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A Dual Circularly Polarized Patch Antenna With High Isolation for MIMO WLAN Applications

IEEE ACCESS 2020年 8卷 117833-117840页

作者： Zhang, Enze Michel, Andrea Pino, Marcos Rodriguez Nepa, Paolo Qiu, Jinghui Harbin Inst Technol Dept Elect & Informat Engn Harbin 150001 Peoples R China Univ Pisa Dept Informat Engn I-56122 Pisa Italy Univ Oviedo Dept Elect Engn Gijon 33203 Spain

A dual circularly polarized (CP) stacked patch antenna for multiple-input multiple-output (MIMO) WLAN applications (2.4-2.485 GHz) is presented, which exploits a square ring slot feeding technique. The antenna occupies an overall area of 96 mm x 96 mm x 39 mm, when also including the metal reflector. The 7-dBic gain antenna prototype presents an axial ratio lower than 2.5 dB as well as a port isolation higher than 25 dB. An envelope correlation coefficient (ECC) lower than 0.02 is also achieved among the two ports, thanks to the polarization orthogonality. Moreover, the stacked patch has been duplicated and used in a two-antenna system for a 4 x 4 MIMO WLAN which fits an overall volume of 157 mm x 96 mm x 39 mm. Antenna performance in terms of S-Parameters, gain, axial ratio, ECC and channel capacity are compared and discussed, together with the effect of the inter-element distance.

关键词： Circular polarization dual-CP isolation patch antenna WLAN multiple-input multiple-output MIMO diversity square ring slot stacked patch

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Performance Study of MIMO Transmissions with Joint Channel Allocation and Relay Assignment

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WIRELESS PERSONAL COMMUNICATIONS 2017年第2期96卷 2651-2665页

作者： Mishra, Sadhana Trivedi, Aditya ABV Indian Inst Informat Technol & Management Dept Informat & Commun Technol Gwalior 474015 India

multiple-input multiple-output (MIMO) techniques have shown numerous benefits in improving communication reliability and spectrum efficiency in wireless communication. In this paper, performance of MIMO transmission schemes with joint channel allocation and relay assignment (JCARA) in MIMO cooperative cognitive radio network (CRN) is studied. The problem of maximizing the spectrum efficiency among multiple CR source-destination pairs under different number of antenna configurations is studied. In order to improve the spectrum efficiency, multiple antennas are exploited at cognitive radio (CR) sources, CR relays, and CR destinations in a cooperative CRN . In this concern, we obtain the spectrum efficiency for various settings of MIMO maximum ratio transmission (MIMO-MRT) and MIMO transmit antenna selection (MIMO-TAS) schemes, which are applied at CR transmitter (i.e., CR sourc/relay) and maximum ratio combining (MRC) is applied at CR receivers (i.e., CR relay/destination), with JCARA. Extensive numerical results are presented to show the effectiveness of the MIMO-MRT and MIMO-TAS schemes. It is also shown that as the number of transmit-receive antenna increases the spectrum efficiency of both the MIMO-MRT and MIMO-TAS schemes increases as compared to single transmit-receive antenna case. Moreover, it is shown that relay assignment offers more benefit of maximization of minimum transmission rate with the MIMO-TAS scheme than the MIMO-MRT scheme.

关键词： Cognitive radio multiple-input multiple-output Cooperative communication Maximum ratio transmission Transmit antenna selection Resource allocation Spectrum efficiency

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Vector Precoding for Gaussian MIMO Broadcast Channels: Impact of Replica Symmetry Breaking

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IEEE TRANSACTIONS ON INFORMATION THEORY 2012年第3期58卷 1413-1440页

作者： Zaidel, Benjamin M. Muller, Ralf R. Moustakas, Aris L. de Miguel, Rodrigo Norwegian Univ Sci & Technol NTNU Dept Elect & Telecommun N-7491 Trondheim Norway Univ Athens Elect Lab Dept Phys Athens 15784 Greece Norwegian Univ Sci & Technol NTNU Dept Elect & Telecommun N-7034 Trondheim Norway

The "replica method" of statistical physics is employed for the large-system analysis of vector precoding for the Gaussian multiple-input multiple-output broadcast channel. The transmitter comprises a linear front-end combined with nonlinear precoding, minimizing transmit energy by means of input alphabet relaxation. For the common discrete lattice-based relaxation, the problem violates replica symmetry and a replica symmetry breaking (RSB) ansatz is taken. The limiting empirical distribution of the precoder's output and the limiting transmit energy are derived for one-step RSB. Particularizing to a "zero-forcing" (ZF) linear front-end, a decoupling result is derived. For discrete lattice-based relaxations, the impact of RSB is demonstrated for the transmit energy. The spectral efficiencies of the aforementioned precoding methods are compared to linear ZF and Tomlinson-Harashima precoding (THP). Focusing on quaternary phase shift-keying (QPSK), significant performance gains of both lattice and convex relaxations are revealed for medium to high signal-to-noise ratios (SNRs) when compared to linear ZF precoding. THP is shown to be outperformed as well. Comparing certain lattice-based relaxations for QPSK against a convex counterpart, the latter is found to be superior for low and high SNRs but slightly inferior for medium SNRs in terms of spectral efficiency.

关键词： Antenna arrays broadcast channel decoupling principle lattice multiple-input multiple-output precoding R-transform replica method zero-forcing (ZF)

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Line-of-Sight 2 x n_r MIMO With Random Antenna Orientations

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2017年第6期66卷 5134-5147页

作者： Natarajan, Lakshmi Hong, Yi Viterbo, Emanuele Indian Inst Technol Hyderabad Dept Elect Engn Sangareddy 502285 India Monash Univ Dept Elect & Comp Syst Engn Melbourne Vic 3800 Australia

Line-of-sight (LoS) multiple-input multiple-output (MIMO) gives full spatial-multiplexing gain when the antenna array geometry and orientation are designed based on the interterminal distance. These known design methodologies that hold for antenna arrays with fixed orientation do not provide full MIMO gains for arbitrary array orientations. In this paper, we study LoS MIMOchannels with random array orientations when the number of transmit antennas used for signaling is 2. We study the impact of common array geometries on error probability, and identify the code design parameter that describes the high signal-to-noise ratio (SNR) error performance of an arbitrary coding scheme. For planar receive arrays, the error rate is shown to decay only as fast as that of a rank 1 channel, and no better than SNR-3 for a class of coding schemes that includes spatial multiplexing. We then show that for the tetrahedral receive array, which uses the smallest number of antennas among nonplanar arrays, the error rate decays faster than that of rank 1 channels and is exponential in SNR for every coding scheme. Finally, we design a LoS MIMO system that guarantees a good error performance for all transmit/receive array orientations and over a range of interterminal distances.

关键词： Antenna array array geometry coding scheme line-of-sight multiple-input multiple-output probability of error

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Fast Converging Semi-Blind Space-Time Equalisation for Dispersive QAM MIMO Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2009年第8期8卷 3969-3974页

作者： Chen, S. Hanzo, L. Univ Southampton Sch Elect & Comp Sci Southampton SO17 1BJ Hants England

A novel semi-blind space-time equaliser (STE) is proposed for dispersive multiple-input multiple-output systems that employ high-throughput quadrature amplitude modulation signalling. A minimum number of training symbols, approximately equal to the dimension of the STE, are first utilised to provide a rough initial least squares estimate of the STE's weight vector. A concurrent gradient-Newton constant modulus algorithm and soft decision-directed scheme is then applied to adapt the STE. The proposed semi-blind adaptive STE is capable of converging fast to the minimum mean square error STE solution. Simulation results confirms that the convergence speed of this semi-blind adaptive algorithm is very close to that of the training-based recursive least squares algorithm.

关键词： multiple-input multiple-output quadrature amplitude modulation space-time equalisation stochastic-gradient adaptive algorithm gradient-Newton adaptive algorithm

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Sum Rate and Fairness Analysis for the MU-MIMO Downlink Under PSK Signalling: Interference Suppression vs Exploitation

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IEEE TRANSACTIONS ON COMMUNICATIONS 2019年第9期67卷 6085-6098页

作者： Salem, Abdeihamid Masouros, Christos Wong, Kai-Kit UCL Dept Elect & Elect Engn London WC1E 6BT England

In this paper, we analyze the sum rate performance of multi-user multiple-input-multiple-output (MU-MIMO) systems, with a finite constellation phase-shift keying (PSK) input alphabet. We analytically calculate and compare the achievable sum rate in three downlink transmission scenarios: 1) without precoding;2) with zero forcing (ZF) precoding;and 3) with closed form constructive interference (CI) precoding technique. In light of this, new analytical expressions for the average sum rate are derived in the three cases, and Monte Carlo simulations are provided throughout to validate the analysis. Furthermore, based on the derived expressions, a power allocation scheme that can ensure fairness among the users is also proposed. The results in this work demonstrate that the CI strictly outperforms the other two schemes, and the performance gap between the considered schemes increases with the increase in MIMO size. In addition, the CI provides higher fairness and the power allocation algorithm proposed in this paper can achieve maximum fairness index.

关键词： Finite constellation signaling zero forcing constructive interference phase-shift keying signaling multiple-input multiple-output

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Optimum beamforming for MIMO multicasting

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EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING 2013年第1期2013卷 1页

作者： Du, Baisheng Jiang, Yi Xu, Xiaodong Dai, Xuchu Univ Sci & Technol China Dept Elect Engn & Informat Sci Hefei 230027 Anhui Peoples R China Silvus Technol Inc San Diego CA 92127 USA

This paper investigates the transmit (Tx) beamforming design to maximize the throughput of a multiple-input multiple-output multicast channel, where common information is sent from the base station to K users simultaneously. This so-called max-min fair beamforming problem is known to be NP-hard. When the base station is equipped with two Tx antennas, we prove that the original complex-valued beamforming problem can be transformed into a real-valued problem and the globally optimal solution can be found by exhausting at most C-K(1) + C-K(2) + C-K(3) hypothesis tests. Moreover, a prune and search algorithm (PASA) is proposed for searching the optimal beamformer with computational complexity O(K-3) in the worst case. When the base station has more than two Tx antennas, we develop an efficient algorithm named iterative two-dimensional optimization which converts the original beamforming problem into a series of two-antenna subproblems by iterations and hence, the beamformer is improved using PASA iteratively. Simulations results are presented to demonstrate the superior performance of the proposed algorithms.

关键词： Physical layer multicasting multiple-input multiple-output Transmit beamforming Semidefinite relaxation (SDR)

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Few-Mode Fibers Supporting More Than Two LP Modes For Mode-Division-multiplexed Transmission With MIMO DSP

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2014年第14期32卷 2468-2479页

作者： Mori, Takayoshi Sakamoto, Taiji Wada, Masaki Yamamoto, Takashi Yamamoto, Fumihiko NTT Corp Access Network Serv Syst Labs Tsukuba Ibaraki 3050805 Japan

We propose a transmission fiber for mode-division-multiplexed transmission with multiple-input multiple-output (MIMO) digital signal processing supporting four and six linearly polarized (LP) modes over the C + L band. We show numerically that a graded-index core can flexibly tune the differential mode group delay (DMD) and a cladding trench can flexibly control the guiding mode number. We optimized the spacing of the core and trench. Accordingly, we can achieve a few-mode operation of more than two LP modes and low DMD while preventing the high-refractive index difference that leads to manufacturing difficulties and any loss increase. Finally, we successfully fabricated fibers for use in a C + L band WDM-MDM transmission with MIMO DSP, and realized a transmission fiber with a total absolute DMD of less than 40 ps/km for four-LP mode operation and of less than 70 ps/km for six-LP mode operation over the entire C + L band.

关键词： Differential mode delay few-mode fibers multiple-input multiple-output

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Solving Doppler-Angle Ambiguity of BPSK-MIMO FMCW Radar System

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IEEE ACCESS 2021年 9卷 120347-120357页

作者： Jung, Jaehoon Lim, Sohee Kim, Seong-Cheol Lee, Seongwook Seoul Natl Univ Coll Engn Inst New Media & Commun Dept Elect & Comp Engn Seoul 08826 South Korea Korea Aerosp Univ Coll Engn Sch Elect & Informat Engn Gyeonggi Do 10540 South Korea

In a multiple-input multiple-output (MIMO) radar system, binary phase-shift keying (BPSK) modulation is widely used to separate signals transmitted from multiple transmit (Tx) antennas. However, when the BPSK modulation is applied to the frequency-modulated continuous-wave (FMCW) radar system, there is an occurrence of Doppler-angle ambiguity due to the properties of the modulation scheme. In other words, the maximum detectable velocity is reduced in proportion to the number of Tx antennas, and the angle estimation performance can be degraded when a moving target induces a Doppler phase shift. Therefore, in this paper, we propose a method for solving the Doppler-angle ambiguity in the BPSK-MIMO FMCW radar system. The proposed method involves comparing and arranging the phases of signals corresponding to the same target in the range-velocity detection results. By arranging the phases to form an arithmetic sequence, the signals from each Tx antenna can be distinguished and the unambiguous velocity and angle of the target can be estimated. In addition, by using a general phase-shift keying (PSK) modulation scheme, the proposed method can be applied to an arbitrary MIMO system regardless of the number of Tx antennas.

关键词： Radar antennas Radar Chirp Transmitting antennas Estimation Binary phase shift keying Receiving antennas Binary phase-shift keying Doppler-angle ambiguity frequency-modulated continuous-wave multiple-input multiple-output

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Concrete Feedback Layers: Variable-Length, Bit-Level CSI Feedback Optimization for FDD Wireless Communication Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2024年第10期23卷 15353-15366页

作者： Ji, Dong Jin Chung, Byung Chang Seoul Natl Univ Sci & Technol Dept Semicond Engn Seoul 01811 South Korea Gyeongsang Natl Univ Dept Intelligence & Commun Engn Tongyeong 53064 South Korea

In this work, we present the innovative Concrete Feedback Layers, designed to enable genuine bit-level, end-to-end Channel State Information (CSI) feedback using deep learning techniques. Overcoming the limitations of traditional discrete operations that impede gradient flow, these layers leverage the concrete distribution to facilitate efficient learning processes. Our extensive simulations reveal that these layers significantly enhance digital CSI feedback, achieving superior performance in terms of Normalized Mean Squared Error (NMSE) and cosine similarity compared to conventional feedback models. Furthermore, the integration of the Concrete Feedback Layers with the Feedback Bit Masking Unit (FBMU) allows for authentic bit-level variable-length CSI feedback, while maintaining a single adaptable model for various feedback lengths. This advancement marks a major leap forward in deep learning-based CSI feedback methods, potentially revolutionizing 6G communication systems with its flexibility and efficiency.

关键词： Machine learning for communications deep learning channel feedback multiple-input multiple-output variable-length feedback 6G wireless systems channel state information (CSI) end-to-end learning neural network architectures channel feedback multiple-input multiple-output variable-length feedback 6G wireless systems channel state information (CSI) end-to-end learning neural network architectures

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