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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

A Joint Activity and Data Detection Scheme for Asynchronous Grant-Free Rateless Multiple Access

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China Communications 2024年第1期21卷 34-52页

作者： Wei Zhang Xiaofeng Zhong Shidong zhou Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

This paper considers the frameasynchronous grant-free rateless multiple access(FAGF-RMA)scenario,where users can initiate access at any symbol time,using shared channel resources to transmit data to the base station.Rateless coding is introduced to enhance the reliability of the system.Previous literature has shown that FA-GFRMA can achieve lower access delay than framesynchronous grant-free rateless multiple access(FSGF-RMA),with extreme reliability enabled by rateless coding.To support FA-GF-RMA in more practical scenarios,a joint activity and data detection(JADD)scheme is proposed.Exploiting the feature of sporadic traffic,approximate message passing(AMP)is exploited for transmission signal matrix estimation.Then,to determine the packet start points,a maximum posterior probability(MAP)estimation problem is solved based on the recovered transmitted signals,leveraging the intrinsic power pattern in the codeword.An iterative power-pattern-aided AMP algorithm is devised to enhance the estimation performance of AMP.Simulation results verify that the proposed solution achieves a delay performance that is comparable to the performance limit of FA-GF-RMA.

关键词： asynchronous grant-free JADD rateless codes

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

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

Pilot Domain NOMA for Grant-Free Massive Random Access in Massive MIMO Marine Communication System

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China Communications 2020年第6期17卷 131-144页

作者： Yongxin Liu Ming Zhao Limin Xiao Shidong zhou Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Tsinghua National Laboratory for Information Science and Technology Tsinghua UniversityBeijing 100084China

We propose a pilot domain non-orthogonal multiple access(NOMA)for uplink massive devices grant-free random access scenarios in massive multiple-input multiple-output(MIMO)maritime communication systems.These scenarios are characterized by numerous devices with sporadic access behavior,and therefore only a subset of them are active.Due to massive potential devices in the network,it is infeasible to assign a unique orthogonal pilot to each device in advance.In such scenarios,pilot decontamination is a crucial problem.In this paper,the devices are randomly assigned non-orthogonal pilots which are constructed by a linear combination of some orthogonal pilots.We show that a bipartite graph can conveniently describe the interference cancellation(IC)processes of pilot decontamination.High spectrum efficiency(SE)and low outage probability can be obtained by selecting the numbers of orthogonal pilots according to the given probability distribution.Numerical evaluatioDs show that the proposed pilot domain NOMA decreases the outage probability from 20%to 2 e-12 at the SE of 4 bits/s/Hz for a single device,compared to the conventional method of slotted ALOHA with 1024 antennas at the BS,or increases the spectrum efficiency from 1.2 bits/s/Hz to 4 bit/s/Hz at the outage probability of2 e-12 in contrast with the Welch bound equality(WBE)non-orthogonal pilots.

关键词： NOMA grant-free random access maritime-communication bipartite graphs density evolution

Static CSI Extraction and Application in the Tomographic Channel Model

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China Communications 2019年第12期16卷 132-144页

作者： Haihan Li Yunzhou Li Shidong zhou Jing Wang Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

In this paper, the statistical properties of parameters of each path in wireless channel models are analyzed to prove that there is the static part in channel state information(CSI) which can be extracted from huge amounts of CSI data. Based on the analysis, the concept of the Tomographic Channel Model(TCM) is presented. With cluster algorithms, the static CSI database can be built in an off-line manner. The static CSI database can provide prior information to help pilot design to reduce overhead and improve accuracy in channel estimation. A new CSI prediction method and a new channel estimation method between different frequency bands are introduced based on the static CSI database. Using measurement data, the performance of the new channel prediction method is compared with that of the Auto Regression(AR) predictor. The results indicate that the prediction range of the new method is better than that of the AR method and the new method can predict with fewer pilot symbols. Using measurement data, the new channel estimation method between different frequency bands can estimate the CSI of one frequency band based on known CSI of another frequency band without any feedback.

关键词： big data tomographic channel model channel prediction channel estimation channel feedback K-means clustering

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

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