier transform and wavelet transform-based filter bank transceivers over the PLC channel. Performance of the proposed LP-based OFDM-OFDE and LP-based WOFDM-OFDE systems is compared with previously proposed equalization structures in terms of bit error rate, peak-to-average power ratio, and computational complexity via computer simulations. Furthermore, the performance of proposed architectures is also compared with classical equalization techniques under impulse noise with different intensities. Results show that not only the proposed LP-based WOFDM-OFDE transceiver performs better than the previous equalization models but also the LP-based OFDM-OFDE at the expense of slight increment in computational complexity.

关键词： adaptive modulation equalization linear precoding impulse noise power line communication wavelet OFDM

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Low Spatial Peak-to-Average Power Ratio Transmission for Improved Energy Efficiency in Massive MIMO Systems

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SENSORS 2021年第16期21卷 5534-5534页

作者： Rezaei Aghdam, Sina Eriksson, Thomas Chalmers Univ Technol Dept Elect Engn S-41296 Gothenburg Sweden

A significant portion of the operating power of a base station is consumed by power amplifiers (PAs). Much of this power is dissipated in the form of heat, as the overall efficiency of currently deployed PAs is typically very low. This is because the structure of conventional precoding techniques typically results in a relatively high variation in output power at different antennas in the array, and many PAs are operated well below saturation to avoid distortion of the transmitted signals. In this work, we use a realistic model for power consumption in PAs and study the impact of power variation across antennas in the array on the energy efficiency of a massive MIMO downlink system. We introduce a family of linear precoding matrices that allow us to control the spatial peak-to-average power ratio by projecting a fraction of the transmitted power onto the null space of the channel. These precoding matrices preserve the structure of conventional precoders;e.g., they suppress multiuser interference when used together with zeroforcing precoding and bring advantages over these precoders by operating PAs in a more power-efficient region and reducing the total radiated distortion. Our numerical results show that by controlling the power variations between antennas in the array and incorporating the nonlinearity properties of PA into the precoder optimization, significant gains in energy efficiency can be achieved over conventional precoding techniques.

关键词： energy efficiency massive MIMO downlink linear precoding spatial PAPR nonlinear power amplifier

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LOW COMPLEXITY LMMSE TURBO EQUALIZATION FOR COMBINED ERROR CONTROL CODED AND linearLY PRECODED OFDM

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Journal of Electronics(China) 2006年第1期23卷 1-6页

作者： Qu Daiming Zhu Guangxi Dept of Electro. ＆ lnfo. Eng. Huazhong University of Sci. ＆ Tech. Wuhan 430074 China

The turbo equalization approach is studied for Orthogonal Frequency Division Multiplexing （OFDM） system with combined error control coding and linear precoding. While previous literatures employed linear precodcr of small size for complexity reasons, this paper proposes to use a linear precoder of size larger than or equal to the maximum length of the equivalent discrete-time channel in order to achieve full frequency diversity and reduce complexities of the error control coder/decoder. Also a low complexity linear Minimum Mean Square Error （LMMSE） turbo equalizer is derived for the receiver. Through simulation and performance analysis, it is shown that the performance of the proposed scheme over frequency selective fading channel reaches the matched filter bound; compared with the same coded OFDM without linear precoding, the proposed scheme shows an Signal-to-Noise Ratio （SNR） improvement of at least 6dB at a bit error rate of 10 6 over a multipath channel with exponential power delay profile. Convergence behavior of the proposed scheme with turbo equalization using various type of linear precoder/transformer, various interleaver size and error control coder of various constraint length is also investigated.

关键词： Orthogonal Frequency Division Multiplexing (OFDM) linear precoding Turbo equalization linear Minimum Mean Square Error (LMMSE)

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