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precoding with interference suppression sequence scheme for OFDM-based cognitive radio systems

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The Journal of China Universities of Posts and Telecommunications 2011年第4期18卷 59-64页

作者： ZHAO Cheng-lin ZHANG Kun SUN Xue-bin JIANG Ting Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

Orthogonal frequency division multiplexing （OFDM） is considered to be one of the promising schemes for cognitive radios （CR） systems, due to its flexibility in spectrum shaping. However, the traditional way of spectrum-notching failed to suppress out-of-band leakage enough, resulting in interference with licensed users （LUs）. A novel spectrum shaping scheme is proposed in this article, where a precoder with interference suppression sequence （ISS） is for the first time introduced for shaping the spectrum of OFDM signals in OFDM-based CR systems. The precoder matrix together with ISS matrix is obtained by minimizing the power of out-of-band interference, which results in the sufficient interference suppression of OFDM signal to LUs Analysis and simulation results show that the proposed scheme can significantly suppress the interference power to LUs at a little cost of precoding efficiency. Meanwhile, the peak-to-average-power-ratio （PAPR） is invariable and the bit-error-rate （BER） performance over Rayleigh fading channel is improved.

关键词： OFDM cognitive radio precoding spectrum shaping

precoding for Multiuser Spatial Multiplexing MIMO Downlink

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Tsinghua Science and Technology 2006年第5期11卷 597-605页

作者：张碧军朱光喜刘应状 Department of Electronics and Information Engineering Huazhong University of Science and Technology

Previous precoding algorithms have concentrated on the single user scenario where the precoding scheme assumes perfect channel state information （CSI） at the transmitter or on limited feedback techniques, such as channel quantization or limited feedback signal designs. This paper proposes a novel unitary downlink precoding design scheme for multiuser spatial multiplexing multiple-input multiple-output （MIMO） systems. With the perfect CSI available at the transmitter and the linear decoder at the receiver, the cost function was constructed based on the minimum average probability of vector symbol error and the design method of the precoding matrices was given. These proposed precoding matrices can completely eliminate co-channel interference for each user at the transmitter, and each user will eventually observe an interference-free single user channel, thus simplify the decoding of each user. The impact of channel feedback errors on the system performance and the upper bounds of several schemes for performance comparison were investigated. The simulation results show that the proposed precoding for multiuser spatial multiplexing system obtains almost the same performance as the single user precoding system.

关键词： multiuser multiple-input multiple-output( MIMO) precoding spatial multiplexing

On the use of H-inf criterion in channel estimation and precoding in massive MIMO systems

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Science China(Information Sciences) 2017年第2期60卷 151-164页

作者： Peng XU Dongming WANG Feng QI School of Computer Science and Engineering Northeastern University National Mobile Communications Research Laboratory Southeast University Key Laboratory of Opto-Electronic Information Processing Institute of AutomationChinese Academy of Science

In this paper, a channel estimation(CE) and precoding scheme by using H-infinity(H-inf) criterion for mitigation of pilot contamination(PC) in massive multiple input multiple output(MIMO) orthogonal frequency division multiplexing(OFDM) systems is investigated. Firstly, different thresholds in H-inf CE and precoding are considered. Secondly, asymptotic analysis is presented to simplify the H-inf precoding, which shows that the complexity of an order of magnitude is reduced. Thirdly, approximate downlink achievable data rates per user are studied for different CE and precoding schemes, such as H-inf and minimum mean square error(MMSE) CE, MMSE, zero-forcing(ZF) and H-inf precoding. The analysis shows that the proposed scheme can provide dual mitigation to the PC. That is, the H-inf CE mitigates the PC by adjusting its thresholds, and the H-inf precoding is utilized to suppress the PC by considering inter-cell interference. The numerical results show that joint use of H-inf CE and H-inf precoding outperforms existing schemes in terms of mitigation to the PC.

关键词： massive MIMO pilot contamination precoding channel estimation H-inf

Massive MIMO system lower bound spectral efficiency analysis with precoding and perfect CSI

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Digital Communications and Networks 2021年第3期7卷 342-351页

作者： Tasher Ali Sheikh Joyatri Bora Md Anwar Hussain Department of Electronics and Communication Engineering North Eastern Regional Institute of Science and TechnologyNirjuliArunachal Pradesh791109India

The analytical lower bound of Spectral Efficiency(SE)of downlink transmission of the Massive Multiple Input Multiple Output(Ma-MIMO)system is *** this paper,we derive some novel and approximate mathematical expressions for the lower bound of the SE of a Ma-MIMO with linear precoding schemes,i.e.,Minimum Mean Square Error(MMSE)and Zero-Forcing(ZF).For simulation analysis of the SE,we consider three joint users and antenna scheduling algorithms,namely,the semi-orthogonal,random,and distance-based user scheduling algorithms,whereas the antennas are selected based on Maximum Signal to Noise Ratio(MSNR)with scheduled *** channel between the user and the transmitter is assumed to have characteristics of Small Scale Fading(SSF)and Large Scale Fading(LSF)with the Rayleigh fading *** investigate the effect of the variation of transmitting SNR,the number of base station antennas(M),and the radius(R)of the cell area on the *** simulate the downlink transmission of Ma-MIMO and compare the simulation and analytical *** is observed that the trends of variation of both results are similar to the variation of identical factors,and the difference between the simulated and analytical lower bounds of the SE is approximately 1-1.5 *** analytical lower bound is smaller than the simulation result.

关键词： Fifth-generation Spectral efficiency Ma-MIMO LSF coefficient precoding

Prospects and Challenges of THz precoding

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Chinese Journal of Electronics 2022年第3期31卷 488-498页

作者： GUO Rongbin TANG Yajie ZHANG Changming LIU Shanyun ZHAO Zhifeng Zhejiang Laboratory

Terahertz(THz) communications are considered as very promising for the sixth-generation(6 G) ultra-dense wireless networks. However, THz signals suffer from well-known severe path loss, which consequently shortens the coverage of THz communication systems. To deal with this issue, precoding technique is expected to be beneficial to extend the limited coverage by providing directional beams with ultra large number of antenna arrays. In this paper, we overview the state-ofthe-art developments of THz precoding techniques such as reconfigurable intelligent surface based precoding, hybrid digital-analog precoding and delay-phase precoding. Based on the survey, we summarize several open issues remaining to be addressed, and discuss the prospects of a few potential research directions on THz precoding, such as one-bit precoding, precoding for hardware impairments and THz security precoding. This overview will be helpful for researchers to study innovative solutions of THz precoding in the future 6 G wireless communications.

关键词： sixth-generation ultra-dense wireless networks terahertz communications THz communication systems one-bit precoding reconfigurable intelligent surface based precoding future 6G wireless communications hybrid digital-analog precoding severe path loss delay-phase precoding THz precoding techniques 6G mobile communication directive antennas security precoding antenna arrays precoding

A precoding Scheme to Reduce the Effect of Channel Correlation for MIMO-PLC System

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China Communications 2023年第2期20卷 216-225页

作者： Wangbin Cao Hui Kang Xiaolin Liang Zhiyuan Xie Xiongwen Zhao School of Electrical and Electronic Engineering North China Electric Power UniversityBaoding 071000/Beijing 102206China School of Electronic and Information Engineering Hebei UniversityBaoding 071002China Hebei Key Laboratory of Power Internet of Things Technology(North China Electric Power University) Baoding 071003China

MIMO technique can provide higher information throughput and transmission reliability for the PLC ***,the MIMO-PLC system based on three-conductor cable has a high correlation among its *** multiplexing technology will be affected by the spatial correlation between MIMO-PLC *** reduce the system bit error rate caused by MIMO-PLC correlation among sub-channels,this paper proposed a phase rotation precoding scheme for the 2×2 closed-loop MIMO-PLC *** to the channel transfer function of high correlation MIMO-PLC system,the phase rotation precoding matrix F is calculated,and the transmission signal matrix S is modulated with the F,the code distance at the receiving point with smallest code distance is increased by phase *** results show that the scheme can effectively reduce the bit error rate of the 2×2 MIMO-PLC system based on ML detection,and significantly improve the system performance.

关键词： carrier transmission on power lines telecommunication cables error correction precoding

Quantized Hybrid precoding Design for Millimeter-Wave Large-Scale MIMO Systems

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China Communications 2019年第4期16卷 130-138页

作者： Zelin Lu Yunliang Zhang Jiayi Zhang International School Beijing University of Posts and Telecommunications School of Electronic and Information Engineering Beijing Jiaotong University National Mobile Communications Research Laboratory Southeast University

Millimeter wave(mmWave) and large-scale multiple input multiple output(MIMO) are two emerging technologies in fifth-generation wireless communication systems. The power consumption and hardware cost of radio frequency(RF) chains increase exponentially with the bit resolution of analog-to-digital converters(ADCs) and digital-to-analog converters(DACs). One promising solution is to employ few RF chains with low-bit ADCs and DACs. In this paper, we consider mmWave large-scale MIMO systems with low bits DACs and ADCs. Leveraging on the Bussgang theorem and the additive quantization noise model(AQNM), a closed-form expression of the achievable rate is derived to show the effect of the ADCs? and DACs? resolution. Moreover, an orthogonal matching pursuit(OMP) based hybrid precoding algorithm is proposed to increase the achievable rate. Our results show that the impact of DACs is more pronounced than the impact of ADCs. Furthermore, 5-bit ADCs and DACs are sufficient at the transceiver to operate without a significant performance loss.

关键词： millimeter wave large-scale MIMO hybrid precoding quantization

Asymptotic Analysis and precoding Design of Integrated Access and Backhaul in Full-Duplex mmWave Networks

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China Communications 2022年第5期19卷 24-45页

作者： Yi Zhang Shuai Han Weixiao Meng Xunan Li Yue Chen Communications Research Center Harbin Institute of TechnologyHarbin 150001China National Computer Network Emergency Response Technical Team/Coordination Center of China Beijing 100000China

In this paper,we consider a full-duplex(FD)millimeter wave(mmWave)multiuser integrated access and backhaul(IAB)system with massive MIMO,and the system asymptotic performance and interference cancellation schemes are ***,the asymptotic performance of the IAB system with massive MIMO is *** the number of macro base station(MBS)and small base station(SBS)antennas approaches infinity,the FD selfinterference(SI),inter-tier interference and noise can be eliminated,which means that only multiuser interference remains in the ***,multiuser interference can be suppressed by the base band(BB)*** all interference and noise are suppressed,the spectral efficiency of the SBS and users are infinite in ***,two interference suppression precoding schemes are proposed.A block diagonalization(BD)-based interference cancellation scheme is designed based on the channel characteristics and null space *** FD SI,intertier interference and multiuser interference are eliminated by BB *** of eliminating interference completely,a signal to leakage and noise ratio(SLNR)-based precoding scheme is derived to suppress both interference and *** utilizing the Rayleigh-Ritz theorem,the SLNRs of the SBS and users are *** results show that all the interference can be effectively eliminated by the BD-based scheme at the cost of spectral efficiency performance loss,while the SLNR-based scheme can balance interference and noise and achieve higher spectral efficiency with comparatively low interference ***,the BD-based scheme is more suitable for interference elimination cases,and the SLNRbased scheme can improve the system performance in low interference scenarios.

关键词： millimeter wave full duplex integrated access and backhaul precoding

Hybrid precoding for mm Wave Massive MIMO Systems with Different Antenna Arrays

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China Communications 2019年第10期16卷 45-55页

作者： Qingfeng Ding Yuqian Deng Xinpeng Gao Mengxia Liu School of Electrical and Automation Engineering East China Jiaotong University

In this paper, the performance of hybrid precoding is investigated for mmWave massive MIMO systems with different antenna arrays. The hybrid precoding with partially connected architecture (PCA) is adopted. The spectral efficiency (SE) and received energy efficiency (EE) are investigated by considering four types of antenna arrays, including uniform linear array (ULA), uniform rectangular planar array (URPA), uniform hexagonal planar array (UHPA), and uniform circular planar array (UCPA), respectively. We focus on analysis at the antenna response vector and utilize the idea of orthogonal matching pursuit algorithm to seek the optimal hybrid precoder. Furthermore, the trade-off of precoding architectures is studied between SE and received EE. Simulation results show that if the uniform planar array antenna is more concentrated, the SE and receive EE will be higher. Considering SE and received EE, the performance of planar arrays outperform linear array. There exist different optimal radio-frequency chain numbers to maximize the SE for planar array and linear array. In addition, the PCA can achieve relatively higher received EE while the SE is close to the fully connected architecture and the full digital architecture.

关键词： massive MIMO mmWave hybrid precoding array antenna spectral efficiency