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Improved Hybrid Beamforming for mmWave Multi-User Massive MIMO

Computers, Materials & Continua 2021年第6期67卷 3057-3070页

作者： Ji-Sung Jung Won-Seok Lee Yeong-Rong Lee Jaeho Kim Hyoung-Kyu Song Department of Information and Communication Engineering and Convergence Engineering for Intelligent Drone Sejong UniversitySeoul05006Korea Department of Electrical Engineering Sejong UniversitySeoul05006Korea

Massive multiple input multiple output(MIMO)has become essential for the increase of capacity as the millimeter-wave(mmWave)communication is ***,hybrid beamforming systems have been studied since full-digital beamforming is impractical due to high cost and power consumption of the radio frequency(RF)*** paper proposes a hybrid beamforming scheme to improve the spectral efciency for multi-user MIMO(MU-MIMO)*** a frequency selective fading environment,hybrid beamforming schemes suffer from performance degradation since the analog precoder performs the same precoding for all *** mitigate performance degradation,this paper uses the average channel covariance matrix for all subcarriers and considers an iterative algorithm to design analog precoder using approximation *** analog precoder is iteratively updated for each column until it *** proposed scheme can reduce errors in the approximating process of the overall spectral *** scheme can be applied to fully-connected and partially-connected *** simulation results show that spectral efciency performance for the proposed scheme is better than the conventional *** proposed scheme can achieve similar performance with full-digital beamforming by using a sufciently large number of RF ***,this paper shows that the proposed scheme outperforms other schemes in the frequency selective fading *** performance improvement can be achieved in both structures.

关键词： Hybrid precoding massive MIMO MU-MIMO mmwave frequency selective fading

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Secure Wireless Multicasting through Nakagami-m fading Channels with Multi-Hop Relaying

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Journal of Computer and Communications 2023年第5期11卷 177-193页

作者： Md. Mizanur Rahman Md. Zahurul Islam Sarkar Mohammad Mahmud Hasan Department of Electrical and Electronic Engineering RUET Rajshahi Bangladesh

The additional diversity gain provided by the relays improves the secrecy capacity of communications system significantly. The multiple hops in the relaying system is an important technique to improve this diversity gain. The development of an analytical mathematical model of ensuring security in multicasting through fading channels incorporating this benefit of multi-hop relaying is still an open problem. Motivated by this issue, this paper considers a secure wireless multicasting scenario employing multi-hop relaying technique over frequency selective Nakagami-m fading channel and develops an analytical mathematical model to ensure the security against multiple eavesdroppers. This mathematical model has been developed based on the closed-form analytical expressions of the probability of non-zero secrecy multicast capacity (PNSMC) and the secure outage probability for multicasting (SOPM) to ensure the security in the presence of multiple eavesdroppers. Moreover, the effects of the fading parameter of multicast channel, the number of hops and eavesdropper are investigated. The results show that the security in multicasting through Nakagami-m fading channel with multi-hop relaying system is more sensitive to the number of hops and eavesdroppers. The fading of multicast channel helps to improve the secrecy multicast capacity and is not the enemy of security in multicasting.

关键词： frequency selective fading Multi-Hop Relaying Probability of Non-Zero Secrecy Multicast Capacity Secure Outage Probability for Multicasting

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On the Probability of Erasure for MIMO-OFDM

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Semiconductor Science and Information Devices 2020年第1期2卷 1-5页

作者： Kasturi Vasudevan A.Phani Kumar Reddy Gyanesh Kumar Pathak Shivani Singh Indian Institute of Technology Kanpur India

Detecting the presence of a valid signal is an important task of a telecommunication *** the receiver is unable to detect the presence of a valid signal,due to noise and fading,it is referred to as an *** work deals with the probability of erasure computation for orthogonal frequency division multiplexed(OFDM)signals used by multiple input multiple output(MIMO)*** theoretical results are validated by computer *** is widely used in present day wireless communication systems due to its ability to mitigate intersymbol interference(ISI)caused by frequency selective fading *** systems offer the advantage of spatial multiplexing,resulting in increased bit-rate,which is the main requirement of the recent wireless standards like 5G and beyond.

关键词： frequency selective fading ISI Millimeter-wave MIMO OFDM Preamble Probability of erasure

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FAST CONVERGENT MONTE CARLO RECEIVER FOR OFDM SYSTEMS

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Journal of Electronics(China) 2005年第3期22卷 209-219页

作者： WuLili LiaoGuisheng BaoZheng ShangYong KeyLabforRadarSignalProcessing XidianUniversityXi＇an710071China DepartmentofElectronics PekingUniversityBeijing100871China KeyLabforRadarSignalProcessing XidianUniversityXi＇an710071China

The paper investigates the problem of the design of an optimal Orthogonal Fre- quency Division Multiplexing (OFDM) receiver against unknown frequency selective fading. A fast convergent Monte Carlo receiver is proposed. In the proposed method, the Markov Chain Monte Carlo (MCMC) methods are employed for the blind Bayesian detection without channel es- timation. Meanwhile, with the exploitation of the characteristics of OFDM systems, two methods are employed to improve the convergence rate and enhance the efficiency of MCMC algorithms. One is the integration of the posterior distribution function with respect to the associated channel parameters, which is involved in the derivation of the objective distribution function; the other is the intra-symbol differential coding for the elimination of the bimodality problem resulting from the presence of unknown fading channels. Moreover, no matrix inversion is needed with the use of the orthogonality property of OFDM modulation and hence the computational load is significantly reduced. Computer simulation results show the effectiveness of the fast convergent Monte Carlo receiver.

关键词： frequency selective fading Orthogonal frequency Division Multiplexing (OFDM) Markov Chain Monte Carlo (MCMC) methods Blind Bayesian detection Bimodality

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