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A high power efficiency method using orthogonal signal decomposition in high PAPR system

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Science China(Information Sciences) 2013年第4期56卷 173-179页

作者： REN ZhiYuan LI YongZhao ZHANG HaiLin HAN Kun state Key Laboratory of Integrated services Network Xidian University Xi'an Communication Institute

To solve the low-power-efficiency problem for high peak to average power ratio systems,such as OFDM,an orthogonal inhomogeneous signal decomposition approach is proposed in this *** novel method decomposes the signal into branch signals orthogonally,which can adapt to the change of saturate power of each branch power ***,the novel method has the advantages of both high power efficiency of power amplifier and low PAPR of branch ***,this is more suitable for practical *** simulation results indicate that the proposed method can increase the power efficiency remarkably without reducing the BER performance in the receiver.

关键词： green radio power amplifier orthogonal inhomogeneous signal decomposed power efficiency energy conservation

Cooperative Jamming for Enhancing Security of Cognitive Radio Networks with Multiple Primary Users

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China Communications 2017年第7期14卷 93-107页

作者： Xiaofeng Feng Xinbo Gao Ru Zong state Key Laboratory of Integrated services Networks School of Electronic Engineering Xidian University

In cognitive radio networks(CRNs), through recruiting secondary user(SU) as friendly jammer, the secrecy rate obtained by primary user(PU) can be improved. Previous work only considered a simple scenario with a single PU in their frameworks. In this paper, we will consider a more complicated scenario with multiple PUs and try to investigate the cooperative jamming between multiple PUs and a single SU. When there are multiple PUs in CRN, in order to obtain more spectrum for data transmission, SU will cooperate with multiple PUs at the same time. Considering that both PU and SU are rational and selfish individuals, the interaction between PUs and SU is formulated as a multi-leaders and single-follower Stackelberg game, wherein PU is the leader and SU is the follower. And the Stackelberg Equilibrium(SE) is considered as the final decisions accepted by all PUs and SU. Furthermore, we also prove that when a specific condition is satisfied, the existence of SE can be guaranteed. And a Gauss-Jacobi iterative algorithm is proposed to compute a SE. Finally, simulation results are given to verify the performance and demonstrate that both of the PUs' secrecy rate and the SU's transmission rate can be improved through cooperation.

关键词： cognitive radio networks cooperative jamming physical layer security spectrum sharing stackelberg game

Joint Resource Allocation for Lifetime-aware Cooperative Multi-carrier DF System

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International Journal of Automation and computing 2014年第1期11卷 87-92页

作者： Chao-Ping Guo Kun Han Xiao-Long Zhang Hai-Lin Zhang state Key Laboratory of Integrated services Network Xidian University Xi'an Communication Institute

In this paper,we study the problem of optimal resource allocation for lifetime maximization in an orthogonal-frequencydivision multiplexing(OFDM)system with decode-and-forward *** goal is to minimize total energy cost of the system by jointly optimizing power allocation,subcarrier pairing and relay *** present a heuristic solution that is composed of two *** first part is an optimal power allocation approach to allocate power to a subcarrier pair of the source and the *** second part is a modified Hungarian algorithm to make subcarrier pairing and relay *** show that the presented scheme outperforms other schemes in the total transmitted data and the network lifetime.

关键词： Cooperative communications resource allocation decode-and-forward orthogonal-frequency-division multiplexing(OFDM) subcarrier pairing power allocation relay selection

Decode-and-Forward Relay Based Bidirectional Wireless Information and Power Transfer

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China Communications 2017年第8期14卷 176-183页

作者： Ruirui Chen Hailin Zhang state Key Laboratory of Integrated services Networks Xidian UniversityXi'an 710071China

In this paper, we propose the decode-and-forward(DF) based bidirectional wireless information and power transfer(BWIPT) in two-hop relay systems, where the bidirectional relay can decode and forward information from the user to the access point(AP), and assist the wireless power transfer from the AP to the user. To maximize the information rate from the user to the AP, we derive the closed form expression of the optimal power splitting(PS) factor, and the time allocation scheme to obtain the optimal time switching(TS) factor. Simulation results show that for both PS and TS protocols, the proposed DF based bidirectional relay systems can improve the information rate as compared with the amplify-and-forward(AF) based bidirectional relay systems.

关键词： decode-and-forward wireless power transfer bidirectional relay power splitting time switching

OAM-Based Hybrid-Duplex Cognitive Frequency Hopping

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Journal of Communications and Information Networks 2020年第4期5卷 381-392页

作者： Liping Liang Zan Li Wenchi Cheng Hailin Zhang state Key Laboratory of Integrated services Networks Xidian UniversityXi’an 710071China

In cognitive radio networks,the jamming attacks,which have the same ability with secondary users(SUs)but access the licensed channels without considering the carrier sense multiple access protocol,can disguise a primary user(PU)or SU to occupy the licensed channels,thus resulting in failing to access the licensed channels for PUs and *** full/half duplex cognitive frequency hopping(CFH),where users sense the occupancy of licensed channels and then dynamically adjust the hopping parameters,can mitigate the hostile ***,due to the explosive growth of serves and data traffic,it is very difficult to significantly increase the anti-jamming results and achieve high capacities with full/half duplex CFH for both PUs and SUs in cognitive radio *** achieve efficient anti-jamming and high capacities for PUs and SUs,in this paper we propose the orbital angular momentum(OAM)-based hybrid-duplex CFH scheme,which jointly uses the half-duplex cooperative sensing and full-duplex transmission modes for PUs and SUs in cognitive radio *** the OAM-based hybrid-duplex CFH scheme,PUs and SUs can identify the occupancy of licensed channels with half-duplex fashion,thus significantly reducing the probability of signals ***,based on the sensing results,the signals are allowed to be transmitted and received by the same time-slots,carrier frequencies,and *** average capacities of PUs and SUs are derived,*** numerical results show that our proposed OAM-based hybrid-duplex CFH scheme can significantly increase the capacities of PUs and SUs in cognitive radio networks under hostile jamming attacks.

关键词： orbital angular momentum(OAM) hybrid duplex cognitive frequency hopping cognitive radio net-works anti-jamming

RIS-SWIPT for Batteryless Users in Disaster Areas

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Journal of Communications and Information Networks 2022年第4期7卷 433-446页

作者： Hanyun Zhang Wenchi Cheng state Key Laboratory of Integrated services Networks Xidian UniversityXi’an 710071China

For trapped users in disaster areas,the available energy of affected user equipment(UE)is limited due to the breakdown of the ground power *** complex geographical condition prevents ground emergency vehicles from reaching disaster-stricken areas,unmanned aerial vehicle(UAV)can effectively work as a temporary aerial base station for serving terrestrial trapped *** wireless information and power transfer(SWIPT)system is intriguing for distributed batteryless users(BUs)by transferring data and energy ***,how to achieve the maximum energy efficiency(EE)and energy transfer efficiency(ETE)for distributed BUs in UAV-enabled SWIPT systems is not very *** this paper,we develop three novel reconfigurable intelligent surface(RIS)-based SWIPT algorithms to solve this nonconvex joint optimization problem using deep reinforcement learning(RL)*** the deployment of RIS-assisted UAVs,we aim to maximize the EE along with the ETE via jointly designing the UAV trajectory,the phase matrix,and the power splitting ratio within strict time and energy *** obtained numerical results show that our developed RL-based algorithms can effectively improve the cost time,the average charging rate,data rate,and the EE/ETE performance of the RIS-assisted SWIPT systems as compared with benchmark solutions.

关键词： SWIPT UAV RIS multi-agent deep reinforcement learning emergency wireless communication(EWC) EE ETE

A Study of Ensemble Feature Selection and Adversarial Training for Malicious User Detection

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China Communications 2023年第10期20卷 212-229页

作者： Linjie Zhang Xiaoyan Zhu Jianfeng Ma state Key Laboratory of Integrated services Networks Xidian UniversityXi’an 710071China

The continuously booming of information technology has shed light on developing a variety of communication networks,multimedia,social networks and Internet of Things ***,users inevitably suffer from the intrusion of malicious *** studies focus on static characteristics of malicious users,which is easy to be bypassed by camouflaged malicious *** this paper,we present a malicious user detection method based on ensemble feature selection and adversarial ***,the feature selection alleviates the dimension disaster problem and achieves more accurate classification ***,we embed features into the multidimensional space and aggregate it into a feature map to encode the explicit content preference and implicit interaction ***,we use an effective ensemble learning which could avoid over-fitting and has good noise ***,we propose a datadriven neural network detection model with the regularization technique adversarial training to deeply analyze the *** simplifies the parameters,obtaining more robust interaction features and pattern *** demonstrate the effectiveness of our approach with numerical simulation results for malicious user detection,where the robustness issues are notable concerns.

关键词： malicious user detection feature selection ensemble learning adversarial training

Low-complexity SAGE-based MMSE channel estimation for CoMP multi-user systems

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The Journal of China Universities of Posts and Telecommunications 2012年第5期19卷 26-31,38页

作者： LI Xiao-hui WANG Xin HEI Yong-qiang state Key Laboratory of Integrated services Networks Xidian UniversityXi'an 710071China

Coordinated multiple point （CoMP） transmission/reception has been investigated recently as a promising technology to increase the cell-edge user performance of long term evolution-advanced （LTE-A）, and channel estimation is a crucial technology for CoMP systems. In this paper, we consider a reduced-complexity minimum mean square error （MMSE） channel estimator for CoMP systems. The estimator uses space alternating generalized expectation maximization （EM）（SAGE） algorithm to avoid the inverse operation of the joint MMSE estimator. In the proposed scheme, the base stations （BSs） in the CoMP system estimate the channels of all the coordinated users serially and iteratively. We derive the SAGE-based estimators and analyze complexity. Simulation results verify that the performance of the proposed algorithm is close to the joint MMSE estimation algorithm while reducing the complexity greatly.

关键词： CoMP multiple user SAGE MMSE channel estimation

Analysis and Design of Scheduling Schemes for Wireless Networks with Unsaturated Traffic

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China Communications 2021年第2期18卷 65-85页

作者： Jianfei Li Juan Wen Min Sheng state Key Laboratory of Integrated services Networks Xidian UniversityXi’an 710071China

Scheduling schemes assign limited resources to appropriate users,which are critical for wireless network *** current schemes have been designed based on saturated traffic,i.e.,assuming users in networks always have data to ***,the user buffer may sometimes be empty in actual ***,these algorithms will allocate resources to users having no data to transmit,which results in resource *** view of this,we propose new scheduling schemes for onehop and two-hop link scenario with unsaturated ***,this paper analyzes their key network performance indicators,including the average queue length,average throughput,average delay and outage *** two scheduling algorithms avoid scheduling the links whose buffers are empty and thus improve the network resource *** the one-hop link scenario,network provides differentiated services via adjusting the scheduling probabilities of the destination nodes(DNs)with different *** the DNs with same priority,the node with higher data arrival rate has larger scheduling *** the two-hop link scenario,we prioritize the scheduling of relay-to-destination(R-D)link and dynamically adjust the transmission probability of source-to-relay(S-R)link,according to the length of remaining *** experiment results show the effectiveness and advantage of the proposed algorithms.

关键词： markov chain unsaturated traffic performance analysis scheduling