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Activity Detection for Enhanced Configured-Grant:A Practical Perspective

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China Communications 2022年第3期19卷 181-191页

作者： Chenmin Sha shidong zhou Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

We try to extend the current configuredgrant(CG)uplink scheme in 5G New Radio(NR)to support massive potential users and study activity detection under this scenario.Characteristics of the continuously varying channel and the multiple repetition scheme are utilized to improve the detection accuracy,which can be an enhancement to existing activity detection algorithms.Numerical results under 3 GPP TDL(Tapped Delay Line)fading channel show the superiority of our algorithm.And system-level simulation reveals that enhancements on activity detection can improve reliability and reduce latency.

关键词： configured-grant massive access activity detection

Eavesdropping Area for Evaluating the Security of Wireless Communications

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China Communications 2022年第3期19卷 145-157页

作者： Xiaofeng Zhong Chenchen Fan shidong zhou Tsinghua University Beijing National Research Center for Information Science and Technology Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

Compared with wired communication,the wireless communication link is more vulnerable to be attacked or eavesdropped because of its broadcast nature.To prevent eavesdropping,many researches on transmission techniques or cryptographic methods are carried out.This paper proposes a new index parameter named as eavesdropping area,to evaluate the anti-eavesdropping performance of wireless system.Given the locations of legitimate transmitter and receiver,eavesdropping area index describes the total area of eavesdropping regions where messages can be wiretapped in the whole evaluating region.This paper gives detailed explanations about its concept and deduces mathematical formulas about performance curves based on region classification.Corresponding key system parameters are analyzed,including the characteristics of eavesdropping region,transmitted beam pattern,beam direction,receiver sensitivity,eavesdropping sensitivity,path loss exponent and so on.The proposed index can give an insight on the confirmation of high-risk eavesdropping region and formulating optimal transmitting scheme for the confidential communications to decrease the eavesdropping probability.

关键词： eavesdropping area wireless communication anti-eavesdropping performance transmitting scheme

Achievable Secrecy Rate Region of Two-Way Communication with Secret Key Feedback

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Tsinghua Science and Technology 2018年第2期23卷 126-134页

作者： Tao Li shidong zhou Department of Electronic Engineering State Key Laboratory on Microwave and Digital Communications and National Laboratory for Information Science and Technology Tsinghua University Beijing100084 China. Department of Electronic Engineering and State Key Laboratory oil Microwave and Digital Communications Tsinghua University Beijing 100084 China.

This paper investigates the achievable secrecy rate region of the Gaussian two-way wiretap channel,which describes the simultaneous secure two-way transmission of a confidential message. Through adjusting the time-sharing factor and the rate at which the random secret key is fed back, the allocation and optimization for the secrecy rates of two-way communication are achieved. Under peak and average power constraints, the achievable secrecy rate regions of the two-way communication are derived respectively.

关键词： physical layer security two-way communication feed back one-time-pad random secret key secrecy rate region

Queue-aware energy-efficient scheduling and power allocation with feedback reduction in small-cell networks

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Science China(Information Sciences) 2018年第4期61卷 246-252页

作者： Hongxin WEI Yunzhou LI Limin XIAO shidong zhou State Key Laboratory on Microwave and Digital Communications Tsinghua National Laboratory Information Science and Technology Department of Electronic Engineering Tsinghua University

In small cell networks(SCNs),the path loss becomes smaller,and energy efficiency could be improved.If plenty of small base stations(BSs)are deployed,the energy consumption of each BSs can be small enough to make the t... 详细信息

关键词： CSI Queue-aware energy-efficient scheduling and power allocation with feedback reduction in small-cell networks

Sectorization based pilot reuse for improving net spectral efficiency in the multicell massive MIMO system

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Science China(Information Sciences) 2016年第2期59卷 97-111页

作者： Jiahui LI Limin XIAO Xibin XU shidong zhou State Key Laboratory on Microwave and Digital Communications Tsinghua National Laboratory for Information Science and Technology Department of Electronic Engineering Tsinghua University

A sectorization method using the uniform circular array(UCA) is proposed to improve the net spectral efficiency(SE) of the multicell massive MIMO system, which is an important index for evaluating the performance of a communication system. We derive the ergodic achievable uplink net SE per cell of a general sectorized system and obtain its deterministic approximation based on the large random matrix theory.Different weight matrices are considered for the sectorized system and the one with the best performance is utilized for further analysis. The consistency of the deterministic approximation with the result of Monte-Carlo simulation is proved at the same time. At last, numerical results indicate that the net SE per cell can be greatly improved compared to the conventional multicell massive MIMO system, which validates the effectiveness of the sectorization method. Moreover, comparisons with other pilot reuse methods are also made in this paper.

关键词： massive MIMO multicell net SE pilot reuse sectorization UCA

Fractional full duplex cellular network: a stochastic geometry approach

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Science China(Information Sciences) 2018年第2期61卷 50-64页

作者： Wenping BI Limin XIAO Xin SU shidong zhou State Key Laboratory on Microwave and Digital Communications Tsinghua National Laboratory for Information Science and Technology Department of Electronic Engineering Tsinghua University

In-band full-duplex(FD) communication has been considered as a promising technology to enhance the spectral efficiency(SE) for the next generation of wireless system. However, the severe interference in FD cellular network may largely degrade the system performance, especially for cell edge users. In this paper, multi-cell cellular network consisting of BSs with FD capability and legacy half duplex(HD) users is studied. In order to relieve the received interference and enhance the system SE, a new resource allocation strategy named fractional FD(FFD) is proposed and its main idea and procedure are described as follows.Firstly, the frequency and time resources are partitioned into FD resource blocks(RBs) and HD RBs based on the network topology. Then all the users are classified into two groups named cell center users(CCUs)and cell edge users(CEUs) based on their channel conditions. At last, in each cell, each FD RB is allocated to a pair of CCUs with one in uplink and the other in downlink transmission direction, while only one CEU in the uplink(or downlink) transmission direction is scheduled over each HD RB. Tractable results of both the coverage probabilities and the ergodic rates of FFD, FD and HD systems are derived using stochastic geometry method. Numerical results show that, FFD can significantly improve the coverage probability of all users especially for CEUs compared with FD cellular system, and higher system SE is obtained compared with FD and HD cellular network. With proper design of the classification criterion and under the simulation settings of this paper, the SE of FFD system outperforms FD and HD system by 1.25 and 1.38 times,respectively.

关键词： full duplex half duplex stochastic geometry radio resources allocation small cell

Path loss model based on cluster at 28 GHz in the indoor and outdoor environments

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Science China(Information Sciences) 2017年第8期60卷 25-35页

作者： Lai zhou Limin XIAO Zhi YANG Jiahui LI Jin LIAN shidong zhou State Key Laboratory on Microwave and Digital Communications Tsinghua University Tsinghua National Laboratory for Information Science and Technology Tsinghua University Department of Engineering Physics Tsinghua University Department of Electronic Engineering Tsinghua University

This paper presents 28 GHz path loss model based on cluster obtained from channel measurement campaigns with rotating platforms and directional antennas in the indoor and outdoor environments. The transmitter(TX) and receiver(RX) both sweep a large range of angles in the azimuth and elevation plane on account of covering main propagation paths and measuring burden. As the sequence number of cluster increases, the path loss exponents(PLEs) increase while shadow factors also have a growing tendency. The PLE of all-clusters is the least because of multi propagation paths, and the LOS PLEs of corridor scenario are less compared with that of office scenario because of corridor’s long and narrow structure. This improved model not only considers cluster characteristics, but also unites directional and omnidirectional models into the same framework, which to some extent improves the 5G mm Wave channel model.

关键词： mm Wave channel measurement office and corridor rotating platform multipath components path loss model based on cluster

Joint Subcarrier and Power Allocation for DF-Based Multiuser Two-Way Relay Networks

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China Communications 2017年第6期14卷 179-188页

作者： Xiang Chen Fei He Limin Xiao shidong zhou School of Electronics and Information Technology SYSU-CMU Shunde International Joint Research Institute Sun Yat-sen Univ.Guangzhou 510006 China Key Lab of EDA Research Institute of Tsinghua University in Shenzhen Shenzhen 518057 China China Academy of Electronics and Information Technology Beijing 100041 China EE Department Research Institute of Information Technology TNList Tsinghua University Beijing 100084 China

Two-way decode-and-forward(DF) relay technique is an efficient method to improve system performance in 5G networks.However,traditional orthogonal frequency division multiplexing(OFDM) based two-way relay systems only consider a per-subcarrier relay strategy,which treats each subcarrier as a separate channel,which results in significant sum rate loss,especially in fading environments.In this paper,a joint coding scheme over multiple subcarriers is involved for multipair users in two-way relay systems to obtain multiuser diversity.A generalized subcarrier pairing strategy is proposed to permit each user-pair to occupy different subcarriers during the two transmission phases,i.e.,the multiple access and broadcast phases.Moreover,a low complexity joint resource allocation scheme is proposed to improve the spectrum efficiency with an additional multi-user diversity gain.Some numerical simulations are finally provided to verify the efficacy of our proposal.

关键词：多用户分集中继技术网络系统子载波功率分配正交频分复用中继系统高频谱效率

Energy-Efficient Resource Allocation for Small-Cell Networks：A Stable Queue Perspective

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China Communications 2017年第10期14卷 142-150页

作者： Hongxin Wei Wei Feng Yunzhou Li shidong zhou State Key Laboratory on Microwave and Digital CommunicationsTsinghua National Laboratory Information Science and Technology Department of Electronic Engineering Tsinghua University Beijing 100084 China

The small-cell technology is promising for spectral-efficiency enhancement. However, it usually requires a huge amount of energy consumption. In this paper, queue state information and channel state information are jointly utilized to minimize the time average of overall energy consumption for a multi-carrier small-cell network, where the inter-cell interference is an intractable problem. Based on the Lyapunov optimization theory, the problem could be solved by dynamically optimizing the problem of user assignment, carrier allocation and power allocation in each time slot. As the optimization problem is NP-hard, we propose a heuristic iteration algorithm to solve it. Numerical results verify that the heuristic algorithm offers an approximate performance as the brute-force algorithm. Moreover, it could bring down the overall energy consumption to different degrees according to the variation of traffic load. Meanwhile, it could achieve the same sum rate as the algorithm which focuses on maximizing system sum rate.

关键词：细胞技术用户分配能量有效队列网络信道状态信息启发式算法稳定