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Towards win-win: weighted-Voronoi-diagram based channel quantization for security enhancement in downlink cloud-ran with limited cSI feedback

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Science china(Information Sciences) 2017年第4期60卷 32-48页

作者： Dongyang XU Pinyi REN Qinghe DU Li SUN Yichen WANG School of Electronic and Information Engineering Xi'an Jiaotong University

Physical layer(PHY) security is recently proved to enable improving the security of wireless communication networks. In downlink frequency division duplex(FDD) cloud radio access network(c-ran), the performance of PHY security highly relies on the channel state information(cSI) which is usually acquired through the codebook-quantization-based technique at the transceiver. However, the conventional quantization method aggravates the leakage of privacy information in c-ran under the eavesdropping environment. In this paper, a novel channel quantization method is investigated to improve the secrecy-rate performance of c-ran by exploiting the high-dimension space geometry. Based on this method, it is proved that when the statistical distribution of the channel matrices of both the legitimate user and the eavesdropper is exploited, a win-win situation can be created where secrecy-rate gains are improved without sacrificing beamforming gains from the point of view of ergodic rate. Particularly, a secrecy-oriented criterion is devised to implement the proposed method for generating codebooks. Then a weighted Voronoi diagram(WVD) is formulated on the complex Grassmann manifold and finally, a vector quantization based algorithm is proposed to build up novel quantization codebooks iteratively. Simulation results further validate the superiority of our proposed codebooks over conventional codebooks in c-ran systems.

关键词： c-ran virtualization physical layer security Grassmann manifold channel quantization

Storage and computing resource enabled joint virtual resource allocation with Qo S guarantee in mobile networks

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Science china(Information Sciences) 2017年第4期60卷 49-59页

作者： Xiaodong XU Jiaxiang LIU Wenwan cHEN Yanzhao HOU Xiaofeng TAO National Engineering Laboratory for Mobile Network Technologies Beijing University of Posts and Telecommunications

Virtualization is the trend for the future mobile networks. With the advantage of virtualization,we can abstract the physical mobile network into the virtual network function(VNF) and design the network without the details. In this paper, we focus on the virtualization of the physical resources so that the resource allocation scheme considers not only the time-varying characteristic of wireless channels but also the amount of storage and computing resources. Virtual resources are composed of radio, storage and computing resources based on the virtualization technology. Since the cloud radio access network(c-ran) is a successful paradigm to introduce computing resources into mobile networks, we investigate the virtual resource allocation scheme in the c-ran architecture. With the content caching technology, we introduce the storage resources into joint resource allocation scheme further. In order to evaluate the performance of proposed scheme, we choose the effective capacity as the metric to include the influence of service latency. The purpose of the optimization problem is maximizing the system effective capacity with constraints of radio, storage and computing resources.It is simplified and converted into a convex problem solved by the subgradient method. Simulation results are provided to demonstrate performance gain of the effective capacity based joint resource allocation scheme.

关键词： virtualization resource allocation cache computing resource effective capacity c-ran

Green circuit Design for Battery-Free Sensors in cloud Radio Access Network

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china communications 2015年第11期12卷 1-11页

作者： ZENG Tengchan MA Zhen WANG Gongpu ZHONG Zhangdui School of Electronic and Information Engineering Beijing Jiaotong University School of computer and Information Technology Beijing Jiaotong University

cloud radio access network(c-ran)is considered as a promising approach to solve the bandwidth crunch problem for future wireless network. Another important element for future network is sensors that can monitor physical or environmental conditions. currently,most sensors need batteries for power,which is energy-consuming and maintenance-heavy. To further improve energy effi ciency(EE) of sensors in c-ran,this paper proposes a new structure as well as practical circuit design for green sensors in c-ran. The structure can enable sensors to harvest energy from radio signals transmitted by neighbor remote radio heads(RRHs) and user terminals(UTs). To demonstrate the validity of the new structure,a practical circuit design is suggested and the corresponding hardware platform is realized. Specifically,selection criteria for electrical component parameters and design of an impedance-matching network are discussed in details. In addition,two methods to stabilize the output voltage are proposed and analyzed. Finally,simulation results as well as experimental results are provided to corroborate our proposed studies.

关键词： energy harvesting c-ran battery-free sensor efficiency

Delay-aware downlink beamforming with discrete rate adaptation for green cloud radio access network

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The Journal of china Universities of Posts and Telecommunications 2017年第1期24卷 26-34页

作者： Yu Zhi Wang Ke Ji Hong School of Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

With the popularity of variety delay-sensitive services, how to guarantee the delay requirements for mobile users （MUs） is a great challenge for downlink beamformer design in green cloud radio access networks （c-rans）. In this paper, we consider the problem of the delay-aware downlink beamforming with discrete rate adaptation to minimize the power consumption of c-rans. We address the problem via a mixed integer nonlinear program （MINLP）, and then reformulate the MINLP problem as a mixed integer second-order cone program （MI-SOcP）, which is a convex program when the integer variables are relaxed as continuous ones. Based on this formulation, a deflation algorithm, whose computational complexity is polynomial, is proposed to derive the suboptimal solution. The simulation results are presented to validate the effectiveness of our proposed algorithm.

关键词： c-ran delay-aware downlink beamfoming discrete rate adaptation green communication mixed integer second-order cone programming

Joint Resource Allocation and coordinated computation Offloading for Fog Radio Access Networks

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china communications 2016年第S2期13卷 131-139页

作者： Kai Liang Liqiang Zhao Xiaohui Zhao Yong Wang Shumao Ou State Key Laboratory of Integrated Service Networks Xidian University Department of computing and communication Technologies Oxford Brookes University

The cloud radio access network(c-ran) and the fog computing have been recently proposed to tackle the dramatically increasing traffic demands and to provide better quality of service(QoS) to user equipment(UE).considering the better computation capability of the cloud ran(10 times larger than that of the fog ran) and the lower transmission delay of the fog computing,we propose a joint resource allocation and coordinated computation offloading algorithm for the fog ran(F-ran),which takes the advantage of c-ran and fog computing.Specifically,the F-ran splits a computation task into the fog computing part and the cloud computing part.Based on the constraints of maximum transmission delay tolerance,fronthaul and backhaul capacity limits,we minimize the energy cost and obtain optimal computational resource allocation for multiple UE,transmission power allocation of each UE and the event splitting factor.Numerical results have been proposed with the comparison of existing methods.

关键词： fog ran c-ran computation offloading resource allocation

cLB:a multilevel co-operative load balancing algorithm for c-ran architecture

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Digital communications and Networks 2019年第4期5卷 308-316页

作者： B.Mahapatra R.Kumar A.K.Turuka S.K.Patra department of computer sciences&engineering national institute of technology rourkelarourkela769008india department of electronics and communication engineering national institute of technology rourkelarourkela769008india

The Fifth-Generation(5G)cellular and wireless communication envisage to integrate multiple technologies to provide a wide range of applications.The rapid growth of Information and communication Technology(IcT)needs a common cellular platform to increase the network’s extensibility and adaptability.The cloud Radio Access Network(c-ran)offers a scalable and flexible Base Station(BS)architecture for the next-generation wireless and mobile networks,where the BS functionality is split into a distributed radio unit known as Remote Radio Head(RRH)and a centralized BaseBand Unit(c-BBU).To further make the c-BBU scalable and flexible,the baseband signal processing is carried out over a virtualized platform.The load at the RRH and c-BBU can vary from under-loaded to overloaded conditions which increase the power consumption and degrade the Quality-of-Service(QoS)of the c-ran.In this paper,we formulate under-loaded and overloaded conditions at the RRH and the c-BBU,and propose a co-operative Load Balancing(cLB)algorithm for handling the cellular traffic in real-time under different load conditions.The proposed cLB aims to maximize the utilization of hardware resources at the RRH and c-BBU.The cLB algorithm is compared with cDI,cZ,NDLB,DLB in the first phase for the RF load balancing.In the second phase of simulation,cLB is compared with the FcFS,IWRR,OLB,GP and TLB algorithms for server(c-BBU)load balancing.The parameters considered for comparison are:User Entity(UE)waiting time,blocking probability and processing time at the RRH and the c-BBU.Simulation results show that the use of co-operative load balancing technique improves the QoS in the c-ran by reducing the blocking probability and UE waiting time.The cLB algorithm is validated with LTE TU-Vienna and cloudSim simulators for the RRH and the c-BBU,respectively.

关键词： c-ran c-BBU cLB RRH Load balancing

Adaptive cell Zooming Strategy Toward Next-Generation cellular Networks with Joint Transmission

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computers, Materials & continua 2021年第10期69卷 81-98页

作者： Abu Jahid Mohammed H.Alsharif Raju Kannadasan Mahmoud A.Albreem Peerapong Uthansakul Jamel Nebhen Ayman A.Aly Department of Electrical and computer Engineering University of OttawaOttawaK1N 6N5ONCanada Department of Electrical Engineering College of Electronics and Information EngineeringSejong UniversitySeoul05006Korea Department of Electrical and Electronics Engineering Sri Venkateswara College of EngineeringSriperumbudur602117India Department of Electronics and communications Engineering A’Sharqiyah UniversityIbra400Oman School of Telecommunication Engineering Suranaree University of TechnologyNakhon RatchasimaThailand Prince Sattam Bin Abdulaziz University College of Computer Engineering and SciencesAlkharj11942Saudi Arabia Department of Mechanical Engineering College of EngineeringTaif UniversityTaif21944Saudi Arabia

The Internet subscribers are expected to increase up to 69.7%(6 billion)from 45.3%and 25 billion Internet-of-things connections by 2025.Thus,the ubiquitous availability of data-hungry smart multimedia devices urges research attention to reduce the energy consumption in the fifthgeneration cloud radio access network to meet the future traffic demand of high data rates.We propose a new cell zooming paradigm based on joint transmission(JT)coordinated multipoint to optimize user connection by controlling the cell coverage in the downlink communications with a hybrid power supply.The endeavoring cell zooming technique adjusts the coverage area in a given cluster based on five different JT schemes,which will help in reducing the overall power consumption with minimum inter-cell interference.We provide heuristic solutions to assess wireless network performances in terms of aggregate throughput,energy efficiency index(EEI),and energy consumption gain under a different scale of network settings.The suggested algorithm allows efficient allocation of resource block and increases energy and spectral efficiency over the conventional location-centric cell zooming mechanism.Extensive system-level simulations show that the proposed framework reduces energy consumption yielding up to 17.5%and increases EEI by 14%.Subsequently,a thorough comparison among different JT-based load shifting schemes is pledged for further validation of varying system bandwidths.

关键词： Wireless networks green communications c-ran coordinated multipoint energy efficiency

Physical layer security strategies for downlink heterogeneous cloud radio access networks

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The Journal of china Universities of Posts and Telecommunications 2014年第5期21卷 47-54,60页

作者： YAN Shi WANG Wen-bo Key Laboratory of Universal Wireless communication Beijing University of Posts and Telecommunications

cloud radio access networks （c-rans） were proposed as promising solutions to increase both spectrum and energy efficiency performance in next generation wireless communication systems. Much works discussed the concrete implementation technology to justify the huge development potential of c-ran. However, only a few litterateurs focused on characterizing the physical layer security in the downlink. The authors studied the physical layer security in downlink heterogeneous c-ran systems in the article. To characterize the random deployment of remote radio units （RRUs） with single antenna configuration, the stochastic geometry is based to evaluate the proposals＇ secrecy transmission capacity performances, where the closed-form expressions are derived. Furthermore, two security strategies based on eavesdropper neutralization region to protect the target RRU user against eavesdropping were presented and analyzed. Simulation illustrates the secrecy transmission capacity performance limits on different system parameters. The presented security strategies show a significant enhancement on the secrecy performance.

关键词： c-ran Poisson point process （PPP） physical layer security heterogeneous

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基于随机几何的云无线接入网络分簇性能分析

基于随机几何的云无线接入网络分簇性能分析

作者：邵一迪内蒙古大学

学位级别：硕士

随着笔记本电脑、智能手机和智能可穿戴设备的普及,无线数据流量出现了前所未有的爆炸式增长。以集中处理、协作式无线电和实时云架构为特点的云无线接入网络（cloud Radio Access Network,c-ran）已经成为第五代移动通信网络（5th Gene... 详细信息

随着笔记本电脑、智能手机和智能可穿戴设备的普及,无线数据流量出现了前所未有的爆炸式增长。以集中处理、协作式无线电和实时云架构为特点的云无线接入网络（cloud Radio Access Network,c-ran）已经成为第五代移动通信网络（5th Generation Mobile Networks,5G）中最有前途的网络架构之一。本文基于随机几何理论,在复合信道衰落条件下,对c-ran场景中不同分簇方案的网络建模与性能分析展开研究。针对以网络为中心分簇的无线通信网络,本文提出了一种复合信道条件下的理论分析方法,重点以中断概率作为性能指标研究无线信道传播特性对网络性能和协作簇大小的影响。首先,分别用二项点过程（Binomial Point Process,BPP）和齐次泊松点过程（Homogeneous Poisson Point Process,HPPP）对协作簇中远端射频头（Remote Radio Head,RRH）和用户的位置进行建模,并将无线信道建模为同时经历路径损耗、瑞利衰落和阴影衰落的复合信道。其次,通过Gauss-Hermite积分给出了用户接收信号功率的拉普拉斯变换的闭合表达式,并在此基础上推导了用户分别与单个RRH关联以及与多个RRH关联时中断概率的表达式。最后,通过仿真验证了理论推导的准确性,并分析了在以上两种关联方式下,网络参数、信道参数以及用户位置对中断概率的影响。由于对以网络为中心分簇方案的分析方法并不适用于以用户为中心分簇方案,因此本文进一步研究了基于随机几何的以用户为中心的分簇问题,提出了一种复合信道条件下的理论分析方法。首先,采用齐次泊松点过程和第II类Matérn硬核点过程（Matérn Hard-core Point Process of type II,MHcPP）分别对网络中RRH和使用相同资源块的用户的位置进行建模。其次,通过点过程近似的方法将较难分析的MHcPP近似为易于分析的HPPP。基于近似后的模型,推导了网络中节点位置的距离分布函数,并在此基础上给出了以用户为中心分簇方案下中断概率的表达式。最后,通过仿真证明了点过程近似的有效性以及理论推导的准确性,同时分析了网络参数、信道参数以及空小区对网络性能的影响。

关键词： c-ran 以网络为中心分簇以用户为中心分簇随机几何中断概率