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A General Digital Predistortion Linearization Scheme for Hybrid Beamforming System

IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2023年第1期72卷 654-663页

作者： Zhao, Linshan Wan, Shaojun Kang, Kai Feng, Weifeng Qian, Hua Chinese Acad Sci Shanghai Adv Res Inst Shanghai 201210 Peoples R China Univ Chinese Acad Sci Beijing 101408 Peoples R China

Hybrid beamforming multiple-input multiple-output (MIMO) system has attracted a lot of attention in recent years since it significantly reduces the hardware cost compared to the fully digital beamforming system. However, with hybrid beamforming, the one-to-one mapping between the radio frequency (RF) chain and the nonlinear power amplifier (PA) is destroyed. The PA nonlinearity cannot be compensated by conventional digital predistortion (DPD) algorithms. In this article, we propose a novel multiple-input DPD model for hybrid beamforming MIMO systems. An extra digital compensation block is introduced in the feedback path. With the feedback compensation block, the proposed DPD can linearize the PA output signal as well as the aggregated far-field signal. What is more, we propose a DPD estimation algorithm with much reduced complexity. Comparing to existing solutions, the proposed scheme achieves satisfactory performance for hybrid beamforming system. It does not rely on the measurement of the channel or the assumption of massive antennas. Simulation results demonstrate the effectiveness of the proposed DPD scheme.

关键词： Digital predistortion hybrid beamforming multiple-input multiple-output multiple-input nonlinear model power amplifier

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Performance improvement of spatial modulation-assisted FSO systems over Gamma-Gamma fading channels with geometric spreading

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PHOTONIC NETWORK COMMUNICATIONS 2017年第2期34卷 213-220页

作者： Pham, Hien T. T. Dang, Ngoc T. Posts & Telecommun Inst Technol Telecommun Engn Hanoi Vietnam Posts & Telecommun Inst Technol Dept Wireless Commun Hanoi Vietnam

A number of studies recently have proposed optical spatial modulation (SM) as a simple, power- and bandwidth efficient modulation scheme for free-space optical communication (FSO) systems. In these studies, it was assumed that an active laser source only sends the signal to one targeted photodetector (PD). However, undesirable PDs still can receive the signal from the active source due to geometric spreading (i.e., laser beam broadening). In addition, if the fading channels between the active source and multiple PDs are correlated, the probability of wrong detection of the active source's index during spatial demodulation process may increase. In this paper, we first analyze the impact of geometric spreading on the performance of FSO systems using SM over uncorrelated Gamma-Gamma fading channel. We find that the advantage in reducing the transmission bandwidth of SM cannot compensate its limitation in suffering from geometric spreading. We then propose to combine N-SM with pulse-position modulation (L-PPM) and transmit diversity ( MISO) to improve the performance of SM-based FSO systems. The numerical results, which are validated by Monte-Carlo simulations, confirm the superiority of the proposed system in comparison with the conventional ones.

关键词： Free-space optical communications Spatial modulation multiple-input multiple-output Atmospheric turbulence Geometric spreading

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Efficient Detection for Improving ASEP Performance of MIMO Composite Fading Channel with Generalized Noise

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WIRELESS PERSONAL COMMUNICATIONS 2018年第3期98卷 2913-2923页

作者： Tiwari, Keerti Saini, Davinder S. Bhooshan, Sunil V. Jaypee Univ Informat Technol Dept Elect & Commun Engn Solan 173234 HP India Chandigarh Coll Engn & Technol Dept Elect & Commun Engn Chandigarh 160019 India

multiple-input multiple-output (MIMO) system has achieved significant benefits by applying optimum detection techniques. Maximum likelihood (ML) detection technique improves the error rate performance of MIMO system at optimum level but with enhanced complexity. Therefore, we have considered minimum mean square error-ordered successive interference cancellation with candidate detection to approach the performance of ML with reduced complexity. The proposed system performance is analyzed in composite Weibull-gamma fading and additive white generalized Gaussian noise (AWGGN) scenario. Some special cases of WG fading and AWGGN yield the simplified results.

关键词： multiple-input multiple-output Maximum likelihood Minimum mean square error-ordered successive interference cancellation with candidate Additive white generalized Gaussian noise

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Effect of Wiring and Cabling Topologies on the Performance of Distributed MIMO OFDM VLC Systems

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IEEE ACCESS 2019年 7卷 52743-52754页

作者： Narmanlioglu, Omer Kizilirmak, Refik Caglar Miramirkhani, Farshad Safaraliev, Sadi Sait, Sadiq M. Uysal, Murat Ozyegin Univ Dept Elect & Elect Engn TR-34794 Istanbul Turkey Nazarbayev Univ Dept Elect & Comp Engn Astana 010000 Kazakhstan Nestel Elect Co TR-45030 Manisa Turkey King Fahd Univ Petr & Minerals Ctr Commun & IT Res Res Inst Dhahran 31261 Saudi Arabia

Since most indoor spaces have multiple luminaires for illumination, for visible light communication (VLC) systems, multiple-input multiple-output (MIMO) communication emerges as a natural solution to improve the data rates and/or the link reliability. The existing works on MIMO VLC systems, however, overlook the characteristics of the lighting infrastructure and the luminaire design, which might have implications for the VLC system design. A luminaire typically consists of multiple LED chips. The wiring topology refers to how the LED chips are connected within the luminaire. The cabling topology, on the other hand, refers to how the luminaires are connected to the communication access point (AP). Based on the type and length of cabling and wiring, significant delays can be introduced, which should be taken into account in channel modeling. In this paper, we adopt the non-sequential ray tracing to model the distributed MIMO VLC channels for various practical wiring and cabling topologies. Based on the developed channel models, we provide a comparative performance analysis of repetition coding (RC), spatial multiplexing (SMUX), and spatial modulation (SMOD) MIMO modes. Our results quantify the effect of wiring/cabling delays and provide insights into the optimized design of lighting infrastructure and luminaires for the support of VLC as an add-on service.

关键词： Visible light communication multiple-input multiple-output OFDM channel modeling cabling delay

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On the Exact Distribution of Mutual Information of Two-User MIMO MAC Based on Quotient Distribution of Wishart Matrices

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EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2017年第1期2017卷 1页

作者： Pivaro, Gabriel Kumar, Santosh Fraidenraich, Gustavo State Univ Campinas Unicamp Dept Commun Campinas SP Brazil Shiv Nadar Univ Dept Phys Gautam Buddha Nagar Uttar Pradesh India

We propose an exact calculation of the probability density function (PDF) and cumulative distribution function (CDF) of mutual information (MI) for a two-user multiple-input multiple-output (MIMO) multiple access channel (MAC) network over block Rayleigh fading channels. This scenario can be found in the uplink channel of MIMO non-orthogonal multiple access (NOMA) system, a promising multiple access technique for 5G networks. So far, the PDF and CDF have been numerically evaluated since MI depends on the quotient of two Wishart matrices, and no closed form for this quotient was available. We derive exact results for the PDF and CDF of extreme (the smallest/the largest) eigenvalues. Based on the results of quotient ensemble, the exact calculation for PDF and CDF of mutual information is presented via Laplace transform approach and by direct integration of joint PDF of quotient ensemble's eigenvalues. Furthermore, our derivations also provide the parameters to apply the Gaussian approximation method, which is comparatively easier to implement. We show that approximation matches the exact results remarkably well for outage probability, i.e., CDF, above 10%. However, the approximation could also be used for 1% outage probability with a relatively small error. We apply the derived expressions to investigate the effects of adding antennas in the receiver and its ability to decode the weak user signal. By supposing no channel knowledge at transmitters and successive decoding at receiver, the capacity of the weak user increases and its outage probability decreases with the increment of extra antennas at the receiver end.

关键词： multiple access channel multiple-input multiple-output Non-orthogonal multiple access Mutual information Outage probability Rayleigh fading Wishart matrices Quotient ensemble Extreme eigenvalues Gap probabilities

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Jointly minimum BER transmitter and receiver FIR MIMO filters for binary signal vectors

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2004年第4期52卷 1021-1036页

作者： Hjorungnes, A Diniz, PSR de Campos, MLR Univ Oslo Dept Informat N-0316 Oslo Norway Univ Fed Rio de Janeiro COPPE Signal Proc Lab BR-21945970 Rio De Janeiro Brazil

A theory is developed for jointly minimizing the bit error rate (BER) between the desired and decoded signals with respect to the coefficients of transmitter and receiver finite impulse response (FIR) multiple-input multiple-output (MIMO) filters. The original signal is assumed to be a vector time-series with equally likely memoryless Bernoulli vector components. The channel model constitutes of a known FIR MIMO transfer function and Gaussian additive noise independent of the original signal. The channel input signal is assumed to be power constrained. Based on the formulas obtained, an iterative numerical optimization algorithm is proposed. When compared with other design methods available in the literature, the proposed method yields better results due to the generality of the model considered and the joint optimization of the transmitter-receiver pair.

关键词： FIR MIMO filters MIMO system multiple-input multiple-output

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Spatial multiplexing for Photon-Counting MIMO-FSO Communication Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2018年第9期17卷 5789-5803页

作者： Abou-Rjeily, Chadi Lebanese Amer Univ Dept Elect & Comp Engn Byblos 961 Lebanon

In this paper, we consider the problem of multiple-input multiple-output (MIMO) free-space optical communications under the Poisson photon-counting detection model. Aiming for high bit rate objectives, we consider the spatial-multiplexing (SMux) solution with M-ary pulse-position modulation, where we propose appropriate optimal and suboptimal decoders and evaluate their complexities. Such novel decoder designs are needed, since the widely spread Gaussian noise-based MIMO decoders are not suitable for the Poisson model. We also carry out an asymptotic performance analysis. This analysis guides a candidate constellation confinement where transmissions are limited to some selected information vectors of the multi-dimensional SMux constellation. This confinement meets the objective of compromising the multiplexing gains for the sake of improved error-rates. The analyzed SMux solutions with both the unconfined and confined constellations transmit at higher data rates compared with the existing single-aperture systems, MIMO systems with repetition coding, and MIMO systems based on spatial modulation.

关键词： Free-space optics FSO multiple-input multiple-output MIMO maximum-likelihood spatial multiplexing Poisson noise suboptimal decoders constellation confinement performance analysis

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Molecular MIMO: From Theory to Prototype

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2016年第3期34卷 600-614页

作者： Koo, Bon-Hong Lee, Changmin Yilmaz, H. Birkan Farsad, Nariman Eckford, Andrew Chae, Chan-Byoung Yonsei Univ Sch Integrated Technol Yonsei Inst Convergence Technol Seoul 120749 South Korea Stanford Univ Dept Elect Engn Stanford CA 94305 USA York Univ Dept Elect & Comp Sci Toronto ON M3J 2R7 Canada

In diffusion-based molecular communication, information transport is governed by diffusion through a fluid medium. The achievable data rates for these channels are very low compared to the radio-based communication system, since diffusion can be a slow process. To improve the data rate, a novel multiple-input multiple-output (MIMO) design for molecular communication is proposed that utilizes multiple molecular emitters at the transmitter and multiple molecular detectors at the receiver (in RF communication these all correspond to antennas). Using particle-based simulators, the channel's impulse response is obtained and mathematically modeled. These models are then used to determine interlink interference (ILI) and intersymbol interference (ISI). It is assumed that when the receiver has incomplete information regarding the system and the channel state, low complexity symbol detection methods are preferred since the receiver is small and simple. Thus, four detection algorithms are proposed-adaptive thresholding, practical zero forcing with channel models excluding/including the ILI and ISI, and Genie-aided zero forcing. The proposed algorithms are evaluated extensively using numerical and analytical evaluations.

关键词： Molecular communication via diffusion multiple-input multiple-output interference Brownian motion 3-D simulation symbol detection algorithm molecular communication testbed

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A 1T2R High-Sensitivity and Dual-Channel Transceiver for Backscatter Communication Systems

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IEEE ACCESS 2024年 12卷 141841-141850页

作者： Lai, Sijia Zhao, Yuxiao Liu, Meng Xu, Shengliang Tang, Kuangfeng Min, Hao Fudan Univ Sch Microelect State Key Lab ASIC & Syst Shanghai 200120 Peoples R China

Owing to the rapid development of the ambient Internet of Things (IoT) industry, Backscatter Communication Systems (BCS) require higher receiver sensitivity for large-scale IoT scenarios than traditional Radio Frequency Identification (RFID) systems. This paper proposes a method of using multiple-input multiple-output (MIMO) technology to compensate for reflected signals in the 920 MHz backscatter communication systems. The researcher first created a MATLAB model to verify the theoretical feasibility and then built a One-Transmitter Two-Receiver (1T2R) BCS transceiver system compatible with the EPC global protocol for practical verification on LabVIEW. The ITIR and 1T2R tests were conducted using the National Instrument (NI) USRP-2952R device, the directional antennas, and the standard RF electronic tags. Through the process of superimposing and utilizing the phase shift between the two reflected carriers, it has been confirmed that the overall signal strength can be enhanced from 2.2 mV to 4.13 mV and 4.37 mV (nearly reaching 4.70 mV by using two Rx antennas in ideal conditions). After calculation, this advancement increases signal strength from -40.14 dBm (when using a single Rx antenna) to -34.18 dBm (when using two Rx antennas). The improvement in signal strength can provide a gain of 5.96 dB to the backscatter communication systems. Experimental results demonstrate that utilizing MIMO technology to the backscatter communication systems can effectively enhance the sensitivity of the receiver at 920 MHz.

关键词： Backscatter Transceivers Communication systems Radiofrequency identification Internet of Things Receiving antennas Sensitivity MIMO ambient Internet of Things backscatter communication systems radio frequency identification multiple-input multiple-output

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Real-Time Multi-Gigabit Receiver for Coherent Optical MIMO-OFDM Signals

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2009年第16期27卷 3699-3704页

作者： Chen, Simin Yang, Qi Ma, Yiran Shieh, William Univ Melbourne Dept Elect & Elect Engn ARC Special Res Ctr Ultra Broadband Informat Netw Melbourne Vic 3010 Australia Univ Melbourne Dept Elect & Elect Engn Natl ICT Australia Victoria Res Lab Melbourne Vic 3010 Australia

In this paper we implement a first multi-gigabit real-time dual-polarization CO-OFDM receiver in a 2 x 2 multiple-input multiple-output (MIMO) configuration. The experimental setup consists of four 1.5 Giga samples per second (GS/s) high-speed analog-to-digital converters (ADC) and one Stratix III field-programmable gate array (FPGA). The signal streams are processed in real-time mode, and the data rates of 3.33 Gb/s and 6.67 Gb/s are realized for 4-QAM and 16-QAM, respectively.

关键词： Coherent communications field programmable gate array multiple-input multiple-output orthogonal frequency-division multiplexing polarization diversity quadrature amplitude modulation

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