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A Reduced-Complexity Heterodyne Multiband MIMO Receiver with Estimation of Analog Devices Imperfection in a Baseband Feedback Loop

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IEICE TRANSACTIONS ON COMMUNICATIONS 2013年第6期E96B卷 1540-1550页

作者： Ohta, Tomoya Denno, Satoshi Morikura, Masahiro Kyoto Univ Grad Sch Informat Kyoto 6068501 Japan Okayama Univ Grad Sch Nat Sci & Technol Okayama 7008530 Japan

This paper proposes a reduced-complexity multiband multiple-input multiple-output (MIMO) receiver that can be used in cognitive radios. The proposed receiver uses heterodyne reception implemented with a wide-passband band-pass filter in the radio frequency (RF) stage. When an RF Hilbert transformer is utilized in the receiver, image-band interference occurs because of the transformer's imperfections. Thus, the imperfection of the Hilbert transformer is corrected in the intermediate frequency (IF) stage to reduce the hardware complexity. First, the proposed receiver estimates the channel impulse response in the presence of the strong image-band interference signals. Next, the coefficients are calculated for the correction of the imperfection at the IF stage, and are fed back to the IF stage through a feedback loop. However, the imperfection caused by the digital-to-analog (D/A) converter and the baseband amplifier in the feedback loop corrupts the coefficients on the way back to the IF stage. Therefore, the proposed receiver corrects the imperfection of the analog devices in the feedback loop. The performance of the proposed receiver is verified by using computer simulations. The proposed receiver can maintain its performance even in the presence of strong image-band interference signals and imperfection of the analog devices in the feedback loop. In addition, this paper also reveals the condition for rapid convergence.

关键词： cognitive radio heterodyne multiband receiver multiple-input multiple-output analog devices imperfection in a feedback loop raising frequency utilization efficiency

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Congestion control based ant colony optimization algorithm for large MIMO detection

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EXPERT SYSTEMS WITH APPLICATIONS 2015年第7期42卷 3662-3669页

作者： Mandloi, Manish Bhatia, Vimal Indian Inst Technol Indore Discipline Elect Engn Indore 453441 Madhya Pradesh India

Employing multiple antennas in wireless communication systems is a key technology for future generation of wireless systems. Symbol detection in multiple-input multiple-output (MIMO) systems with low complexity is challenging. The minimum bit error rate (BER) performance can be achieved by maximum likelihood (ML) detection. However, with increase in number of antennas in MIMO systems, the ML detection becomes impractical. For example, sphere decoder (SD) is a well known ML detector for MIMO systems, however because of its high complexity it is practical only up to 32 real dimensions. Recently, bio-inspired algorithms are being used for improving the BER performance of MIMO symbol detector, along with low complexity. In this article, we propose a congestion control based ant colony optimization (CC-ACO) algorithm for large MIMO detection. We also discuss the robustness of the proposed algorithm under channel state information (CSI) estimation error. The simulation results shows the effectiveness of the proposed algorithm in terms of achieving better bit error rate (BER) performance with low complexity. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Ant colony optimization multiple-input multiple-output Minimum mean squared error Zero forcing Channel estimation error Successive interference cancellation Maximum likelihood

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Performance analysis of MIMO-OFDM free space optical communication system with low-density parity-check code

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PHOTONIC NETWORK COMMUNICATIONS 2016年第1期32卷 104-114页

作者： Sharma, Manish Chadha, D. Chandra, Vinod Indian Inst Technol Dept Elect Engn New Delhi 110016 India

In this paper, we have evaluated the performance of a low-density parity-check (LDPC)-coded multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) free space optical (FSO) communication system. Closed form expressions for the average bit error rate and throughput with diversity using equal gain combining have been obtained for the system under consideration. The Monte Carlo simulation has been carried out for the verification of the results. The performance of the QPSK and 16 QAM modulations is evaluated for different weather and atmospheric turbulence conditions. The results are also compared for both, QPSK and 16 QAM for SISO-OFDM, and MIMO-OFDM FSO communication system. The results show that the performance of the system under consideration improves, as we move from SISO-OFDM to MIMO-OFDM. The results also show that the effect of weather is very much pronounced on the system and the performance in terms of average bit error rate of QPSK is better than 16 QAM in the presence of every weather condition. However, the later provides better throughput. Regular LDPC codes with code rate 1/2 have been applied to the simulated results, yielding high coding gains. Coding gain of 29.5 and 22 dB is achieved for QPSK and 16 QAM, respectively, for MIMO-OFDM.

关键词： Average bit error rate Free space optical communication Low-density parity-check codes multiple-input multiple-output Orthogonal frequency division multiplexing

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Dual-Polarized IRS-Assisted MIMO Network

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2024年第4期23卷 2519-2532页

作者： Munawar, Muteen Lee, Kyungchun Seoul Natl Univ Sci & Technol Res Ctr Elect & Informat Technol Dept Elect & Informat Engn Seoul 01811 South Korea

This study considers a dual-polarized intelligent reflecting surface (DP-IRS)-assisted multiple-input multiple-output (MIMO) single-user wireless communication system. The transmitter and receiver are equipped with DP antennas, and each antenna features a separate phase shifter for each polarization. We attempt to maximize the system's spectral efficiency (SE) by optimizing the operations of the reflecting elements at the DP-IRS, precoder/combiner at the transmitter/receiver, and vertical/horizontal phase shifters at the DP antennas. To address this problem, we propose a three-step alternating optimization (AO) algorithm based on the semi-definite relaxation method. Next, we consider asymptotically low/high signal-to-noise ratio (SNR) regimes and propose low-complexity algorithms. In particular, for the low-SNR regime, we derive computationally low-cost closed-form solutions. According to the obtained numerical results, the proposed algorithm outperforms the various benchmark schemes. Specifically, our main algorithm exhibits a 65.6% increase in the SE performance compared to random operations. In addition, we compare the SE performance of DP-IRS with that of simple IRS (S-IRS). For $N = 50$ , DP-IRS achieves 24.8%, 28.2%, and 30.3% improvements in SE for 4 x 4 , 8 x 8 , and 16 x 16 MIMO, respectively, compared to S-IRS.

关键词： Intelligent reflecting surface dual polarization multiple-input multiple-output alternating optimization

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OFDM-Based Generalized Optical MIMO

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2021年第19期39卷 6063-6075页

作者： Chen, Chen Zhong, Xin Fu, Shu Jian, Xin Liu, Min Yang, Helin Alphones, Arokiaswami Fu, H. Y. Chongqing Univ Sch Microelect & Commun Engn Chongqing 400044 Peoples R China Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore Tsinghua Univ Tsinghua Berkeley Shenzhen Inst TBSI Shenzhen 518055 Peoples R China

The combination of multiple-input multiple-output (MIMO) transmission and orthogonal frequency division multiplexing (OFDM) modulation has been shown to be an effective way to substantially enhance the capacity of bandlimited optical wireless communication (OWC) systems. In this paper, we propose four OFDM-based generalized optical MIMO (GO-MIMO) techniques for intensity-modulation and direct-detection OWC systems, including OFDM-based frequency-domain generalized spatial modulation (FD-GSM), frequency-domain generalized spatial multiplexing (FD-GSMP), time-domain generalized spatial modulation (TD-GSM) and time-domain generalized spatial multiplexing (TD-GSMP). For OFDM-based FD-GSM and FD-GSMP, spatial mapping is performed in the frequency domain, while it is carried out in the time domain for OFDM-based TD-GSM and TD-GSMP. To efficiently estimate both spatial and constellation symbols in each OFDM-based GO-MIMO technique, a corresponding maximum-likelihood (ML) detection algorithm is designed. Extensive simulations are conducted to evaluate and compare the performance of OFDM-based GO-MIMO techniques under various MIMO settings in a typical indoor environment. Simulation results demonstrate that there exists an optimal GO-MIMO technique to achieve a target spectral efficiency for a given receiver location, and the obtained optimal GO-MIMO technique is also related to the specific location of the receiver.

关键词： MIMO communication Optical transmitters Modulation Light emitting diodes GSM Optical modulation Frequency-domain analysis Optical wireless communication orthogonal frequency division multiplexing multiple-input multiple-output

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A low complexity semidefinite relaxation for large-scale MIMO detection

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JOURNAL OF COMBINATORIAL OPTIMIZATION 2018年第2期35卷 473-492页

作者： Nayak, Rupaj Kumar Biswal, Mahendra Prasad Int Inst Informat Technol Dept Math Bhubaneswar Orissa India Indian Inst Technol Dept Math Kharagpur W Bengal India

Many wireless communication problems is based on a convex relaxation of the maximum likelihood problem which further can be cast as binary quadratic programs (BQPs). The two standard relaxation methods that are widely used for solving general BQPs such as spectral methods and semidefinite programming problem (SDP), each have their own advantages and disadvantages. It is widely accepted that small and medium sized SDP problems can be solved efficiently by interior point methods. Albeit, semidefinite relaxation has a tighter bound for large scale problems, but its computational complexity is high. However, Row-by-Row method (RBR) for solving SDPs could be opted for an alternative for large-scale MIMO detection because of low complexity. The present work is a spectral SDP-cut formulation to which the RBR is applied for large-scale MIMO detection. A modified RBR algorithm with tighter bound is presented to specify the efficiency in detecting massive MIMO.

关键词： multiple-input multiple-output Maximum likelihood detection Semidefinite relaxation Spectral cut Row-by-Row method

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Ergodic interference alignment for MIMO interference system with variable channel

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The Journal of China Universities of Posts and Telecommunications 2015年第1期22卷 11-16页

作者： Ren Haiying Liu Yuan'an Liu Fang Gao Jinchun Liu Kaiming Xie Gang School of Electronic Engineering Beijing University of Posts and Telecommunications

The authors pay focus on the K user multiple-input multiple-output（MIMO） Gaussian interference channel（IC） with M transmitting antennas and N receiving antennas, in which min（M, N）/max（M, N）≧（K-1）/[K（K-2）] and K 〉3. The channel coefficients are variable, time varying or frequency selectively drawn from a continuous distribution. Based on ergodic interference alignment（IA）, an achievable scheme was proposed to achieve a total of KMN/（M ＋N） degrees of freedom（DoF）. The ergodic IA scheme can reach the optimal Do F value with simply linear beamforming and finite symbols. Furthermore, the achievable rate of the ergodic IA scheme was derived at any signal-to-noise ratio（SNR）. With numerical simulation, the performance of the proposed scheme is evaluated.

关键词： degrees of freedom ergodic interference alignment interference channel multiple-input multiple-output

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Linear Precoding for Finite-Alphabet inputs Over MIMO Fading Channels With Statistical CSI

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2012年第6期60卷 3134-3148页

作者： Zeng, Weiliang Xiao, Chengshan Wang, Mingxi Lu, Jianhua Tsinghua Univ Dept Elect Engn Tsinghua Natl Lab Informat Sci & Technol TNList Beijing 100084 Peoples R China Missouri Univ Sci & Technol Dept Elect & Comp Engn Rolla MO 65409 USA

This paper investigates the linear precoder design that maximizes the average mutual information of multiple-input multiple-output fading channels with statistical channel state information known at the transmitter. It formulates the design from the standpoint of finite-alphabet inputs, which leads to a problem that is very important in practice but extremely difficult in theory: First, the average mutual information lacks closed-form expression and involves prohibitive computational burden. Second, the optimization over the precoder is nonconcave and thus easily gets stuck in local maxima. To address these issues, this study first derives lower and upper bounds for the average mutual information, in which the computational complexity is reduced by several orders of magnitude compared to calculating the average mutual information directly. It proves that maximizing the bounds is asymptotically optimal and shows that, with a constant shift, the lower bound actually offers a very accurate approximation to the average mutual information for various fading channels. This paper further proposes utilizing the lower bound as a low-complexity and accurate alternative for developing a two-step algorithm to find a near global optimal precoder. Numerical examples demonstrate the convergence and efficacy of the proposed algorithm. Compared to its conventional counterparts, the proposed linear precoding method provides significant performance gain over existing precoding algorithms. The gain becomes more substantial when the spatial correlation of MIMO channels increases.

关键词： Finite-alphabet inputs multiple-input multiple-output precoder design statistical channel state information

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Interference Alignment in a Poisson Field of MIMO Femtocells

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2013年第6期12卷 2633-2645页

作者： Tri Minh Nguyen Jeong, Youngmin Quek, Tony Q. S. Tay, Wee Peng Shin, Hyundong Kyung Hee Univ Dept Elect & Radio Engn Yongin 446701 Gyeonggi Do South Korea Singapore Univ Technol & Design Singapore Singapore Inst Infocomm Res Singapore Singapore Nanyang Technol Univ Singapore 639798 Singapore

The need for bandwidth and the incitation to reduce power consumption lead to the reduction of cell size in wireless networks. This allows reducing the distance between a user and the base station, thus increasing the capacity. A relatively inexpensive way of deploying small-cell networks is to use femtocells. However, the reduction in cell size causes problems for coordination and network deployment, especially due to the intra-and cross-tier interference. In this paper, we consider a two-tier multiple-input multiple-output (MIMO) network in the downlink, where a single macrocell base station with multiple transmit antennas coexists with multiple closed-access MIMO femtocells. With multiple receive antennas at both the macrocell and femtocell users, we propose an opportunistic interference alignment scheme to design the transmit and receive beamformers in order to mitigate intra- (or inter-) and cross-tier interference. Moreover, to reduce the number of macrocell and femtocell users coexisting in the same spectrum, we apply a random spectrum allocation on top of the opportunistic interference alignment. Using stochastic geometry, we analyze the proposed scheme in terms of the distribution of a received signal-to-interference-plus-noise ratio, spatial average capacity, network throughput, and energy efficiency. In the presence of imperfect channel state information, we further quantify the performance loss in spatial average capacity. Numerical results show the effectiveness of our proposed scheme in improving the performance of random MIMO femtocell networks.

关键词： Beamforming femtocell network interference alignment interference channel multiple-input multiple-output random spectrum allocation stochastic geometry

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Doppler Spread Estimation in MIMO Frequency-Selective Fading Channels

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2018年第3期17卷 1951-1965页

作者： Mohammadkarimi, Mostafa Karami, Ebrahim Dobre, Octavia A. Win, Moe Z. Mem Univ Newfoundland Dept Elect & Comp Engn St John NF A1C 5S7 Canada MIT Informat & Decis Syst Lab Cambridge MA 02139 USA

One of the main challenges in high-speed mobile communications is the presence of large Doppler spreads. Thus, accurate estimation of maximum Doppler spread (MDS) plays an important role in improving the performance of the communication link. In this paper, we derive the data-aided (DA) and non-data-aided (NDA) Cramer-Rao lower bounds (CRLBs) and maximum likelihood estimators (MLEs) for the MDS in multiple-input multiple-output (MIMO) frequency-selective fading channel. Moreover, a low-complexity NDA-moment-based estimator (MBE) is proposed. The proposed NDA-MBE relies on the second-and fourth-order moments of the received signal, which are employed to estimate the normalized squared autocorrelation function of the fading channel. Then, the problem of MDS estimation is formulated as a non-linear regression problem, and the least-squares curve-fitting optimization technique is applied to determine the estimate of the MDS. This is the first time in the literature, when DA- and NDA-MDS estimation is investigated for MIMO frequency-selective fading channel. Simulation results show that there is no significant performance gap between the derived NDA-MLE and NDA-CRLB, even when the observation window is relatively small. Furthermore, the significant reduced-complexity in the NDA-MBE leads to low root-mean-square error over a wide range of MDSs, when the observation window is selected large enough.

关键词： Maximum Doppler spread data-aided non-data-aided multiple-input multiple-output frequency-selective Cramer-Rao lower bound (CRLB) fourth-order moment autocorrelation non-linear regression maximum likelihood estimator (MLE)

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