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Performance Improvement of Multi-User multiple-Input multiple-output Protocol for WLAN

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Communications and Network 2017年第2期9卷 124-141页

作者： Maha Bakalla Mznah Al-Rodhaan Yuan Tian Department of Computer Science College of Computer and Information Sciences King Saud University Riyadh KSA

The increase in the number of devices with a massive revolution in mobile technology leads to increase the capacity of the wireless communications net-works. Multi-user multiple-Input multiple-output is an advanced procedure of multiple-Input multiple-output, which improves the performance of Wireless Local Area Networks. Moreover, Multi-user multiple-Input multiple-output leads the Wireless Local Area Networks toward covering more areas. Due to the growth of the number of clients and requirements, researchers try to improve the performance of the Medium Access Control protocol of Multi-user multiple-Input multiple-output technology to serve the user better, by supporting different data sizes, and reducing the waiting time to be able to transmit data quickly. In this paper, we propose a Clustering Multi-user multiple-Input multiple-output protocol, which is an improved Medium Access Control protocol for Multi-user multiple-Input multiple-Out-put based on MIMOMate clustering technique and Padovan Backoff Algorithm. Utilizing MIMOMMate focuses on the signal power which only serves the user in that cluster, minimizes the energy consumption and increases the capacity. The implementation of Clustering Multi-user multiple-Input multiple-output performs on the Network Simulator (NS2.34) platform. The results show that Clustering Multi-user multiple-Input multiple-output protocol improves the throughput by 89.8%, and reduces the latency of wireless communication by 43.9% in scenarios with contention. As a result, the overall performances of the network are improved.

关键词： Clustering Multi-User multiple-Input multiple-output Multi-user multiple-Input multiple-output MIMOMate Padovan Backoff Algorithm Wireless Local Arewa Network

Taylor expansion MUSIC method for joint DOD and DOA estimation in a bistatic MIMO array

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Frontiers of Information Technology & Electronic Engineering 2019年第6期20卷 842-848页

作者： Wen-tao SHI Qun-fei ZHANG Cheng-bing HE Jing HAN School of Marine Science and Technology Northwestern Polytechnical University Xi'an 710072 China Science and Technology on Electronic Information Control Laboratory Chengdu 610041 China

We propose a Taylor expansion multiple signal classification(TE MUSIC) method for joint direction of departure(DOD) and direction of arrival(DOA) estimation in a bistatic multiple-input multiple-output(MIMO)array. First, using a Taylor expansion of the steering vector, a two-dimensional(2D) search in the conventional MUSIC method for MIMO arrays is reduced to a two-step one-dimensional(1D) search in the proposed TE MUSIC method. Second, DOAs of the targets can be achieved via Lagrange multiplier by a 1D search. Finally, substituting the DOA estimates into the 2D MUSIC spectrum function, DODs of the targets are obtained by another 1D ***, the DOD and DOA estimates can be automatically paired. The performance of the proposed method is better than that of the MIMO ESPRIT method, and is similar to that of the 2D MUSIC method. Furthermore, due to the 1D search, the TE MUSIC method avoids the high computational complexity of the 2D MUSIC method. Simulation results are presented to show the effectiveness of the proposed method.

关键词： Bistatic multiple-input multiple-output array Direction of departurc Direction of arrival multiple signal classification Taylor expansion Computational complexity

Hybrid Precoder and Combiner Design with Finite Resolution PSs for mmWave MIMO Systems

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China Communications 2019年第2期16卷 95-104页

作者： Ran Zhang Weixia Zou Ye Wang Mingyang Cui Key Lab of Universal Wireless Communications MOEBeijing University of Posts and Telecommunications State Key Lab.of Millimeter Waves Southeast University

Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.

关键词： millimeter wave multiple-input multiple-output finite resolution phase shifters hybrid precoding alternate optimization

Antenna selection for MIMO system based on pattern recognition

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Digital Communications and Networks 2019年第1期5卷 34-39页

作者： Ping Yang Jing Zhu Yue Xiao Zhi Chen National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China Chengdu 611731 China

This paper proposes a novel multiple-Input multiple-output (MIMO) transmission scheme based on Pattern Recognition (PR), which is termed as the PR aided Transmission Antenna Selection MIMO (PR-TAS aided MIMO). As the conventional TAS algorithms need to search all possible legitimate antenna subsets, they may impose some redundant calculations. In order to avoid this problem, we employ some pattern recognition methods to carry out the TAS algorithm in this paper. To be specific, two PR algorithms, namely the K-Nearest Neighbor (KNN) algorithm and the Support Vector Machine (SVM) algorithm, are introduced and redesigned to obtain a TAS with lower complexity but higher efficiency. Moreover, in order to improve the performance of the SVM, we propose a new feature extraction of channel matrix for the TAS. Our simulation results show that the proposed KNN and SVM based PR-TAS algorithms are capable of striking a flexible tradeoff between the complexity and the Bit Error Rate (BER), and the new feature can effectively improve the BER performance compared with the conventional feature extraction method.

关键词： Antenna selection K-nearest neighbors multiple-input multiple-output Pattern recognition Support vector machine

Design and Analysis of a Power Efficient Linearly Tunable Cross-Coupled Transconductor Having Separate Bias Control

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Circuits and Systems 2012年第1期3卷 99-106页

作者： Vijaya Bhadauria Krishna Kant Swapna Banerjee 不详

A common current source, generally used to bias cross-coupled differential amplifiers in a transconductor, controls third harmonic distortion (HD3) poorly. Separate current sources are shown to provide better control on HD3) . In this paper, a detailed design and analysis is presented for a transconductor made using this biasing technique. The transconductor, in addition, is made to offer high Gm, low power dissipation and is designed for linearly tunable Gm with current mode load as one of the applications. The circuit exhibits HD3) of less than –43.7 dB, high current efficiency of 1.18 V-1 and Gm of 390 μS at 1 VGp-p @ 50 MHz. UMC 0.18 μm CMOS process technology is used for simulation at supply voltage of 1.8 V.

关键词： Analog electronics low power Analog CMOS Circuit Operational Transconductance Amplifier (OTA) multiple-output OTA (MOTA) MOS Transconductors linearly tunable Gm Current efficiency Linearization Techniques Harmonic Distortion Analysis

A Virtual Channel-Based Approach to Compensation of I/Q Imbalances in MIMO-OFDM Systems

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International Journal of Communications, Network and System Sciences 2010年第9期3卷 711-721页

作者： Shichuan Ma Deborah D. Duran Hamid Sharif Yaoqing (Lamar) Yang 不详

multiple-input multiple-output (MIMO)-orthogonal frequency-division multiplexing (OFDM) scheme has been considered as the most promising physical-layer architecture for the future wireless systems to provide high-speed communications. However, the performance of the MIMO-OFDM system may be degraded by in-phase/quadrature-phase (I/Q) imbalances caused by component imperfections in the analog front-ends of the transceivers. I/Q imbalances result in inter-carrier interference (ICI) in OFDM systems and cause inaccurate estimate of the channel state information (CSI), which is essential for diversity combining at the MIMO receiver. In this paper, we propose a novel approach to analyzing a MIMO-OFDM wireless communication system with I/Q imbalances over multi-path fading channels. A virtual channel is proposed as the combination of multi-path fading channel effects and I/Q imbalances at the transmitter and receiver. Based on this new approach, the effects of the channel and I/Q imbalances can be jointly estimated, and the influence of channel estimation error due to I/Q imbalances can be greatly reduced. An optimal minimal mean square error (MMSE) estimator and a low-complexity least square (LS) estimator are employed to estimate the joint coefficients of the virtual channel, which are then used to equalize the distorted signals. System performance is theoretically analyzed and verified by simulation experiments under different system configurations. The results show that the proposed method can significantly improve system performance that is close to the ideal case in which I/Q are balanced and the channel state information is known at the receiver.

关键词： I/Q Imbalance multiple-Input multiple-output (MIMO) Orthogonal Frequency-Division multiplexing (OFDM) Alamouti Scheme

Impact of Depolarization Phenomena on Polarized MIMO Channel Performances

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International Journal of Communications, Network and System Sciences 2008年第2期1卷 124-129页

作者： Nuttapol PRAYONGPUN Kosai RAOOF Laboratoire Grenoble Images Paroles Signal Automatique (GIPSA-LAB)

The performance and capacity of multiple-input multiple-output (MIMO) wireless channels are limited by the spatial fading correlation between antenna elements. This limitation is due to the use of mono polarized antennas at receiver and transmitter sides. In this paper, in order to reduce the antenna correlation, the polarization diversity technique is employed. Although the spatial antenna correlation is attenuated for multi-polarization configurations, the cross-polar components appear. This paper highlights the impact of depolarization effect on the MIMO channel capacity for a 4&#215;4 uniform linear antenna array. We assume that the channel is unknown at the transmitter and perfectly known at the receiver so that equal power is distributed to each of the transmit antennas. The numerical results illustrate that for low depolarization and spatial correlation, the capacity of single-polarization configuration behaves better than that of multi-polarization configuration.

关键词： multiple-input multiple-output (MIMO) Channel Capacity Spatial Fading Correlation Multi-polarized Antenna Arrays Depolarization Effects.

Downlink MBER Transmit Beamforming Design Based on Uplink MBER Receive Beamforming for TDD-SDMA Induced MIMO Systems

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Communications and Network 2010年第3期2卷 145-151页

作者： Sheng Chen Lie-Liang Yang 不详

The downlink minimum bit error rate (MBER) transmit beamforming is directly designed based on the uplink MBER receive beamforming solution for time division duplex (TDD) space-division multiple-access (SDMA) induced multiple-input multiple-output (MIMO) systems, where the base station (BS) is equipped with multiple antennas to support multiple single-antenna mobile terminals (MTs). It is shown that the dual relationship between multiuser detection and multiuser transmission can be extended to the rank-deficient system where the number of users supported is more than the number of transmit antennas available at the BS, if the MBER design is adopted. The proposed MBER transmit beamforming scheme is capable of achieving better performance over the standard minimum mean square error transmit beamforming solution with the support of low-complexity and high power-efficient MTs, particularly for rank-deficient TDD-SDMA MIMO systems. The robustness of the proposed MBER transmit beamforming design to the downlink and uplink noise or channel mismatch is investigated using simulation.

关键词： Minimum Bit Error Rate Time Division Duplex multiple-Input multiple-output Transmit Beamforming Receive Beamforming Space-Division multiple-Access

LDPC-CPM Scheme and Its Iterative Receiving for MIMO System

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International Journal of Communications, Network and System Sciences 2017年第5期10卷 154-162页

作者： Rui Xue Xue Lv Yang Cao College of Information and Communication Engineering Harbin Engineering University Harbin China Tianjin Key Laboratory of Intelligent Information Processing in Remote Sensing Tianjin China

One of the advantages of multiple-Input multiple-output (MIMO) techniques is that they can provide link throughput, but the reliability of them remains to be improved. In order to improve the performance of bit error, based on the decomposed model of continuous phase modulation (CPM), combined with LDPC code and random interweaver, a scheme of joint coded modulation is introduced. In this paper, the model of LDPC-CPM iterative MIMO system is established firstly, then scheme of receiver by iterative detection realized and the decoding is proposed, finally the effect of main parameters on the performance of the system is studied, which can provide the reference basis for practical application. The research results show that the proposed scheme can improve channel capacity and BER performance in the background of extremely low SNR effectively, and give attention to both high-speed transmission and reliable transmission.

关键词： Communication Technology Continuous Phase Modulation multiple-Input multiple-output (MIMO) Iterative Detection and Decoding