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Joint Optimization of Resource Allocation and Trajectory Based on User Trajectory for UAV-Assisted Backscatter Communication System

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China communications 2024年第2期21卷 197-209页

作者： Peizhong Xie Junjie Jiang Ting Li Yin Lu School of Communication and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing 210003China key lab.of Broadband wireless Communication and Sensor Network Technology(Nanjing University of Posts and Telecommunications) Ministry of EducationNanjing 210003China

The Backscatter communication has gained widespread attention from academia and industry in recent years. In this paper, A method of resource allocation and trajectory optimization is proposed for UAV-assisted backscatter communication based on user trajectory. This paper will establish an optimization problem of jointly optimizing the UAV trajectories, UAV transmission power and BD scheduling based on the large-scale channel state signals estimated in advance of the known user trajectories, taking into account the constraints of BD data and working energy consumption, to maximize the energy efficiency of the system. The problem is a non-convex optimization problem in fractional form, and there is nonlinear coupling between optimization *** iterative algorithm is proposed based on Dinkelbach algorithm, block coordinate descent method and continuous convex optimization technology. First, the objective function is converted into a non-fractional programming problem based on Dinkelbach method,and then the block coordinate descent method is used to decompose the original complex problem into three independent sub-problems. Finally, the successive convex approximation method is used to solve the trajectory optimization sub-problem. The simulation results show that the proposed scheme and algorithm have obvious energy efficiency gains compared with the comparison scheme.

关键词： energy efficiency joint optimization UAV-assisted backscatter communication user trajectory

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Hybrid Precoder and Combiner Design with Finite Resolution PSs for mmWave MIMO Systems

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China communications 2019年第2期16卷 95-104页

作者： Ran Zhang Weixia Zou Ye Wang Mingyang Cui key lab.of universal wireless communications MOEBeijing University of Posts and Telecommunications State key lab.of Millimeter Waves Southeast University

Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.

关键词： millimeter wave multiple-input multiple-output finite resolution phase shifters hybrid precoding alternate optimization

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On Multi-Frequency Channel Interference Alignment of 3 Channels and 4 Users

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China communications 2016年第1期13卷 22-32页

作者： DU Guanglong ZOU Weixia ZHOU Zheng key lab.of universal wireless communications MOEBeijing University of Posts and Telecommunications State key lab.of Millimeter Waves Southeast University

This paper explores the multi-frequency independent channel interference alignment(MFC-IA) system of 3 channels and4 users,and single data stream transmit,i.e.(3×3,1)~4 *** derive the analytic solution for(3×3,1)~4 MFC-IA *** on the analytic solution,an optimization problem is proposed aim at the optimal IA *** based on such a math model,we propose a simulated annealing(SA) algorithm to search optimal IA *** simulation results show that the simulated annealing IA algorithm has a better sum rate performance than iterative maximize signal to interference plus noise ratio(Max-SINR) *** result can be extended to single data stream multi-antenna IA system with 3 antennas and4 users.

关键词： communication and information system interference alignment multi-frequency channel analytic solution simulated annealing

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Low Complexity Joint Hybrid Precoding for Millimeter Wave MIMO Systems

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China communications 2019年第2期16卷 49-58页

作者： Mingyang Cui Weixia Zou key lab.of universal wireless communications MOEBeijing University of Posts and Telecommunications State key lab.of Millimeter Waves Southeast University

In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, we propose a joint hybrid precoding algorithm for single-user mmWave MIMO systems in this paper. By using the concept of equivalent channel, the proposed algorithm skillfully utilizes the idea of alternating optimization to complete the design of RF precoder and combiner. Then, the baseband precoder and combiner are computed by calculating the singular value decomposition of the equivalent channel. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance with quite low complexity. Moreover, we investigate the effects of quantization on the analog components and find that the proposed scheme is effective even with coarse quantization.

关键词： millimeter wave MIMO 5G joint hybrid precoding low complexity

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Estimation of synchronization impairments in multi-relay DF cooperative networks

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The Journal of China Universities of Posts and Telecommunications 2013年第6期20卷 18-23页

作者： LIU Meng-meng ZHANG Jian-hua SHEN Chao ZHANG Ping key lab.of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications

Cooperative communication systems can effectively increase channel capacity and combat fading. Effective cooperation requires synchronization impairments such as multiple timing offsets and multiple carrier frequency offsets to be accurately estimated and mitigated. This paper seeks to address the joint estimation of synchronization impairments in multi-relay decode-and-forward （DF） cooperative networks. Firstly, a simple yet effective estimation method based on the devised training signals is presented for achieving synchronization. Then, an iterative algorithm is further derived in order to improve the performance associated with the estimation of synchronization impairments. Our proposed algorithm converts the difficult multiple parameter estimation problem into more tractable sub-problems of estimating many individual impairments pairs for the independent relays. Simulations indicate that, the proposed estimator can asymptotically achieve the mean square error （MSE） for the perfectly timing or frequency synchronized case.

关键词： cooperative communication decode-and-forward synchronization

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A survey on one-bit compressed sensing： theory and applications

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Frontiers of Computer Science 2018年第2期12卷 217-230页

作者： Zhilin LI Wenbo XU Xiaobo ZHANG Jiaru LIN key lab.of universal wireless communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

In the past few decades, with the growing popularity of compressed sensing （CS） in the signal processing field, the quantization step in CS has received significant attention. Current research generally considers multi-bit quantization. For systems employing quantization with a sufficient number of bits, a sparse signal can be reliably recovered using various CS reconstruction algorithms. Recently, many researchers have begun studying the one- bit quantization case for CS. As an extreme case of CS, one- bit CS preserves only the sign information of measurements, which reduces storage costs and hardware complexity. By treating one-bit measurements as sign constraints, it has been shown that sparse signals can be recovered using certain reconstruction algorithms with a high probability. Based on the merits of one-bit CS, it has been widely applied to many fields, such as radar, source location, spectrum sensing, and wireless sensing network. In this paper, the characteristics of one-bit CS and related works are reviewed. First, the framework of one-bit CS is introduced. Next, we summarize existing reconstruction algorithms. Additionally, some extensions and practical applications of one-bit CS are categorized and discussed. Finally, our conclusions and the further research topics are summarized.

关键词： compressed sensing one-bit quantization sign information support consistency

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Efficient caching strategy based on graph coloring for moving users in ultra dense networks

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The Journal of China Universities of Posts and Telecommunications 2019年第3期26卷 1-7页

作者： Hu Chengjia Li Xi Ji Hong Zhang Heli key laboratory of universal wireless communications Beijing University of Posts and Telecommunications

Caching popular files in small-cell base stations(SBSs) is considered as a promising technique to meet the demand of ever growing mobile data traffic in ultra dense networks(UDNs). Considering the limited cache capacity and dense deployment of SBSs, how to support uninterrupted and successful caching downloading for moving users is still a challenging problem. In this paper, a graph-coloring-based caching(GCC) algorithm in UDN for moving user under limited SBS storage capacities is proposed. Firstly, considering there may be downloading interruption or even failure due to the random moving of users and small coverage of SBSs, graph coloring algorithm(GCA) is employed for grouping the SBS to cache fragments of several files. Then, the problem of how to conduct caching placement on SBSs is formulated aiming to maximize the amount of data downloaded from SBSs. Finally, an efficient heuristic solution is proposed to get an optimal result. Simulation results show that the algorithm performs better than other caching strategies in prior work, in terms of reducing both backhaul traffic and user download delay.

关键词： ultra dense network graph coloring caching moving user download delay

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End-to-end energy-efficient resource allocation in device-to-device communication underlaying cellular networks

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The Journal of China Universities of Posts and Telecommunications 2015年第1期22卷 24-30页

作者： Xu Quansheng Ji Hong Li Xi Xiong Danni key laboratory of universal wireless communications Beijing University of Posts and Telecommunications

A proposed resource allocation （RA） scheme is given to device-to-device （D2D） communication underlaying cellular networks from an end-to-end energy-efficient perspective, in which, the end-to-end energy consumptions were taken into account. Furthermore, to match the practical situations and maximize the energy-efficiency （EE）, the resource units （RUs） were used in a complete-shared pattern. Then the energy-efficient RA problem was formulated as a mixed integer and non-convex optimization problem, extremely difficult to be solved. To obtain a desirable solution with a reasonable computation cost, this problem was dealt with two steps. Step 1, the RU allocation policy was obtained via a greedy search method. Step 2, after obtaining the RU allocation, the power allocation strategy was developed through quantum-behaved particle swarm optimization （QPSO）. Finally, simulation was presented to validate the effectiveness of the proposed RA scheme.

关键词： energy-efficiency resource allocation D2D communication mixed integer and non-convex optimization problem

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Optimal transmission mode proportion for heterogeneous networks of cellular and device-to-device communications

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The Journal of China Universities of Posts and Telecommunications 2013年第4期20卷 21-27页

作者： LIU Zi-yang PENG Tao WANG Wen-bo key laboratory of universal wireless communications Beijing University of Posts and Telecommunications

This paper discusses about the optimal mode allocation for the heterogeneous networks, in which the network can schedule users working in the device-to-device （D2D） mode or cellular mode. The D2D user is allowed to reuse the uplink resource of cellular system and the problem is formed as a sum-capacity optimization issue with outage constraints for both cellular and D2D links. The method for the optimal user proration is proved to be divided into three cases according to the total user density： when the total user density is small, the optimal proration trends to all users utilizing one mode; when the total user density is large, the optimal proration is all of users choosing D2D mode; and when the total user density situates in the between, there is a unique optimal transmission mode proportion for the hybrid networks to maximize its sumcapacity. The simulation results demonstrate the validity of the conclusions in the analysis part.

关键词： device-to-device mode proration sum-capacity optimization

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Performance analysis of opportunistic amplify-and-forward two-way relaying in two-wave with diffuse power fading channels

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The Journal of China Universities of Posts and Telecommunications 2015年第2期22卷 7-14页

作者： Zhou Jia Wang Xiaoxiang Qi Yanyan key laboratory of universal wireless communications Beijing University of Posts and Telecommunications

This paper considers cooperative amplify-and-forwards （AF） two-way relay networks （TWRNs） with opportunistic relay selection （ORS） in two-wave with diffuse power （TWDP） fading channels. To investigate the system performance, we first derive an easy-to-computer approximated expression for the exact outage probability to reduce computational cost. Furthermore, we presented compact expressions for the asymptotic outage probability and asymptotic symbol error rate, which characterizes two factors goveming the network performance at high signal-to-noise ratio （SNR） in terms of diversity order and coding gain. Additionally, based on the asymptotic outage probability, we determine the optimal power allocation solution between the relay and the sources to minimize the overall outage probability under the assumption that both the sources have identical transmit power. The correctness of the analysis is validated through Monte Carlo simulations. Our derived results can be applied to general operating scenarios with distinct TWDP fading parameters which encompass Rayleigh and Rician fading as special cases and arbitrary number of relays.

关键词： two-way relay opportunistic relay TWDP TWDP AF

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