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Impact of non-ideal UE hardware on cell-free massive MIMO network with centralized operation

Science China(Information Sciences) 2024年第4期67卷 255-271页

作者： Ning LI pingzhi fan Institute of Mobile Communications Southwest Jiaotong University

This paper investigates the impact of non-ideal user equipment(UE) hardware on a cell-free(CF) massive MIMO(mMIMO) network with centralized operation under spatially correlated channels. The minimum mean-squared error(MMSE) estimator can be derived with the help of the generic non-ideal UE hardware model. It is demonstrated that even if the effective signal-to-noise ratio approaches infinity, pilot contamination and imperfect hardware can cause a non-zero estimation error floor. After that, a lower bound is determined for the ergodic uplink capacity of the centralized CF mMIMO network under non-ideal UE hardware. Moreover, the optimal receive combining vector is obtained to maximize the uplink spectral efficiency(SE). The maximum ratio(MR) and regularized zero-forcing(RZF) combining schemes are offered as alternatives in light of the computational complexity of the MMSE receiver. Comparing the RZF to the MMSE scheme under different levels of hardware impairments, our findings indicate that the RZF receiver suffers a negligible loss in total SE. For MR combining, a novel closed-form uplink achievable SE expression is obtained based on the MMSE estimator and the use-and-then-forget bounding technique. This expression gives vital insights into the achievable uplink performance with UE hardware impairments. Besides, for various hardware impairment factors, the impact of pilot sequence length on average sum SE is disclosed for different receive combining schemes. To increase the overall SE of the max-min fairness scheme, a heuristic fractional power control scheme with UE hardware impairments is developed, which can essentially avoid sacrificing the SE of other UEs while maximizing the SE of the unluckiest UE in the whole network. Finally,our theoretical performance analysis and power control algorithm are validated by simulation results, and fundamental design guidelines are provided for selecting hardware satisfying the practical UE requirements.

关键词： cell-free massive MIMO centralized operation spatially correlated channels hardware impairments channel estimation uplink spectral efficiency optimal receive combining pilot length design fractional power control

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Distributed Cell-Free Massive MIMO Versus Cellular Massive MIMO Under UE Hardware Impairments

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Chinese Journal of Electronics 2024年第5期33卷 1274-1285页

作者： Ning LI pingzhi fan School of Information Science and Technology Southwest Jiaotong University

This paper first investigates and compares the uplink spectral efficiency(SE) of distributed cell-free massive multiple-input multiple-output(mMIMO) and cellular mMIMO networks, both with user equipment(UE)hardware impairments. We derive a lower bound on the uplink ergodic channel capacity of the cellular mMIMO with UE hardware impairments, based on which we determine the optimal receive combining that maximizes the instantaneous effective signal-to-interference-and-noise ratio. Then, a lower bound on the uplink capacity of a distributed cellfree mMIMO with UE hardware impairments is derived using the use-and-then-forget technique. On this basis, the optimum large-scale fading decoding vector is found using generalized Rayleigh entropy. By using three combining schemes of minimum mean-square error(MMSE), regularized zero-forcing(RZF), and maximum ratio, the uplink SEs of distributed cell-free mMIMO and cellular mMIMO networks are analyzed and compared. The results show that the two-layer decoding distributed cell-free mMIMO network with MMSE combining outperforms the cellular mMIMO network, and the advantage is more evident as the hardware impairment factor increases. Finally, the uplink energy efficiency(EE) of the distributed cell-free mMIMO networks is analyzed and evaluated through the established realistic power consumption model with hardware impairments. Simulation results show that two-layer decoding provides higher SE and EE than single-layer decoding. In addition, RZF achieves almost the same SE and EE as MMSE in a two-layer decoding architecture.

关键词： Massive multiple-input multiple-output (mMIMO) Cell-free mMIMO Cellular mMIMO Hardware impairments Uplink Energy efficiency Optimal receive combining Massive multiple-input multiple-output (mMIMO) Cell-free mMIMO Spectral efficiency Spectral efficiency Hardware impairments Uplink Energy efficiency Optimal receive combining ENERGY EFFICIENCY SYSTEMS NETWORKS DESIGN UPLINK PERFORMANCE

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Next generation multiple access for IMT towards 2030 and beyond

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Science China(Information Sciences) 2024年第6期67卷 448-450页

作者： Zhiguo DING Robert SCHOBER pingzhi fan H.Vincent POOR Department of Computer and Information Engineering Khalifa University Department of Electrical and Electronic Engineering University of Manchester Institute for Digital Communications Friedrich Alexander-University Erlangen-Nurnberg (FAU) CSNMT International Cooperation Research Center (MoST) Southwest Jiaotong University Department of Electrical and Computer Engineering Princeton University

Multiple access techniques are fundamental to the design of wireless communication systems,since many crucial components of such systems depend on the choice of the multiple access technique[1].For example,the use of ...

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Doppler-resilient waveform design in integrated MIMO radar-communication systems

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Science China(Information Sciences) 2024年第1期67卷 187-202页

作者： Zhengchun ZHOU Bing LIU Bingsheng SHEN Avik Ranjan ADHIKARY pingzhi fan Institute of Mobile Communications Southwest Jiaotong University Department of Mathematics Southwest Jiaotong University

In recent years,the increased high-rate wireless services(5G and 6G) and reliable sensing capabilities(automotive radar,air traffic control,geophysical monitoring),have led to more serious spectrum ***,radars and communication systems are often seen to be “competing” for the same *** this scenario,an integrated platform for radar and communication systems seems to be an optimal solution to address the *** this paper,we propose a preamble waveform design based on zero-correlation zone(ZCZ) and zero odd-correlation zone(ZOCZ) sequence sets,which are Doppler resilient in multiple-input,multiple-output(MIMO) *** preamble waveforms can be simultaneously used for channel estimation and radar sensing in RadCom *** ambiguity function of the proposed waveforms displays low/zero sidelobes within a time-delay correlation ***,we give some numerical results to show the efficiency of the proposed waveforms in radar sensing and channel estimation.

关键词： ambiguity function correlation channel estimation integrated radar and communication (Rad-Com) systems MIMO radar zero correlation zone (ZCZ) sequence set zero odd-correlation zone (ZOCZ) sequence set

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A New Approach for Performance Evaluation of TCP over Interference-Limited Wireless Channels over Interference Wireless Channels

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Journal of Electronic Science and Technology of China 2003年第1期1卷 18-21页

作者： luo rui fan pingzhi(School of Computer and Communications Enginerring,Southwest Jiaotong University Chengdu 610031 China) School of Computer and Communications Enginerring Southwest Jiaotong University Chengdu 610031 China

A new metric for performance evaluation of transport control protocol(TCP) overwireless channels based on the interference-limited characteristics of code division multipleaddress(CDMA) system is *** to the new metric,the performance of TCP over CDMAcorrelated channel for different protocol parameters and different versions is *** resultsshow that appropriate selection of protocol parameters and packet error rate(PER) operation point canimprove significantly the capacity of packet-switched CDMA-based network.

关键词： effective factor capacity code division multiple address(CDMA) transport control protocol(TCP)

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Ultra Reliable Load-Aware Connection Management(LACM)Algorithm in WIA-FA Systems

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China Communications 2024年第8期21卷 142-161页

作者： Liu Gang Jiang Chunhao Ren Xiaochun fan pingzhi Liang Chengchao Ma Zheng Southwest Jiaotong University Chengdu 611756China State Key Laboratory of Rail Transit Engineering Informatization(FSDI) Xi’an 710043China Chongqing University of Posts and Telecommunications Chongqing 400065China

The increasing demand for industrial automation and intelligence has put forward higher requirements for the reliability of industrial wireless communication *** an international standard based on 802.11,Wireless networks for Industrial Automation-Factory Automation(WIA-FA)greatly improves the reliability in factory automation scenarios by Time Division Multiple Access(TDMA).However,in ultra-dense WIA-FA networks with mobile users,the basic connection management mechanism is *** of the handover and resource management algorithms are all based on frequency division multiplexing,not suitable for the TDMA in the WIA-FA ***,we propose Load-aware Connection Management(LACM)algorithm to adjust the linkage and balance the load of access devices to avoid blocking and improve the reliability of the *** then we simulate the algorithm to find the optimal settings of the *** comparing with other existing algorithms,the result of the simulation proves that LACM is more efficient in reliability and maintains high reliability of more than 99.8%even in the ultra-dense moving scenario with 1500 field ***,this algorithm ensures that only a few signaling exchanges are required to ensure load bal-ancing,which is no more than 5 times,and less than half of the best state-of-the-art algorithm.

关键词： connection management load-aware multi-connectivity reliability retransmission WIAFA

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Multi-UAV cooperative maneuver decision-making for pursuitevasion using improved MADRL

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Defence Technology（防务技术） 2024年第5期35卷 187-197页

作者： Delin luo Zihao fan Ziyi Yang Yang Xu School of Aerospace Engineering Xiamen UniversityXiamen 361102China School of Civil Aviation Northwestern Polytechnical UniversityXi'an 710072China

Aiming at the problem of multi-UAV pursuit-evasion confrontation, a UAV cooperative maneuver method based on an improved multi-agent deep reinforcement learning(MADRL) is proposed. In this method, an improved Comm Net network based on a communication mechanism is introduced into a deep reinforcement learning algorithm to solve the multi-agent problem. A layer of gated recurrent unit(GRU) is added to the actor-network structure to remember historical environmental states. Subsequently,another GRU is designed as a communication channel in the Comm Net core network layer to refine communication information between UAVs. Finally, the simulation results of the algorithm in two sets of scenarios are given, and the results show that the method has good effectiveness and applicability.

关键词： Reinforcement learning UAV Maneuver decision GRU Cooperative control

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AWells-Riley/based COVID-19 infectiousrisk assessment model combining both short rangeandroom scale effects

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Building Simulation 2024年第1期17卷 93-111页

作者： Yinshuai Feng Yifan fan Xiaoyu luo Jian Ge College of Civil Engineering and Architecture Zhejiang UniversityHangzhouChina Center for Balance Architecture Zhejiang UniversityHangzhouChina International Research Center for Green Building and Low-Carbon City International CampusZhejiang UniversityHainingChina

There is growing evidence of the high transmission potential of COVID-19 through virus-laden *** aerosols are inhaled in various concentrations,an overall assessment of transmission risks at different indoor scales is ***,a comprehensive risk assessment method that evaluates the direct link between short-range and room-scale zones is stl *** this paper,a risk assessment model combining both short-range and room-scale effects is developed to obtain effective reproduction number in confined indoor environments,called Turbulent Jet Wells Riley(TJWR)*** with the viral load data and aerosol generation data of different human respiratory activities,the Monte Carlo simulation method is applied to calculate the quanta emission rate,which further provides the input parameters of the TJWR *** known outbreaks(Hangzhou banquet hall X,Guangzhou restaurant Y,and Hong Kong restaurant Z,China)are chosen to validate the TJWR *** show that the TJWR model is more efficient than the original Wells-Riley *** average relative error of the TJWR model ranges between 9%and 44%,while for the Wells-Riley model,it ranges between 57%and 78%.The TJWR model also proves that infection risk assessments using the well-mixed assumption can systematically underestimate the transmission risk for those close to the ***,there is a significant positive linear correlation between the total number of exposed individuals at the short-range and the effective reproduction *** newly developed TJWR model has great potential for rapid and real-time overall airborne transmission risk assessment in buildings and cities.

关键词： COVID-19 airborne transmission infection risk Wells-Riley model Monte Carlo simulation

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Comparison of the hygrothermal performance of two light-framed timber structure buildings under different operation modes

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第1期25卷 18-35页

作者： Wanqing XU Yucong XUE Jiang LU Yifan fan Xiaoyu luo College of Civil Engineering and Architecture Zhejiang UniversityHangzhou310058China International Research Center for Green Building and Low-Carbon City International CampusZhejiang UniversityJiaxing314400China School of Civil Engineering and Architecture Zhejiang University of Science and TechnologyHangzhou310023China

Light-framed timber structure(LTS)buildings have been highly valued in recent years due to their low-carbon ***,the applicability of the building envelope is closely related to indoor and outdoor *** hot summer and cold winter(HSCW)climate zone in China has high humidity and great temperature variation throughout the year,resulting in distinct outdoor environments in different *** indoor environment is greatly affected by energy-consumption patterns and window-opening habits,which largely depend upon the regulation operations of *** these interrelated factors lead to extremely complex boundary conditions on each side of the building *** the structures of LTS buildings are applicable in this climate zone,therefore,needs to be carefully *** this study,two LTS buildings with different envelopes were established in Haining,China,situated in the HSCW climate zone,and selected as the study *** operation modes were adopted to create a variety of indoor *** each condition,the processes of heat and moisture transfer within the building envelopes and the indoor environment were monitored and *** comparison indicated that the building envelope with high moisture storage and insulation ability maintained a relatively stable indoor environment,especially when the environment changed ***,if the outdoor environment was equable(e.g.,relative humidity within the range of 30%–60%)or intermittent energy consumption modes were adopted,the building envelope with a low thermal inertia index and weak moisture-buffering ability performed better because it enabled a faster response of the indoor environment to air ***,a high risk of moisture accumulation between the thermal insulation layer and other materials with a large water vapour transfer resistance factor was also identified,suggesting a higher requirement for the vapour insulation of the env

关键词： Light-framed timber structure(LTS)buildings In-situ experiment Typical operation mode Indoor environment Heatand moisture transfer

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Injection of a Self-propelled Polymer into a Small Circular Cavity

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Chinese Journal of Polymer Science 2024年第6期42卷 886-894页

作者： Chao Wang Yan-Li Zhou Xiao Yang fan Wu Meng-Bo luo Department of Physics Taizhou UniversityTaizhou318000China Department of Physics Zhejiang UniversityHangzhou310027China

The injection of a polymer chain into a small circular cavity under tangential self-propelled force is studied by using Langevin dynamics *** indicate that the injection dynamics of the active polymer shows strong correlation with the polymer conformation inside the cavity depending on the polymer rigidity(k_(b)).The injection timeτvaries nonmonotonously with increasing k_(b),and reaches its minimum at k_(b)^(*).When k_(b) is small(k_(b)≪k_(b)^(*)),the polymer is nearly random coil in the cavity,and spends a long time at the final stage of the injection process due to the large repulsion between monomers inside the *** k_(b) is moderate(k_(b)∼k_(b)^(*)),the part of polymer inside the cavity forms spiral configuration under the tangential active force,and the whole polymer moves synchronously with a constant velocity during the injection process,leading to a small injection *** k_(b) is large(k_(b)≫k_(b)^(*)),the polymer is nearly straight at the initial stage of the injection process,and takes a long time to bend itself,leading to a large injection time.

关键词： Active Polymer Injection Dynamics Simulation

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