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Length minimization of uniform linear antenna array for millimeter wave communications with maximum capacity

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The Journal of China Universities of Posts and Telecommunications 2017年第2期24卷 96-102页

作者： Chen Ruirui zhang hailin State Key Laboratory of Integrated Service Networks Xidian University

For uniform linear antenna array （ULA） based millimeter wave communications, the maximum capacity can be achieved by the optimal antenna separation product （ASP）. However, due to the practical size limitation, it is necessary to decrease the ULA length. In this paper, an optimization problem is formulated to minimize the ULA length for millimeter wave communications with maximum capacity. We decompose the problem into two subproblems： length selection optimization and orientation deployment optimization. The optimal length selection can be obtained when the transmit and receive ULAs have equal length. By using the property of trigonometric function, we derive the optimal orientation deployment and study the influence of orientation deviation on ULA length. Simulation results are presented to validate the analyses.

关键词： millimeter wave length minimization uniform linear antenna array antenna separation product

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

Joint Power Allocation and Mode Selection for D2D Communications with Imperfect CSI

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China Communications 2015年第7期12卷 73-81页

作者： MA Bei zhang hailin zhang Zhaowei Broadband Wireless Communications Laboratory Information Science InstituteState Key Laboratory of Integrated Service NetworksXidian University

Device-to-device(D2D) communications can be underlaid with a cellular infrastructure to increase resource utilization, improve user throughput and save battery energy. In such networks, power allocation and mode selection are crucial problems. To address the joint optimization of power and mode selection under imperfect CSI, we propose an optimal, energy-aware joint power allocation and mode selection(JPAMS) scheme. First, we derive the closed-form solution for the power minimization for both D2 D and cellular links while satisfying different quality of service(Qo S) constraints. Second, we address the mode selection problem in presence of imperfect CSI, based on the derived power allocation. Moreover, the theoretical analysis and simulation results are presented to evaluate the proposed scheme for the D2 D communications.

关键词： power allocation mode selection D2D communications imperfect CSI energy-aware

Soft-output stack algorithm with lattice-reduction for MIMO detection

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Journal of Systems Engineering and Electronics 2010年第2期21卷 197-203页

作者： Yuan Yang hailin zhang Junfeng Hue Datang Linktech Infosystem Co Ltd Beijing 100083 E R. China State Key Laboratory of ISN Xidian University Xi'an 710071 R R. China

A computationally efficient soft-output detector with lattice-reduction （LR） for the multiple-input multiple-output （MIMO） systems is proposed. In the proposed scheme, the sorted QR de- composition is applied on the lattice-reduced equivalent channel to obtain the tree structure. With the aid of the boundary control, the stack algorithm searches a small part of the whole search tree to generate a handful of candidate lists in the reduced lattice. The proposed soft-output algorithm achieves near-optimal perfor- mance in a coded MIMO system and the associated computational complexity is substantially lower than that of previously proposed methods.

关键词： multiple-input multiple-output (MIMO) soft-output de- tection lattice-reduction stack algorithm.

Caching and D2D Assisted Wireless Emergency Communications Networks with Statistical QoS Provisioning

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Journal of Communications and Information Networks 2020年第3期5卷 282-293页

作者： Jianyu Wang Wenchi Cheng hailin zhang State Key Laboratory of Integrated Services Networks Xidian UniversityXi’an 710071China

Along with natural disasters,the destruction of communication infrastructures leads to the congestion or failure of communication *** aerial vehicles(UAVs),which are with a high flexibility,can be employed as temporary base stations to establish emergency *** relieve the backhaul burden of UAVs,some imperative contents can be cached by terrestrial cache-enabled rescuers(CERs)and provide for victims with device-to-device(D2D)*** support the effectiveness and timeliness of emergency communication,the delay-bounded quality-of-service(QoS)requirement and network throughput are desired to be comprehensively considered,which imposes a new challenge for caching placement and CER *** this paper,we focus on joint caching placement and CER deployment to maximize the effective capacity subject to delay-bounded QoS *** overall non-convex problem is transformed into the caching placement and the CER deployment ***,we develop the QoS-aware caching placement scheme with fixed CER deployment density and obtain the QoS-aware CER deployment density with fixed caching *** on the block-coordinate descent method,we also propose the joint caching placement and CER deployment scheme,which can not only effectively enhance average effective capacity but also guarantee the delay-bounded QoS ***,numerical simulations are conducted to show the performances of the proposed schemes.

关键词： unmanned aerial vehicles(UAVs) device-todevice(D2D) emergency wireless networks quality-ofservice(QoS) caching placement effective capacity

A semantic-centered cloud control framework for autonomous unmanned system

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Journal of Systems Engineering and Electronics 2022年第4期33卷 771-784页

作者： PANG Weijian LI Hui MA Xinyi zhang hailin Academy of Military Sciences Beijing 100091China Beijing Aeronautical Engineering Technology Research Center Beijing 100076China Air Forces Command College Beijing 100097China

Rich semantic information in natural language increases team efficiency in human collaboration, reduces dependence on high precision data information, and improves adaptability to dynamic environment. We propose a semantic centered cloud control framework for cooperative multi-unmanned ground vehicle(UGV) system. Firstly, semantic modeling of task and environment is implemented by ontology to build a unified conceptual architecture, and secondly, a scene semantic information extraction method combining deep learning and semantic web rule language(SWRL) rules is used to realize the scene understanding and task-level cloud task cooperation. Finally, simulation results show that the framework is a feasible way to enable autonomous unmanned systems to conduct cooperative tasks.

关键词： scene understanding cloud control ontology autonomous cooperation

Fractal Uniform Circular Arrays Based Multi-Orbital-Angular-Momentum-Mode Multiplexing Vortex Radio MIMO

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China Communications 2018年第9期15卷 118-135页

作者： Linjun Zhao hailin zhang Wenchi Cheng State Key Laboratory of Integrated Services Networks (ISN) and School of Telecommunications EngineeringXidian University Xi'an 710071 China School of Electrical Engineering Shaanxi University of Technology Hanzhong 723000 China

A radio wave driven by Orbital angular momentum(OAM) is called a vortex radio and has a helical wavefront. The differential helical wavefronts of several vortex radios are closely related to their topological charges or mode numbers. In physics, two or more radio waves with different mode numbers are orthogonal to their azimuth angles. With the development of radio communication technologies, some researchers have been exploring the OAM-based multi-mode multiplexing(multi-OAM-mode multiplexing) technologies in order to enhance the channel spectrum efficiency(SE) of a radio communication system by using the orthogonal properties of vortex radios. After reviewing the reported researches of OAM-based radio communication, we find that some breakthroughs have been made in the combination of OAM and traditional Multi-Input-Multi-Output(MIMO). However, the existing technology is not sufficient to support OAM-based MIMO system to achieve maximum the channel SE. To maximize the spectrum efficiency of OAM-based MIMO system, we present a reused multi-OAM-mode multiplexing vortex radio(RMMVR) MIMO system, which is based on fractal uniform cir-cular arrays(UCAs). The scheme described in this study can effectively combine multiOAM-mode multiplexing with MIMO spatial multiplexing. First, we present the generation of RMMVR MIMO signals. Second, under line-of-sight(LOS) propagation conditions, we derive the channels of the RMMVR MIMO system. Third, we separate the RMMVR MIMO signals using an orthogonal separation method based on full azimuth sampling. Finally, we introduce the method for calculating the channel capacity of the RMMVR MIMO system. Theoretical analysis shows that the scheme proposed in this study is feasible. Moreover, the simulation results show that spatial and mode diversity are obtained by exploiting fractal UCAs. However, to enhance the channel SE of RMMVR MIMO system, an interference cancellation method needs to be introduced for zero-mode vortex radios, and some

关键词： vortex radio reused multi-OAM-mode multiplexed vortex radio (RMMVR) MIMO fractal uniform circular arrays(UCAs) signal orthogonal separation.

APO-Based Parallel Algorithm of Channel Allocation for Cognitive Networks

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China Communications 2016年第6期13卷 100-109页

作者： Ming Zhong hailin zhang Bei Ma State Key Laboratory of Integrated Service Networks Xidian University

This article investigates channel allocation for cognitive networks, which is difficult to obtain the optimal allocation distribution. We first study interferences between nodes in cognitive networks and establish the channel allocation model with interference constraints. Then we focus on the use of evolutionary algorithms to solve the optimal allocation distribution. We further consider that the search time can be reduced by means of parallel computing, and then a parallel algorithm based APO is proposed. In contrast with the existing algorithms, we decompose the allocation vector into a number of sub-vectors and search for optimal allocation distribution of sub-vector in parallel. In order to speed up converged rate and improve converged value, some typical operations of evolutionary algorithms are modified by two novel operators. Finally, simulation results show that the proposed algorithm drastically outperform other optimal solutions in term of the network utilization.

关键词： CRNs channel allocation parallel computing APO PSO

Joint channel selection and power control for video streaming over D2D communications based cognitive radio networks

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The Journal of China Universities of Posts and Telecommunications 2018年第1期25卷 1-14页

作者： Gao Ya zhang hailin Lu Xiaofeng State Key Laboratory of Integrated Services Networks Xidian University College of Physics and Electronic Information Luoyang Normal University

A joint channel selection and power control scheme is developed for video streaming in device-to-device （D2D） communications based cognitive radio networks. In particular, physical queue and virtual queue models by applying ＇M/G/1 queue＇ and ＇M/G/1 queue with vacations＇ theories are built up, respectively, to evaluate the delays experienced by various video traffics. Such delays play a vital role in calculating the packet loss rate for video streaming, which reflects the video distortion. Based on the distortion model, a video distortion minimization problem is formulated, subject to the rate constraint, maximum power constraint, primary users＇ tolerant interference constraint, and secondary users＇ minimum data rate requirement constraint. The optimization problem turns out to be a mixed integer nonlinear programming （MINLP） , which is generally nondeterministic in polynomial time. A Lagrangian dual method is thus employed to reformulate the video distortion minimization problem, based on which the sub-gradient algorithm is used to determine a relaxed solution. Thereafter, applying the iterative user removal yields the optimal joint channel selection and power control solution to the original MINLP problem. Extensive simulations validate our proposed scheme and demonstrate that it significantly increases the peak signal- to-noise ratio （PSNR） compared with the existing schemes.

关键词： channel selection power control cognitive radio networks D2D communications video streaming convex optimization