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When the gain of predictive resource allocation for content delivery is large?

Science China(information Sciences) 2023年第12期66卷 179-193页

作者： Chenzuo ZHANG Jia GUO Chenyang YANG school of electronic and information engineering Beihang University

By predicting future information such as data rate with sensory wireless data, radio resources can be pre-allocated for content delivery. Such an integrated sensing and communications technique can help improve network performance and user experience. To justify the cost paid for predicting future information,it is important to understand in which scenarios predictive resource allocation yields a large gain over the non-predictive counterpart. In this paper, we strive to identify the key factors that affect the gain of predictive resource allocation by deriving the closed-form expression of the gain. We are concerned with minimizing the transmission time required for content delivery such as file downloading to users with an expected deadline,where the resources of base stations are shared with real-time services. Then, the performance gain is measured by the difference of the average time required by predictive and non-predictive resource allocation.Inspired by the solution of the optimization problem, we resort to the theory of order statistics for deriving the performance gain. We find that the gain depends on the statistics(i.e., mean value and standard deviation)of the user’s average data rates in the prediction window. Then, we separately analyze how the statistics of the bandwidth available for content delivery and user mobility affect the gain. We use simulation with a real dataset of traffic load to validate the analysis and quantify the impact of the key factors. Our results show that predictive resource allocation can reduce the transmission time even for non-moving users. The performance gain is high when the network is busy or the cell radius is large.

关键词： predictive resource allocation performance analysis average data rates residual bandwidth user mobility

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Temporal Modal Analysis of Small Radiators

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Chinese Journal of electronics 2022年第6期31卷 1112-1120页

作者： WU Qi The school of electronic and information engineering Beihang University

Resonance is a common physical phenomenon in real world, and the modal analysis is a useful tool. Within the regime of electromagnetics, characteristic mode theory is established in frequency domain(FD),and it is doubtful that whether we can find similar modes in time domain(TD). In this paper, resonating modes of a vibrating string are briefly reviewed. Special attentions are paid to the time-domain behaviors of the resonating modes, by following which a temporal modal analysis is proposed. Additionally, a narrow plate is selected as an example since it has a similar structure as the vibrating string. Temporal modal behaviors of the plate are presented and discussed. To further demonstrate this concept, a rigorous analysis of a sphere is provided. A frequency-independent condition is discussed and verified for small objects, and it results in a band-limited constraint. In addition, the temporal modal analysis with excitations is presented, and its potential applications are discussed with emphasis on the analyzing and optimizing transient behaviors of antennas. This work expands largely the field of characteristic mode and may find applications for scattering and antennas.

关键词： Characteristic modes Fourier transform Time domain

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Network Element Placement for Space-Air-Ground Integrated Network:A Tutorial

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Chinese Journal of electronics 2022年第6期31卷 1013-1024页

作者： GENG Yuhui CAO Xianbin CUI Huanxi XIAO Zhenyu school of electronic and information engineering Beihang University

With the demand for Internet connectivity in remote areas, the space-air-ground integrated network(SAGIN) was proposed to achieve ubiquitous coverage and enhance service capabilities of extant terrestrial networks. The paradigm of virtual network element placement(NEP) is applied into SAGIN. It can save energy and operating costs by placing specific network elements(NEs) as software instances. In addition, it helps to provide services in end-to-end networks with its ability to allocate and manage resources flexibly. However, NEP faces some challenges in SAGIN. The network topologies can be dynamic, and links such as the satellite-to-ground and air-to-ground ones are prone to fail. These will make NEP management more complicated. Moreover, the static NEP schemes are hard to accommodate the time-varying traffic. In this context, this work explains the NEP problem in SAGIN from three aspects, i.e., the SAGIN radio access network(RAN), the SAGIN core network(CN), and the SAGIN barrier network(BN). First, the physical and networking architectures of SAGIN are introduced. Then the status of the network element placement and corresponding challenges are described from these two aspects. Finally, this paper discusses future research directions and key technical challenges.

关键词： Network element placement Space-airground integrated network (SAGIN) Software defined network (SDN) Network function virtualization (NFV) Network architectures Resource allocation

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A systematic review for smart identifier networking

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Science China(information Sciences) 2022年第12期65卷 36-48页

作者： Hongke ZHANG Bohao FENG Aleteng TIAN school of electronic and information engineering Beijing Jiaotong University

The current Internet has revealed numerous shortcomings due to the limitations in its original design, and is being challenged by the user’s increasingly complicated requirements for efficient data distribution. To this end, a novel network paradigm namely SINET(smart identifier networking) is proposed,aiming to shift the communication pattern of the traditional IP networks from passive best-effort packet delivery to the active on-demand adaptation of network and service resources. In this way, SINET is able to provide agile, differentiated and customizable traffic steering and performance enhancement for customers of different scenarios with various service quality guaranteed. In this paper, we are going to summarize the main design principles and associated key mechanisms of SINET, and briefly introduce its research outcomes in several typical application scenes.

关键词： identifier networking smart collaborative networking smart integration identifier networking smart identifier networking the next-generation networking

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Secure cooperative output regulation for linear parameter-varying systems under DoS attacks: a resilient observer approach

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Science China(information Sciences) 2023年第9期66卷 35-49页

作者： Chengcheng FU Hao ZHANG Chao HUANG Zhuping WANG Huaicheng YAN school of electronic and information engineering Tongji University school of information Science and engineering East China University of Science and Technology

This paper investigates the cooperative output regulation problem of heterogeneous linear parameter-varying multi-agent systems under denial-of-service(DoS) attacks. The matrix and state of the exosystem are taken to be unknown to the followers. Moreover, with the assumption that only a directed spanning tree exists in the communication topology, a resilient observer is proposed to exponentially estimate the global information, which can also be effective under DoS attacks with a certain intensity. Afterward,to avoid using the exact value of the exosystem matrix, a distributed online algorithm is proposed, through which the linear parameter-varying output regulation equation is asymptotically solved. Based on the resilient observer and the solution of the output regulation equation, a distributed regulator is proposed to achieve asymptotic cooperative output regulation for all agents. Some numerical simulations are conducted to verify the effectiveness of the proposed observer, algorithm, and controller.

关键词： cooperative output regulation heterogeneous multi-agent systems DoS attacks linear parameter-varying systems

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A Novel Wideband Wilkinson Pulse Combiner with Enhanced Low Frequency Isolation

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Chinese Journal of electronics 2023年第4期32卷 683-691页

作者： WANG Zitong WU Qi SU Donglin The school of electronic and information engineering Beihang University

In this paper, a novel Wilkinson pulse combiner(WPC) is proposed for the combination of Gaussian pulse signals. The WPC requires a very wide bandwidth, small size and high port isolation. To improve the operating bandwidth, the design adopts the form of eight-section WPC. Eight capacitors are connected in series with the isolating resistors of each section.After capacitive loading, isolation between WPC input ports is significantly improved at low frequency. Consequently, the operating bandwidth of WPC has been increased from 13:1 to 31:1. Compared with the conventional Wilkinson combiner with the same bandwidth, the proposed WPC reduces the size by 40%. In addition, all the ports are well impedance matched and the insertion loss in the operating frequency band is less than 0.5 dB. To verify the feasibility of the design, a prototype was fabricated and measured. Experiment shows that the novel WPC is more advantageous to generate dual-Gaussian pulse signals.

关键词： Capacitive loading Dual-Gaussian pulse signals Isolation Insertion loss Wilkinson pulse combiner

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A Wideband Self-Decoupled Microstrip Patch Antenna Array Using Characteristic Modes of Ground Plane

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Chinese Journal of electronics 2022年第6期31卷 1161-1172页

作者： LAI Qixuan PAN Yongmei school of electronic and information engineering South China University of Technology

The reduction of mutual coupling between antenna elements has been a research hotspot in the design of multi-input multi-output(MIMO) systems.In this paper, a review of the existing theory of characteristic mode(TCM) based decoupling methods is introduced, and they are summarized and divided into two categories according to mechanisms. The first category consists of the use of the modal properties of the radiator whereas the second one is based on the ground plane to enhance isolation. Moreover, a wideband self-decoupling method is implemented for the MIMO microstrip patch antenna(MPA) array using the characteristic modes(CMs) of the ground plane. It is found that, by adjusting the dimension of the ground plane, their CMs along with two or three null-field regions, can be excited by the active MPA. When the feeding position of the adjacent passive MPA is arranged in the null-field region, the energy cannot be coupled with the receiving port, thereby achieving a good isolation level. For verification, a prototype of the proposed MIMO MPA array has been fabricated and tested. The results show that a wide usable bandwidth of 24.2% has been achieved.

关键词： Multi-input multi-output array Mutual coupling Theory of characteristic mode Microstrip patch antenna

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Antenna Decoupling Based on Characteristic Modes Cancellation

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Chinese Journal of electronics 2022年第6期31卷 1138-1145页

作者： CHU Qingxin ZENG Wenfeng school of electronic and information engineering South China University of Technology

The demand for a high transmission data rate in 5G leads to the wide application of the multi-input, multi-output(MIMO) technique. However, the narrow design space in mobile phone causes severe unexpected coupling between antenna units and deteriorate the system performance dramatically. In this paper, we focus on the antenna coupling within the MIMO system. Some decoupling techniques are summarized, such as neutralization line, decoupling network, common/differential mode cancellation, etc. Finally, new decoupling research developments of modal currents cancellation based on the theory of characteristic mode are elaborated. Two design examples are shown to validate the benefit of the proposed decoupling method. The-6 dB impedance bandwidth of the head-to-head antenna pair can cover 3.4–3.6 GHz.The isolation level is improved from more than 3.7 dB to more than 13 dB. The tail-to-tail antenna pair can cover 3.3–5 GHz and the isolation level is improved from more than 5 dB to more than 10 dB in the whole operating bandwidth. Both antenna pairs can achieve an envelop correlation coefficient of less than 0.2 and the antenna efficiencies are more than 40%.

关键词： Antenna decoupling Characteristic mode Mobile phone antenna MIMO antenna

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On the local delay and energy efficiency under decoupled uplink and downlink in HetNets

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Science China(information Sciences) 2022年第3期65卷 225-234页

作者： Tianjie HUANG Fu-Chun ZHENG Lifeng LAI school of electronic and information engineering Harbin Institute of Technology (Shenzhen)

With the proliferation of the Internet of Things, uplink transmission performance has become more and more important. Moreover, with the traditional coupled uplink(UL)/downlink(DL) access(CUDA) mode, it is becoming hard to improve the system performance of UL in ultra dense heterogeneous networks(UDN, or Het Nets). In this paper, we have conducted a UL performance comparison study for the decoupled UL/DL access(DUDA) mode over the CUDA mode in UDN. The key performance indicators of local delay and energy efficiency(EE) were investigated with respect to SIR threshold, ratio of small cell base station(SBS) and macro cell base station(MBS) densities, and fractional power control(FPC) factor.Numerical and simulation results confirm that the local delay is lower and the EE is higher under DUDA than under CUDA, and as such the DUDA mode is superior to the CUDA mode for the UL performance of UDN.

关键词： coupled and decoupled UL/DL access HetNets stochastic geometry local delay energy efficiency UDN

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Accurate and efficient planar near-field measurements: a new perspective from electromagnetic information theory

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Science China(information Sciences) 2023年第10期66卷 321-322页

作者： Junhao ZHENG Xiaoming CHEN Zhengpeng WANG Jianxing LI Juan CHEN Wei E.I.SHA Lixin GUO school of information and Communications engineering Xi'an Jiaotong University school of electronic information engineering Beihang University College of information Science and electronic engineering Zhejiang University school of Physics Xidian University

Near-field measurement can obtain the far-field radiation pattern of the antenna under test(AUT) by performing near-field-to-far-field transformation(NFT) [1]. Generally,the minimum bounding for AUTs with different fo... 详细信息

关键词： information theory

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